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  • 1
    Electronic Resource
    Electronic Resource
    Soft x-ray tomography on the RTP tokamak : Eighth topical conference on high—temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3067-3069 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A soft x-ray tomography system is being constructed for the RTP tokamak. The main aim of this system is to measure fluctuations in the plasma emissivity with relatively high poloidal m number. Five pinhole cameras will be distributed inside the vessel in such a way that it becomes possible to reconstruct modes up to m=4, without making any assumption about the plasma rotation. The system has been designed to obtain a minimum bandwidth of 200 kHz and a temporal resolution of 1 μs. We describe the hardware that is under construction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141729
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  • 2
    Electronic Resource
    Electronic Resource
    Ion temperature measurements in tokamak plasmas by Rutherford scattering (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3359-3368 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A Rutherford scattering diagnostic has been applied at the TEXTOR tokamak to obtain spatially and temporally resolved information on the temperature of the bulk ions in the plasma. In the experimental setup, a helium atomic beam (30-keV, 12-mA equivalent current) passes vertically through the plasma core. A small part of the injected atoms is scattered elastically by the thermally moving plasma ions. The ion temperature in the scattering volume can be determined from the broadening of the energy spectrum of the scattered particles. Energy analysis of the scattered atoms is performed by a mass-selective time-of-flight analyzer detecting the particles at an observation angle which is selectable between 3° and 8°. Coincidence techniques have been successfully applied in this detector for rejection of background events triggered by detections of neutrons and gamma radiation. Ion temperature profiles were measured on a shot-to-shot basis by shifting the cross section of the diagnostic beam and the observational volume of the analyzer through the plasma. The ion temperatures measured in ohmic deuterium plasmas were found to be in reasonable agreement with those obtained from passive neutral particle analysis. Up to now, ion temperatures have been measured throughout the complete discharge with an accuracy of 8% and a time and space resolution of 100 ms and 0.10 m at a scattering angle of 7°. Deuteron density profiles could be deduced from the scattering yield measured at different radial positions in the plasma. The ratio of the isotopes, hydrogen and deuterium, was determined from their separate contributions to the spectrum of helium particles scattered on hydrogen and deuterium. Although theoretical predictions showed that the majority of the probing helium atoms loses one of its electrons during the elastic scattering process on multiply charged carbon and oxygen ions, contributions from impurities to the observed experimental spectrum are shown to appear dominant for impure plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142553
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  • 3
    Electronic Resource
    Electronic Resource
    Soft x-ray tomography diagnostic at the RTP tokamak (1994)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2295-2305 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An 80-channel soft x-ray tomography system has been constructed for diagnosing the RTP (Rijnhuizen Tokamak Project) tokamak plasma. Five pinhole cameras, each with arrays of 16 detectors are distributed more or less homogeneously around a poloidal plasma cross section. The cameras are positioned close to the plasma edge to enable viewing angles which could not be reached otherwise. The system can be used for making tomographic reconstructions of the soft x-ray emissivity with a relatively high poloidal mode number (up to both components of m=4), which is an improvement with respect to other plasma tomography systems presented in literature. The temporal resolution of the system is 5 μs. Apart from a description of the hardware and geometrical layout of the system, the paper will focus on two important issues, namely the calibration of the detectors and the positioning of the cameras in the vacuum vessel of the tokamak. A dedicated x-ray source has been designed for the relative calibration of the detectors of each individual camera. Misalignment causes several artifacts in tomographic reconstructions obtained with multicamera systems. Therefore, two new methods are proposed which make use of the plasma itself for improving the knowledge about the positions of the cameras.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144680
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  • 4
    Electronic Resource
    Electronic Resource
    H−-conversion aided detection of low-energy H0 fluxes from the TORTUR tokamak in a time-of-flight analyzer (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 2223-2231 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A time-of-flight spectrometer has been developed to examine the velocity distribution of the hydrogen charge-exchange particles emitted from the TORTUR tokamak. To investigate the scrape-off layer, the spectrometer has been made sensitive to low-energy hydrogen atoms. This has been done by converting the hydrogen atoms into more easily detectable negative hydrogen ions on a cesiated monocrystalline tungsten surface. This detection technique enables examination of the neutral particle flux in a large energy range (5–2000 eV). Typical examples of time-of-flight spectra recorded during TORTUR discharges will be shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143143
