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  • 1
    Electronic Resource
    Electronic Resource
    Ion sources for dry etching: Aspects of reactive ion beam etching for Si technology (invited) (abstract)a) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2367-2367 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Aspects of ion beam sources are treated which emerge from their use for reactive ion beam etching (RIBE) in silicon VLSI technology. As a basis for this treatment, the requirements for dry etching for VLSI are elaborated, as well as the consequences of these requirements for ion beam sources to be used for such technology. Practical experience with two types of ion beam sources for this application are highlighted, a classical Kaufman source and a first-generation ECR source. Aspects relevant for microfabrication related to grid optics, and the use of reactive gases, are discussed. Most important in this context are the internal microdivergence of an ion beam and the fragmentation of molecular gases taking place in the source and the ion beam as well. The consequence for potential application of RIBE for micropatterning must be to characterize sources by measuring their energy- and angle-resolved particle fluxes to the wafer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142931
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  • 2
    Electronic Resource
    Electronic Resource
    Negative ion beam technology for materials science (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2368-2373 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Negative-ion beams can be used in materials science, i.e., ion implantation and ion beam deposition, since various types of high current negative-ion sources have recently been developed. Two types of these the NIABNIS and rf sputter types, were developed by the present authors. There are major differences between negative- and positive-ion implantations with regard to beam transport (collisional cross sections with residual gas particles) and secondary electron emission factors, but little difference in the projected ranges of implanted ions. By using negative ions in ion beam deposition, the effects of the kinetic energy and number of atoms of an ion may be clarified because negative ions have much less reactivity resulting from their internal potential energy of electron affinity than do positive ions resulting from their ionization potential.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142932
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  • 3
    Electronic Resource
    Electronic Resource
    Cluster ion sources (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2374-2379 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Clusters from gases as well as from metal vapors can be obtained from an expanding nozzle flow with the appropriate set of flow field conditions, characterized by a condensation scaling parameter Γ*. Cluster ion beams are characterized by a low specific charge. Accelerated cluster ion beams allow formation of energetic particle beams in the interesting range of 0.01–10 keV/atom, and the specific characteristics of cluster ion beams have led to new applications in science and technology. In this paper a status report on clusters and cluster ions from nozzle sources is given. As example the construction and results of a source for high-intensity silver cluster beams to be used for thin film formation are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142933
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  • 4
    Electronic Resource
    Electronic Resource
    Ion sources for ion beam assisted deposition of thin films and coatings (invited) (abstract) : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2380-2380 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Ion beam assisted deposition (IBAD) is a coating technique which combines a thin-film deposition method such as evaporation with irradiation by highly energetic ions from an ion source. Application of an ion source and a vapor source which are operated independently of each other render the IBAD technique highly controllable, reproducible, and flexible. Ion flux, atom flux, ion energy, ion impact angle, and other parameters can be controlled independently over a wide range. In order to take advantage of the beneficial features of this technique and obtain optimum process conditions, ion sources with special properties are required. In this paper different ion source types and equipment which has been used for IBAD to date are presented and their special features discussed. Ion sources which should be applicable for IBAD are described. Finally, general requirements of IBAD ion sources are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142934
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  • 5
    Electronic Resource
    Electronic Resource
    High efficiency ion sources for on-line mass separators: A brief review (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2381-2386 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A review on low-charge state high-efficiency ion sources used at on-line isotope separators (ISOL) is given. These sources for which the efficiency is optimized, can be distinguished from ion sources used at, e.g., accelerators where essentially the output current is optimized. Recent developments conducted to meet the special requirements necessary for on-line ion sources−high efficiency, selectivity, and short delay times−are presented and new ionization schemes like ECR sources or laser resonant photo ionization, implemented during recent years at ISOL systems, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142935
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  • 6
    Electronic Resource
    Electronic Resource
    The ECR ion source at the TRIUMF isotope separator TISOL : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2387-2389 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The installation at the isotope separator TISOL of a single-staged ECR (electron cyclotron resonance) ion source has been completed. The source can now routinely deliver radioactive species extracted from the production target when bombarded by 500 MeV protons. Among the radioactive species detected so far are isotopes of He, C, N, O, Ne, Cl, Ar, Kr, and Xe in single- and multiple-charge states as well as as molecular species. The yields obtained exceed in many cases those of the isotope separator ISOLDE at CERN. For stable species the source has shown high efficiencies often exceeding 10%. Details of the source construction, the isotope separator TISOL, and the variation of source parameters under operational conditions will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142936
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  • 7
    Electronic Resource
    Electronic Resource
    Surface modification by ion bombardment : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2390-2392 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In recent years the production of thin high-quality films has become more and more important. At the University of Giessen, radiofrequency ion sources for material treatment (RIM) had been designed and optimized. The presented results show some of our analyses of RIM-produced thin films and RIM-modified surfaces. By means of an oscillating quartz crystal, the distribution of sputtered atoms and the properties of the growing thin film were measured. Furthermore, the formation of seed textures on the sputtered surfaces were analyzed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142937
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  • 8
    Electronic Resource
    Electronic Resource
    Ion beam assisted deposition with a duoplasmatron (abstract)a) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2393-2393 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: One of the recent applications of ion sources is their use for ion beam assisted deposition of thin films and coatings. This method combines a coating technique such as evaporation or sputtering with bombardment with ions in the keV energy range. The required ions with defined energy, flux, and impact angle are delivered from an ion source. An apparatus for ion beam assisted evaporation with a duoplasmatron ion source is described. The features of the duoplasmatron with respect to application for ion beam assisted deposition such as beam shape, uniformity and intensity, ion-to-neutral ratio, and focused and defocused mode are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142938
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  • 9
    Electronic Resource
    Electronic Resource
    Ion beam diagnostics by Doppler shifted light emissions (abstract)a) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2393-2393 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Broad low-energy ion beams in the energy range of 0.2 to 1.5 keV originating from a filament source with argon as feed gas have been analyzed by high-resolution emission spectroscopy. The Doppler structure of Ar+ emissions reveals the existence of different velocity classes. Besides slow ions and ions possessing the main beam energy, electronically excited Ar+ ions with twice the main beam energy are detected which are attributed to a single-electron capture process in Ar++/Ar collisions. As a preliminary result from a reactive beam extracted from a microwave CF4 source, plasma fast F atoms are detected which are attributed to charge exchange and dissociative collisions in the process chamber.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142939
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  • 10
    Electronic Resource
    Electronic Resource
    Investigation of a 2.45 GHz ECR plasma for ion etching : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2394-2396 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Reactive ion-stream etching of SiO2 by CF4 ECR plasma has been investigated using different magnetic configurations. Whereas a permanent multipole field yielded the best results concerning the homogeneity over a large area, the highest etching rates were achieved with a longitudinally gradient field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142940
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  • 11
    Electronic Resource
    Electronic Resource
    Bakeable duoplasmatron ion gun for SIMS microanalysis : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2397-2399 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 10-keV duoplasmatron ion gun with ion optical column is presented. The system is fully bakeable; copper gaskets and alumina isolators are used. The source can operate with hot filament or hollow cathode. The differentially pumped ion optical column consists of a set of three lenses, double octupole stigmator, deflection-scanning system, and diaphragm set.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142941
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  • 12
    Electronic Resource
    Electronic Resource
    Performance investigation of a focused ion beam for sputter deposition : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2400-2402 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Recently, focused ion beam sources have been widely used in various film deposition. This paper introduces the performance investigation of a focused ion beam source for sputter deposition. A 3.5-cm-diam ion source was used in the experiments. The results of the tests show that (1) at given ion beam energy there is an optimum value of ion beam current which gives the maximum value of ion beam current density; (2) at higher beam energy the peak of ion beam current density is higher and is obtained at larger beam current; (3) the ion beam current density increases with increasing magnetic flux density but there is an optimum value of magnetic flux density, and (4) the ion beam current density increases with increasing discharge voltage and gas flow rate, decreases with increasing accelerator voltage. Finally, these results are analyzed and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142942
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  • 13
    Electronic Resource
    Electronic Resource
    The formation of coatings from ionized vapor : Proceecings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2406-2407 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The structure and properties of metallic coatings from ionized vapor are investigated. A method of evaporating materials in vacuum by means of a non-self-maintained discharge was developed. The evaporator, consisting of a heated cathode, focusing elements, and anode (the material to be evaporated), generates an atom flux variable from 1016 to 5×1017 cm−2 s−1 and fractional ionization from 2% to 100%. The properties of the non-self-maintained discharge have been investigated over the voltage range from 30 to 700 V and current range from 1 to 50 A. The ionization of the vapor flux and control over the energy provide a deposit of strongly adhering coatings with small crystalline structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142944
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  • 14
    Electronic Resource
    Electronic Resource
    Characteristics of an ECR ion beam source for low-pressure etching : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2403-2405 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have investigated an ECR ion beam source operated with a pair of coils and a two-grid extraction optics. The most important parameter for the source operation at low pressure (p〈10−3 mbar) is the magnetic field in the source. A basic understanding of the physics occurring in this source can be obtained by simply registrating the total ion beam current through the first grid as a function of the magnetic field from the coils. From these characteristics we find that for the wave-propagation through the plasma column the magnet next to the microwave feed (rear magnet) is the important one. The other one (front magnet) controls the electron losses if the plasma generation is mainly located in the rear magnet. For certain magnetic field distributions we find harmonics of the ECR resonance, indicating nonlinear plasma wave interactions occurring in the source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142943
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  • 15
    Electronic Resource
    Electronic Resource
