ALBERT

Notes: We demonstrate a linear radio-frequency trap for confining strontium ions that is simply constructed nearly entirely with commercial off-the-shelf components. The electrodes of this trap are spaced to allow tight radial confinement, and segmented to give tight axial confinement with minimal distortion of the radio-frequency field. The resulting secular frequencies of the trap are 1 MHz in the radial direction and 100 kHz in the axial direction, the ions can be imaged with 2–3 μm resolution, and we detect over 20 000 photons per second per ion. This article describes the construction of the vital parts of the trap system, the laser system and optics used to Doppler cool the ions and to observe quantum jumps, and the operation and behavior of the complete system. © 2002 American Institute of Physics.

Notes: The design and operation of an ultrahigh vacuum (UHV) compatible ionization chamber for fluorescent x-ray detection in the hard-x-ray regime is described. The detector is comprised of two main components: an UHV compatible, bakeable housing and multiple, 90% transparent, nickel wire-mesh internal collectors. The detector has been used successfully to study molecular beam epitaxy prepared metal thin films in situ. © 2002 American Institute of Physics.

Notes: High-frequency oscillations (1–100 MHz) in Hall thrusters have not received sufficient experimental scrutiny. A diagnostic setup, consisting of a single Langmuir probe, a special shielded probe connector-positioner, and an electronic impedance-matching circuit, was successfully built and calibrated. Through simultaneous high-frequency probing of the Hall-thruster plasma at multiple locations, high-frequency plasma waves have been successfully identified and characterized (Ref. 1). © 2002 American Institute of Physics.

Notes: Aperture, pin-hole and collimator detection systems are often used in plasma diagnostics, for example, in soft x-ray detection and bolometer systems. In this article the simultaneous optimization of viewing-beam overlap and light yield is considered in multi-channel aperture and collimator systems for two-dimensional (2D) tomography. This article briefly highlights the relation between beamwidth overlap and spatial aliasing in tomography, and how aliasing can be avoided in theory and in practice. Three-dimensional (3D) single-channel aperture and collimator systems can be approximated by a combination of two planar systems if the aperture is rectangular. Three ways to optimize beamwidth overlap and light yield for planar aperture and collimator systems are considered in detail: overlap of the angular étendue at the full width at half maximum (FWHM), overlap of the geometric function at the FWHM a certain distance from the aperture, and arbitrary overlap for a given maximum beamwidth. The combination of 2D effects from all three optimization methods were used in the design of 3D apertures for a new multi-channel bolometer camera on the Joint European Torus tokamak. The resulting apertures are complex, but the new camera has several advantages over previous cameras. © 2002 American Institute of Physics.

Notes: Two problems of technological importance for microelectromechanical systems (MEMS) and microelectronics industry are addressed: fatigue of thin films and nanoscale film cracking. A device is described that can (1) conduct biaxial fatigue tests on thin films and (2) be utilized to study fracture patterns in nanoscale coatings under biaxial stress state. Thin-film specimens, in the form of circular membranes, are exposed to cyclic pressures between two fixed pressure limits. Corresponding pressure and specimen deflection are measured. Experimental results, including hysteresis loops spanning deflections of 15–50 μm are presented for 4.6-μm-thick polyimide films. Furthermore, the evolution of crack patterns in a 150-nm-thick Al film deposited on a polyimide substrate is studied. Critical mode I stress intensity factor for Al is extracted from experimental results. © 2002 American Institute of Physics.

Notes: The characterization of a direct current, low-pressure, and high-density reflex discharge plasma source operating in argon and in nitrogen, over a range of pressures 1.0–10−2 mbar, discharge currents 20–200 mA, and magnetic fields 0–120 G, and its parametric characterization is presented. Both external parameters, such as the breakdown potential and the discharge voltage–current characteristic, and internal parameters, like the charge carrier's temperature and density, plasma potential, floating potential, and electron energy distribution function, were measured. The electron energy distribution functions are bi-Maxwellian, but some structure is observed in these functions in nitrogen plasmas. There is experimental evidence for the existence of three groups of electrons within this reflex discharge plasma. Due to the enhanced hollow cathode effect by the magnetic trapping of electrons, the density of the cold group of electrons is as high as 1018 m−3, and the temperature is as low as a few tenths of an electron volt. The bulk plasma density scales with the dissipated power. Another important feature of this reflex plasma source is its high degree of uniformity, while the discharge bulk region is free of electric field. © 2002 American Institute of Physics.

Notes: We present a new three-step auto-alignment algorithm for the specimen stage of an ellipsometer with adjustable angle of incidence. Correction of errors in tilt angle and position of the specimen stage can be performed by locating the reflected light spot at the center of the detector at two different angles of incidence. The current method does not need auxiliary focusing equipment. The alignment algorithm works to high precision in both model simulation and practical experiments with a rotating analyzer ellipsometer. © 2002 American Institute of Physics.

Notes: A measuring system that integrates a low-temperature optical cell UV-visible (UV-Vis) for air exclusion experiments with a liquid x-ray absorption spectroscopy (XAS) cell (x-ray absorption near-edge spectroscopy and extended x-ray absorption fine structure) is reported here together with its application in studies of organometallic complexes. UV-Vis measurements are performed in a three-compartment glass vessel, fitted with an external fiber optics probe. This UV-Vis cell is suitable for the measurement of oxygen- and air-sensitive compounds at variable temperatures (RT to −78 °C). The liquid XAS cell is filled with the UV-Vis solution at low temperature and can be used in both fluorescence- or transmission-mode measurements with (frozen) solutions. The complete measuring system is reusable and easy to clean and handle. To test the performance of these cells the oxygenation behavior of a dinuclear organometallic copper(I) complex was studied in acetone by UV-Vis and XAS. It is shown that direct correlation of low-temperature UV-Vis and XAS data is possible in organic solvents. © 2002 American Institute of Physics.

Notes: We have conducted measurements at five different thermal neutron wavelengths to determine the transmission characteristics of a tapered monolithic focusing lens with a focal length of 100 mm, suitable for time-of-flight diffraction. Both the width of the focused beam and the intensity gain of the optic increase as a function of wavelength. We have performed similar measurements on a polychromatic beam on a pulsed neutron source, where the results are subject to background from short wavelength neutrons. The use of a beryllium filter shows the increased effective gain for the longer wavelengths at the expense of an increased focused beam width by a factor of 2. © 2002 American Institute of Physics.

Notes: Kapton film is used to image K+ ion beams in the 0.4 to 2 MeV energy range. Dose response is shown to be linear and to follow a simple model for a range of exposures. The measured profiles agree with profiles obtained with a slit scanner. Kapton has excellent spatial resolution, dynamic range, and discrimination against stray low energy and low mass particles. © 2002 American Institute of Physics.

Notes: For compensation of the magnetically deflected beamlets, a new type of grid system has been applied to a large negative ion source of a negative-ion-based neutral beam injector in the Large Helical Device (LHD) fusion experimental machine. Corresponding to deviation of the negative ion beamlet trajectory due to the electron suppression magnetic field at the extraction grid, the exit aperture of the extraction grid is displaced to cancel the beamlet deflection by electrostatic lens effect. As a result, the beamlet deflection was suppressed less than 2 mrad in a wide range of energy of 110–180 keV, and the port-through efficiency of the injected beam was improved to 90%–95% from 70%–75% in the case of the previous compensation by the grounded grid aperture displacement. The injected beam power was increased to 3.5 MW with an energy of 165 keV using one injector. To improve beam uniformity of the large area beam, individual arc currents through filaments are controlled for uniform plasma production, with independent 12 arc power supplies connected to 12 filament power supplies. The initial results show good controllability of the individual arc current distribution at a high arc power. The improvement of the ion source performance would lead to an increase in the injection power in the following LHD experimental campaign. © 2002 American Institute of Physics.

Notes: The target performance for the KAMABOKO ion source on the MANTIS test bed in Cadarache is to accelerate a beam of D− with a current density of 200 A/m2 and 〈1 extracted electron per accelerated D− ion, at an injected power ranging between 1 and 2 kW per liter of source volume, at a source pressure of 0.3 Pa. For ITER, a continuous neutral beam must be assured for pulse lengths of 500 s, but beams of up to 3600 s are also envisaged. During the last campaign, continuous beam pulses of duration up to 1000 s were demonstrated both in hydrogen and in deuterium. In this article, the source performance, the effect of the plasma grid temperature for long pulse operation, and the limits of the present experimental setup are described. Additionally, the effect of changing the strength of the magnetic filter in the ion source on the extracted ion and electron currents and the beam transmission is reported. © 2002 American Institute of Physics.

Notes: The application of the folded pendulum (FP) as a tiltmeter is proposed and some features of it have been studied both theoretically and experimentally. First, FP could have a quite low resonance frequency due to its mechanical structure. The period of our prototype FP is 6.2 s and the amplification factor is about 100. Second, FP is not sensitive to the environmental temperature variation but seriously affected by the temperature gradient. The experiment with a temperature gradient modulation shows that the static equilibrium position of the FP will change by 2.5 μrad if the temperature difference between the horizontal platform and the base of the FP is 0.1 °C. With a prototype FP, we have observed obvious tilt tides, and the calibration result shows that the resolution of the FP is about 1.2 nrad. © 2002 American Institute of Physics.

Notes: This article reports on the frequency stability measurement system based upon the dual-mixer time-difference scheme working at 10 MHz with 1 Hz beat note. The principle of the system is reviewed, the design approach is described, and the experimental results are presented. The measurement system shows a stability of 5.6×10−14/τ (Allan deviation) and a temperature sensitivity of some picoseconds per Kelvin. An approach to reduce crosstalk problems has been tested. © 2002 American Institute of Physics.

