bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved system for perpendicular electron-cyclotron emission measurements on TMX-U
Authors: Lasnier C. J. , Ellis R. F. , James R. A.
Published: July 2002

Perpendicular electron-cyclotron emission (PECE) is used on Tandem Mirror Experiment-Upgrade (TMX-U) to diagnose thermal-barrier hot electrons (TH∼100–400 keV, yielding the time history of the temperature of these relativistic electrons. We describe an improved quasioptical viewing system for these measurements that uses high-sensitivity superheterodyne receivers at fixed frequencies of 60, 98, 130, and 196 GHz. The improved viewing and transport system consists of an off-axis ellipsoidal mirror that images the plasma onto a V-band conical collection horn, an overmoded circular waveguide ( 7/8 in. diam) that transports the radiation outside the vacuum vessel where the polarization is selected, and a high-absorptivity Macor beam dump to prevent internal wall reflections from entering the viewing system. A relativistic code is used to calculate optically thin PECE signals from relativistic electrons for various energy and pitch angle distributions.
In situ electric field perturbations of deep trap accumulation in silicon during proton ion implantation
Authors: Erokhin Yu. N. , Ravi J. , Rozgonyi G. A. , White C. W.
Published: July 2002

The influence of in situ perturbations of the silicon target crystal electronic subsystem during H+ ion implantation has been studied in terms of the type, density, and spatial distribution of accumulated deep traps. A perturbation of the electronic subsystem was achieved through application of a reverse bias to diode test structures. A substantial decrease in deep trap concentration is observed when ion implantation is accompanied by a superimposed reverse bias. The effect is especially pronounced for hydrogen related deep traps at Ec−0.3.
Two-dimensional Thomson scattering system for ATF
Authors: Kindsfather R. R. , Rasmussen D. A. , Murakami M. , Thomas C. E. , Painter S. L. , Hays P. S. , Morris R. N. , Tolnas E. L.
Published: July 2002

A two-dimensional Thomson scattering system is being designed for the Advanced Toroidal Facility (ATF) torsatron experiment. This system will provide electron temperature and density measurements at 15 points along a vertical chord with each shot from a two-dimensional Te and ne map of an ATF toroidal cross section can be obtained. The horizontal Thomson scattering viewing port is offset by 15° toriodally from the ports passing the vertical laser beam. Translating and rotating mirors will be used to relay light from the viewing port to the collection lens. This makes it possible to scan horizontally, view as much of the vertical laser beam as possible, and to use a fixed focal length, fixed position lens. Three sets of spectrometers optimized to three temperature ranges will be used. At the output of each spectrometer, dispersed light will be detected by an array of five, seven, or eight photomultiplier tubes, depending on the temperature range of the spectrometer.
Design of a high-power long-pulse CO2 laser for alpha-particle Thomson scattering
Authors: Hutchinson D. P. , Vander Sluis K. L.
Published: July 2002

A high-power CO2 laser is being constructed to measure the velocity distribution of alpha particles in a burning plasma. The laser system is being designed around a Lumonics 602 TEA CO2 laser. A low-pressure cell will be placed in the unstable resonator cavity to produce a long-pulse, narrow-linewidth beam. Details of the laser design will be presented. This research was supported by the Office of Fusion Energy, U.S. DOE, under Contract No. DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc.
Summary of control and data acquisition systems for NOVA experiments (invited)
Authors: McCauley E. W. , Campbell E. M. , Auerbach J. M. , Montgomery D. S. , Martin V. A. , Randolph J. E. , Shaw J. G. , Stewart B. L. , Stone G. F.
Published: July 2002

The NOVA laser has completed its first year of operation. During this period, emphasis has been placed on activation of the facility and of the numerous target and beam diagnostics. Two separate target chambers are in use. NOVA operation is separated into two broad functions: laser operations and experiments. The operations group provides the laser system control, operation, and data acquisition and the experiments group provides experiment definition, diagnostic instrumentation, and overall data processing. On the operations side, VAX 11/780 computers are used to set up diagnostic operating parameters and collect data recorded by the CAMAC and CCD modules. These data are delivered in files by electronic link to the Laser Experiments and Analysis Facility (LEAF) VAX 11/785 of the experiments group for processing. Film data are digitized at LEAF and the film data files are also processed on the LEAF VAX. The LEAF provides collection, processing, analysis, and archiving of the experimental data. The many applications software packages written for LEAF provide the experimental physicists and NOVA operations staff with programs and data bases for interpretation of experimental results. This software makes fundamental use of the ORACLE relational data base management system to both access the required data and archive the obtained results. Post-shot data processing produces sets of scalar values, x, y profiles and x, y, z contour data. The scalar data are stored in the ORACLE DB; the more extensive results are stored in binary files on disk. All data forms are accessed by a comprehensive software system, the electronic SHOTBOOK, developed around the ORACLE DBMS. This software also provides the means to archive relevant data about each experimental activity and allows the physicists to annotate displayed experimental results with technical comment.
Software architecture for the ORNL large-coil test facility data system
Authors: Blair E. T. , Baylor L. R.
Published: July 2002

The VAX-based data-acquisition system for the International Fusion Superconducting Magnet Test Facility (IFSMTF) at Oak Ridge National Laboratory (ORNL) is a second-generation system that evolved from a PDP-11/60-based system used during the initial phase of facility testing. The VAX-based software represents a layered implementation that provides integrated access to all of the data sources within the system, decoupling end-user data retrieval from various front-end data sources through a combination of software architecture and instrumentation data bases. Independent VAX processes manage the various front-end data sources, each being responsible for controlling, monitoring, acquiring, and disposing data and control parameters for access from the data retrieval software. This paper describes the software architecture and the functionality incorporated into the various layers of the data system.
Diagnostic software development for TFTR
Authors: Christianson G. , Davis W. , Diesso M. , Lagin L. , Malsbury J. , Matone J. , Schechtman N. , Snyder J. , Terpstra T.
Published: July 2002