    A field portable scanner for analysis of thin layer chromatography plates based on multiwavelength image processing (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4333-4341 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A field portable, multiwavelength, digital image processing system for the analysis of thin layer chromatography plates is described. The imaging module consists of a two-dimensional charge coupled device detector, a xenon strobe light source, a stepper driven filter wheel for wavelength selection, and hardware to digitize images. The instrument is controlled by a laptop computer resulting in a compact device the size of a 6-in. thick briefcase. As a representative application, software has been developed for the automated analysis of sulfa residues in pork products by thin layer chromatography (USDA SOS-test). Response to analyte concentration is linear over two and one half orders of magnitude with a correlation coefficient of 0.9998. Detection limit is 80 pg for sulfamethazine spotted on a plate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143733
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  • 16
    Electronic Resource
    Electronic Resource
    A high-energy spherical grating monochromator for soft x rays at the Daresbury SRS (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4349-4353 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A vertically dispersing high-energy spherical grating monochromator (HESGM) has been installed on the synchrotron radiation source (SRS) at the Daresbury Laboratory. The instrument has no entrance slit and provides a high intensity source of x rays of energy 250–1400 eV focused into a small spot suitable for surface spectroscopy. Photoabsorption features of 240 meV have been resolved, but the resolution of the instrument is dependent on the SRS stored beam current. The degree of linear polarization has been measured at the carbon K edge to be 0.80.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143735
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  • 17
    Electronic Resource
    Electronic Resource
    Thermal property measurements of liquid samples using photoacoustic detection (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4398-4402 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this paper we describe the use of so-called open-photoacoustic cell (OPC) for thermal characterization of transparent liquid samples. The samples used to demonstrate the usefulness of the OPC configuration are water, glycerol, and diffusion pump oil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143740
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  • 18
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    The Frascati Tokamak Upgrade Thomson scattering system: The optical and spectral analysis equipments (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4403-4409 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An overall view of the Frascati Tokamak Upgrade (F.T.U.) Thomson scattering system is illustrated and particular attention is paid to the optical and spectral analysis equipments. The system includes the laser source, the collection optics, a set of filter polychromators, all the electronic equipments necessary to collect the data relevant to the scattered light and to send them to the F.T.U. data acquisition system. The features of this system can be summarized as follows: rejection to laser wavelength: ≥107, laser energy: ≥5 J, overall optical efficiency: ≥40%, and capability of multiple time and space measurements on the Thomson scattered light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143741
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  • 19
    Electronic Resource
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    Relativistic detuning limit on energy in electron cyclotron resonance x-ray source (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4439-4442 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this paper, a detailed theoretical analysis of electron acceleration in a TE111 cylindrical resonant cavity used as a cyclotron resonance accelerator is presented. The relativistic detuning limit on energy is found to depend critically on the externally applied dc magnetic field. The optimum value of the magnetic field, for a given operating frequency, electric field, and the cavity dimensions, is calculated. The cavity dimensions are optimized to get maximum peak-to-peak electric field so that higher electron energy can be obtained. It is also shown that most of the electrons, depending on the time of emission, end up in two accelerating bunches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143693
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  • 20
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    Fast curve fitting using neural networks (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4450-4456 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neural networks provide a new tool for the fast solution of repetitive nonlinear curve fitting problems. In this article we introduce the concept of a neural network, and we show how such networks can be used for fitting functional forms to experimental data. The neural network algorithm is typically much faster than conventional iterative approaches. In addition, further substantial improvements in speed can be obtained by using special purpose hardware implementations of the network, thus making the technique suitable for use in fast real-time applications. The basic concepts are illustrated using a simple example from fusion research, involving the determination of spectral line parameters from measurements of B iv impurity radiation in the COMPASS-C tokamak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143696
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  • 21
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    A simple and efficient low-temperature sample cell for infrared spectrophotometry (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4459-4460 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is often helpful in infrared spectrophotometry to contain a liquid sample in a cell that is maintained at a subambient or nearly cryogenic temperature. Volatile samples and solvents being studied can vaporize and form bubbles in conventional liquid sample cells, especially under the influence of the infrared radiation from the source in a continuous-wave instrument. This will result in the formation of spikes on the spectra. In addition, some analytes are thermally labile and must be protected from warming while the spectrum is recorded. An easily constructed cell cooled with a vortex tube can solve many of these problems, and is in many ways an improvement over commercial devices. In this note, such a cell is described and its application to volatile alternative refrigerants is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143698
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  • 22
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    Magnetic-spiker sustainer discharge excitation of a wide aperture small-gap TEA-CO2 laser (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4467-4468 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Magnetic-spiker sustainer technology has been used to generate pulsed TEA-CO2 laser outputs of ∼2 J from ultrawide aperture (8 cm), small electrode gap (1 cm) discharges with a laser efficiency of 10.6%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143702
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  • 23
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    The ATF heavy ion beam probe (invited) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4505-4510 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A heavy ion beam probe (HIBP) has been implemented on the ATF torsatron at Oak Ridge National Laboratory with the primary goal of providing direct measurements of the plasma potential radial profile and thus of the radial electric field. The complex ATF geometry and magnetic field structure presented a diagnostic environment more challenging than that found on previous beam probe systems. Particular attention has therefore been given to in situ system alignment and control capabilities. Measurements of electric potential profiles, electron density profiles, electron density fluctuations, and electric potential fluctuations have now been made with this system. Most of the data obtained were for ECH heated discharges, but we were also able to make measurements of a few NBI heated plasmas. In addition to our calibration techniques, we were able to establish a reasonable confidence level for the data obtained since we could identify the most important potential profile characteristics predicted by theory and to corroborate our measurements with information from other diagnostics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143706
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  • 24
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    Validation of spatial profile measurements of neutron emission in TFTR plasmas (invited) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4517-4522 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The TFTR multichannel neutron collimator provides spatially localized information on nuclear reaction rates in fusion plasmas. Absolutely calibrated NE 451 ZnS scintillators detect chord-integrated neutron emission along ten vertical sightlines, which are defined by a massive shielding structure in the facility basement. If such observations are to be of value, virgin neutrons along each sightline must be distinguishable from a background of gamma rays and scattered neutrons, and the measurements must be sufficiently precise, over a wide range of plasma conditions, to allow meaningful comparison with results of transport analysis computer codes. As a useful check, the volume-integrated neutron emission must agree with independent measurements of the global neutron source strength. Although NE 451 detectors are insensitive to gamma rays and to neutrons with energy less than ∼2 MeV, the scintillation pulse height distribution depends on both the incident neutron energy spectrum and the physical parameters of the individual detector. In order to establish the validity of our measurements, we have carried out a detailed characterization of our detectors, including computer modeling of scintillation pulse height spectra and of temporal pulse pileup effects in the counting circuitry. Satisfactory operation of the system has been demonstrated for all deuterium plasmas encountered in TFTR. The detector modeling, together with further laboratory measurements, will enable us to prepare for deuterium–tritium experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143708
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  • 25
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    Status of the neutron diagnostic experiment for Alcator C-Mod : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4530-4532 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Alcator C-Mod experiment is expected to produce neutrons at a rate of up to 1 × 1016 n/s during its highest performance operation. The global neutron detection system must provide accurate measurement of this production over the full operating regime of the experiment, 1011–1016 n/s. This is accomplished using a series of uranium fission detectors enriched in U235 of staggered sensitivity. These are distributed in two moderator assemblies. A BF3 detector is added to each moderator to cover the lowest operational range. Preliminary calibration of the system has been accomplished using a 65.4 μg Cf252 source placed inside the Alcator C-Mod vacuum vessel. The system design and calibration is discussed herein.
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    URL: http://dx.doi.org/10.1063/1.1143711
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    A neutron camera for burning plasmas : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4545-4547 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Profile diagnosis of tokamak plasmas with neutron cameras is discussed, especially with regard to neutron detection limitations and possibilities in burning DT plasmas. A new detection method based on the magnetic proton recoil spectrometer technique is presented.
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    URL: http://dx.doi.org/10.1063/1.1143715
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    Improved calibration of the neutron yield measurement system on the FTU tokamak : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4554-4557 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The neutron yield measurement system on FTU was initially composed of six BF3 proportional chambers for the start-up phase. The present reliable operations in deuterium, at higher plasma current, produce higher temperature discharges with higher neutron yields, therefore requiring less sensitive detectors: three fission chambers were chosen. We report the results of the new detector system calibration performed in September 1990. The BF3 detectors were also recalibrated as large scattering masses had been added around the machine since the previous calibration (November 1989). The calibration was performed by placing a 252Cf source (5.81×107 n/s) at different radial and toroidal positions inside the vacuum vessel; an increased number of points on the torus axis, with the inclusion of some off-port positions, represents the improvement with respect to the previous calibration campaign. Data on the response of the different detectors as a function of the source position are presented. The computation procedures of the relationship between the counts of a single detector and the total neutron yield from an extended plasma are discussed. A comparison between the two detection systems is carried out and, for the BF3 chambers, the data of the '89 calibration are compared with the present ones. Finally, preliminary results of the neutron emission from FTU ohmic discharges (campaign 1991) are presented.
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    URL: http://dx.doi.org/10.1063/1.1143665
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    Absolute calibration of the JT-60U neutron monitor using a 252Cf neutron source (abstract)a) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4558-4558 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Absolutely calibrated measurements of the neutron yield are important for the evaluation of the plasma performance such as the fusion gain Q in D-D operating tokamaks. The time-resolved neutron yield is measured with 235U and 238U fission chambers and 3He proportional counters in the JT-60U tokamak. The in situ calibration was performed by moving the 252Cf neutron source toroidally through the JT-60 vacuum vessel. Detection efficiencies of three 235U and two 3He detectors were measured for 92 locations of the neutron point source in toroidal scans at two different major radii. The total detection efficiency for the torus neutron source was obtained by the averaging the point efficiencies over the whole toroidal angle. The uncertainty of the resulting detection efficiency for the plasma neutrons is estimated to be ±11%.