Notes: A multipoint vibration sensor realized in integrated optics is presented. The sensor is composed of four optical heads that have been conceived for the simultaneous measurement of vibrations (in terms of displacement) in several points of a vibrating mechanical system with the aim of an industrial diagnostic. The system presented here is realized on small silicon chips (28 mm×28 mm) using integrated optic (IO) technology, each chip realizing a dual Michelson interferometer. The conditioning and acquisition system for the signal, based on an A/D conversion board is reported together with a brief description of the optical circuit. Experimental tests carried out on the sensor have provided maximum velocity and maximum operating frequency of the sensing system. Frequency response function tests carried out with a commercial single-point laser Doppler displacement sensor are reported in the present article together with the laboratory setup and test results. The network of vibration sensors in integrated optics, the object of the study, have proven to be capable of measuring the vibration displacement of varnished metal surfaces optically untreated with good accuracy (1% standard uncertainty on the instantaneous amplitude) in a frequency range 0–200 Hz with surface velocities up to 100 mm/s. Limitation of the data processing unit have been discussed for vibration frequencies higher then 200 Hz. © 2002 American Institute of Physics.

Notes: A high power fiber delivery system has been developed for a Q-switched Nd:YAG laser. Multimode fibers with a core diameter of 400 μm were tested with a view to transmitting the maximum possible amount of optical energy. The importance of surface finish was investigated by employing a number of different polishing procedures. Atomic force microscopy and laser-induced damage threshold measurements were used to identify a clear correlation between surface finish and transmission capability. Surface roughness measurements as low as 3 nm were made and the transmission of up to 30 J/cm2 achieved. The front face of the fibers would be improved during laser testing due to plasma formation which acts to anneal the surface. The various damage mechanisms that limit the performance of the fiber have been studied and attributed to different optical and physical effects. The nature of the light spot emerging from the fiber was analyzed and quantified by beam profilometry. A number of different methods for altering the beam profile were tried but changing the length of the fiber was found to be the most effective. © 2002 American Institute of Physics.

Notes: In this article, we present a variation on the design of the micromachined flextensional transducer for use to eject liquids. The transducer is constructed by depositing a piezoelectric thin film to a thin, edge clamped, circular annular plate. By placing a fluid behind one face of a vibrating compound plate that has an orifice at its center, we achieve continuous or drop-on-demand ejection of the fluid. We present results of ejection of water and isopropanol. The ejector is harmless to sensitive fluids and can be used to eject fuels, organic polymers, low-k dielectrics, chemical, and biological samples. Micromachined two-dimensional array piezoelectrically actuated flextensional droplet ejectors were realized using planar silicon micromachining techniques. Typical resonant frequency of the micromachined device ranges from 400 kHz to 4.5 MHz. The ejection of water through a 5 μm diameter orifice at 3.5 MHz was demonstrated by using the developed micromachined two-dimensional array ejectors. © 2002 American Institute of Physics.

Notes: A compact plasma accelerator concept based on plasma production at a magnetic cusp was designed and fabricated. Plume and discharge characteristics of the device were documented using a Faraday probe and a retarding potential analyzer. The discharge current variations with increasing discharge voltage were nonlinear with the discharge current increasing rapidly with voltage. The device demonstrated the capability of generating ion beamlets (∼80 eV) with downstream peak current densities comparable to that of higher power ion thruster devices (7 mA/cm2). In general, the device appeared to operate best at very low flow rates. High propellant utilization fractions (ionization fractions) were measured below 1 SCCM of Xe flow (88% at 0.48 SCCM). Floating potential measurements made downstream of the device were used to estimate the downstream electric field. These measurements, which were used to qualitatively assess beam neutralization, indicated beam neutralization does occur downstream of the device. Based on the measurements, the compact plasma accelerator concept could potentially be used as a low energy ion source for propulsion applications or for low energy plasma/materials processing applications.

Notes: We demonstrate high-speed near-field scanning optical microscopy using a tapered fiber tip that is inserted in a perforated quartz-crystal resonator. With this high-frequency dithering probe, we have obtained near-field optical images at the scanning speed of 1.3 mm/s and it takes only 0.5 s to image the surface area of 100 μm2 for 64×64 pixels without any compromise of spatial lateral resolution. As an application, we have obtained sequential scanning images of the diffusing microspheres in water, which shows slow change of the sample configuration in the time scale of several minutes. © 2002 American Institute of Physics.

Notes: An optical fiber interferometer for measuring the d33 coefficient of piezoelectric samples is described. Its configuration is based on the Mach–Zehnder interferometer, and a double incidence on the thin-film samples successfully suppresses the undesirable bending effect of the substrate. Detection of the small displacement is based on an active homodyne scheme. Results are reported for a bulk piezoelectric transducer (PZT) sample and a PZT thin-film incorporated in a microactuator. © 2002 American Institute of Physics.

Notes: A simple optical multiple reflection system is developed with two cylindrical concave mirrors at an appropriate spacing. The two cylindrical mirrors have different focal lengths and their principal sections are orthogonal. The alternate focusing of the two cylindrical mirrors at different direction keep the reflecting spots small. The reflecting spots fall on Lissajous patterns on the cylindrical mirrors. The mathematics for this optical system is described and the calculated coordinates of beam spots are very close matches of the experimental observations. The cylindrical mirror optical system is easy to construct and align, with a suitable method for obtaining long optical paths and a large number of passes in small volumes. In a photoacoustic spectrometer the beam family enhance the effective power in the photoacoustic cell and thus the signal-to-noise ratio of photoacoustic signal. An experimental result for photoacoustic spectrum of HDSe gas is given. © 2002 American Institute of Physics.

Notes: A laser-based instrument is described for the study of femtosecond dissociation dynamics of gas phase molecules via time-resolved vacuum ultraviolet and soft x-ray photoelectron spectroscopy. Visible or UV pump pulses are generated with nonlinear crystal techniques on a Ti:sapphire laser output, while soft x-ray probe pulses are created via high-order harmonic generation of the same laser in rare gases. Here we describe the optical layout of the pump-probe system, the means for separation of the high-order harmonics in the soft x-ray probe beam, including a description of the two grating setup used to compress the high-harmonic pulses and the magnetic bottle photoelectron spectrometer used for data collection. The feasibility of using the generated high-harmonic pulses for an array of gaseous phase photoelectron spectroscopy experiments is established. These include measurements of valence shell and core-level photoelectron transitions in atoms and molecules, the tunability of the soft x-ray harmonic through Rydberg resonances, and the energy bandwidths of the harmonics. Cross correlations between the visible/UV and soft x-ray pulses, by above threshold ionization, are used to establish the pulse timing, pulse duration, and spatial overlap for ultrafast studies. The observed real time photodissociation of Br2 serves as a demonstration of the pump-probe ultrafast technique and the applicability to ultrafast time-resolved chemical dynamics. © 2002 American Institute of Physics.

Notes: A method allowing the making of any multiphase, voltage-controlled, sinusoidal signal generator is presented. To prove its feasibility, a three-phase, voltage controlled, sine wave signal generator was built. The differences between the three phase sine waves are kept precisely at 120° and a perfect matching of the signal magnitudes is obtained whatever the frequency value. A very low distortion rate and a wide frequency range can be obtained. The described circuit is particularly attractive to build low or ultralow frequency multiphase sinusoidal oscillators. © 2002 American Institute of Physics.

Notes: We present a new instrument for space-based observational solar physics, recently flown successfully on a sounding rocket, designed to provide high spatial resolution, time-resolved images of the solar corona at specific wavelengths in the extreme ultraviolet (XUV). The primary instrument employs multilayer x-ray mirrors in a novel geometry that affords quasi-monochromatic imaging at wavelengths tunable continuously over the spectral range from 17.1 to 21.1 nm. The secondary instrument also uses multilayer x-ray mirrors to provide high-resolution imaging at three fixed XUV wavelength bands. Both instruments use charge coupled device detectors and thin A1 filters for rejection of unwanted wavelengths. We describe the design, construction, and performance of the instrument and discuss prospects for the future. © 2002 American Institute of Physics.

Notes: This article describes a wide-field time-domain fluorescence lifetime imaging (FLIM) microscope with optical sectioning. The FLIM system utilizes a wide-field time-gated optical image intensifier, with a minimum gate width of 85 ps, to achieve high temporal resolution of fluorescence decays induced by ultrashort laser pulses. Different configurations, using excitation pulses of picojoule energy at 80 MHz repetition rate and of nanojoule energy at 10 kHz, are compared. The instrument has a temporal dynamic range spanning from 100 ps to tens of μs and is shown to have a temporal discrimination better than 10 ps. When applied to laser dye samples, it has produced FLIM maps demonstrating sensitivity to variations in both chemical species and local environment, e.g., viscosity. Wide-field optical sectioning is achieved using the technique of structured illumination, which is applied to remove out-of-focus light that can result in lifetime artifacts. The sectioning strength, which may be adjusted by choosing an appropriate spatial modulation frequency, is characterized and shown to be comparable to that of a confocal microscope. Practical considerations concerned with improving the quality of sectioned fluorescence lifetime maps, including using a large bit depth camera, are discussed. © 2002 American Institute of Physics.

Notes: A digital image tracking algorithm based on Fourier-transform cross-correlation has been developed to correct for instrumental drift in scanning tunneling microscope images. A technique was developed to eliminate cumulative tracking errors associated with fractional pixel drift. This tracking algorithm was used to monitor conductance changes associated with different conformations in conjugated molecular switch molecules and to trace the diffusion of individual benzene molecules on Ag{110}. Molecular motions have been tracked for up to 25 h (400 images) of acquisition time. © 2002 American Institute of Physics.

Notes: A simple device for simultaneously measuring two spatially separated contact forces is described. The device uses a monolithic dual-cantilever touch sensor driven by a piezoelectric PZT actuator. A phase-locking method allows measurement of resonant frequency shifts at constant phase, based on the strain response of a second attached PZT. Calibration and force measurement procedures are developed to extract applied contact forces from the dual-cantilever's coupled, nonlinear response. Based on a preliminary calibration, the present device exhibits maximum relative measurement error on the order of 6%. Procedures for reducing this error are described. © 2002 American Institute of Physics.

