bluuebunny/crossref_metadata_2025 huggingface dataset:
X-ray detection characteristics of microchannel plates in the energy range from 1.8 to 8 keV
Authors: Yamaguchi N. , Cho T. , Kondoh T. , Hirata M. , Miyoshi S. , Aoki S. , Maezawa H. , Nomura M.
Published: July 2002

The characteristics of microchannel plates (MCPs) for detection of x rays have been investigated using synchrotron radiation in the energy range from 1.8 to 8 keV. The current response curve of MCPs is measured with approximately continuous x-ray energy variation, which is added to the previous data [T. Kondoh et al., Rev. Sci. Instrum. 59, 252 (1988)]. It is confirmed that there is a minimum in the current response at the x-ray energy of about 4 keV. The precise current response curve has been completed for the wide x-ray energy range from 0.6 to 20 keV. A transition in the incident angle dependence of current response is found from the feature based on single cylindrical photocathode model for soft x rays to that based on multiple channel activation due to the penetration of x rays through channel walls for hard x rays. In the current response of MCPs the structure similar to that in EXAFS is observed near the Si K edge.
A diamond anvil cell for advanced microscopic observations and its application to the study of crystal growth under pressure
Authors: Takemura K. , Shimomura O. , Sawada T.
Published: July 2002

A new type of diamond anvil cell has been designed for microscopic observations under pressure with high-resolution and high-magnification capability. The cell allows the use of objective lenses with working distances as small as 6 mm, resulting in a typical objective magnification of 40× (total magnification of ∼800×), and facilitating advanced microscopic techniques such as the differential interference method and the dark-field method. The aberration by diamond can be reduced significantly by optimizing its thickness, with the use of objective lenses corrected for optical windows like quartz or glass. Pressure can be changed smoothly with the use of bellows without disturbing the observation. A microscopic observation system incorporating the present cell has been employed successfully to the study of crystal growth under pressure from an aqueous solution.
Deep-level transient spectroscopy in MOS structures with a dual-channel boxcar integrator and arbitrarily chosen gate-width–data analysis
Authors: Dmowski K. , Jakubowski A.
Published: July 2002

New formulas are proposed describing the correlation signals of bulk traps and interface states in metal-oxide-semiconductor structures for constant voltage and constant capacitance deep-level transient spectroscopy analog measurement systems with a dual-channel boxcar integrator and an arbitrary gate width. An analysis presented enables one to maximize sensitivity of these systems for the study of low-concentration processing-induced defects and interface states in metal-oxide-semiconductor devices.
Modulation effects in wedge and strip anodes
Authors: Smith Andy , Kessel Robert , Lapington J. S. , Walton David M.
Published: July 2002

We present results on the image distortion or ‘‘modulation’’ produced when a wedge and strip anode (WSA) position readout is used with a charge cloud of size comparable with that of the pattern repeat pitch. We use a standard detector consisting of a microchannel plate (MCP) intensifier and wedge and strip anode to investigate the effect of detector operating parameters on image modulation. We find that modulation depends on the MCP gain of each event and on the MCP voltage, and is minimized when the plates are run at high gains and with high rear MCP operating voltages. We compare the experimental results obtained using this detector with the response calculated numerically in a computer simulation. From the simulation it becomes apparent that for a detailed understanding of wedge and strip performance the microchannel plate charge cloud distribution must be considered. However, some of the general features of the wedge and strip anode performance are independent of the charge cloud form. The most important of these is that modulation distortion displaces a vertical line (parallel to the direction of increasing wedge) to another vertical line, while a horizontal line (parallel to the direction of increasing strip) is distorted into a wave-shaped curve with the periodicity of the pattern pitch.
Metal C ring window seal
Authors: Duignan Michael T. , Gerhardt David J. , Whitney W. T.
Published: July 2002

We have constructed an optical cell with CaF2 windows which are sealed with metal C rings. We have demonstrated vacuum leak rates for He of less than ∼10−9 std atm cc/s between 20 and 110 °C, as well as pressure cycling between ∼10−4 Pa and ∼5 MPa. This seal is useful where outgassing or permeability of elastomeric O rings would present problems.
A reliable dual Blumlein device
Authors: Noggle R. C. , Adler R. J. , Hendricks K. J.
Published: July 2002

In this article, we describe the 500 kV, 100 kA (each arm) GEMINI dual Blumlein accelerator at the Air Force Weapons Laboratory. Novel isolation, trigger, and trigger timing techniques are utilized in this device in order to allow two Blumleins to be charged by one Marx generator, and discharged at different times. The timing circuits are unique in that they make use of saturable magnetic circuits to provide the relative timing of the two outputs. We demonstrate that this technique is reliable, reproducible, and straightforward. We isolate the two Blumlein switches using an inductor wound so that it has minimal inductance when both Blumleins are charging, but maximum inductance when one is fired and the second Blumlein is delayed. Utilization of this technique allows us to isolate the two Blumleins without using resistive isolation with its associated energy loss, or simple inductive isolation with the associated cost in increasing the water line charge time. Complete operational and design data is presented, along with detailed data from the switch trigger arms.
Improving vacuum management in the JEOL 2000FX stem
Authors: Wilson A. R. , Lambrianidis L. T. , Shenton J.
Published: July 2002