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    URL: http://dx.doi.org/10.1063/1.1143666
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    Operating experiences with the TFTR escaping alpha detectors : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4565-4567 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper reviews the operating experiences obtained with a set of scintillator-based escaping fast ion detectors which have been used successfully for several years on the TFTR tokamak. There have been several operational problems which need to be resolved before these detectors are used to measure 3.5 MeV DT alphas in 1993. The main problem has been overheating by edge plasma heat flux for large major radius plasmas, when the detectors were not shadowed by the adjacent limiter. Other problems have been due to runaway electron-induced x-ray flux and scintillator and foil damage.
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    URL: http://dx.doi.org/10.1063/1.1143669
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    Electron density profile measurement with a heavy ion beam probe : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4571-4573 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The feasibility of electron density profile measurements using a heavy ion beam probe in high-temperature plasmas has been demonstrated earlier [J. Schwelberger et al., Bull. Am. Phys. Soc. 36, 2292 (1991); Yu. N. Dnestrovskij et al., Sov. J. Plasma Phys. 12, 130 (1986)]. Two algorithms were developed to obtain density profiles from the heavy ion beam probe on the Advanced Toroidal Facility (ATF). A comparison of the algorithms is presented with a detailed study of the errors involved in the measurements. The errors can be due to uncertainties in cross sections, electron temperature, the line average density measurement, and the ion trajectory calculations. The heavy ion beam probe density profile measurement is not very susceptible to errors as long as the electron temperature stays above 30 eV. If the electron temperature is below this value, a small uncertainty in the temperature introduces a large error in the density. Also, important for a good density profile measurement is the calculation of the correct ion trajectories. Examples of density profiles are shown for ECH plasmas on ATF together with a detailed error analysis. The heavy ion beam probe results are in good agreement with multichannel far-infrared laser interferometry and Thomson scattering results.
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    URL: http://dx.doi.org/10.1063/1.1143671
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    Evolution of the 2-MeV electrostatic energy analyzer for TEXT-Upgrade (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4582-4582 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The development of an electrostatic energy analyzer to be used with the 2-MeV heavy ion beam probe on the TEXT-Upgrade tokamak has presented several very interesting voltage breakdown phenomena. In order to maintain a 400-kV potential on large surface area plates (46.2 cm×152 cm) various configurations of support dielectrics, voltage feedthrough, plate materials, and plate geometry have been evaluated. Experimental evaluation of several designs and the resulting modifications leading to a working analyzer will be presented. This work was supported by the U.S. Department of Energy.
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    URL: http://dx.doi.org/10.1063/1.1143675
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    The new JET 2.5-MeV neutron time-of-flight spectrometer : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4586-4588 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A major upgrade of the JET 2.5-MeV neutron time-of-flight spectrometer has been completed. The improvement has permitted ion temperature measurements for Maxwellian deuterium plasmas with Ti(approximately-greater-than)4 keV to be obtained in 0.5-s intervals. By combining observations of neutron and x-ray energy spectra with studies of γ-ray emission from reactions between fast deuterons and impurities, the effects of ICRF heating on the deuterium energy distribution have been studied. The time evolution of neutron energy spectra from deuterium-beam heated deuterium plasmas is illustrated and a method for evaluating the ion temperature from such sequences is indicated. Furthermore, the spectrometer has shown stable performance during high neutron fluxes.
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    URL: http://dx.doi.org/10.1063/1.1143678
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    A multiple-sample, cesium-sputter, negative ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2450-2452 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A multiple-sample, cesium-sputter, negative-ion source which permits sample changes without disruption of on-line tandem electrostatic accelerator operations is described. The source is equipped with provisions for remotely selecting and moving into the beam position any one of 60 samples by means of stepping motors equipped with absolute shaft encoders. A spherical-sector cesium ionizer is used to produce the cesium beam for sputtering the sample material. The source is equipped with a three-element electrode system which has been designed to increase the perveance for cesium ion beam generation and to improve negative ion beam extraction from the source.
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    URL: http://dx.doi.org/10.1063/1.1142907
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    Physics and technology of electrohydrodynamic ion emitters in the USSR : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2460-2462 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A review of an investigation in the physics and technology of electrohydrodynamic (liquid metal) ion emitters, developed in the USSR, is presented. The EHD emission of high brightness ion beams from melted dielectric and EHD emission of negative ions are discussed. The dynamics of spontaneous and forced oscillation with a quasidiscrete spectrum in the frequency range of up to 108 Hz, transient processes in emission, emission stability at low and high current, and physical models for the emission surface size calculation has been studied. The evolution of the momentum distribution function is analyzed. Some examples of the utilization of the designed EHD sources for submicron ion beam production, for micromachining and microdiagnostics, and for high voltage accelerators are discussed too.
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    Performance evaluation of the TFTR gyrotron CTS diagnostic for alpha particles : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4644-4646 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A large-angle, 60-GHz collective Thomson scattering (CTS) diagnostic system for localized measurements of DT alpha-particle velocity distribution and fraction is being implemented on TFTR. Calculations of expected CTS spectra, signal-to-noise ratio per receiver channel, and estimated error in determining the temperature and fraction of alpha particles are being carried out. The experimental spectra are simulated by adding noise to the theoretical calculation by a Monte Carlo technique. Error analysis is then performed by using a relative intensity calibrated nonlinear curve fitting code to calculate the desired plasma parameters (Ti, Tα, nα/ni). Simulation results indicate that expected background emission of 20 eV during Supershot in TFTR poses no problem to the experiment. Also short integration times (〈10 ms) can be used to resolve the energetic ion features, thus offering a possibility for the study of temporal evolution of energetic ion velocity distribution during a single plasma shot.
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    URL: http://dx.doi.org/10.1063/1.1143646
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    Characteristics of gyrotron scattering system for α particle diagnostics in TFTR (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4647-4647 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In D-T plasmas, the understanding of the physics of confined α particles is extremely valuable for the future fusion plasma device. Among the various proposed α diagnostics, an X-mode collective Thomson scattering system employing a high-power gyrotron source (P(approximately-equal-to)200 kW, f=60 GHz, pulse length (approximately-equal-to)0.5 s, and modulation frequency=10–25 kHz) is being designed for TFTR. The detailed description of the gyrotron source, transmission lines, optical designs, beam and viewing dump design, and receiver system will be presented in this paper. In particular, the test results of the beam and viewing dump indicate that the stray light can be reduced by 60 dB. The background emission level (∼20 eV) near 60-GHz range during high Q discharge may also be reduced with beam and viewing dump further. The optical system is designed to measure the radial profile of α particles and to orient the incident wavevector (k0) to test the electromagnetic effects of the scattered spectrum. Prior to the study of α physics in D-T plasmas, this scattering system will be used to measure not only a bulk ion temperature but also the scattered spectrum due to fast ions produced by NB and ICRF heating in TFTR. This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76-CHO-3073.
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    Receiver calibration of the JET fast ion and alpha particle diagnostic : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4648-4650 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A collective Thomson scattering diagnostic is being implemented at JET to diagnose the velocity distribution and density of alpha particles and energetic ions. This diagnostic consists of a number of major subsystems including: a high-power 140-GHz gyrotron, a 32-channel 12-GHz bandwidth heterodyne receiver, efficient corrugated waveguide systems, variable polarizers, and in vacuum beam steering mirrors. Proper calibration of these subsystems for signal level losses, positioning, and polarization is imperative for the successful operation of the diagnostic and to facilitate the interpretation of the scattered data. A low-power Gunn oscillator was used to verify the polarization rotation induced by the seven miter bends in the receiver transmission line. The full bandwidth receiver front end losses, including the sapphire tokamak vacuum window, were initially calibrated by using the hot tokamak vessel wall as a blackbody source at approximately 310 °C. Background ECE measurements will be presented.
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    Precision of ion temperature and impurity fractional density measurement using the JET collective Thomson scattering diagnostic : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4651-4652 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this work some calculations are reported about the possibility of a simultaneous determination of the temperatures and densities of several different plasma ions using the JET gyrotron collective scattering diagnostic. It should be possible to determine the ion temperatures with a 20% error and the ion densities with ∼50% error, because of the high S/N (signal-to-noise ratio) that can be obtained in this experiment. These figures are obtained assuming 400 kW of incident power, a short integration time (10 ms), the central frequencies and the bandwidths of a 14 channels filter bank of the detection system, and a global (ECE background+detection system) noise temperature of ∼600 eV. The results are obtained using a multiparameter fit of an "experimental spectrum'' obtained averaging the calculated form factor in each channel of the filter bank and associating an error to this number calculated using the heterodyne S/N signal-to-noise ratio. The model function used in the fit is a known function of ion temperatures and densities. A deuterium plasma has been considered with hydrogen, carbon, and beryllium impurities. Te and ne are assumed to be known from other diagnostics. These conclusions are confirmed using a Monte Carlo code, which takes into account the statistics of the scattered signal.
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    Broadband heterodyne reflectometry on the W7-AS stellarator (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4653-4653 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broadband heterodyne reflectometer, operating in the frequency range 75–110 GHz, has been installed and operated at the W7-AS Stellarator in Garching for the study of density fluctuations and fast density profile determination. Both local (LO) and signal (rf) oscillators can be swept over the whole frequency range. Due to the balanced detection scheme, all drifts, as well as the broadband noise of the BWO (rf and LO) oscillators, are canceled at the different downconversion stages. After installation on W7-AS, first results reproduced the original findings of the former homodyne system [J. Sanchez, H. J. Hartfuss, E. Anabitarte, A. P. Navarro, et al. Nucl. Fusion 30, 2383 (1990)] as well as new results on the radial distribution of density fluctuations have been obtained. A phase drift due to asymmetries in the spectrum around the last IF has been observed; this phenomenon is strongly dependent on the plasma conditions and could be caused by plasma rotation. It is presently under study. The system offers broadband operation together with the possibility to decouple phase and amplitude oscillations of the reflected beam. The high dynamic range (up to 80 dB) is able to overcome the large amplitude oscillations of the reflected beam. The reflectometer described offers a good basis for further developments on large devices, which will require a very high sensitivity due to the long waveguide runs, together with the advantage of the operation in a continuous frequency range and fast sweeping capability.