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  • 5
    Electronic Resource
    Electronic Resource
    Physicochemical studies on the interaction of pancreatic phospholipase A2 with a micellar substrate analog (1981)
    s.l. : American Chemical Society
    Biochemistry 20 (1981), S. 4068-4073 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00517a019
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  • 6
    Electronic Resource
    Electronic Resource
    Binding of porcine pancreatic phospholipase A2 to various micellar substrate analogs. The involvement of histidine-48 and aspartic acid-49 in the binding process (1981)
    s.l. : American Chemical Society
    Biochemistry 20 (1981), S. 4074-4078 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00517a020
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  • 7
    Electronic Resource
    Electronic Resource
    Localization of the second calcium ion binding site in porcine and equine phospholipase A2 (1983)
    s.l. : American Chemical Society
    Biochemistry 22 (1983), S. 2470-2478 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00279a025
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  • 8
    Electronic Resource
    Electronic Resource
    An electrostatic time-of-flight analyzer for simultaneous energy and mass determination of neutral particles (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 110-117 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A neutral particle energy analyzer has been developed to measure both the energy and the mass of the incoming particles with only one array of detectors. Energy analysis is performed by means of deflection in an electrostatic field. The mass of the particle is determined by measuring the flight time from a stripping foil to a channel electron multiplier in the focal plane of the analyzer. The application of a stripping foil instead of a gas cell increases the stripping efficiency and simplifies the vacuum system. Monte Carlo simulation studies and first calibration experiments show that the analyzer can be used even at energies down to 1 keV, as long as the stripping foil does not exceed a thickness of 2.0 μg/cm2. These simulations take into account the angular and energy straggling processes that take place in the foil. A triple-coincidence technique can be applied to decrease the sensitivity of the analyzer to neutron and gamma background radiation considerably, as will be shown by calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142317
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  • 9
    Electronic Resource
    Electronic Resource
    Multichannel interferometer/polarimeter system for the RTP tokamak : Eighth topical conference on high-temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 2882-2884 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A nine-channel interferometer/polarimeter system is designed for the RTP tokamak (Rijnhuizen Tokamak Project, a =0.16 m, R =0.72 m, BT =2.5 T, Ip ≤ 200 kA, and plasma pulse duration 200 ms). A CO2-pumped dual-cavity FIR laser system is used to obtain two FIR laser beams of λ =432 μm with a frequency difference of 1 MHz. The FIR beams are expanded by a set of parabolic mirrors. Corner-cube mixers with Schottky diodes are used as detectors. The mixers are mounted on a linear rail system, such that their positions can be easily changed. The interferometer can be operated with a maximum of 19 channels, and will be extended with a polarimeter to measure the poloidal magnetic field distribution. It will be tried to increase the accuracy of the polarimeter by modulating the polarization of the incoming beam. A scheme for polarization modulation which is based on the idea of Dodel and Kunz will be presented in this paper. This scheme has the advantage that only one set of detectors is needed to measure the electron density and current density. The complete system will be presented along with some pilot experiments concerning the polarization modulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141814
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  • 10
    Electronic Resource
    Electronic Resource
    A time-of-flight spectrometer for detection of low-energy hydrogen atoms : International conference on ion sources (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 622-624 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article deals with an application of the technique of converting hydrogen atoms into negative ions on a low-work-function surface, which is similar to the method nowadays utilized in H− surface sources. This conversion technique is the basis for a time-of-flight spectrometer, for which a proof of principle has recently been established. The conversion takes place on a tungsten (110) crystal target that is covered with cesium. By mounting this target in the detector part of the spectrometer, this apparatus is made sensitive to hydrogen atoms that have energy in the range 10–1000 eV. This feature makes the spectrometer a very powerful and unique tool for detection of low-energy hydrogen atoms. It is, for instance, capable of detecting low-energy hydrogen atoms that are emitted from the edge of a tokamak plasma, and therefore it can yield information on the hydrogen recycling inside the tokamak and hence on the energy balance of the plasma. In the paper we discuss the principle of the detection method, along with a presentation of some time-of-flight spectra that have been obtained from a tokamak plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141938
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