Notes: Potentiostatic circuit configurations with work electrodes and auxiliary electrodes at ground potential have been reviewed and compared. Though the former is by far the best known and most used, the latter was more convenient and accurate in interfacial capacity measurements. © 2002 American Institute of Physics.

Notes: The optimization of mixed-principle operation pressure balance consisting of two parts: simple-piston and re-entrant cylinder units is reported. The maximum high pressure corrections for low pressure effective area of the system can be reduced by 50%. The solution was obtained by application of a small reduction (step) of the piston diameter. The modified design is characterized by the performance of the metrological piston of 10 mm2 nominal cross-sectional area with a (1–3) μm inward circumferential step located between the upper (simple piston) and lower (re-entrant) parts of the cylinder in the area where existing intermediate pressure is constant. © 2002 American Institute of Physics.

Notes: We attempt to improve the Helmholtz coil by adding a third coil with the same radius connected in series. In this three-coil array, the distance from the outside coils to the central coil is 0.760 times radius of the coils, and the ratio of the number of turns, central to the outside, is exactly 59 to 111. Numerical results demonstrate that the uniform region of magnetic field in the improved Helmholtz coil is larger than that of the Helmholtz coil and of Maxwell's tricoil. © 2002 American Institute of Physics.

Notes: In this article we describe the design and construction of a laboratory astrophysics experiment that recreates the harsh conditions of the Interstellar Medium (ISM) and is used to study the heterogeneous chemistry that occurs there. The Nottingham Surface Astrophysics Experiment is used to determine, empirically, accurately, and usually for the first time, key physical and chemical constants that are vital for modeling and understanding the ISM. It has been designed specifically to investigate gas–solid interactions under interstellar conditions. The pressure regime is ideally matched to molecular densities in dusty disks in protostellar or protoplanetary regions. The ultrahigh vacuum system is routinely capable of obtaining pressures that are only three orders of magnitude above those in the ISM, with similar relative concentrations of the two most abundant gases in such regions, H2 and CO, and an absence of any other major gas components. A short introduction describes the astronomical motivation behind this experiment. In Sec. II we then give details of the design, construction, and calibration of each component of the experiment. The cryostat system has far exceeded design expectations, and reaches temperatures between 7 and 500 K. This is comparable with the ISM, where dust temperatures from 10 K have been observed. Line-of-sight mass spectrometry, reflection absorption infrared spectroscopy, and quartz crystal microbalance mass measurements were combined into a single instrument for the first time. The instrument was carefully calibrated, and its control and data acquisition system was developed to ensure that experimental parameters are recorded as accurately as possible. In Sec. III we present some of the experimental results from this system that have not been published elsewhere. The results presented here demonstrate that the system can be used to determine desorption enthalpies, ΔdesH, bonding systems, and sticking probabilities between a variety of gases and ices common to the ISM. This instrument will greatly facilitate our understanding of surface processes that occur in the ISM, and allow us to investigate "mimic" ISM systems in a controlled environment. In this article we illustrate that laboratory surface astrophysics is an exciting and emerging area of research, and this instrument in particular will have a major impact through its contributions to both surface science and astronomy. © 2002 American Institute of Physics.

Notes: A compact tape drive applicable in experiments with repetitively pulsed lasers is described. By exposing fresh material to the laser pulse at each shot, it is possible to obtain up to 104 shots in a single run. A particular tape can be used many times. The tape target provides stable output, is easy to adjust, and is low cost in operation. The possibility of illuminating samples with the rear-side emission is a further advantage for many applications. Experiments are described in which a copper tape, 10 m long, 12 mm wide, and 25 μm thick, is used to generate Cu Kα radiation. Applying 2 TW titanium–sapphire laser pulses, yields 2.7×109 Kα photons/Sr per shot. Bragg and powder spectra generated with this radiation are shown. © 2002 American Institute of Physics.

Notes: We present the design principles of a compact general-purpose fast high-power (and low-cost) pulser for inductive load, using an isolate gate bipolar transistor, a dedicated smart driver unit and digital control designed in very high speed integrated circuit hardware description language. We demonstrate the performance of this pulser as a driver for a high-pressure supersonic pulsed valve. © 2002 American Institute of Physics.

Notes: We report on the generation of a background-free nearly transform-limited picosecond pulse using a simple quenching scheme in a distributed feedback dye laser. The pulsewidth and spectral linewidth were 65 ps and 10 pm, respectively. The product of these values is 0.650, which is close to the transform limit of 0.441 for a Gaussian pulse. © 2002 American Institute of Physics.

Notes: A facile tool is suggested for cutting the protruding flange of photoresist (PR) along the edge of a small substrate surface, which is caused by the spin-coating process in lithography. When the dimension of the substrate reduces to a few millimeters, the edge problem of PR cannot be ignored. Since the PR's thickness along the edge of the sample is much larger than that in the middle, a traditional double exposure method does not work well. The cutter proposed here consists of a blade and a sample holder, which are installed in a base. By adjusting the blade at a suitable dip angle and pushing it to the flange of PR along the edge of substrate fixed by the sample holder, the flange of PR of small samples will be eliminated completely with great ease. © 2002 American Institute of Physics.

Notes: A comparison of different calibration methods for optical tweezers with the differential interference contrast (DIC) technique was performed to establish the uses and the advantages of each method. A detailed experimental and theoretical analysis of each method was performed with emphasis on the anisotropy involved in the DIC technique and the noise components in the detection. Finally, a time of flight method that permits the reconstruction of the optical potential well was demonstrated. © 2002 American Institute of Physics.

Notes: A low cost interrogation scheme is demonstrated for a refractometer based on an in-line fiber long period grating (LPG) Mach–Zehnder interferometer. Using this interrogation scheme the minimum detectable change in refractive index of Δn∼1.8×10−6 is obtained, which is the highest resolution achieved using a fiber LPG device, and is comparable to precision techniques used in the industry including high performance liquid chromatography and ultraviolet spectroscopy. © 2002 American Institute of Physics.

Notes: To extend the measurement range to 100 GPa, a modified manganin gauge was prepared and examined. The modifications were focused on the package materials and technique. The manganin sensing elements were first deposited by magnetron sputtering on Al2O3 substrates, and then covered by a layer of Al2O3 films several μm thick by electron beam evaporation. After being placed on slabs of Al2O3 ceramic, the gauges were shocked to 40–80 GPa with a light gas gun. The stress-time profiles showed a good plateau of about 1 μs in duration. The initial calibration resulted in a linear curve with piezoresistance coefficient of 0.0198±0.0002 GPa−1. © 2002 American Institute of Physics.

Notes: An angular motion feedthrough capable of supporting a large diameter linear motion feedthrough has been designed and built for the large experiment on instabilities and anisotropies at West Virginia University. With a combination of linear, angular, and rotary motion, a probe can be positioned in the vacuum chamber within a cone-shaped volume. © 2002 American Institute of Physics.

Notes: We present a new automated device for measurement of time-resolved frequency chirp of optical transmitters. It measures chirp in real time by utilizing two temperature-tunable silicon-wafer etalons as frequency discriminators. The time-resolved frequency chirp in a range of ±12 GHz can be measured with a time resolution of approximately 40 ps. © 2002 American Institute of Physics.

Notes: Traditionally, mass spectrometry has relied on manipulating the sample target to provide scanning capabilities for laser desorption microprobes. This has been problematic for an internal source laser desorption Fourier transform mass spectrometer (LD-FTMS) because of the high magnetic field (7 Tesla) and geometric constraints of the superconducting magnet bore. To overcome these limitations, we have implemented a unique external laser scanning mechanism for an internal source LD-FTMS. This mechanism provides adjustable resolution enhancement so that the spatial resolution at the target is not limited to that of the stepper motors at the light source (∼5 μm/step). The spatial resolution is now limited by the practical optical diffraction limit of the final focusing lens. The scanning mechanism employs a virtual source that is wavelength independent up to the final focusing lens, which can be controlled remotely to account for focal length dependence on wavelength. A binary index provides an automatic alignment feature. The virtual source is located ∼9 ft from the sample; therefore, it is completely outside of the vacuum system and beyond the 50 G line of the fringing magnetic field. To eliminate reproducibility problems associated with vacuum pump vibrations, we have taken advantage of the magnetic field inherent to the FTMS to utilize Lenz's law for vibrational dampening. The LD-FTMS microprobe has exceptional reproducibility, which enables successive mapping sequences for depth-profiling studies. © 2002 American Institute of Physics.

Notes: Two new straightforward methods for the evaluation of optical losses in planar waveguides are proposed and discussed. The first method exploits a single nonsliding isosceles prism and it allows the attenuation to be determined through the measurement of the power exiting the waveguide and the evaluation of the coupled power. It requires a very simple operation procedure, it allows a mode-selective determination of losses, and it presents a good accuracy provided that the sample is not too short. The second method uses end-fire coupling and it is based on the measurement of the output power together with the power back-reflected by the output face of the waveguide. The main advantage of the method is that it can be very accurate also for shorter waveguides and that its accuracy is to a high degree insensitive with respect to the optical depth of the waveguide. It provides better results in the case of high refractive index waveguides that give an intense back-reflected signal. Experimental results obtained with both methods on two different waveguides are presented. © 2002 American Institute of Physics.

Notes: A long undulator is a direct way to create a brilliant synchrotron radiation source. However, the length of undulators has been bounded by technical limitations and available space in accelerators. The first long undulator was developed at SPring-8, which is a third-generation synchrotron radiation facility equipped with four 30-m-long straight sections, making it the most brilliant x-ray source in the world. The magnets are placed inside a vacuum chamber and this makes it possible to arrange 780 periods continuously for 25 m. The absolute flux and spectrum of the output radiation were measured and compared with theory. The observed spectrum is in a good agreement with theory once the electron beam orbit was corrected for geomagnetic fields. © 2002 American Institute of Physics.