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    URL: http://dx.doi.org/10.1063/1.1143650
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    Amplitude modulation reflectometry for large fusion devices : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4654-4656 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: One of the main problems which arises in density profile measurements by reflectometry is the need for continuous tracking of the phase delay; fast density fluctuations and strong modulation on the amplitude of the reflected signal can cause "fringe jumps'' in the phase signal. Amplitude modulation reflectometry performs a time delay measurement by the determination of the phase delay of the modulating envelope of a millimeter wave reflected by the plasma. The phase delays involved are small, the measurement is not affected by the fluctuations and can be directly performed without complicated fringe counters; the method provides a promising possibility for real time determination of the plasma position and density profile. In the present paper the principles of the method are presented as well as the analysis on the effects of phase and amplitude fluctuations, dispersive effects, and accuracy requirements.
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    URL: http://dx.doi.org/10.1063/1.1143651
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    TFTR microwave reflectometer (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4657-4657 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microwave reflectometer is in operation on TFTR for the measurement of density fluctuations. The system operates in the X mode and comprises three channels with fixed frequencies of 140, 132, and 125 GHz, and one with stepped frequency of 111–123 GHz. All channels use solid state Gunn oscillators and a heterodyne detection scheme. The system is located outside of the TFTR test cell with the power conveyed to the tokamak vessel by low-loss corrugated waveguides and remotely controlled parabolic mirrors. Preliminary results indicate that the level of density fluctuations with k⊥ 〈1 cm−1 is very small in the central region of Ohmic plasmas (ñ/n〈10−3), and that it increases monotonically with minor radius to values of ≈10−2 at r/a=0.9. This work supported by U.S. Department of Energy Contract No. DE-AC02-76-CHO-3073.
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    Development of a transient internal probe diagnostic : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5148-5150 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The transient internal probe (TIP) diagnostic is a novel method for probing the interior of hot magnetic fusion plasmas. In the TIP scheme, a probe is fired, using a two-stage light gas gun, through a hot plasma at velocities up to 5 km/s, and makes direct, local measurements of the internal magnetic field structure. The data are relayed to the laboratory optical detection system using an incident laser that is directed through a Faraday rotator payload acting as a magneto-optic sensor. Ablative effects are avoided by minimizing the probe size, limiting the time that the probe is in the hot plasma, and encasing the probe with a diamond cladding. The degree to which the diamond probe cladding is susceptible to ablative effects will determine the plasma density and temperature regime in which the TIP diagnostic can be used. If the TIP suffers significant ablation it is an indication that the diagnostic is not usable on this hot and dense of a plasma (or that greater velocity must be imparted to the probe to further minimize the time that it is in the plasma). A quantitative experimental study of the ablation rates of diamond is planned as part of the TIP development. The integrated TIP system will be functional in 1992 and installed on the Helicity Injected Torus (HIT) [T. R. Jarboe, Fusion Tech. 15, 9 (1989)] at the University of Washington.
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    The multichannel motional Stark effect diagnostic on TFTR : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5157-5160 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Although the q profile plays a key role in theories of instabilities and plasma equilibrium, it has been quite difficult to measure until the recent development of the motional Stark effect (MSE) diagnostic. A multichannel motional Stark effect polarimeter system has recently been installed on the Tokamak Fusion Test Reactor (TFTR). The diagnostic can measure the magnetic field pitch angle [γp=tan−1(Bp/BT)] at ten radial locations. The doppler shifted Dα radiation from a TFTR heating beam is viewed near tangential to the toroidal magnetic field via a re-entrant front surface reflecting mirror. The field of view covers from inboard of the magnetic axis to near the outboard edge of the plasma with a radial spatial resolution of 3–5 cm. A high throughput f/2 optics system results in an uncertainty for γp of ∼0.1°–0.2° with a time resolution of ∼5–10 ms. Initial pitch angle profiles from TFTR have been obtained. The MSE data is consistent with the estimated magnetic axis position from external magnetic measurements and the q=1 radius is in good agreement with the inversion radius from the electron cyclotron emission temperature measurements.
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    Midplane Faraday rotation: A densitometer for large tokamaks : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5154-5156 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The density in a large tokamak such as International Thermonuclear Experimental Reactor (ITER), or any of the proposed future US machines, can be determined by measuring the Faraday rotation of a 10.6 μm laser directed tangent to the toroidal field. If there is a horizontal array of such beams, then ne(R) can be readily obtained with a simple Abel inversion about the center line of the tokamak. For a large machine, operated at a full field of 30 T m and a density of 2×1020/m3, the rotation angle would be quite large−about 60° for two passes. A layout in which a single laser beam is fanned out in the horizontal midplane of the tokamak, with a set of retroreflectors on the far side of the vacuum vessel, would provide good spatial resolution, depending only upon the number of reflectors. With this proposed layout, only one window would be needed. Because the rotation angle is never more than 1 "fringe,'' the data is always good, and it is also a continuous measurement in time. Faraday rotation is dependent only upon the plasma itself, and thus is not sensitive to vibration of the optical components. Simulations of the expected results show that ITER, or any large tokamak, existing or proposed, would be well served even at low densities by a midplane Faraday rotation densitometer of ∼64 channels.
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    A nanometer notch filter with high rejection and throughput : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5161-5163 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The superior etendu available from a Fabry–Perot spectrometer is also accessible when used in reflective mode in producing a narrow bandwidth rejection, or "notch,'' filter. We consider the instrumental defects and the practical effects involved in realizing a useful device. A simple figure of merit is obtained which allows the Fabry–Perot characteristics to be specified according to the desired performance of the rejection filter. A comparison is made between calculations and a prototype Fabry–Perot notch filter.
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    URL: http://dx.doi.org/10.1063/1.1143467
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    A novel multichord spectrometer for plasma velocity measurements : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5164-5166 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A diagnostic has been designed to study edge plasma velocities in (JET) with good space and time resolution. To eliminate ambiguities in the measurement arising from atomic physics effects opposing views are provided. Each viewing direction incorporates ten fibers imaged on the path of a neutral heating beam with a channel spacing of 1.5 cm. The chord views are imaged onto a spectrometer with 20 individual entrance slits arranged in a rectangular array. The dispersed spectra from adjacent slits form linear images 25 mm long that are recorded using four fast optical multichannel analyzers. To prevent crosstalk of signals from adjacent slits the instrument incorporates a low dispersion spectrometer to limit the bandpass of the system. The principal advantage of this design is the ability to match the f number of the fiber optic arrays. This results from the rectangular arrangement of the slits which allows for a 4× magnification of the fiber images without requiring an exceptionally long (70 mm) entrance slit. This matching optimises the light collection efficiency of the complete diagnostic which ultimately sets the shortest time resolution. The minimum readout time for all 20 channels is 0.5 ms, although longer integration times are generally needed in JET.
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    URL: http://dx.doi.org/10.1063/1.1143468
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    Multichord spectroscopy of the DIII-D divertor region : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5167-5169 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A multichannel spectrometer with high spectral resolution (0.01 nm) and high temporal resolution (0.5 ms) has been configured to collect data simultaneously from eight viewchords spanning the divertor region of DIII-D. Fiber optically coupled to a wide-field lens with a vertical view of the vessel floor, the instrument will be capable of differentiating the behavior of impurity line emission at the inner and outer divertor strike points, on and off the Advanced Divertor Program ring, on the face of the Divertor Material Exposure System probe, and in the region of the lower centerpost. Used with a coarse grating (300 grooves/mm), spectral coverage of each spatial channel is 15 nm with 0.3 nm resolution; used in high order with a 1200 groove/mm grating, the instrument is capable of resolving Doppler profiles. Spatial variation of gas recycling and impurity influx will be studied for both single- and double-null divertor configurations in low and high density operating regimes.
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    Laboratory test of a LSM-based narrow bandpass and high throughput camera for Tokamak plasma imaging between 100 and 200 A(ring) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 5171-5173 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A narrow-bandpass (∼7 A(ring)) and high-throughput (f/5.5) extreme ultraviolet (XUV) camera using layered synthetic microstructure (LSM) coated optics has been built and tested at the Johns Hopkins University laboratory in order to image tokamak plasma emission between 100 and 200 A(ring). The LSM camera was tested with a Penning ionization discharge emission source. The test measures the spectral bandpass, the spatial resolution, and the relative photosensitivities. The XUV camera will be used to measure the O vi 150 A(ring) line brightness on the Phaedrus-T tokamak with a tangential view to investigate the impurity transport.
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    URL: http://dx.doi.org/10.1063/1.1143471
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    Polarized ion sources (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2519-2524 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Sources producing beams of nuclear spin polarized atoms or ions of H, D, 6Li, 7Li, 23Na are routinely used in many laboratories. Principles and performances of these sources are described, with emphasis on the light particles (H, D). Recent progress in these sources as well as some physical or technical limits are discussed. An updated table comparing working sources of H+,D+ and H−,D− is given.
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    URL: http://dx.doi.org/10.1063/1.1142876
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    Radio-frequency ion sources for space propulsion (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2513-2518 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: After more than 25 years of research, development, and qualification work at Radiofrequency Ion Thrusters, so-called RIT, the RIT 10 engine, designed for north–south stationkeeping of geosynchronous satellites, is now ready for a space test onboard the European Retrievable Carrier EURECA. Since two years, the European Space Agency ESA/ESTEC is working at a new technological satellite, called ARTEMIS, at which ion propulsion shall be used operationally for north–south stationkeeping. In the scope of the RIT 10 ground qualification work, an ion beam diagnostic device has been designed and built up to determine the mechanical beam parameters. Moreover, a small test stand has been designed that allows full thruster operation in order to measure the radiated electromagnetic spectrum in an anechoic test chamber. Besides, the development and tests of a scaled-up 50 mN engine RIT 15 have been continued successfully with xenon, krypton, and also argon as propellants. The ion beam profiles have been measured and the influence of the accel-decel ratio on the beam divergence has been studied. A large ion engine with 35 cm ionizer diameter, the RIT 35, has been developed for primary propulsion aiming at a thrust level in the 250 mN range. A laboratory prototype has been subjected to extensive testing and performance mapping. This preliminary work has been finished waiting for further programmatic decisions.