Failure of vacuum valves on the JEOL 2000FX scanning transmission electron microscope (STEM) fitted with a sputter ion pump (SIP) was caused by inadequate logic control and feedback from the SIP controller to the vacuum controller. Two low-cost circuit modifications to the SIP controller solved this problem.
Coded-aperture x- or γ-ray telescope with least-squares image reconstruction. I. Design considerations
Authors: Kohman Truman P.
Published: July 2002

Reconstruction of multiplex images produced by coded-aperture telescopes for extended sources of radiation which cannot be reflected or refracted (moderate- to high-energy x rays and low-energy γ rays) can be accomplished by least-squares solution of an overdetermined set of simultaneous equations linking the object, the aperture, and the image. A necessary condition is that the object field (an area of the sky) have a smaller number of pixels than the multiplex image recorded by the position-sensitive detector, which requires that the projection of the object field onto the detector plane be smaller than the detector. This can be achieved by the use of an auxiliary completely open aperture of carefully chosen size and position (‘‘limiter’’) ahead of the coded aperature. The latter consists of regularly spaced elements which are made open or closed either randomly or according to some pattern, subject to solubility of the resulting set of equations. It may be larger or smaller than the detector, the undersize configuration having several advantages. A companion article [T. P. Kohman, Rev. Sci. Instrum. 60, 3410 (1989)] and supporting materials discuss various aspects of the implementation of the design for deployment on balloons or Earth satellites, describe a computer program developed for simulation of the operation of this telescope, and present the results of many simulations, which have demonstrated the feasibility of this approach to coded-aperture imaging.
Fully automated electrophoretic light-scattering device
Authors: Hakim B. H. , Betrencourt C. , Volochine B.
Published: July 2002

A new electrophoretic light-scattering experimental device, fully automated, compact, and very easy to use, is described. It is completely driven by a microcomputer which controls the different experiment steps, performs the data acquisition in 128, 256, or 512 points, the fast Fourier transform analysis of the photocurrent for different frequency bandwidths, 10, 20, 50, 100, 200, 500 Hz, and performs all mathematical calculations needed before displaying the results. The optical setup is a heterodyne device, using two separate beams. A focusing lens (f=30 cm) and the chosen geometry allows one to improve the signal-to-noise ratio and to work with one coherence area. A special mirror holder permits one to select scattering angles from 1° to 50°. The chamber is thermostated. Its coating (in order to minimize electro-osmosis) has an average working lifetime of 8 h. The use of this experimental device for a colloid solution of 25 mg/ℓ of TiO2 (1 μm) in 100 mg/ℓ of KCl, and 10 mg/ℓ of Na4P2O7, pH=6.8, gave an electrophoretic mobility μ=(−3.27±0.17)10−8 m2s−1 V−1 at 20 °C in good agreement with results found in the literature.
Multichannel detection high-resolution electron energy loss spectrometer
Authors: Jeong Eue-Jin , Erskine J. L.
Published: July 2002

A new general-purpose high-resolution electron energy loss spectrometer has been constructed and tested. Novel features of the electron optics include multichannel energy detection and tandem four-element zoom lenses that incorporate beam defining apertures. Compact design of the lenses permit scattering measurements in which the total scattering angle is less than 40°. This feature permits probing bulk phonon modes. The lens system permits electronic adjustment of the analyzer collection angle, and yields high transmission at retardation/acceleration ratios of 400:1. Performance characteristics include simultaneous detection of 50 energy channels at 4-meV energy resolution and target currents exceeding 2×10−10 A. Separate monochromator and analyzer goniometers permit access to out-of-plane scattering configurations which enables probing odd symmetry shear surface modes.
Infrared spectroscopic ellipsometry using a Fourier transform infrared spectrometer: Some applications in thin-film characterization
Authors: Ferrieu F.
Published: July 2002

The prototype of an infrared spectroscopic ellipsometer using a Fourier transform PC-based infrared spectrometer is described. Several applications in thin-film characterization are given, particularly in the case of bulk substrate, thick-layered materials, and determination of the dielectric function of layered materials such as silicon oxide and silicon nitride. The sensitivity and possible improvements of this technique are discussed.
Automated rejection of parasitic frequency sidebands in heterodyne-detection LIDAR applications
Authors: Esproles Carlos , Tratt David M. , Menzies Robert T.
Published: July 2002

The authors describe an electronic technique for detecting the sporadic onset of multiaxial mode behavior of a normally single-mode TEA CO2 laser and demonstrate how this information can be used to facilitate rejection of unsuitable pulses in a heterodyne-detection LIDAR context.
Preparation and characterization of STM tips for electrochemical studies
Authors: Nagahara L. A. , Thundat T. , Lindsay S. M.
Published: July 2002

We report on a fabrication technique for scanning tunneling microscopy (STM) tips for in situ electrochemical investigations. Unwanted Faradaic currents were minimized by insulating the STM tips with Apiezon wax. Cyclic voltammetry showed Apiezon wax to be inert in various electrolytes.
Sensitivity analysis of bulk traps detection in analog deep-level transient spectroscopy measurement systems with exponentially weighted average
Authors: Dmowski K. , Jakubowski A.
Published: July 2002