Notes: Experiments have been carried out to optimize the yield of Pb+4 ions from the plasma produced by a 100 J CO2 laser. The laser power density on the target surface was varied between 1010 W/cm2 and 9×1010 W/cm2 by changing the focal spot size. Data on the production of Pb+4 to Pb+10 ions are presented for the 15 and 40 ns laser pulse durations. The 10 mA/80 μs pulses of Pb+4 ions (about 1012 ions per pulse) were directed into an extraction aperture of 3.4 cm in diameter for optimal irradiation conditions. This is comparable with the parameters of the MEVVA ion source. Laser ion sources can be especially attractive due to the absence of the "noise" problem, typical for the MEVVA ion source, and because of the possibility of generating higher charge states. The emittance of the lead ion beam extracted from the laser-produced plasma was measured by using a 5 J laser, which provided plasma parameters (the electron temperature, ion velocities, and the charge state distribution) close to those of the plasma generated by the 100 J CO2 laser under optimized (for the yield of Pb+4 ions) conditions. The emittance was measured for 30 and 50 kV extraction voltages with a 10 μs temporal resolution. The value of about 400 π mm mrad was obtained for the lead ion beam with the total current of 10 mA, and a pulse length of 75 μs for about 75% of the beam ions. © 2002 American Institute of Physics.

Notes: An electrostatic energy analyzer is described that allows parallel acquisition of the energy spectrum of charged particles over a wide range of energies and over the complete range of azimuthal directions. The analyzer is similar to the cylindrical mirror analyzer except that a linear potential variation is applied in the axial direction to the outer cylinder. The analyzer can also be used in a second-order focusing mode to analyze a narrow range of energies with higher energy resolution. A position sensitive detector is required, the shape of which depends on the way in which the analyzer is used. Comparisons with existing electron energy analyzers are given. © 2002 American Institute of Physics.

Notes: A new experimental setup for time resolved x-ray diffraction is described. Designed for the LURE H10 beamline and its 4 (+2) circles goniometer, it allows simultaneous recordings of x-ray patterns with a rate of 30 patterns per second, a maximum 2θ range of 120°, infrared thermography at the same rate, and thermocouples readings at a frequency of up to 3×104 Hz. Preliminary results obtained using this setup are presented, showing how it is possible to analyze a solid–solid or solid-liquid reaction. As an example, an in situ study of phase transformation and temperature evolution during the self-sustaining synthesis of an FeAl intermetallic compound starting from a mechanically activated mixture is investigated. The versatility of the setup was proved and could even be enhanced by the design of new sample holders, thus expanding its area of use at low cost. © 2002 American Institute of Physics.

Notes: In this article, we describe the design rationale and performance features of an integrated multichannel continuous wave (cw) near-infrared (NIR) optical tomographic imager capable of collecting fast tomographic measurements over a large dynamic range. Fast data collection (∼70 Hz/channel/wavelength) is achieved using time multiplexed source illumination (up to 25 illumination sites) combined with frequency encoded wavelength discrimination (up to four-wavelength capability) and parallel detection (32 detectors). The described system features a computerized user interface that allows for automated system operation and is compatible with various previously described measuring heads. The results presented show that the system exhibits a linear response over the full dynamic measuring range (180 dB), and has excellent noise (∼10 pW noise equivalent power) and stability performance (〈1% over 30 min). Recovered images of laboratory vessels show that dynamic behavior can be accurately defined and spatially localized. © 2002 American Institute of Physics.

Notes: We studied different schemes of noise reduction using active compensation of environmental magnetic field noises in order to develop a high-temperature-superconductor (HTS) magnetometer system for the measurement of magnetocardiographic signals. The active compensation was combined with weak passive shielding of about 20 dB by the use of a magnetically shielded room (MSR) having a single layer of surrounding μ-metal. A novel method using a normal detection coil and compensation coils that were wound around the walls of the MSR to enable magnetic coupling was examined. Effective suppression of environmental field noises of more than 20 dB at 0.5–10 Hz and 10 dB at 10–100 Hz, covering the low-frequency range of biological signals, was obtained. In an alternative method using a reference HTS magnetometer in the MSR for noise detection, a compensation coil was set in the MSR and served as a feedback coil in operating the magnetometer. Residual field noises that were limited by the intrinsic noise of the reference magnetometer were obtained. Using such active compensation and weak passive shielding, measurement of magnetocardiogram was possible with a sensing HTS magnetometer in a wide frequency range of 0.5–100 Hz. © 2002 American Institute of Physics.

Notes: In the transportation of ion beams in a rarefied gas the plasma is formed due to the ionization of gas particles by the beam ions, and this plasma partially compensates the space charge of the ions (and thus improves the conditions of beam transportation). Moreover, in the case of a negative ion beam at a certain critical value of gas pressure, the electric field in the beam changes its sign so that at high pressure the beam is transported in the focusing field. The regime of high pressures is attractive also for the reason that ion–electron and ion–ion instabilities, which develop at that, are not harmful—they may cause just a little growth of the beam emittance. However, in this regime losses of the beam ions due to recharging are essential. As to pressures lower than the critical one, at which these losses are not so essential, the beam transportation is practically impossible due to large-scale ion instability which in certain time points results in almost complete decompensation of the beam space charge. In the present proceeding the way of stabilization of this instability is proposed, which gives the possibility of negative ion beam transportation at low pressures. Mechanism of the stabilization consists in diminishing the wavelength of unstable oscillations by means of the shielding action of the electrons introduced from the heated emitter and held in the beam by a periphery magnetic field. Experiments performed with the beam of hydrogen negative ions with 30 mA current and 10 keV energy have shown that introducing the electrons into the beam, which is transported at low pressure, really provides a essential reduction of ion–ion oscillations amplitude and, correspondingly, improves transportation characteristics of the beam. © 2002 American Institute of Physics.

Notes: The response time of a pressure sensor is required when it is used in control systems and in some measurement applications. It is often difficult to measure the response time of a pressure sensor since it is difficult to obtain changes in fluid pressure sufficient to characterize the sensor dynamic response. In this article we describe a relatively simple system for measuring or validating the response time of pressure sensors with fast dynamic response. The system consists of two chambers isolated by a graphite rupture disk, a device that fully and rapidly opens at a known rupture or break pressure. A pressure transient in the second chamber is initiated by slowly increasing the pressure in the first chamber until reaching the nominal break pressure of the rupture disk. Performance of the system was validated by comparing the rise time predicted by a theoretical model with the rise time of the pressure transient measured by a piezoelectric pressure transducer. The method was evaluated by comparing the response to the pressure transient of an optical based pressure transducer with the response of the reference piezoelectric pressure transducer. The time constant of the tested fiber optic pressure sensor was found using the method presented in this article to be 0.488 ms, which is close to the time constant of 0.455 ms measured by a comparison method. © 2002 American Institute of Physics.

Notes: The Linac Coherent Light Source (LCLS) program involves a collaboration of several U.S. National Laboratories and universities with the goal of designing and building the first fourth-generation hard x-ray source, an x-ray free-electron laser (FEL). This FEL will utilize extremely short, intense, low-emittance electron pulses created by the high-energy linear accelerator at the Stanford Linear Accelerator Center. The FEL radiation produced will feature unprecedented peak brightness, short pulse length, and spatial coherence, tunable over an energy range of 0.8–8 keV. With favorable funding, major construction will begin by 2004 and the LCLS will be operating late in 2006. The LCLS facility will include experimental stations for carrying out groundbreaking experiments in several scientific fields. Current research and development efforts are directed at experimentally studying the physics of high-gain FELs, and refining the details of the plan for the LCLS facility. The FEL experiments, at Argonne and Brookhaven National Labs (along with experiments carried out at the German laboratory DESY), have confirmed the basic physical concepts upon which LCLS is based, and have demonstrated that many of the stringent technical requirements can already be met. © 2002 American Institute of Physics.

Notes: Practically all synchrotron x-ray sources to data are based on the use of storage rings to produce the high current electron (or positron) beams needed for synchrotron radiation (SR). The ultimate limitations on the quality of the electron beam, which are directly reflected in many of the most important characteristics of the SR beams, arise from the physics of equilibrium processes fundamental to the operation of storage rings. It is possible to produce electron beams with superior characteristics for SR via photoinjected electron sources and high-energy linacs; however, the energy consumption of such machines is prohibitive. This limitation can be overcome by the use of an energy recovery linac (ERL), which involves configuring the electron-beam path to use the same superconducting linac as a decelerator of the electron beam after SR production, thereby recovering the beam energy for acceleration of new electrons. ERLs have the potential to produce SR beams with brilliance, coherence, time structure, and source size and shape which are superior to even the best third-generation storage ring sources, while maintaining flexible machine operation and competitive costs. Here, we describe a project to produce a hard x-ray ERL SR source at Cornell University, with emphasis on the characteristics, promise, and challenges of such an ERL machine. © 2002 American Institute of Physics.

Notes: To use the unique element-specific nature of polarized x-ray techniques to study a wide variety of problems related to magnetic materials, we have developed a dual-branch sector that simultaneously provides both hard and soft x-ray capabilities. This facility, which is located in sector 4, is equipped with two different insertion devices providing photons in both the intermediate (0.5–3 keV) and hard x-ray regions (3–100 keV). This facility is designed to allow the simultaneous branching of two undulator beams generated in the same straight section of the ring. © 2002 American Institute of Physics.

Notes: Suppression of beam instabilities has become an important goal at synchrotron radiation light sources, where highly sensitive applications like metrology, Fourier transform spectroscopy, and microscopy are now in use. We describe measurements connecting beam size and position changes to the onset of the saw-tooth instability and an instability generated by attempts to enlarge the vertical beam size for lifetime improvements.