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    Negative hydrogen ion ECR source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2529-2531 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To find optimum conditions for the generation of negatively charged hydrogen ions, an ECR source has been investigated. The source consists of a cylindrical cavity placed between Sm-Co disk-type magnetic poles, and microwave and extraction systems. The way in which the negative ions are produced is by the capture of low-energy electrons by vibrationally excited molecules as a result of which the dissociative attachment of negatively charged molecules takes place. Molecules are excited in the plasma volume. The low-energy electrons emerge due to bombardment of the first electrode of the extraction system by the ECR-heated electrons. The intensity of the extracted negative hydrogen ion beam appears to be sensitive not only to pressure, microwave power, and extraction voltage, but also depends on the shape of the ECR surface. Experiments indicate that the hyperboloid of one sheet-type resonance surface is the most effective. Measurements carried out with microwave of 600 W at 2.45 GHz, and at a pressure of 0.3 mTorr show that the negative ion yield attains 1.2 mA through a 0.3-cm-diam extractor hole.
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    ECR ion source using slow wave structures : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2525-2528 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this ECR ion source, the possibility of maintaining the plasma by slow wave structures (SWS), helical coil, and slotted line antennas, in the region where wce, wpe (very-much-greater-than) wrf (wce, wpe, and wrf are electron cyclotron, plasma, and microwave frequencies, respectively) is exploited. The plasma parameters, plasma density, and electron temperature are maximized by coupling microwave (frequency: 2.45 GHz; power: 650 W) at two places in a magnetic mirror machine (mirror ratio Rm (approximately-equal-to) 1.45) to obtain higher beam current. Initially, the plasma is produced by coupling microwave to SWS at the mirror throat. The microwave is coupled by exciting the dominant slow wave field component of SWS, using an E-plane horn antenna. Then the plasma is brought to the region wce, wpe (very-much-greater-than) wrf at the mirror throat by increasing the magnetic field. Simultaneously, the ECR region is shifted from mirror throat to the center where second microwave coupling is done at the resonant region using another horn antenna. The characterization of plasma parameters are presented for both helical coil and slotted line antennas. Enhancement of plasma parameters are observed in the present scheme. Also, the SLA is found to produce better plasmas (ne ∼ 7 × 1012 cm−3 and Te ∼ 12 eV) than the helical coil and hence the SLA is chosen for the ion beam characterization. The extracted ion beam current density in the present scheme is ∼25 mA/cm2 at 2-kV extraction voltage.
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    Development of a compact 2.45 GHz ECR ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2532-2534 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: ECR-heated plasmas as produced by microwave discharges in magnetic fields are now routinely utilized for production of intense singly and multiply charged ion beams. Such ECR ion sources ("ECRIS'') can be operated during extended lifetimes even with reactive working gases. Our requirement for a simple, long-lived, high current Li+ ion source for Li-CXS tokamak plasma diagnostics led to a study on plasma production with a coaxial 2.45 GHz microwave discharge (23 mm outer diameter) embedded in a variable magnetic field configuration. The chosen geometry is compatible with Li vapor production from heat pipe ovens or externally heated LiAl alloy liners, and also permits incorporation of a permanent magnet quadrupole structure for enhancing the ion confinement in the discharge region. As a first step, with a simple magnetic mirror field generated by two axially adjustable solenoids the microwave discharge properties and extractable ion beam currents have been investigated with H2, He, and Ar as feeding gases.
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    Numerical modeling of a compact ECR ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2535-2537 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact ECR ion/plasma source is numerically modeled using a Monte Carlo particle method coupled with a solution of the Maxwell equations. The source modeled is a small, coaxial cavity source that utilizes rare earth permanent magnets to create electron cyclotron resonance (ECR) zones in the cavity. The model includes the calculation of the static magnetic field produced by the permanent magnets, the microwave fields at 2.45 GHz, the electron spatial and energy distributions, and the ion spatial and energy distributions. The numerical model is a 2d3v model that assumes an axial symmetry. The electric fields and time-varying magnetic fields are solved using a time-domain finite-difference solution of the Maxwell equations. The electron and ion behaviors are modeled by using the Monte Carlo particle technique, where each particle moves subject to the Lorentz force equation and to the appropriate elastic and inelastic collision processes. The solution obtained is a self-consistent solution where the Maxwell equations are solved iteratively with the particle technique until a steady state condition is reached. Sample simulation results are presented including a spatial electron heating distribution.
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    An ECR ion source for ion implantation : Proceecings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2538-2540 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The lifetime advantage of the filamentless discharge of high-current ECR ion sources is still often diminished through the degradation of the dielectric microwave transmitting window or the antenna. A 2.45 GHz ECR ion source that is now under construction and intended for the production of singly charged ions from reactive or contaminating gases is presented. The microwave power of up to 500 W is coupled into the entirely metallic discharge chamber through a resonant slit. The teflon vacuum sealing window is placed far from the plasma behind a high vacuum waveguide bend and is thus protected from backstreaming electrons and covering source material.
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    A low power 2.45 GHz ECR ion source for multiply charged ions : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2541-2543 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An electron-cyclotron-resonance ion source (ECRIS) designed for use on a high voltage terminal that has limited power availability and space has been built. To reduce the power consumption of the ion source, the necessary magnetic fields were produced entirely by permanent magnets. Eighteen FeNdB magnets divided into three hexapolar arrangements yielded a min-B structure with an axial magnetic mirror ratio of 4:1. The microwave power at a frequency of 2.45 GHz with up to 300 W cw was supplied to the plasma by means of a slotted line radiator. This antenna, known as a Lisitano-Coil, allowed the use of a plasma vessel much smaller in diameter than is usually required by the wavelength of the utilized microwaves. The ion source produced stable beams of multiply charged ions at various intensities up to a total ion current of 8 mA for oxygen.
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    A 2.45 GHz multicusp ECR-ion source for neutral–beam diagnostics at the tokamak TEXTOR : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2544-2546 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In order to implement a new setup for neutral–beam activated impact excitation spectroscopy at the nuclear fusion experiment "TEXTOR'' (Tokamak Experiment for Technology Oriented Research) a 2.45 GHz ECR multicusp ion source was built. Special emphasis was given to extract an intense He+-ion beam, which will be used in the forthcoming experiment. After neutralization the slow (2.2 × 107 cm/s, 1 keV) He atoms are injected into the tokamak plasma. Necessarily the atom beam has to have a small divergence. To optimize the extraction optics, calculations concerning the multihole extraction aperture have been made, taking different ECR-plasma parameters into account. The divergence shows a strong dependence on the extracted beam current density ((approximately-greater-than)5 mA/cm2) and the chosen optics. The ion source has to be operated in a pulsed mode (max. 5 kHz, duty cycle 50%) due to experimental requirements.
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    Characterization and stabilization of an electron-cyclotron resonance plasma source using an automatic microwave tuner : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2547-2549 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An automatic microwave stub tuner (AST) has been developed and used to characterize and stabilize an electron-cyclotron resonance (ECR) plasma source. The tuner provides a new method for measuring plasma impedance dynamically without disturbing the plasma. The Ar ECR plasmas were excited by a 2.45 GHz microwave (〈800 W) in the presence of the static axial magnetic fields ranging from 875 to 2000 G, and the characteristics were investigated using a double probe and the AST. Results of these measurements indicated that the Ar ECR plasma had discrete stable modes where the plasma parameters and impedance varied continuously. For certain operating conditions, slight shifts of microwave power and/or magnetic-field strength brought about discontinuous mode transitions. In the transition regions, the drastic changes of plasma characteristics were observed, resulting in the instability of the plasma. It was quite effective for stabilizing the unstable plasmas to control the reflection coefficient of the microwave transmission line.
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    Pulsed operation of a MPDR-type ECR-plasma source for high-power applications : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2550-2552 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed and tested a new kind of 2.45 GHz microwave plasma disk ion source based on the Asmussen and Root approach1 using only metal, ceramics, and metal–ceramic sealings for high-power operation in excess of 1.2 kW. This corresponds to power densities of more than 1 W/cm3. To reduce thermal runaway, the discharge chamber is fabricated from high-purity aluminia. Ion extraction optics with diameters up to 75 mm (3 in.) can be mounted. The source works in various single-mode resonance conditions controlled by an automatic matching unit. Pulsed magnetron power supplies with pulse frequencies up to 20 kHz and duty cycles adjustable in 10% steps have been found to be very efficient with respect to the extractable ion current density (Jextr.). Therefore this mode of operation makes possible high-power applications while simultaneously lowering the thermal load of the plasma chamber.
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    A compact microwave ion source with permanent magnet : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2553-2555 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact microwave ion source has been developed. The magnetic field in the source is produced by a permanent magnet. The dimension of the source is 46 mm in diameter and 50 mm in height. The discharge chamber and extraction hole is 20 and 2 mm in diameter, respectively. The microwave frequency is 2.45 GHz and the power consumption is less than 50 W. It is easy to extract a total beam current of more than 1 mA from this compact source.
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    Production of ions in open-ended region of coaxial-type microwave cavity : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2565-2567 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Characteristics of a microwave planar magnetron ion source are described. This source, using a tuned coaxial-type cavity which excited the plasma at the end of the coaxial line, is able to produce a 100-mm-diameter by 20-mm-thick plasma disk that is well matched, stable, and allows continuous operation over a wide range of gas pressures. The isotropic microwave propagation from the surface of the magnetized plasma column to the center is one of the most effective coupling methods to obtain a high-density disk-like plasma. Argon ion current densities of 20–50 μA/cm2 have been obtained at energies ranging from a few to 70 eV. The beam uniformity is ±2% within a diameter of 5 cm. This new source has the potential to produce low-energy broad-beams.