Improved formulas are proposed describing the correlation signals of bulk traps in semiconductor devices (Schottky barrier diodes and p-n junctions) for constant voltage and constant capacitance deep-level transient spectroscopy analog measurement systems with exponentially weighted average. The presented formulas describe the correlation signals for the two kinds of these systems most often used in practice, i.e., systems utilizing a two-channel boxcar integrator or utilizing a simple one-channel correlator with a bipolar rectangular weighting function. These formulas take into account arbitrary gate width of the applied correlator and the so-called Lambda effect. New analytical formulas describing the rate window for an arbitrarily chosen gate width are proposed. A comparative analysis has been made of the potential sensitivity of these systems as a function of gate width based on two figures of merit: the normalized correlation signal and the normalized output signal-to-noise ratio. The analysis presented enables one to maximize sensitivity of these systems for the study of low-concentration, processing-induced defects in semiconductor devices.
Improved Lyman-alpha hygrometer. Part III: Performance of a field version for small scale atmospheric turbulence measurements over the sea
Authors: Mestayer P. G. , Goutail F. , Larsen S. E.
Published: July 2002

An all-weather ruggedized and simplified version of the IMST/SA–CNRS improved Lyman-alpha hygrometer has been developed in cooperation with Riso/ National Laboratory to measure the small-scale, high-frequency fluctuations of humidity at an open-sea research platform. This version is characterized by the integration of the photomultiplier detection electronics inside the support and by a casings design especially adapted to operation in adverse conditions. Comparisons with other fast hygrometers during the HEXOS Main Experiment indicate that this instrument has probably, to date, the best sensitivity, signal-to-noise ratio, and effective frequency limit. It is able to measure the entire inertioconvective subrange of scales and probably, under some conditions, a part of the dissipation range.
Improved multidetector for time-resolved electron energy loss spectroscopy
Authors: Richter L. J. , Mieher W. D. , Whitman L. J. , Noonan W. A. , Ho W.
Published: July 2002

Modifications to a multianode position-sensitive electron detector employed for time-resolved electron energy loss spectroscopy (TREELS), aimed at reducing interchannel crosstalk, improving response uniformity, and increasing the maximum supportable event rate, are described. The critical importance of the resolution of the electron-dispersing element in determining the multiplex advantage of multidetector analyzers is explored, and its relevance to the maximum attainable multiplex advantage in TREELS is discussed.
In situ sample cell for EXAFS measurements on materials treated at elevated temperatures in vacuo
Authors: Kuroda Yasushige , Maeda Hironobu , Morimoto Tetsuo
Published: July 2002

We describe the design and utilization of a simple in situ cell for extended x-ray absorption fine structure measurements on catalysts which are treated at elevated temperatures in vacuo. Such a special apparatus permits observation of spectral changes of a sample continuously under in situ condition.
Investigation of fragmentation processes following 3d core photoexcitation of trimethylgallium in the vapor phase
Authors: Nagaoka Shin-ichi , Suzuki Shinzo , Nagashima Umpei , Imamura Takashi , Koyano Inosuke
Published: July 2002

Ionic fragmentation following 3d core photoexcitation of trimethylgallium has been studied in the vapor phase using synchrotron radiation. The threshold electron spectrum and photoionization efficiency curves are presented and discussed. The Ga+ and GaMe+ ions are predominantly produced following 3d photoexcitation. The fragmentation patterns following the 3d core excitation of trimethylgallium can be explained in terms of the hybrid orbitals constructed from the 3d, 4s, and 4p atomic orbitals.
Application of a low-frequency-pass filter in exponentially decaying signals
Authors: Chu Benjamin , Xu Renliang
Published: July 2002

A digital low-frequency-pass filter is tested and applied to the data pretreatment of exponentially decaying signals. If the high-frequency cutoff of the low-frequency-pass filter is chosen properly, the filtration process can improve the signal-to-noise ratio of the data. Furthermore, correct characteristic parameters which would otherwise be buried by high-frequency noises can now be retrieved from the filtered signal. The technique is simple to implement using a personal computer and may find use in measurements of slowly decaying functions and kinetic studies.
Si wafers uniformly spaced; bonding and diagnostics
Authors: Rhee Ilsu , Gasparini Francis M. , Petrou Athos , Bishop David J.
Published: July 2002

A new Si-SiO2 bonding process has been developed to achieve a uniform spacing between two silicon wafers of 2 and 3 in. diam. Spacings between 0.1 and 3.9 μm have been obtained so far. Hydrostatic pressure is used to force the two wafers into intimate contact at points where bonding is desired. The bonding is performed at a temperature of ∼1150 °C. The uniformity of bonding and spacing between the wafers is checked by a Fabry–Perot interferometer technique at room temperature and by measurements of superfluid density of He II at low temperature. These results are compared with ellipsometer and stylus measurements of the oxide thickness which is designed to govern the wafers’ spacing. We find that these different techniques yield consistent results.
Photomultiplier housing for vacuum operation of side-on 1P28-type tubes
Authors: Braun W. , Klein R. , Fahr A. , Mele A.
Published: July 2002

A design for the mounting of a side-on tube such as the 1P28 type which has proven simple to construct, reliable, and convenient is described.
Construction of a new flow switch for liquid
Authors: Chao W. K. , Yip S. T. , Wong H. K.
Published: July 2002

A new design of flow switch for liquid is described.
Temperature controller using an error signal modulation
Authors: Lee Ho Seong , Yang Sung Hoon , Chung Nak Sam
Published: July 2002