Notes: We report the initial performance of an argon gas proportional counter consisting of a microstructure: the microhole and strip plate (MHSP). The MHSP combines desirable features of both a gas electron multiplier (GEM) and a microstrip plate (MSP) into a single integrated microstructure. Like the GEM, the MHSP is fabricated with flexible printed-circuit technology. As implemented, the MHSP provides two charge-amplification stages: slotted holes that function as a GEM, and microstrip anodes that also function as the charge-collection electrode. With two stages of amplification the microstrip can be operated with bias voltages well below the breakdown threshold. Results for the operation of the MHSP in argon are presented. A charge amplification factor of seven was achieved in the microholes with a maximum electron transmission approaching 100%. The measured energy resolution for 5.9 keV x rays was 30%. Future plans include the incorporation of a photocathode into the MHSP for applications as an ultraviolet photosensor. © 2002 American Institute of Physics.

Notes: The Advanced Photon Source has 29 insertion devices (IDs) installed in the 7 GeV electron storage ring; 28 of these devices, most of which are 3.3 cm period undulators, use two horizontal permanent magnet structures positioned over a straight vacuum chamber. A support and drive mechanism allows the vertical gap between the magnet structures to be varied, thus changing the x-ray energy produced by the ID [J. Viccaro, Proc. SPIE 1345, 28 (1990); E. Gluskin, J. Synchrotron Radiat. 5, 189 (1998)]. Most of these IDs use a drive scheme with two stepper motors, one driving each end through a mechanism synchronizing the upper and lower magnet structures. Our experience in almost 5 yr of operating this system will be discussed. All of the IDs are in continuous operation for approximately 10 weeks at a time. Reliability of operation is of paramount importance, as access to the storage ring for servicing of a single ID inhibits operation for all users. Our experience in achieving highly reliable ID operation is reviewed. Accuracy of operation and repeatability over time are also vital. To this end, these devices use absolute optical linear encoders with submicron resolution for primary position feedback. Absolute rotary encoders are used as a backup to the linear encoders. The benefits and limitations of each type of encoder, and our experience dealing with radiation and electrical noise are reviewed. The insertion devices operate down to gaps as small as 8.5 mm, with clearance over the vacuum chamber as small as 200 μm. The vacuum chamber has a minimum wall thickness of only 1 mm. A number of levels of safeguards are used to prevent contact between the magnet structure and the vacuum chamber. These safeguards and their evolution after gaining operational experience are presented. © 2002 American Institute of Physics.

Notes: Recent work on the synthesis of new heavy nuclei is reviewed. Special attention is given to future experiments and the possible demands for more intense beams. © 2002 American Institute of Physics.

Notes: This workshop was the eighth in a series of meetings on the theme of fusion diagnostics that has been held in Varenna at intervals between two and four years since 1975. Whereas previous meetings have concentrated on diagnostics for magnetic confinement fusion, this meeting had the specific purpose of bringing together diagnosticians from magnetic and inertial confinement fusion. The meeting concentrated on advanced diagnostics in these fields. © 2002 American Institute of Physics.

Notes: For the needs of future heavy ion accelerators, electron cyclotron resonance ion sources (ECRISs) should be able to deliver higher intensities and higher charge states. The 1e mA level intensity has already been reached by room temperature ECRIS for medium charge states of light elements (O6+, Ar8+). However, such level of intensity for heavy elements (like Pb27+ for CERN/LHC and GSI) requires more powerful ECRIS with higher electron densities (up to 1013 cm−3). On the other hand, an optimized magnetic configuration system has to be used in order to obtain the suitable compromise between the electron confinement and the high flux ion losses. Before the design of the future "high intensity ECRIS," experiments have been performed with the superconducting SERSE source both at 18 and 28 GHz. After an overview of major results recently obtained, some scaling laws will be presented. Our results show that much larger intensities and charges can be reached with ECRIS. Then, we will show how the next ECRIS generation will look like, based on the scaling laws derived in the above-mentioned experiments. © 2002 American Institute of Physics.

Notes: Research in nuclear physics with heavy ions continues to drive the development of electron cyclotron resonance (ECR) ion sources to both higher charge states and greater intensities. Already, the beam intensities from ECR ion sources have reached the 1 emA level for beams such as O6+ and Ar8+. However, the production of mA level beams from heavier, higher charge state beams presents significant challenges. The first challenge is to generate and confine a sufficiently dense plasma with a very low neutral density and high electron temperature to produce the needed ions. Fortunately, the density of the high charge state ECR plasmas scales roughly with the square of the microwave frequency, provided the magnetic field is scaled linearly with frequency and Bconfinement∼2Becr is maintained. At 28 GHz, the optimum confining fields are about 2 T, which can only be produced with superconducting magnets. The second challenge is to produce high intensity beams from solid feeds and this requires specialized ovens located close to the hot electron plasma. The third challenge is to efficiently extract and transport the intense beams without degrading the emittance. Traditionally, ECR sources have operated in the 10–20 kV range but at these voltages the space charge forces cause beam losses when the total extracted currents are many mA. The two main approaches are to operate at higher extraction voltage and to separate the desired charge state from the others extracted as early in the beam transport as possible. In this article we will review the current performance of high-field, high-frequency ECR ion sources such as RIKEN-18 GHz ECR, SERSE, and Phoenix, describe other ion sources now under construction such as the superconducting source VENUS at Berkeley, and discuss progress on the beam transport issues. © 2002 American Institute of Physics.

Notes: Intense beams of heavy ions with medium charge states (1.3 mA of Ar8+, 200 μA of Xe20+) have been produced from a RIKEN 18 GHz electron cyclotron resonance ion source (ECRIS) using various kinds of techniques, e.g., utilization of an aluminum cylinder and a biased disk, and optimization of the plasma electrode position. Furthermore, we have recently constructed two superconducting ECRISs (operational frequencies of 14 and 18 Hz) which have unique characteristics, i.e., they do not need liquid He to obtain the superconductivity of solenoid coils and utilize the G–M refrigerator instead. These sources are suitable to generate intense beams of heavy ions with very high charge states. We obtained 10 μA of Xe30+, 5 μA of Xe33+, and 1.5 μA of Xe36+ at a radio frequency power of 700 W (14 GHz microwave) without using the gas mixing method. Through various experiments, we confirmed that not only the magnetic field strength and microwave power but also the characteristics of the plasma chamber surface play the essential role for the production of highly charged heavy ions. © 2002 American Institute of Physics.

Notes: The plasma confinement within an electron cyclotron resonance ion source significantly influences the charge state distribution and hence the performance of the source. The different axial and radial diffusion processes govern the confinement time. In many experiments it has been shown that negatively biasing the end plate in the injection region improves the charge state distribution. In a few x-ray and vacuum ultraviolet spectroscopy experiments to clarify the mechanism it is observed that the biasing improves the confinement of the plasma. It is estimated that the effect cannot be explained solely by secondary electron emission from the plate into the plasma. We propose that by biasing, the overall balance between radial ion losses and axial electron losses will change, resulting in a different diffusional mode of the entire plasma. Hence, the plasma potential and the average charge state of ions in the plasma are significantly influenced. Usually, the ion flux is dominating radial diffusion while the electron flux is dominating axial losses. This is possible due to compensating wall currents in the electrical conducting plasma chamber ("Simon short circuit"). Thus the usual approach of ambipolar diffusion does not hold in this situation. A similar effect takes place if the plasma chamber is coated with electrically insulating materials. The condition of overall flux balance to the walls is no longer fulfilled and has to be replaced by the local ambipolar particle movement. Again the entire diffusion profile of the plasma changes and the confinement improves. We examine the short circuit current as a measure for the diffusion mode in more detail and try to develop an approximate calculation on the influence of plasma potential and average charge ion state Z in the plasma. First results are presented and discussed. © 2002 American Institute of Physics.

Notes: The large number of different experiments performed at the 88 Inch Cyclotron requires great variety and flexibility in the production of ion beams. This flexibility is provided by the two high performance electron cyclotron resonance (ECR) ion sources, the LBL ECR and the AECR-U, which can produce beams of ions as light as hydrogen and as heavy as uranium. With these two sources, up to six different metals can be preloaded using two types of ovens. The ovens are mounted radially on the ion sources and inject the metal vapor though the open sextupole structure into the plasma chamber. For the superconducting ECR ion source VENUS, which is under construction at Lawrence Berkely National Laboratory, the use of radial ovens is no longer possible, because the magnetic structure is closed radially. Therefore, we are developing two new axial oven types for low and high temperature applications. Metal ion beam production in ECR ion sources using the oven technique is discussed. The design of the axial oven is presented. Finally, the efficiency of the axial oven is compared with the radial oven for the production of Ca. © 2002 American Institute of Physics.

Notes: BIE100, an all-permanent-magnet-based electron cyclotron resonance (ECR) ion source, has been under development at Berkeley Ion Equipment (BIE). With a relatively small but optimized source magnet volume, the maximum peak magnetic field strengths of the BIE100 reach 13 kG on axis and 11 kG at the plasma chamber walls, respectively. Microwaves of frequencies of 12.75 and 14 GHz are to simultaneously heat the plasma electrons. The development goal of this ECR ion source is to further explore the capabilities of ECR ion source in the efficient production of the intermediate and high charge state rare ion beams needed for the generation of rare ion beams and industrial applications. This article will present the design features of the BIE100 ion source and its current status. © 2002 American Institute of Physics.