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    Advanced high-current ECR ion sources for implanters : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2559-2561 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have already introduced a high-current ECR ion source producing a 200-mA beam of oxygen ions with an 80% O+ fraction. Two more advanced ECR sources with a high-current density of more than 100 mA/cm2 have been newly developed. One source provides high-current density without the accompanying damage to the microwave transmitting window found with the earlier source. This damage, which occurs when high-speed backstream electrons attack the window, limits source lifetime. By adopting a multiple microwave inlet configuration for the introduction of microwaves into the plasma chamber, the ECR condition can be satisfied and high-density plasma can be generated without an attack by backstream electrons. The other is a very compact source producing a high-current beam at a very low-power consumption. This is achieved by reducing the inner diameter of the plasma chamber to 5 cm φ, which is smaller than the cutoff dimensions for propagation of the 2.45 GHz microwave. A high-plasma density of 1 × 1013 cm−3 has been obtained at the low microwave power of 250 W.
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    A high-current microwave ion source for ion implantation : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2562-2564 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new 2.45 GHz microwave ion source has been developed for high-current ion implantation. The source uses permanent magnets to generate the ECR magnetic field. This leads to a much simpler and more compact design than typical solenoidal field microwave sources. The strong magnetic field and high-microwave power density are used to achieve a 11B+ ion fraction of up to 30% in extracted boron beams. Previous work on microwave ion sources for ion implantation has ordinarily not dealt with performance or lifetime issues for boron operation, which are critical in evaluating the overall utility of an implanter ion source. This is due to the generally poor performance of microwave sources with boron, as well as the limited source lifetime. Details of the performance and lifetime characteristics of this source with BF3 are presented in this paper.
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    Experimental characterization of a compact ECR ion source : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2556-2558 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A small ECR plasma source is experimentally evaluated. The compact, coaxial cavity source has an outer diameter of about 5.8 cm and is less than 15 cm in length, and can therefore be fitted on vacuum ports on existing MBE machines. Double- and single-Langmuir probes and an energy analyzer are used to measure ion density, electron temperature, plasma potential, and energy distributions at various downstream and cross-sectional positions in the plasma beam. The measurements are made for a variety of flow rates (2–30 sccm) and the corresponding pressures (from about 10−5 to 10−4 Torr), incident powers ranging from 80 to 164 W, and various gas types including argon and oxygen. The experimental measurements show that the ion source provides ion density of about 1011/cm3 at relatively low powers of 123 W and at sub-mTorr pressures. The ions created follow typical ambipolar diffusion out of the discharge creation region. Ions impinging downstream on a grounded substrate in an argon discharge show a narrow, peaked energy distribution that varies with pressure and power. Low-energy ion beams with energies less than 35 eV can easily be produced by varying the pressure and input power.
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    The study of a fundamental law in extracting metal ions from a rf ion source by applying a plasma chemical reaction : Proceecings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2568-2570 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Experimental metal ions are extracted from a rf ion source by applying a plasma chemical reaction. The process has been generalized into a law; it is used in practicing and many metal ions are extracted, such as: Re+, W+, Mo+, Ta+, Pt+, Pd+, Au+, Ag+, Nb+, Ti+, V+, Cr+, Ni+, Fe+, Cu+, Zn+, Ga+, Ge+, Se+, Si+, Al+, Mg+, Be+, Li+, Bi+, In+, Sn+, Pb+, Cd+, etc., and rare-earth ions Y+, Nd+, Ce+, Sm+, Tm+, Dy+, Gd+, Er+, and so on.
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    URL: http://dx.doi.org/10.1063/1.1142891
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    Nuclear radiation effects in fused SiO2 lightguides : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4735-4737 
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    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High purity fused silica fibers are widely used in controlled fusion research to conduct visible light (down to about 4000 A(ring)) away from the hostile environment of the tokamak. These fibers are not totally radiation immune, however. We see both luminescence and loss of transmission induced by radiation at the present levels of D–D fusion yields on Tokamak Fusion Test Reactor (TFTR). The luminescence shows spectral structure and is brightest near the widely used Hα–Dα wavelength of 6562 A(ring). The induced opacity has both transient (time scale of seconds) and permanent components. Extrapolation to D–T plasmas, which are planned for TFTR, yields levels of both luminescence and opacity which range from annoying to fatal if current practices are continued.
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    URL: http://dx.doi.org/10.1063/1.1143624
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    e-beam probe potential diagnostic in spherical electrostatic-inertial plasma confinement (SEIC) (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4731-4731 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new e-beam probe is developed to study the potential structure inside a SEIC device [G. H. Miley et al., Fusion Technol. 19, 840 (1991)]. The device has a spherical grid negatively biased inside a spherical vacuum chamber. Ions oscillate through the highly transparent grid, forming a single potential well inside the cathode. The potential in turn attracts electrons from ionization of background gas. The measurement of this complex potential profile is the objective of this work. The e-beam probe offers advantages over the e-emitting probes and the laser heterodyne method. It minimizes perturbations (versus a physical probe) and detects smaller charge density variations than possible with laser techniques. The present e-beam probe utilizes a higher voltage and a modified focus compared to the earlier version used by Swanson [Swanson et al., Phys. Fluids 16, 1939 (1973)]. The characteristic e-beam deflection patterns observed are compared to predictions from an impulse approximation model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143622
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    Performance characteristics of a capacitively coupled 3 cm rf ion source (abstract)a) : Proceecings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2574-2574 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel 13.56 MHz radio frequency capacitively coupled ion source has been developed and characterized with special emphasis on low-energy (〈1 keV) broad ion beam extraction. When operating the source with chamber pressures ranging from 1 × 10−4 to 1.7 × 10−3 mbar (O2 and Ar), rf-power levels from 5 to 120 W, axial air coil magnetic fields up to 70 mT, and maximum extraction voltages of 650 V extractable ion currents were as high as 50 mA. With a total grid area of 7 cm2 and a transparency of 46%, this amounts to a grid current density of more than 7 mA/cm2 while the ion saturation current density is calculated as 9.3 mA/cm2. The potential oscillation amplitude of the rf excitation electrode can be as high as 650 V. Due to an external axial magnetic field, a dc bias up to 70 V is induced between the grounded accelerator grid and cylindrical anode. The performance data are traced back to constructional source details such as plasma excitation geometry, axial magnetic field, and floating electrostatic end confinement. Under all operating conditions, the source shows an excellent long-time stability even with reactive gases (e.g., more than 100 h without maintenance with oxygen).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142893
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    Production of mixed metal–gas and pure metal ion beams with an electrodeless rf ion source in the low keV regime : Proceeding of the fourth International Conference on ion sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2578-2580 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Mixed metal–gas or even pure metal ion beams with current densities in the order of 1 mA cm−2 can be generated by electron beam evaporation of metals into the plasma chamber of an rf ion source operated in electron-cyclotron wave resonance. The operation principle of this novel ion beam source is described, and examples for the production of Ag+ and Cu+ beams with varying fractions of Ar+ ions are presented.
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    URL: http://dx.doi.org/10.1063/1.1142895
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    Electron temperature and plasma density of capacitive rf-discharges in noble gases : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2581-2583 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Electrical discharges in He, Ne, Ar, and Kr at medium pressure (density of neutral atoms from 1021 to 1023 m−3), sustained by an rf electric field of 27.12 MHz, are investigated. Electron temperature and plasma density were measured with a Langmuir probe at 8, 13, and 20 W total discharge power. The plasma density was found to increase with the input power, whereas the electron temperature depends only weakly on the input power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142896
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    Impedance measurements at rf plasmas in noble gases by use of the four-terminal network formalism : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2584-2586 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: At medium pressure (density of neutral atoms from 1021 to 1023 m−3) plasma was generated by an rf electric field of 27.12 MHz. The plasma impedance has been measured in He, Ne, Ar, and Kr. In order to avoid errors by stray reactances, the power input line was treated as a four-terminal network. The corresponding coefficients were determined by measurements with known load impedances instead of the plasma.
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    URL: http://dx.doi.org/10.1063/1.1142897
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    An ECR microwave plasma cathode for ion sources with electrostatic reflex containment : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2587-2589 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Ion sources for industrial reactors are used in a lot of applications such as ion beam sputtering or etching, ion assisted thin-film deposition, and surface treatment. They must satisfy several conditions; three of them are most important for reactive, especially oxygen, ion beams: (1) a lifetime longer than 100 h, (2) no deposition of an insulating film on the electrodes, (3) the electron energy must be chosen in a given range in order to control the fragmentation of the injected neutrals. The aim of this work was to compare the behavior of two ion sources having the same microwave plasma cathode, where the plasma is created by a microwave field (2.45 GHz) under an ECR condition: an electrostatic reflex ion source (ERIS) and a multipolar electrostatic reflex ion source (MERIS). Typically, we have produced an oxygen beam current of 83 mA with the ERIS structure and 118 mA with the MERIS structure, in 84 mm diameter for an extracted energy of 1200 eV. We have obtained broad uniform oxygen beams during about 100 h with both sources. A comparison between figures of the two structures is given, concerning the discharge characteristics, the extracted current, the yield, and finally, the extracted beam profile.
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    URL: http://dx.doi.org/10.1063/1.1142898
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    Preparing diagnostic data for the snap transport code : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4750-4752 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes the program snapin which is used to prepare data for transport analysis with the snap code. The data input to snap includes diagnostic profiles [ne(R), Te(R), Ti(R), vφ(R), Zeff(R), Prad(R)] and measurements such as total plasma current, Rmajor, beam power, gas puff rate, etc. snapin reads in the necessary TFTR data, allows editing of that data, including graphical editing of profile data and the selection of physics models. snapin allows comparison of profile data from all diagnostics that measure a quantity, for example, electron temperature profiles from Thomson scattering and electron cyclotron emission (ECE). A powerful user interface is important to help the user prepare input data sets quickly and consistently, because hundreds of variables must be specified for each analysis. snapin facilitates this by a careful organization of menus, display of all scalar data and switch settings within the menus, the graphical editing and comparison of profiles, and step-by-step checking for consistent physics controls [J. Murphy, S. Scott, and H. Towner, The snap User's Guide, Technical Report PPPL-TM-393, Princeton Plasma Physics Laboratory (1992)].