A temperature controller for laser diode using modulation of an error signal which is proportional to the difference between the sensor temperature and the setpoint temperature is described. By controlling the amplitude of the modulation signal automatically we obtained a temperature stability of ±60 μK at 22.75 °C in a laboratory environment with temperature variations of about 4 K.
Computer reconstruction of optical observations of acoustic fields
Authors: Severcan M. , Diodati P.
Published: July 2002

A gray scale pattern reconstruction method is used to obtain simulations of optically observed patterns due to the Lamb waves propagating in a plate. By comparing the theoretical pictures obtained with the experimental patterns, a confirmation or a correction of the used theoretical values are deducible. We present here the method and some technical details.
Micropipette adaptor for spectrophotometers
Authors: Garner H. R. , Lewis A. C. , Thomas M. K.
Published: July 2002

A simple device has been built that will allow spectrophotometric measurements of very small samples (2–5 μℓ ) in capillary tubes. This attachment is sized to fit in the standard 12.5×12.5 mm2 sample holder slot of commercially available spectrophotometers. A cylindrical quartz lens focuses light from the source onto quartz (for UV measurements and visible measurements) micropipettes and a second lens recollimates the light before it is sent to the detector to optimize the light efficiency. This device was initially used to measure the concentration of small samples of concentrated pUC 8 DNA which has an absorption line at 260 nm.
Method for determination of neutral atomic oxygen flux
Authors: Carruth M. R. , DeHaye R. F. , Norwood J. K. , Whitaker A. F.
Published: July 2002

A method for determining the flux of atomic oxygen atoms to a probe surface has been developed. Two probes are used. One is a glass probe enclosing a small, ceramic resistor heater and a thermocouple for determining the ambient local temperature. Another probe has a silver tip and inside it is only a thermocouple. In an atomic oxygen environment, such as a laboratory oxygen plasma, the silver probe will quickly develop a silver oxide coating which provides for atomic oxygen recombination. The temperature increase of the silver probe caused by energy release in the recombination reaction is matched by the glass probe using the resistive heater. The energy input to the glass probe allows determination of the atomic oxygen flux to the silver oxide probe. This is similar to other approaches using such probes except that by matching the temperature with a resistive heater in the glass probe, whose surface does not allow for recombination of atomic oxygen, a direct measure of the energy deposited on the silver probe may be obtained.
Amplitude and phase acoustic microscope using digital heterodyning
Authors: Reinholdtsen P. A. , Khuri-Yakub B. T.
Published: July 2002

We have built a low-frequency (3–10 MHz) scanning acoustic microscope (SAM) that measures amplitude and phase of rf tone bursts quickly and accurately. The amplitude has a 70-dB dynamic range; the phase is measured to better than 0.1°. The electronics are capable of operating at greater than a 100-kHz repetition rate. The signal is mixed with a reference that is shifted discretely in-phase between tone bursts, the product is integrated and digitized, and the amplitude and phase are computed using at least three digitized values. This general technique operates at a rate limited by the digitizer.
Method to measure current distribution of an electric arc at tubular plasma torch electrodes
Authors: Szente R. N. , Drouet M. G. , Munz R. J.
Published: July 2002

A novel technique was developed to measure the current distribution of an electric arc foot on the electrodes of a plasma torch. The method is based on the induced voltage generated by the passage of the arc over the measuring probe. The technique is suitable for long operation times in plasma torches. Examples of measurements are given for arcs in pure Ar and in Ar+0.3% CO, moving at 9 m/s at 100 and 140 A, respectively. The peaks in the linear current density were 7.6 and 4.2×104 A/m for Ar and Ar+0.3% CO, respectively. The current density was estimated to be around 104 A/cm2 for Ar and 2×103 A/cm2 for Ar+0.3% CO.
The efficiency of consuming rare isotopes in a PIG ion source
Authors: Kutner V. B. , Bogomolov S. L. , Efremov A. A. , Pasyuk A. S. , Tretyakov Yu. P.
Published: July 2002

The efficiency of consuming a working substance in the cyclotron arc ion source during operation at the LNR JINR cyclotrons is analyzed in comparison with the results obtained for the ECR ion source of GANIL and the Berkeley cyclotrons. The experimental results described have been obtained during the acceleration of rare isotopes ion beams (Mg-Ge) at the U-400 and U-300 cyclotrons. Some features of solid working substances fed into the cyclotron ion source are described. The optimal conditions for the efficient use of working substances in the arc discharge are discussed. The results of producing and accelerating rare gas isotopes ion beams, including the radioactive isotope carbon-14, are presented. Prospects for the future development of efficient ion sources for the LNR cyclotron complex consisting of the U-400 and the U-400M are also discussed.
A lithium liquid metal ion source suitable for high voltage terminal applications
Authors: Read P. M. , Maskrey J. T. , Alton G. D.
Published: July 2002

Liquid metal ion sources offer potential improvement in lateral resolution over conventionally used gaseous sources for MeV microprobe applications because of their intrinsic brightnesses. The use of a Li liquid metal ion source is particularly attractive because of the increased sensitivity of lithium for detecting hydrogen (hydrogen profiling) and for detecting near-surface contaminants through high-resolution Rutherford backscattering spectrometry. However, the technical difficulty of occasional sparking between the needle and extraction electrode requires that the needle of the Li liquid metal ion source be rewetted before reignition can be effected; this problem makes Li liquid metal ion sources of the usual design risky for operation in the insulated high-voltage terminals of accelerators used in such applications. We have designed a reliable, long-lived, Li liquid-metal ion source which has provisions for overcoming this limitation. The design features and performance characteristics of the source are described in this article.
Ion sources for light-ion fusion (invited)
Authors: Gerber R. A. , Bieg K. W. , Dreike P. L. , McKay P. F. , Pregenzer A. L. , Tisone G. C.
Published: July 2002