Notes: In order to study the possibilities to produce high currents of pulsed heavy ion beams dedicated to synchrotron injection, two new approaches of ECR devices are now underway. The basic principle consists in maintaining a functioning point of the source with the highest density as possible and a minimum confinement time for the production of a given charge state. It means that for a constant neτi product we try to maximize ne and minimize τi. For this purpose two experiments are in progress at ISN/Grenoblea and IAP/Nizhny Novgorod.b The first one consists of using a minimum |B| magnetic structure with a 1.8 mirror ratio characteristic value with a 28 GHz frequency injection. In this case we explore different functioning points up to 10 kW of UHF power. The second one consists of a simple mirror magnetic system (simple mirror ion source, SMIS) working at 37.5 GHz with a mirror ratio up to 3 (2.5 T) where we study discharges with a peak power up to 100 kW. We will show that, in spite of a very short rising time of the current, we can maintain the production of multicharged ions and that we can observe very high current densities. In the future, the challenge will be the design of an extraction geometry matching theses current levels. © 2002 American Institute of Physics.

Notes: An experimental procedure intended for crevice corrosion studies on Ni–Cr–Mo alloys is demonstrated. In this procedure a potentiostatic control of crevice corrosion specimens is applied to an immersible crevice cell design that uses a fluoroelastomer gasket crevice former. The procedure is demonstrated for a crevice susceptibility study on Alloy 625 in elevated temperature natural seawater, where crevice corrosion initiation and propagation are shown to be influenced by the electrochemical potential. Potentiostatic current monitoring establishes the crevice initiation time and rate of propagation, while post-mortem inspections confirm the extent of crevice damage. © 2002 American Institute of Physics.

Notes: A microtomography beamline has been recently assembled and is currently operating at the Louisiana State University's Center for Advanced Microstructures and Devices synchrotron (CAMD). It has been installed on a bending magnet white-light beamline at port 7A. With the storage ring operating at 1.5 GeV, this beamline has a maximum usable x-ray energy of ∼15 keV. The instrumentation consists of computer-controlled positioning stages for alignment and rotation, a CsI(Tl) phosphor screen, a reflecting mirror, a microscope objective (1:1, 1:4), and Linux/LabVIEW-controlled charge coupled device. With the 1:4 objective, the maximum spatial resolution is 2.25 μm. The positioning and image acquisition computers communicate via transfer control protocol/internet protocol (TCP/IP). A small G4/Linux cluster has been installed for the purpose of on-site reconstruction. Instrument, alignment and reconstruction programs are written in MATLAB, IDL, and C. The applications to date are many and we present several examples. Several biological samples have been studied as part of an effort on biological visualization and computation. Future improvements to this microtomography station include the addition of a double-multilayer monochromator, allowing one to evaluate the three-dimensional elemental composition of materials. Plans also include eventual installation at the CAMD 7 T wiggler beamline, providing x rays in excess of 50 keV to provide better penetration of higher mass-density materials. © 2002 American Institute of Physics.

Notes: Physical Science Laboratory's new generation of spherical grating monochromators incorporates a laser interferometer to control scan angle and an in-vacuum absolute angle reference, as well as other improvements. The design accommodates up to six gratings which can be moved axially (under motor control, with encoder position readback) at any scan angle. The gratings are cooled by means of spring-loaded clamps which conduct heat to a water-cooled plate. The instruments feature hollow roller bearings on the scan axis to minimize bearing runout, and a pseudosine-bar drive for precise control of grating angle. The interferometer angle-measuring optics are mounted inside the vacuum chamber and measure the angle between the grating scan axis and the instrument's granite base. The laser interferometer measures the grating angle with a resolution of approximately 0.02 arcsec over the entire scan range of 40°. To provide a reference for the interferometer angle measurement, we have built an in-vacuum optical reference which uses custom chrome-on-glass reticles mounted inside the vacuum chamber. Collimated light from a source outside the vacuum passes through the reticles to yield quadrature signals which precisely define an absolute reference angle for the interferometer. Repeatability of the grating angle is within a range of ±0.05 arcsec. Two of these instruments are in operation at SRRC (Taiwan) and a third instrument has been delivered to NSLS (Brookhaven). © 2002 American Institute of Physics.

Notes: Crystals bent to logarithmic spirals have been used in applications where large acceptance of divergent x rays from a small source is needed. Small acceptances can be easily handled with cylindrically bent crystal. In cases where larger acceptances are needed differential bending may be adequate. However, the largest acceptance is obtained from a flat crystal plate when bent into the logarithmic spiral shape that allows the crystal to present the same angle of incidence to the beam emanating from a point source. The bending of such crystals generally can be accomplished by forcing the crystal into the required shape with a metal frame. A preliminary theoretical study of crystal shapes that when bent will naturally form logarithmic spiral shapes has been done. This study was done for the case of a cantilever beam with fixed end and a normal force applied to a point at the other end. A fixed thickness-variable width beam was considered. The crystal profile in width (direction perpendicular to the diffraction plane) can be spatially varied to achieve this spiral shape. Equations for both cases will be given. © 2002 American Institute of Physics.

Notes: A rotating crystal beam chopper that can be synchronized to the synchrotron storage ring frequency has been successfully fabricated and tested. The crystal chopper uses the storage ring frequency master clock as input and operates at 1/500 times its input frequency. It is phase locked to the input frequency. At the Advanced Photon Source, using the ring frequency clock (∼271 kHz), the crystal beam chopper rotates at about 542 Hz, with less than 3 ns jitter in the period. With its Si(111) reflecting surfaces, this corresponds to a transmission window of about 10 ns for 10 keV x rays, assuming the upstream monochromator is also Si(111). By dividing its input frequency, it is possible to operate the crystal chopper at 271 and 135.5 Hz for wider transmission windows. To date, this is the only device that has demonstrated a ns range transmission window and operates phase locked to the synchrotron storage ring frequency. © 2002 American Institute of Physics.

Notes: The Experimental Physics and Industrial Control System (EPICS) software is used in Synchrotron Radiation facilities around the world. An obstacle blocking small research groups such as beamline developers from using, or at least evaluating, EPICS has been the need to purchase the commercial operating system used by the EPICS base software. The goal of recent EPICS development has been to remove this requirement by allowing EPICS to run on a much wider range of operating systems. This article presents the results of this development for one particular operating system, the freely available, open-source, Real-Time Executive for Multiprocessor Systems (RTEMS). The capabilities of RTEMS are described and shown to provide an adequate basis for supporting EPICS. Performance comparisons between previous versions of EPICS and the RTEMS implementation are presented. Ongoing efforts to add support for more hardware are described. © 2002 American Institute of Physics.

Notes: At BESSY a multipurpose infrared (IR) beamline is being built for biological and materials science investigations. It will provide useful IR intensities over the energy range from about 10 000 down to 50 cm−1 and lower. After commissioning the first beamline section in the spring of this year first quantitative measurements on the performance have been made in the near and mid-infrared wavelength region. © 2002 American Institute of Physics.

Notes: A new bending mechanism for an indirectly water cooled monochromator crystal has been developed. The main design goals were a lightweight construction, ease of manufacture, and control. The construction consists of a U-shaped first Si(111) crystal, which can be bent by compressed air to compensate the bowing induced by the heat load from the impinging white synchrotron radiation. The performance of the system was tested at the x-ray undulator beamline BW1 at HASYLAB (Hamburg, Germany). For heat loads between ∼100 and 400 W, rebending of the crystal significantly increases the intensity of the monochromatic beam while the rocking curve is narrowed accordingly, typical widths obtained at 8.9 keV photon energy amount to about 10 arc sec. © 2002 American Institute of Physics.

Notes: X-ray excited optical luminescence (XEOL) studies of several classes of light emitting materials excited using soft x rays (photon energy ranging from 10 to 2500 eV) are presented. We show that XEOL with soft x rays (short penetration depths) is often site specific and is ideally suited for the study of light emitting thin films and devices. Several examples including porous silicon, organic light emitting diode materials, and CdS based nanostructures are used to illustrate the unique properties of XEOL and its applications in the soft x-ray energy region. © 2002 American Institute of Physics.

Notes: In order to evaluate and find the proper conditions for residual stress (RS) measurements, two kinds of preliminary x-ray diffraction experiments were conducted at the Advanced Photon Source: angle-dispersive x-ray diffraction and energy-dispersive x-ray diffraction. These two experimental methods and their precision were investigated for RS measurement. The results obtained and various factors that may influence the accuracy of these experiments are discussed. © 2002 American Institute of Physics.

Notes: The effects of synchrotron radiation (SR) irradiation on the electrical properties of tin-doped In2O3 (ITO) thin films prepared by rf magnetron sputtering have been studied. A white SR beam focused by a cylindrical mirror was used to irradiate ITO thin films at doses of 0.35, 1.98, 3.50, and 6.64 mA h. We have achieved resistivity of 2×10−4 Ω cm on ITO thin film at an irradiation dose of 3.5 mA h without extra heating. The mobility of the ITO films did not decrease after SR irradiation. The electrical properties in connection with the structural change due to SR are discussed.© 2002 American Institute of Physics.

Notes: In recent years, progress concerning the production of high intensity of metallic ion beams (58Ni, 48Ca, 76Ge) at GANIL have been performed. The metallic ion from volatile compound method has been successfully used to produce a high intensity nickel beam with the ECR4 ion source: 20 e μA of 58Ni11+ at 24 kV extraction voltage. This beam has been maintained for 8 days and accelerated up to 74.5 MeV/u by our cyclotrons with a mean intensity of 0.13 pμA on target. This high intensity, required for experiment, led to the discovery of the doubly magic 48Ni isotope. The oven method has been first tested with natural metallic calcium on the ECR4 ion source, then used to produce a high power beam (740 W on target, i.e., 0.13 pμA accelerated up to 60 meV/u) of 48Ca still keeping a low consumption (0.09 mg/h). A germanium beam is now under development, using the oven method with germanium oxide. The ionization efficiencies have been measured and compared. © 2002 American Institute of Physics.