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    URL: http://dx.doi.org/10.1063/1.1143629
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    Rotational soft x-ray tomography of noncircular tokamak plasmas : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4757-4759 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A rotational tomography technique for noncircular tokamak plasmas has been developed. Using a linear transformation from an elliptic coordinate system to the circular one, and compensating for the Shafranov shift, the elliptic plasma shape is transformed to the concentric circular shape. Fitting the data of a quarter rotation to the Fourier–Bessel expansions, the tomography is performed. This technique is applied to the snake oscillation, to the slow sawtooth crash, and to the post-cursor oscillations of noncircular plasmas on JET.
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    URL: http://dx.doi.org/10.1063/1.1143631
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    Modeling fast alpha-particle distributions : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4760-4762 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a code for following the radial diffusion and slowing down of alpha particles from DT fusion. The partial differential equation is solved by a finite-difference method. Ion as well as electron drag is included. Any given source function of radius, time, and energy width can be handled correctly. The code has been used to examine time waveforms, radial distributions, and energy spectra. The results can be used to model signals expected from the alpha charge exchange recombination spectroscopy and collective Thomson ("gyrotron'') scattering diagnostics. The code has also been used to calculate, as a function of diffusion coefficient, the flux of escaping fast ions that enters a lost-ion detector, and thus to deduce from measurements an upper limit for the diffusion of fast charged fusion products.
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    URL: http://dx.doi.org/10.1063/1.1143632
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    Data analysis on TFTR using the SNAP transport code : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4753-4756 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes the between shots data analysis on TFTR using the one-dimensional equilibrium kinetic analysis code SNAP. SNAP accepts as input data: the measured plasma size and current, toroidal field, surface voltage, plasma composition (total Zeff and Zeff contribution from metallic impurities), edge neutral density, auxiliary heating power data (neutral beam power, energy, injection geometry and/or rf power and frequency), and measured profiles of Te(R), ne(R), Ti(R), Vφ(R), and Prad(R). SNAP iteratively calculates: (1) the mapping of profile data to a minor radius grid, (2) the magnetic topology including Shafranov shifted circular flux surfaces, (3) neutral beam attenuation and deposition profiles, (4) unthermalized beam ion density and beam power density delivered to thermal plasma species from a numerical solution to the Fokker–Planck equation, (5) the neutral density profile, (6) local heat and particle transport coefficients consistent with the measured profiles and calculated source terms, (7) ICRF power profiles from a reduced order full wave analysis and isotropic Stix quasilinear model, and (8) total neutron emissivity and plasma stored energy. Several ion heat transport models (including neoclassical χi and χi∝χe) are available to calculate an expected Ti(r) profile in the absence of measurements.
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    URL: http://dx.doi.org/10.1063/1.1143630
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    Beam measurements on a CHORDIS ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2604-2606 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present beam measurements which have been carried out using a CHORDIS ion source supplied with a modified extraction system. This system is designed to handle extraction voltages up to 60 kV. For beam diagnostics, a Faraday cup and a sector magnet have been used. Presented are measurements on beam current, mass, and energy spectra in dependence on various source parameters as gas pressure, arc voltage, and extraction voltage.
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    URL: http://dx.doi.org/10.1063/1.1142851
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    Beam investigations at a multicusp ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2607-2609 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In cooperation with the Lawrence Berkeley Laboratory, a multicusp ion source has been investigated. The goal of these investigations is to generate a nearly pure atomic nitrogen (N+) ion beam. To achieve this, the discharge chamber is divided into two parts of different plasma parameters by means of a filter magnetic field. As beam diagnostics, a bending magnet and a faraday cup have been used. Measurements of the beam current density and the ion composition for a wide range of discharge conditions have been performed. By using a Langmuir probe, we have performed measurements of electron temperature and electron density.
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    URL: http://dx.doi.org/10.1063/1.1142852
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    A modified electrostatic ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2610-2612 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The oscillating electron ion source has been modified to obtain an improved form by extracting more low-energy ions from it. It has been found that biasing of the oscillating ions by applying a negative potential to the cathodes would increase the output beam current to about three times its value for the same ion source plasma parameters, whereas applying the same negative potential on the screens and Faraday cups, while the cathodes connected to earth will increase the beam current five times its value. The discharge starts at lower values of discharge voltage, or higher values of beam current are obtained at the same value of discharge voltage as the applied negative potential is increased. It is concluded that the electrode configuration constitutes a convergent lens when the negative potential on the screens and Faraday cups is only one-ninth as large as that of the positive anode electrode.
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    URL: http://dx.doi.org/10.1063/1.1142853
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    Versatile cold cathode ion source for use with materials in any thermodynamic phase : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2613-2615 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new type of cold cathode ion source has been designed that is suitable for beams of variable cross sections and can also employ source elements in any thermodynamic phase: it has been given the name universal cold cathode ion source (UCCIS). There are two versions of this ion source: the first (LE-UCCIS), suited to low energy operations such as ion beam assisted deposition (IBAD) and etching, the second (HE-UCCIS) suited to high energy processes such as ion implantation and ion mixing. A prototype of the LE-UCCIS has been built and is undergoing testing. The main feature of the LE-UCCIS when used for IBAD processes is to combine in a single unit both the source of neutrals that grow the film and the source of ions that assist the deposition
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    URL: http://dx.doi.org/10.1063/1.1142854
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    Atomic nitrogen ion beam from a pulsed duoplasmatron ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2616-2618 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A duoplasmatron ion source fed with nitrogen usually produces a N+ fraction of approx. 60% in dc mode. In pulsed mode, the duoplasmatron ion source turns out to be a nearly perfect source for atomic nitrogen ions with a high fraction of more than 90% in the milliampere range. This is achieved by pulsing the arc discharge and not by use of any filter magnets. Parameters of operation will be given, such as the comparatively low gas inlet pressure and the arc current, which far exceeds the arc current in dc mode.
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    URL: http://dx.doi.org/10.1063/1.1142855
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    Some characteristics of the hollow-anode ion source : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2619-2620 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Hollow-anode ion source with a glass discharge tube has been studied. Such a source, apart from its simple construction, is suitable for the study of the hollow-anode discharge characteristics and their influence on the ion source properties. Ion current of 1 mA (limited by the extraction power supply), when operating gas is hydrogen, has been obtained.
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    URL: http://dx.doi.org/10.1063/1.1142856
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    Operational characteristics of the ion source for the RFQ (abstract) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2621-2621 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high current, light ion duoplasmatron ion source was designed and has been brought into operation. This ion source has been designed to deliver up to a maximum of 20-mA light ion beam at an energy of 20 keV and will serve as an injector to the RFQ accelerator. The magnetic field mapping in the anode column region and studies of the filament characteristics have been carried out. The effects of the gas pressure, magnetic field, puller voltage, and screen voltage on the ion current have been studied to obtain the optimized values. The spatial beam distribution has been mapped in two orthogonal planes. So far the source has yielded about 12 mA of unanalyzed proton beam at an extraction voltage of 15 kV and arc current of 2.5 A. Tests at higher extraction voltages and the detailed beam emittance studies are being carried out.
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    URL: http://dx.doi.org/10.1063/1.1142857
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    Proton beam targets shot on PBFA-II : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4779-4781 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In recent proton beam experiments on PBFA-II, foam-filled gold targets and gas-filled spherical exploding pushers were shot as physics targets. Surrounding these targets were gold foils used to characterize the beam. The target fabrication and characterization are presented in this paper.
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    URL: http://dx.doi.org/10.1063/1.1143560
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    Analysis of a proton driven, exploding pusher target on PBFA II (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4778-4778 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: During the past year we have conducted a series of PBFA II target experiments. The design of the experiments was threefold: to characterize the response of targets to ion beams, develop our experimental diagnostic capability, and benchmark our theoretical ability to design and predict the response of the experimental diagnostics to ion-beam-heated, ICF targets. We present here an analysis of spherical exploding pusher experiments. The targets were 6-mm-diam, 100-μm-thick, Cl-doped CH spheres, filled with 1.2 atm of deuterium doped with 7 Torr of H2S. The diagnostics included XRDs, x-ray pinhole, framing, and streak cameras, and a spatially resolved, x-ray crystal spectrometer. Our analysis includes comparisons between experimental results and theoretical predictions of diagnostics responses and sulfur line emission from the compressed target using one- and two-dimensional radiation/hydrodynamic code runs. This work supported by the U. S. Department of Energy under Contract No. DE-AC04-76-DP00789.
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    URL: http://dx.doi.org/10.1063/1.1143559
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    Divergence measurement of light ion beams using ultracompact ion pinhole cameras on PBFA II (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4782-4782 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Ion beam divergence reduction will increase the power density deliverable to an ICF target and is one step towards demonstrating a credible path to target ignition. Measurement of the divergence is made with an ultracompact ion pinhole camera (UC-IPC). The UC-IPC is mounted in the PBFA II diode near the ion source at a 10° angle to compensate for beam bending in the diode's applied magnetic field. The beam is transported through an entrance pinhole and down an entrance tube to a gold scattering foil. The beam is scattered 90° through a second pinhole to CR39 film where the ion track count is recorded. This paper will describe the results of off-axis ion beam divergence measurements using the UC-IPC. Together with other diagnostics, the UC-IPC provides information about beam species and charge state, about particle energy and about divergence of the beam. This paper will also describe UC-IPC simulation using PICDIAG, a 2D code that models the ion transport and diagnostic response of experiments on Sandia's PBFA II accelerator. This work supported by the U. S. Department of Energy Contract No. DE-AC04-76DP00789.