Light-ion drivers offer a potentially efficient and low-cost method to compress and heat an inertial-confinement fusion (ICF) target. In order to produce a significant thermonuclear burn of the fuel, focused ion-beam intensities of 100 TW/cm2 are required. The ion sources for these pulsed-power drivers should produce a single-ion species and should be capable of providing current-density levels up to 5 kA/cm2, in pulse widths of 10–20 ns, at voltages up to several tens of megavolts. Most ion sources used in the past have produced multiple-ion species, including protons and heavier ions, such as carbon and oxygen. In the last few years there has been a substantial research effort to produce single-species sources. The major effort since 1983 has been directed towards developing a pure, high-current Li+ source for the light-ion fusion accelerator, PBFA II. There are two types of ion sources being used for intense ion-beam generation: (1) passive sources which are produced directly or indirectly by the diode voltage itself; and (2) active sources, in which a preformed plasma is generated before the arrival of the power pulse. A survey of existing ion sources and those under development will be given. Emphasis will be given to the lithium-ion sources being developed at Sandia National Laboratories (SNL).
Low-energy extraction with simple two grid accelerator system
Authors: Yucai Feng , Minghua Pu
Published: July 2002

An experimental investigation for extending the ion extraction capabilities of a two grid accelerator system to low energy is described. The preliminary results have shown that low-energy ion beams ranging from 15 to 80 eV can be extracted by biasing the screen grid potential to be negative to the ground at small grid separation distance. The beam currents which have been extracted are 20–60 mA. Beam current densities ranging from 0.15 to 0.45 mA/cm2 with good uniformities are measured at a location 20 cm downstream of the grids. It is found that the extraction capabilities are mainly determined by the operation parameters of the ion source, but they can be substantially effected by changing the grid separation distance and the magnetic field geometry and strength in the discharge chamber.
Characteristics of sheet plasma ion source
Authors: Fukui R. , Takagi K. , Higuchi K. , Tsugueda T. , Yamakawa H. , Kikuchi R. , Takayama K.
Published: July 2002

A sheet plasma ion source has been developed. The new technology will allow simultaneous irradiation of large area samples of 500 mm in width with a high-current ion beam. As a first step of this development, a sheet ion beam of 90 mm width and currents of 38 mA had been successfully extracted from the stable sheet plasma. Both characteristics of the sheet plasma discharge and the sheet ion beam extraction are reported in this article.
The influence of axial magnetic fields on the extraction of an ion beam from a plasma source
Authors: Spädtke Peter , Wituschek Herbert
Published: July 2002

ECR (electron cyclotron resonance) sources are now commonly in use for the production of highly charged ions. For the operation of this type of source a solenoidal magnetic field is necessary. In the present work the influence of this axial field on the extracted ion beam is investigated. The ion optics are mainly determined by the curvature of the plasma boundary. Computer simulations demonstrate the dominant role of space charge.
Development of heavy ion sources at GSI
Authors: Wolf B. H. , Bossler J. , Emig H. , Leible K. D. , Müller M. , Rück D. M. , Spädtke P.
Published: July 2002

For the heavy ion accelerator Unilac Penning ionization gauge (PIG) ion sources are used to deliver multiply charged ions (<10+) of nearly any element of the periodic table. Typical operational ion currents are given. In the future electron cyclotron resonance (ECR) ion sources will play a dominant role for the Unilac. The development of a new 14-GHz ECR ion source for very high charge states (<28+ ) was carried out by Centre d’Études Nucléaires de Grenoble at Grenoble for a new Unilac injector. For the new heavy ion synchrotron Schwen Ionen synchrotron higher ion currents than those available from the PIG sources are required. The high current source CHORDIS was developed at Gesellschaft für schwerionenforschung (GSI) to deliver singly charged ions in the 10–100 mA range. In comparison to CHORDIS a Metal vapor vacuum arc ion source is being studied at GSI in cooperation with Lawrence Berkeley Lab. Typical operation conditions and ion yields are given for the different ion sources.
Performance of a volume H− ion source with a toroidal discharge chamber
Authors: Prelec K. , Alessi J. G.
Published: July 2002

A new volume H− ion source with a toroidal discharge chamber has been designed. Its main feature is a full rotational symmetry, including a conically shaped dipole field separating the main toroidal discharge from the central extraction chamber. Measurements of the H− yield and the accompanying electron component have been performed, both for this rotationally symmetric geometry and for a standard line dipole geometry. With the rotationally symmetric geometry, the H− yield was up to 30 mA through an aperture of 1 cm2 , while the ratio Ie /IH− depended greatly on the value of IH− and was about 20–30 for the highest currents. The beam emittance was measured for the rotationally symmetric geometry, and was found to be εn (90%)≊0.094 π cm mrad for a 21-mA beam. An estimate of the H− ion temperature from the measured emittance gives a value of approximately 3.6 eV.
A compact rf-driven, dc ion source
Authors: Dooling J. C. , Moses K. G.
Published: July 2002