Notes: The CERN heavy ion community, and some other high energy physics experiments, are starting to demand other ions, both heavy and light, in addition to the traditional lead ions. Studies of the behavior of the afterglow for different operation modes of the ECR4 at CERN have been continued to try to understand the differences between pulsed afterglow and continuous operation, and their effect on ion yield and beam reproducibility. The progress in adapting the source and ion beam characteristics to meet the new demands will be presented, as will new information on voltage holding problems in the extraction. © 2002 American Institute of Physics.

Notes: The medium energy x-ray double crystal monochromator (DCM) is currently being designed at the Canadian Light Source (CLS). Design goals for the DCM are to provide photons between 1750–5500 eV with a resolving power better than 3000 and photon flux better than 5×1010 photons/s/0.1% bandwidth for 500 mA beam current. A set of indium antimonide crystals [InSb(111)] will be used over the energy range of 1750–3700 eV, with resolution ranging from 0.52–1.05 eV. Although InSb allows one to probe the important silicon K edge at ∼1840 eV, it has the disadvantage of poor thermal conductivity. Exposure to high heat loads from the CLS synchrotron on the first crystal (∼56.5 W of power for 2 mrad of horizontal bending magnet radiation, ∼0.54 W/mm2 power density) will cause crystal distortion and thereby intensity/resolution degradation. A second set of silicon crystals [Si(111)] are proposed for the energy range of 3700–5500 eV. Resolution ranges linearly from ∼0.41 to ∼0.70 eV over this energy range. A harmonic filter mirror has been included in the design to reject higher harmonic orders. SHADOW ray-tracing results show that the experimental focus should be 334 μm [horizontal full width at half-maximum (FWHM)]×296 μm (vertical FWHM) when the CLS is operational under 2008 conditions. © 2002 American Institute of Physics.

Notes: Sagittal focusing of synchrotron x rays with asymmetric Laue crystals has been proposed and demonstrated [Z. Zhong, C. C. Kao, D. P. Siddons, and J. B. Hastings, J. Appl. Crystallogr., Pts I&II (submitted)]. At high x-ray energies, sagittal focusing by a Laue crystal is preferred because of the small extent of the beam's footprint on such a crystal, and the ability to use the inverse-Cauchois geometry in the meridional plane to improve energy resolution. Reflectivity curves of sagittally bent Laue crystals were measured at x rays energies from 15 to 70 keV. A model for the diffraction properties of sagittally bent Laue crystals, which takes into account the anisotropy in the elastic property of the crystals, was developed. Analytical formulas were derived for the rocking-curve width of such crystals, including both the contribution from the lattice angle change and the d-spacing change due to sagittal bending, across the thickness of the crystal. The contribution of the orientation-dependent elastic compliance S23 is as important as S13 in the specific case of sagittally bent Laue crystals. The widths of the rocking curves, calculated using the analytical model, were compared with measurements on crystals of two different orientations (111) and (100). Good agreements were found. An interesting sign reversal in the slope of the lattice angle versus depth curve between the (111)- and (100)-oriented crystals is predicted by the model, as a result of the highly anisotropic properties of silicon crystal. Results of depth-resolved rocking-curve measurements and high-resolution diffraction, designed to confirm these theoretical findings, are discussed. © 2002 American Institute of Physics.

Notes: We review here our recent work on a high dynamic range, subpicosecond x-ray streak camera. Our subpicosecond streak camera (PX1) has been coupled to a 10 Hz Ti: sapphire laser system and tested with 500 fs UV light pulses (266 nm) in jitter-free accumulation mode. A novel design for the photoconductive switches that are coupled to the camera's deflection plates has been successfully used to eliminate the jitter induced by the laser intensity fluctuations and by the temporal shape of the laser beam. Results demonstrate that this detection system gives simultaneously a high dynamic range and a subpicosecond resolution at a repetition rate of 10 Hz. © 2002 American Institute of Physics.

Notes: We have built a high-resolution high-efficiency superconducting soft x-ray spectrometer for synchrotron-based fluorescence-detected absorption spectroscopy. The sensor is a 3×3 array of 200×200 μm2 superconducting Nb–Al–Al2O3–Al–Nb tunnel junctions with an energy resolution around 15 eV below 1 keV and a total count rate capability of (approximate)100 000 counts/s. This sensor array is cooled to (approximate)0.1 K by a two-stage adiabatic demagnetization refrigerator while held at the end of a 40-cm-long cold finger that can be inserted into an UHV sample chamber for x-ray fluorescence measurements. We present L-edge absorption spectra of dilute transition metals ((approximate)few 100 ppm) and discuss spectrometer performance with respect to the analysis of metalloproteins. © 2002 American Institute of Physics.

Notes: A new electron cyclotron resonance (ECR) ion source (LECR3—Lanzhou Electron Cyclotron Resonance Ion Source No. 3) has been constructed this year. The main purpose of this source is to provide highly charged ion beams for atomic physics and surface physics research. The design of this ion source is based on the IMP 14.5 GHz ECR ion source (LECR2—Lanzhou Electron Cyclotron Resonance Ion Source No. 2) with double rf heating by inserting waveguide directly and aluminum chamber. Furthermore, the volume of the plasma chamber is larger than that of LECR2 so as to increase the rf power and improve beam intensity for highly charged ions. But the hexapole field on the chamber wall is kept the same value in order to compare with the performance of LECR2. After only four days conditioning the first test results were obtained. The final result of this ion source is expected to be better than LECR2's. © 2002 American Institute of Physics.

Notes: The combination of cyclotron and electron cyclotron resonance (ECR) ion source provides the ability to accelerate "cocktails" of ions, mixtures of ions of near-identical charge-to-mass ratio. This concept was developed soon after the first ECR ion source became operational at the 88 Inch Cyclotron and has become a powerful tool in the field of heavy ion radiation effects testing. The standard 4.5 MeV/nuc cocktail at a charge-to-mass ratio of 0.2 contains ions from B2+ to Bi41+. Copper and cobalt are provided by the direct insertion method, B is produced utilizing the MIVOC technique and Bi is produced with the oven technique. Recently, following upgrades to the AECR and the cyclotron vacuum system, a new high-energy heavy cocktail beam has been developed. This cocktail at a charge-to-mass ration of 0.27 using 400 MeV Ar11+ as a "pilot" beam, contains ions from B3+ to Xe38+ and provides accelerated ions with a range of 100 μm in Si, of great advantage for some of the newer-generation microelectronics. It has joined the 4.5 MeV/u heavy ion cocktail and the 32.5 MeV/u light ion cocktail as standards in the cyclotron's cocktail repertoire. © 2002 American Institute of Physics.

Notes: When a large current is accelerated, many radio frequency quadrupole (RFQ) LINAC are needed, because the acceleration limit of a RFQ LINAC is 20 mA–30 mA. Therefore the same number of ion source are needed. But the limit is not the current limit of ion source. If the RFQ LINAC has many RFQ channels, it can accelerate large currents. We designed an accelerator with four RFQ channels to prove this principle. An ion source which extracts four equal beams from one chamber is needed for this RFQ LINAC. A four-hole ECR ion source was designed and manufactured after calculating the magnetic fields by OPERA, and simulating beam trajectory using the program FUGUN. In this ion source, since four extraction holes are located off axis by about 50 mm, the beam is deflected. We calculated this deviation. © 2002 American Institute of Physics.

Notes: A compact 2.45 GHz electron cyclotron resonance (ECR) ion source has been developed as an etching device for diffusion experiments in the solid-state matter. This source is a little bit different from those of a usual industrial ECR device, i.e., it is to extract high intensity beams from a relatively small single hole with low emittance under the extraction voltage of several kV and high vacuum. Summary of the design, manufacture, and the initial beam extraction tests are described. © 2002 American Institute of Physics.

Notes: A new electron cyclotron resonance ion source has been designed and equipped with the new cyclotron at the Cyclotron and Radioisotope Center, Tohoku University. The ion source consists of a full permanent-magnet system with a microwave frequency of 14.5 GHz. The source has the following three main features: (1) V-style magnetization, (2) flat-bottomed magnetic-field distribution, and (3) field adjusting system. The measured magnetic-field strength in the plasma chamber is about 8% weaker than the calculated value. The extracted beam current is measured as the preliminary result. © 2002 American Institute of Physics.

Notes: The National Institute of Standards and Technology (NIST) has operated the Synchrotron Ultraviolet Radiation Facility (SURF) continuously since the early 1960s. The original accelerator was converted into a storage ring, called SURF II, in 1974. Then in 1998, motivated mainly by limitations in the accuracy of radiometric calibrations and the wish to extend the spectrum of the emitted synchrotron radiation to shorter wavelengths, a second major upgrade was performed. This time the whole magnet system was replaced to improve the calculability and allow for higher magnetic fields. Since the recommissioning of SURF III we have been working to improve the stability of the stored electron beam through modifications of the radio-frequency system, leading to operations with unprecedented stability and new record injection currents topping 700 mA. © 2002 American Institute of Physics.

Notes: The Synchrotron Radiation Center operates the Aladdin electron storage ring at energies of 800 meV or 1 GeV in support of a broad range of national and international research programs with a major focus on the study of valence electrons, spectromicroscopy, and nanolithography. Upgrades to the storage ring have improved the stability of the source, and experiments with low emittance lattice configurations show the feasibility of increased brightness for new or enhanced research. Three recently installed undulators, two pure permanent magnet devices and an electromagnetic device, and the associated instrumentation offer experimentalists high flux combined with high resolution. The status of the existing instrumentation, recent scientific results, and an overview of plans for new undulator-based instruments to cover the photon energy range from 7.8 to 400+ eV will be presented. © 2002 American Institute of Physics.