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    URL: http://dx.doi.org/10.1063/1.1143561
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    A simple unfold method for Rutherford scattering, intense ion-beam spectrographs : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4786-4788 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Elastic Rutherford scattering with subsequent momentum analysis has become a powerful tool for analyzing intense, pulsed light-ion beams for inertial confinement fusion studies. The ion spectrum is obtained by mathematical inversion of the data. This paper reports a product-integration solution to the inverse problem which is readily adapted to rapid data analysis and is simpler in form than reported previously. While this approach introduces some unphysical (negative) components into the solution, these are often negligible. Discussed here are the unfold method together with its accuracy and precision.
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    URL: http://dx.doi.org/10.1063/1.1143563
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    Analyzing noisy spectral line shapes : Proceedings of the 9th topical conference on high temperature plasma diagnotics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4783-4785 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In many situations it is necessary to analyze spectral line shapes where the data contain significant amounts of noise or statistical fluctuations. Our visible spectroscopy measurements exploring ion diode physics on the PBFA II accelerator typically result in noisy spectra because the harsh environment limits the number of photons collected. The spectral line profiles include contributions from Doppler (Ti∼1–3 keV), Stark (ne∼1017 cm−3), and instrument broadening, as well as from Stark shifting (E∼3–10 MV/cm) and Zeeman splitting (B∼2–10 T). We extract a range of parameters (e.g., ion temperature from Doppler broadening) that fit the data by determining a range of fits that are consistent with the uncertainty due to the noise in the data. The range of fits is generated by a Monte Carlo technique. This method effectively distinguishes between actual spectral features and artifacts due to noise. It provides not only estimates of physical parameters, but also their uncertainties. We evaluated the technique over a range of signal-to-noise ratios and found that it works well for our application.
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    URL: http://dx.doi.org/10.1063/1.1143562
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    Cautions in using x-ray measurements derived from broad spectral response functions to determine the peak voltage of flash bremsstrahlung sources : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4789-4791 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Because a direct measurement of the voltage (V) in pulsed power bremsstrahlung sources can be difficult, the energy spectrum of x rays emitted is sometimes used to infer V. Both the voltage and current in such sources vary with time. Moreover, for modern x-ray simulators with multiple cathodes, multiple voltages may exist simultaneously. We demonstrate here how such sources lead to systematic errors in several types of simple-to-field x-ray voltage measurements, especially those with broad spectral response functions, when calibrated against constant-potential bremsstrahlung spectra.
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    URL: http://dx.doi.org/10.1063/1.1143564
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    A differential absorption spectrometer for bremsstrahlung diode voltage measurement : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4792-4794 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An indirect voltage measurement of a relativistic electron beam diode can be deduced from the high energy tail of its bremsstrahlung spectrum. Our spectrometer contains seven silicon pin diode detectors with filters optimized to cover the 0.5–2 MV range. Theoretical response functions were calculated using the CYLTRAN Monte Carlo transport code with the next event estimator method. Diode voltage measurements performed with the spectrometer on the PITHON x-ray simulator are in good agreement with the standard electrical measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143565
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  • 91
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    Study on the mechanism of negative ion formation in cesium sputter-type negative ion sources : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2643-2645 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The mechanism of forming negative ions in cesium sputter negative ion sources is studied by means of a modified dipole layer model and quantum theory. Formulas of the change of work function on the metal surface adsorbing cesium layer and the electron transfer probability are given. The formation probabilities of the negative ions are derived using a quantum tunneling model. The negative ion yield is also calculated. The calculated results are in essential agreement with the experimental data. The philosophy described in this paper may offer a useful theoretical model for the mechanism study of cesium sputter negative ion sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142866
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  • 92
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    Voltage monitors for high-power 10–20 MV pulsed electron accelerators : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4795-4798 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Four monitoring techniques that can determine peak voltage (Vp) to a precision of ∼5% for high-intensity, pulsed electron accelerators operating in the 10 to 20 MV range are discussed and applied to the 14-TW HERMES III accelerator. The techniques utilize parapotential flow theory, the range of H− ions, the bremsstrahlung from electron interactions with an electron target, and the photoneutron fluence from neutrons generated in a bremsstrahlung target. Application of these techniques to HERMES III shows that when the accelerator is operating under nominal conditions, Vp=(18.7±0.7) MV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143566
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  • 93
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    Remote operation of the TFTR BES experiment from an off-site location : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4803-4805 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The capability of controlling a diagnostic subsystem and interactively participating in the experimental program on Tokamak Fusion Test Reactor (TFTR) from a remote site has been developed and demonstrated on the TFTR BES experiment. Interactive communications are established from multiscreen remote workstations at the University of Wisconsin to the Princeton Plasma Physics Laboratory VAX cluster via multiple terminal sessions across the InterNet national network. Full control of the diagnostic, access to all relevant machine parameters and wave forms, and operations run logs are all available with automatic updates between plasma shots. A real-time count-down shot clock with timer, machine event status, and shot number provides a real-time interface to the TFTR shot sequence. This means of remote participation in a central fusion experiment provides vital experience for extrapolation to implementation on an ignition device to test engineering concepts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143568
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  • 94
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    Is it advantageous to use a commercial CCD for data acquisition in pulsed experiments? (abstract) : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4809-4809 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We found that a CCD compared favorably with the film currently used to record gated XUV camera images from plasma physics experiments. The CCD was 20 times as sensitive as the film, indicating that the CCD has an effective ISO of 40 000. The camera was successfully shielded from electromagnetic pulses with electric field strengths of 0.7–1 kV/m and pulse widths of 30–65 ns. The CCD also survived the γ-ray pulse, and no degradation in performance was seen after an accumulated dose of 10–20 rad. We also successfully acquired optical light images of a Z pinch using a commercial camcorder.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143570
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  • 95
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    Plasma sputter negative ion source with ECR discharge (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2669-2671 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A plasma sputter type of negative ion source with an electron cyclotron resonance (ECR) discharge has been developed at KEK. The ECR discharge was produced by a 2.45-GHz microwave. In this ion source, negative heavy ions are produced at the surface of the metal which is placed in a Xe plasma confined by a cusp magnetic field. In preliminary experiments, the beam current of 7 mA for Cu− was obtained in pulsed mode operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142871
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  • 96
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    Negative ions generated by laser-material interaction (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2672-2675 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Different applications and results in the generation of laser-induced negative ions are reviewed. Emphasis is put on analytical achievements as well as recent developments in very high negative ion currents. Yields up to 4 mA have been observed. The production mechanism is discussed. Three-body collisions in the extremely dense laser plasma are considered to be the origin of the strong yields observed. Already, a dedicated source has been constructed, but, e.g., a conventional cesium-beam sputter source is also well suited to serve as a laser ion source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142872
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  • 97
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    20 years of cesium catalysis for negative ion production in gas discharges (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2660-2668 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Cesium catalysis, considerable acceleration of negative ion production in a gas discharge by injecting a small admixture of cesium or other substances with low ionization potential (for example, the first or the second group elements), is used now very widely in ion sources. The cesium injection turns on the catalysis of negative ion production on the electrodes surface, bombarded by particles from discharge plasma. The cesium adsorption significantly increases the probability of the electron capture from the electrode surface to the electron affinity levels of sputtered and reflected particles by decreasing the surface work function from 4–5 eV up to 1.5 eV. It increases considerably negative ion containment in particle flux from the surface. Ion sources using cesium catalysis have been named surface plasma sources (SPS), because for their operation a strong interaction of gas discharge plasma with a surface is very important. However, volume negative ion production depends on cesium admixture and surface processes also. Highly efficient cesium catalysis has been discovered in Novosibirsk Institute of Nuclear Physics on July 1, 1971. During 20 years in many laboratories around the world wide investigations of physics processes in surface-plasma sources have been executed. Various types of SPS, optimized for different applications in accelerators, in plasma physics and thermonuclear research, in technology, have been developed. The distinctive features of physical processes in SPS and technological development for high efficient SPS operation are reviewed in presented papers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142870
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  • 98
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    Plasma diagnosis related to ion sources (invited) : Proceedings of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2676-2682 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The different kinds of ion sources have been most commonly classified according to the extracted beam parameters: ion charge state, energy and current, and beam quality. We adopt here a somewhat different approach: ion sources are usually plasma sources where each component (ionic as well as electronic) plays an important role. This article deals with the experimental techniques which can be used to get information on the plasma state of an ion source. In Section II the interest of the different plasma parameters is discussed. Section III describes a few well-known techniques of plasma diagnostics; examples of their applications on ion sources or related devices are given and limitations of these existing techniques are discussed. Section IV presents some of the work that is needed to get a more accurate description of the plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143806
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  • 99
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    Experiments on the multiampere negative ion source in National Institute for Fusion Science : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2683-2685 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The multiampere negative hydrogen ion source has been developed in National Institute for Fusion Science (NIFS). The ion source is a volume-production type multicusp one with an extraction area of 25×25 cm2. It is found that high density negative hydrogen ions of more than 1 × 1012 cm−3 are produced in the center of the arc chamber with a double magnetic filter configuration. A supply of a small amount of cesium vapor into the arc chamber has greatly enhanced the H− ion current and reduced the operation pressure. The H− ion current of 3.3 A has been extracted from a Cs-seeded plasma at the pressure of 0.9 Pa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142822
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  • 100
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    H− and D− temperature in volume sources : Proceeding of the fourth International Conference on Ion Sources (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2686-2688 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new technique using laser induced photodetachment has been developed for measuring the negative ion temperature in H− and D− sources. Using this technique, we have investigated the dependence of the negative ion temperature on source parameters such as pressure, discharge current, and electron temperature. Simultaneous measurements of negative ion density, temperature, and extracted current lead to the conclusion that the extracted negative ion current is, at most, equal to the thermal flux.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142823
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