A helium atom beam has been extracted from a rf plasma source with beam energies ranging from 22 to 35 kV. At optimum conditions, a beam of approximately 15 mA equivalent current of 30-keV neutral atoms displays a minimum angular beam divergence of 0.3°. The beam system can be operated continuously in a chopped mode with a 50% duty factor by square-wave modulation of the extraction voltage. Frequency of the modulation can be varied up to 500 Hz. The beam system is also capable of dc operation, having been run in this mode for periods of time exceeding 2 h.
The properties of high-intensity heavy-negative-ion source, NIABNIS
Authors: Tsuji Hiroshi , Ishikawa Junzo , Maekawa Takeshi , Takagi Toshinori
Published: July 2002

The production and destruction of negative ions, which are very important factors for designing high-intensity heavy-negative-ion sources, have been experimentally investigated. For the optimum production of negative ions by sputtering, the control of both the cesium supply and the target temperature is essential. The production probability of carbon negative ions was obtained to be 18.3% at the maximum of sputtered particles. Single- and double-electron detachment cross sections are found in the order of 10−15 and 10−16 cm2 , respectively, in a velocity range of 105 m/s. The heavy-negative-ion source NIABNIS, developed by the authors, can deliver continuous high negative-ion currents of 735 μA for C−, 200 μA for C−2 , 320 μA for Cu−, and 170 μA for Si−.
Characteristics of a sheet plasma and its application to a large extraction area negative ion source
Authors: Wada Motoi , Takeshima Shigeki , Tsuda Hiroshi , Sasao Mamiko
Published: July 2002

A sheet plasma with a thickness as thin as several millimeters was produced by the combination of a pair of dipole magnetic fields and a mirror magnetic field. The negative hydrogen ion produced in the peripheral region of the sheet plasma was measured with a movable Faraday cup. The maximum negative ion current was observed when the extraction electrode of the Faraday cup was biased slightly negative with respect to the plasma potential. The optimum position for the negative ion extraction appeared to be 2 to 3 cm from the center of the sheet plasma. A large concentration of high-energy electrons was found inside of the sheet plasma. The measured negative ion current showed a dependence on the density of high-energy electrons in the sheet plasma.
The ion sources research and development work in the Egyption Atomic Energy Authority
Authors: Abdelaziz Mohamed E.
Published: July 2002

This paper reviews the research and development work on ion sources in the department of Plasma and Accelerators of the Egyptian AEA. Description is given of the dc ion sources used in our laboratory, namely, the duoplasmatron and the electrostatic oscillatory ion source. Then a survey is made of the radio frequency (rf) ion source starting with development of the radial-extraction rf source whereby the beam is extracted radially at the plasma center. The next modifications made on the radial-extraction source which aim at further improvements of the source’s properties are the introduction of central constriction to the plasma tube, then the addition of an electron gun to inject an electron beam into the rf plasma.
Low-duty pulsed PIG source in HIMAC
Authors: Sato Y. , Yamada T. , Ogawa H. , Kimura T. , Yamada S. , Sato K. , Itano A. , Kanazawa M. , Kohno T. , Hirao Y.
Published: July 2002

A low-duty pulsed PIG source has been developed for the injector (e/m= (1)/(7)–1/4 ) of HIMAC. This source is of an indirectly heated PIG type. The requirement for this source is a high current with a low repetition rate and a low-duty factor. To obtain good stability during pulsed operation, the source is operated in a positive arc impedance range. Pulsed operation also allows the arc voltage to be high (1.4 kV), resulting in a high yield of multiply charged ions. With an arc pulse width of 500 μs (1 Hz and a duty of 0.05%), a useful beam pulse width of 200 μs with a peak intensity of 120 μA for Ar6+ has been obtained at an optimum gas pressure of 10−3 Torr. This intensity is higher than for cw mode by a factor of 5. A 90% emittance has also been measured to be 250π mm mrad in both the X and Y directions.
A versatile broad-beam ion source
Authors: Rao Yusheng , Tang Duiyi , Liu Xiaozeng , Shen Boli
Published: July 2002

A broad-beam ion source has been developed for thin-film technology and ion implantation. A broad ion beam of 20–3000 eV and 100 mA can be extracted from the source. Three shapes of beam can be produced that are suitable for appropriate thin-film processes, uniform, convergent, and spherically divergent beams. The ion optics for forming these multishaped beams is discussed. According to the various beam-extraction energy, triple, double, and single grids are employed. A single-grid system is used for an ion energy less than 200 eV. It can operate with a variety of gases, such as N2, O2, Ar, CH4, etc. The source has been applied to ion-beam sputtering deposition, ion-beam direct deposition, ion-beam-assisted deposition, and ion implanter without mass analyzer.
Ion source studies at the ORNL ECR source facility
Authors: Meyer F. W. , Hale J. W.
Published: July 2002

Using high resolution magnetic analysis, we have measured energy spreads of Ar+q (1<q<12) ion beams extracted from the ORNL ECR ion source under a number of different ECR plasma conditions. The measured energy spreads for the different charge states fall in the range 8–20 eV per charge and are all roughly proportional to the ion charge. In addition, we have used a combination of magnetic and electrostatic analysis to investigate the high charge state tail of the extracted Ar+q charge state distribution. Charge states up to +16 have been positively identified; in addition, tentative identification of extracted Ar+17 ions has been made, with total intensity in the range of 10–20 kHz.
Operating principle of the plasma beam ion source
Authors: Langbein K.
Published: July 2002