Notes: The electrostatic plasma lens provides an important tool for the manipulation of high current heavy ion beams with moderate energy of 1–100 keV. Applications can include, for example, high dose ion implantation and particle accelerator injection. Here we briefly review the plasma lens (PL) fundamentals and summarize some recent developments and experiments performed at the Institute of Physics NASU (Kiev) and LBNL (Berkeley). We also describe progress in experimental investigations of the nonlinear electron vortex structures that arise due to the drift instability in the high current plasma lens, and lens operation in the low magnetic field regime. We show that there is a very narrow range of low magnetic field for which the focusing properties of the PL improve markedly. Under these conditions a significant decrease (by more than an order of magnitude) in the amplitude of oscillations in the lens volume and focused ion beam are observed. © 2002 American Institute of Physics.

Notes: The J. Bennett Johnston Sr., Center for Advanced Microstructures and Devices (CAMD) is a synchrotron radiation facility owned by Louisiana State University and operated with financial support from the State of Louisiana (for information how to submit a project proposal go to: http://www.camd.lsu.edu). The centerpiece of CAMD is a 1.3–1.5 GeV electron storage ring. CAMD supports a strong program in x-ray lithography micromachining (XRLM) or LIGA. A total of four beamlines equipped with different scanners is available for exposures. A 2.500 sq. ft class 100 clean room provides basic processing capability for MEMS including optical lithography, thin film deposition, electroplating, and metrology. Three micromachining beamlines are connected to bending magnets. All beamlines are "white light" beamlines, terminated with a beryllium window. The typical source point to scanner distance is 10 m and the horizontal acceptance ranges from 6.5 to 10 mrad. A number of low Z filters can be inserted into the beam adapting the exposure spectrum to the resist thickness. Two beamlines are equipped with commercial scanners from Jenoptik GmbH (for details see Jenoptik's webpage at www.jo-mikrotechnik.com/) and one beamline with a "vacuum" scanner designed in house. The latest model of Jenoptik's DEX02 scanner has been installed at CAMD's XRLM1 beamline in December 2000 and allows advanced exposures using overlay as well as tilt and rotate functions. In addition to these beamlines CAMD has installed a "white light" beamline at its 7 T wiggler source. Preliminary exposure tests in ultrathick samples (1 mm and thicker) have been conducted using an "air scanner." Currently this beamline is dismantled and will be reinstalled together with a PX beamline. In the article further details of the beamlines and scanners as well as some examples of applications of LIGA microstructures fabricated at CAMD will be discussed. © 2002 American Institute of Physics.

Notes: Automatic tuning of double-crystal monochromators presents an interesting challenge in software. The goal is to either maximize, or hold constant, the throughput of the monochromator. An additional goal of the software feedback is to disable itself when there is no beam and then, at the user's discretion, re-enable itself when the beam returns. These and other routine goals, such as adherence to limits of travel for positioners, are maintained by software controls. Many solutions exist to lock in and maintain a fixed throughput. Among these include a hardware solution involving a wave form generator, and a lock-in amplifier to autocorrelate the movement of a piezoelectric transducer (PZT) providing fine adjustment of the second crystal Bragg angle. This solution does not work when the positioner is a slow acting device such as a stepping motor. Proportional integral differential (PID) loops have been used to provide feedback through software but additional controls must be provided to maximize the monochromator throughput. Presented here is a software variation of the PID loop which meets the above goals. By using two floating point variables as inputs, representing the intensity of x rays measured before and after the monochromator, it attempts to maximize (or hold constant) the ratio of these two inputs by adjusting an output floating point variable. These floating point variables are connected to hardware channels corresponding to detectors and positioners. When the inputs go out of range, the software will stop making adjustments to the control output. Not limited to monochromator feedback, the software could be used, with beam steering positioners, to maintain a measure of beam position. Advantages of this software feedback are the flexibility of its various components. It has been used with stepping motors and PZTs as positioners. Various devices such as ion chambers, scintillation counters, photodiodes, and photoelectron collectors have been used as detectors. The software provides significant cost savings over hardware feedback methods. Presently implemented in EPICS, the software is sufficiently general to any automated instrument control system. © 2002 American Institute of Physics.

Notes: A volume production type negative ion source is under development for a high intensity proton linear accelerator. The source plasma is produced by an arc discharge using tungsten filaments. The cesium vapor was introduced into the plasma chamber by using an oven. The beam extractor consists of three electrodes with a single aperture of 8 mm in diameter. Negative ion current of 72 mA was achieved at the arc discharged power of 56 kW. The emittance measurement indicated that normalized emittances were 0.13 (horizontal plane) and 0.15 (vertical plane) π mm mrad at 70 keV and 60 mA. © 2002 American Institute of Physics.

Notes: The development of a high current bismuth ion source is motivated by heavy ion driven fusion (HIF) and is part of the conceptual design of a HIF-relevant Bi+ test injector with four beamlets, which could serve as a HIF driver front end element. Envisaged is the development of a 300 mA Bi+ injector that can deliver four parallel beams from a 500 kV platform with 75 mA per beam. The first prototype source is driven by an arc discharge and provides singly charged Bi ions with a fraction more than 92% of the total extracted current. At its perveance limit this source delivers current of 70 mA, with the corresponding voltage being 27.5 kV. The emittance of a 21 mA/18.2 keV beam was measured and it amounted to 0.27 π mm mrad (80%, normalized, 4 root mean square) provided by a seven hole extraction system. Based on these investigations a new ion source will be designed and tested that will deliver current of 75 mA at ion energies up to 65 keV. In order to fulfill the requirements of HIF the emittance has to be in the vicinity of 0.4 π mm mrad (normalized). In this article we give a brief description of the design of an advanced ion source. Based on experimental experience using the previous prototype source one major modification made is the construction of an external oven. The use of more than one filament to increase the source lifetime is also planned. © 2002 American Institute of Physics.

Notes: Presently the Heavy Ion Fusion Virtual National Laboratory is researching ion sources and injector concepts to understand how to optimize beam brightness over a range of currents (50–2000 mA argon equivalent). One concept initially accelerates millimeter size, milliamp beamlets to 1 MeV before merging them into centimeter size, ampere beams. Computer simulations have shown the final brightness of the merged beams is dominated by the emittance growth of the merging process, as long as the beamlets' ion temperature is below a few electron volts. Thus, a radio frequency multicusp source capable of high current density can produce beams with better brightness compared to ones extracted from a colder source with a large aperture and lower current density. Initial experiments with such a source have successfully demonstrated simultaneously high current density, ∼100 mA/cm2, and fast turn on, ∼1 μs. Results from these experiments are presented as well as progress and plans for the next set of experiments for these sources. © 2002 American Institute of Physics.

Notes: Transport process of negative hydrogen ions (H−) in a large hybrid multicusp H− source, "Camembert III," has been analyzed by a three-dimensional Monte Carlo simulation code. The realistic geometry and multicusp magnetic-field configuration are taken into account. Various important destruction processes of H− and Coulomb collision with background plasma are also included in the model. Both the volume- and surface-produced H− ion trajectories are followed. For volume-produced H− ions, most of the H− ions can reach the wall in the low-pressure case (1 mTorr), while in the high-pressure case (3 mTorr) most of the H− ions are destructed by volume loss reactions before reaching the wall. This shows that the wall loss is significant at low pressure as in the experiments. For surface-produced H− ions, the influence of its birthplace on the H− current is studied. Negative ions created on the sidewall hardly can reach the center of the source due to trapping by the multicusp magnetic field. As a result, H− ions created on the sidewall do not have a significant effect on the H− current. © 2002 American Institute of Physics.

Notes: The results of the three-dimensional (3D) self-consistent simulations of a 14 GHz minimum-B electron cyclotron resonance ion source plasma obtained upon 1.8×104 microwave periods by the particle-in-cell code are reported. The initial density of plasma contained in a chamber of 24 cm length and 6.3 cm in diameter is 0.6×1012 cm−3. We have used the explicit Boris-leap-frog scheme on the three-dimensional computer grid of 32×32×64 size. The results of the relativistic simulations show that the confined plasma has a complex spatial structure with a zone of periodic bounce oscillations as well as areas where banana trajectories are observed. The obtained electron energy distribution function makes it evident that in the electron cyclotron resonance minimum-B plasma there coexist three separable electron groups: a group of cold electrons with the energy up to 80 eV, a group of hot electrons whose energy extends to 80 keV, and a group of superhot electrons accelerated up to hundreds of kilo-electron volts. The space distributions of plasma ions have been found. © 2002 American Institute of Physics.

Notes: An updated and more accurate database for single- and double-ionization cross sections for almost all argon ions has been developed for the modeling of the charge state distribution (CSD) within an electron cyclotron resonance ion source. When the highly non-Maxwellian anisotropic electron-distribution function, is modeled by a Fokker–Planck code, one has to use the ionization cross sections instead of the Maxwellian rate coefficients. Most of the fitting coefficients used within the well-established semi-empirical formulas for direct ionization and double ionization have been recalculated using more accurate crossed-beam experimental data available. The shift of the CSD to higher-charge states due to the contribution of excitation autoionization and double ionization is presented by comparing the GEM code modeling using the Lotz formula and the cross sections with updated fitting coefficients. © 2002 American Institute of Physics.

Notes: A one-dimensional (1D) fluid computer model for multiple ion species in an electron cyclotron resonance ion source (ECRIS) plasma has been developed. The ions species are assumed to be highly collisionally coupled and are treated using 1D fluid equations. The non-Maxwellian anisotropic electron distribution function is modeled by a 1D bounce-averaged Fokker–Planck code. ECR heating is included in the model as a quasilinear rf-diffusion term including relativistic detuning, rf pitch-angle scattering, and multiple resonance frequencies/locations. In a typical ECRIS, the electrons are very noncollisional and confined magnetically. The ions follow this electron confinement via the electrostatic potential. The 1D axial electrostatic potential profile predicted by the model shows an ion confining core electrostatic well as expected in ECRIS plasmas. Modeling results for the Argonne National Laboratory ECR-I ECRIS configuration are presented along with a discussion of the difficulties in benchmarking the model with Faraday cup measurements. © 2002 American Institute of Physics.