The plasma beam ion source is a high current ion source of the plasmatron family. It was originally designed for the injection of low energy proton beams into RFQ accelerators. The source consists of a duoplasmatron and one or two adjacent chambers, where the plasma from the primary DP-discharge is guided and compressed by an inhomogeneous solenoidal field. A high density plasma column of 200 mm length and 1–4 mm diameter is formed. In this second stage the plasma can be manipulated with a great degree of independence from the primary discharge, thus allowing, for instance, the adjustment of the electron energy to enhance a certain ionization process (e.g., a proton fraction >90% can be obtained). With argon as an auxiliary gas in the primary discharge the production of oxygen ions in the second stage is possible. By the insertion of a probe into the fringe of the plasma beam and the subsequent evaporation, ions from various solids including carbon, iron, copper, or tungsten have been produced.
Operation of a dc large aperture volume-production H− source
Authors: Kwan J. W. , Ackerman G. D. , Anderson O. A. , Chan C. F. , Cooper W. S. , deVries G. J. , Leung K. N. , Lietzke A. F. , Steele W. F.
Published: July 2002

In testing a multicusp volume-production H− ion source (20 cm diameter, 23 cm long), we optimized the gas pressure, the plasma electrode bias potential, and the magnetic filter. At the optimum pressure of 9 mTorr, the H− beam output increased linearly with discharge power. The maximum H− beam, measured with a current transformer downstream of the accelerator, was 100 mA while using a 6.67-cm2 aperture. Presently we are limited by overheating of the cathodes by the plasma ions. Under similar discharge conditions the maximum H− current density was found to vary as a−0.7, where a is the aperture radius. Results from emittance measurements showed that the effective H− ion temperature increased with a for a>0.8 cm. Thus, the brightness of the beam decreased with increasing aperture radius. Operating the source with cesium would increase the H− output; however, our accelerator must be improved to avoid breakdowns caused by the cesium contamination.
Infrared television pupillometer revised: Bright-pupil illumination and computer automation
Authors: Watanabe Takeru , Ikeda Manabu , Suzuki Takahiro , Nakamura Fukuzo
Published: July 2002

A new-generation infrared-television pupillometer is described and related issues are discussed. In order to obtain a back-lit image of the pupil of the eye, and infrared-LED illuminator that outputs a squeezed beam and a recent CCD camera having enhanced sensitivity in the near-infrared region were incorporated. The infrared-ray exposure to the eye by this method was determined to be quite low and hence a prolonged reconding could be made with safety. The bright-pupil image gives a definite pupil/iris boundary so that more accurate tracing of pupillary movement becomes feasible. In particular, intrinsic responses of the pupil in dim and dark adapted conditions can be measured stably and precisely. Simple, carefully designed, and inexpensive hardware implementation using a microcomputer, as well as a necessary control program for autonomous data acquisition, is presented in detail.
The UofA/TRIUMF radioactive beam ECR ion source
Authors: McNeely P. , Roy G. , Soukup J. , D’Auria J. M. , Buchmann L. , McDonald M. , Schmor P. W. , Sprenger H. , Vincent J.
Published: July 2002

One of the objectives of the TISOL (Test Isotope Separator On Line) facility at TRIUMF is the production of low Z radioactive isotopes, with a special interest in those related to nuclear astrophysics. A part of experimental objectives is the installation of an electron cyclotron resonance ion source on-line to test its suitability for this use. In collaboration with TISOL, the University of Alberta has designed, built, and tested off-line a single stage ECRIS. As part of the source, testing measurements were carried out to determine the efficiency of the source; some preliminary results indicate efficiencies of 20% for Ne+ and 30% for Ar+. In general, it was attempted to test the source under as wide as possible a set of operating conditions. The final off-line testing is completed. It is hoped that the source will go on-line in the early summer of 1989.
A technique for shell compression measurements of laser fusion targets by neutron activation of a rubidium tracer
Authors: Lane Stephen M. , Nelson Michael B.
Published: July 2002

At the Nova Laser, the activation of a rubidium tracer incorporated in the shell of ICF targets has become a standard diagnostic technique for measuring the compressed shell areal density 〈ρΔR〉. The isotope 85Rb is activated by 14 MeV implosion neutrons to produce the isomer 84mRb (t1/2=20.5 min) which is used to determine the shell 〈ρΔR〉 while the radioactive isotope 86Rb (t1/2=18.8 d) is used to determine the fraction of target debris collected as well as to assay the amount of rubidium in the target. The 85Rb(n,2n)84mRb cross section at 14.1 MeV was measured (σ=0.514±0.080 b). Details of the detector system and experimental technique are given.
Plasma diagnostics for the DIII-D divertor upgrade (abstract)
Authors: Hill D. N. , Futch A. , Buchenauer D. , Doerner R. , Lehmer R. , Schmitz L. , Klepper C. C. , Menon M. , Leikind B. , Lippmann S. , Mahdavi M. A. , Schaffer M. , Smith J. , Salmonson J. , Watkins J.
Published: July 2002

The DIII-D tokamak is being upgraded to allow for divertor biasing, baffling, and pumping experiments. This paper gives an overview of the new diagnostics added to DIII-D as part of this advanced divertor program. They include tile current monitors, fast reciprocating Langmuir probes, a fixed probe array in the divertor, fast neutral pressure gauges, and Hα measurements with TV cameras and fiber optics coupled to a high-resolution spectrometer.
Nova two beam automated target inserter (abstract)
Authors: Holliday M. A. , Selchow N. J.
Published: July 2002

To improve overall laser experiments system efficiency and provide an accurate, repeatable reentrant plasma diagnostic platform, an in-vacuum automated robotic target inserter was designed and built. The instrument combines accurate target acquisition and deployment as well as linear positioning of the laser target in the two beam chamber. The linear translation system can extend unsupported over 4 ft in length with ∓0.01 mm resolution with repeatability of less than ∓10 μm. Any one of three laser targets can be selected from a control computer and be automatically inserted to target chamber center in less than 20 s. The system is modular by design in that the two degree-of-freedom end effector can easily be removed or replaced. Plasma diagnostics that can be installed on the linear positioning component of the instrument include imaging x-ray spectrometers, pinhole cameras, and reentrant imaging targets such as those used for x-ray backlighting. The flexibility in control of this system is based on its programmability and closed loop feedback inputs from optical motor encoders and position control switches integrated into the target array and linear translation system.
TFTR vertically viewing electron cyclotron emission diagnostic
Authors: Taylor G.
Published: July 2002

The Tokamak Fusion Test Reactor (TFTR) Michelson interferometer has a spectral coverage of 75–540 GHz, allowing measurement of the first four electron cyclotron harmonics. Until recently the instrument has been configured to view the TFTR plasma on the horizontal midplane, primarily in order to measure the electron temperature profile. Electron cyclotron emission (ECE) extraordinary mode spectra from TFTR Supershot plasmas exhibit a pronounced, spectrally narrow feature below the second harmonic. A similar feature is seen with the ECE radiometer diagnostic below the electron cyclotron fundamental frequency in the ordinary mode. Analysis of the ECE spectra indicates the possibility of a non-Maxwellian 40–80 keV tail on the electron distribution in or near the core. During 1990 three vertical views with silicon carbide viewing targets will be installed to provide a direct measurement of the electron energy distribution at major radii of 2.54, 2.78, and 3.09 m with an energy resolution of approximately 20% at 100 keV. To provide the maximum flexibility, the optical components for the vertical views will be remotely controlled to allow the Michelson interferometer to be reconfigured to either the midplane horizontal view or one of the three vertical views between plasma shots.
Photoluminescence of strained Si1−yCy alloys grown at low temperature
Authors: Boucaud P. , Francis C. , Larré A. , Julien F. H. , Lourtioz J.-M. , Bouchier D. , Bodnar S. , Regolini J. L.
Published: July 2002

The photoluminescence of strained Si1−xCx alloys grown at low temperature by rapid thermal chemical vapor deposition is investigated. The photoluminescence spectra are mainly characterized by a deep level broadband at low energy which subsists up to room temperature. This low energy emission is associated with the low-temperature growth process required for the incorporation of carbon into substitutional sites. The stability of the layers after thermal annealing is monitored using this low energy radiative recombination. A blue shift of the photoluminescence energy peak is observed and the peak intensity presents a maximum versus annealing time. The blue shift and the associated increased linewidth is explained in terms of the local strain induced band-gap fluctuations. Infrared transmission spectra of the annealed samples suggest that silicon carbide precipitates appear during the anneal and that oxygen and carbon complexes contribute to the formation of the deep level band.
In situ Hall-effect system for real-time electron-irradiation studies
Authors: Ziebro B. S. , Look D. C. , Hemsky J. W. , Rice W.
Published: July 2002

A unique system capable of taking in situ Hall-effect measurements during electron irradiation has been developed. The key element is a small, powerful rare-earth magnet. Measurements can be taken while the electron beam is on, resulting in a considerable time savings and eliminating problems associated with mounting and demounting the sample. High resolution electron concentration and mobility versus fluence data are quickly and easily obtained, making possible detailed defect production rate studies as functions of energy and flux.
A torsion balance to measure hysteretic levitation forces in high T
c superconductors
Authors: Weeks David E.
Published: July 2002

A simple torsion balance is described which is used to measure the levitation force on a magnet as a function of height above bulk samples of the new high Tc superconductors. Results are presented for a the YBa2Cu3Ox (Tc∼90 K) and the Tl-Ba-Ca-Cu-O (Tc∼120 K) superconducting systems. Possible uses for the balance are discussed.
Method for calibrating resonant-mass gravitational wave detectors
Authors: Boughn S. , Bassan M. , Fairbank W. M. , Giffard R. P. , Michelson P. F. , Price J. C. , Taber R. C.
Published: July 2002

A simple and accurate method of calibrating the response of a resonant-mass gravitational wave detector to an impulsive signal is discussed. The procedure automatically includes the effects of the detection electronics chain and any filtering algorithm that is applied. The method provides a direct measure of the frequency dependence of the signal-to-noise ratio (SNR) referred to a signal that has a white frequency spectrum. Measurement of this quantity allows us to determine the pulse detection noise temperature that can be obtained by optimum linear filtering of the detector output. Experimental results are presented.