The development of diagnostic software for the tokamak fusion test reactor (TFTR) machine is discussed. Key problems in the development process are the control of a large body of applications code and the provision of an environment that maximizes the productivity of the applications programmers. Control of the large body of code is accomplished through the use of a common method of software module specification, standard naming conventions, standard documentation, and automated utility programs to check the consistency of source code. The productivity of the applications programmers is enchanced by the presence of services providing graphics capabilities, terminal and user dialog management, data access, smoothing and compression, hardware device access and testing, and program execution tracing.
Neutron diagnosis of compressed ICF targets
Authors: Richardson M. C. , Keck R. F. , Letzring S. A. , McCrory R. L. , McKenty P. W. , Roback D. M. , Soures J. M. , Verdon C. P. , Lane S. M. , Prussin S. G.
Published: July 2002

The final stages in the compression of microencapsulated DT fueled ICF targets require detailed characterization for meaningful comparison with predictions of hydrodynamic codes. The determination of such parameters as the fuel and shell areal densities, the average ion temperature, and the impact of implosion nonuniformities in high-density target implosions present a strong challenge. We describe several approaches utilizing the self-generated neutrons to diagnose these conditions, including neutron spectrometry, neutron activation of tracer gas and shell materials, and neutron scattering techniques. The importance of making simultaneous measurements of several core parameters to limit ambiguity in interpretation is discussed.
Determining plasma-fueling sources with an end-loss ion spectrometer
Authors: Grubb D. P. , Foote J. H.
Published: July 2002

To help identify the major sources of fueling gas in Tandem Mirror Experiment-Upgrade (TMX-U), we mounted a mass-sensitive, E‖‖B, end-loss ion spectrometer (ELIS) near the machine’s centerline. We set the electric field in the ELIS to simultaneously measure the axial loss currents of both hydrogen and deuterium. We then initiated plasma discharges, where we injected either hydrogen or deuterium gas into the central cell. We also selected and deselected the central-cell neutral beams that were fueled with hydrogen gas. The end-cell neutral beams were always selected and fueled with deuterium. By taking the ratio of the hydrogen end-loss current to the deuterium end-loss current (with a known deuterium-gas feed rate), we were able to infer the effective fueling rates that were due to wall reflux, central-cell beams, and end-cell beams. The results were the following: wall reflux, 6 Torr l/s; central-cell beams, 15 Torr l/s; and end-cell beams 1 Torr l/s.
PLT and PDX perpendicular charge exchange analyzers
Authors: Mueller D. , Hammett G. W. , McCune D. C.
Published: July 2002

The perpendicular charge-exchange systems used on the poloidal divertor experiment and the Princeton large torus are comprised of ten-channel, mass-resolved, charge-exchange analyzers. Results from these systems indicate that instrumental effects can lead to erroneous temperature measurements during deuterium neutral beam injection or at low hydrogen concentrations.
Optically thin perpendicular electron-cyclotron emission from hot electrons in TMX-U
Authors: James Reed A. , Lasnier C. J. , Ellis R. F.
Published: July 2002

Perpendicular electron-cyclotron emission (PECE) from relativistic (TH∼100–400 keV) hot electrons within the thermal-barrier region of Tandem Mirror Experiment-Upgrade (TMX-U) is detected at 35, 60, 94, and 98 GHz. For the operating regime of TMX-U, these signals are optically thin (τ≪1) and thus proportional to the radial hot-electron line density. A relativistic code is used to calculate the theoretical temperature dependence of the perpendicular emission coefficient, j⊥(ω, TH), for each of the detected frequencies. This dependence has been verified experimentally by x-ray measurements of the hot electron temperature, TH. The observed qualitative agreement demonstrates that optically thin PECE signals can be used to determine the temporal evolution of TH. An inability to absolutely calibrate the present PECE waveguide system has prevented quantitative agreement.
Thomson parabola ion energy analyzer with a coincident and jitter-free applied electric field ramp
Authors: Yoneda H. , Horioka K. , Kim Y. , Kasuya K.
Published: July 2002

A simple Thomson parabola ion energy analyzer for intense pulsed ion beam is demonstrated. Beam ions collimated by two apertures, are deflected by a time ramping electric field and a static magnetic field. The ramping electric field is produced with a stacked cable pulser powered by a voltage divider of the pulse power generator. As there is no additional switching tube and no high-voltage generator other than the main machine, the analyzer has an electric field ramp that is coincident and has no jitter with the ion beam. A temporal history of ion beam energy is measured as an example and a reasonable agreement with the measured diode voltage is obtained.
Small oven for obtaining temperatures to 1350 °C
Authors: Gordon J. E.
Published: July 2002

A small, inexpensive oven capable of achieving a temperature of 1350 °C with a power consumption of less than 1 kW is described. The oven has a working volume which is roughly 10×6×12 cm. It has been used for bonding gold to sapphire substrates, but would be suitable for use in any application which requires elevated temperatures in a working volume of 500–1000 cm3.
Improved indium seal for LiF windows of resonance lamps for use at low temperatures
Authors: Harvey K. C.
Published: July 2002

A method of attaching crystalline LiF windows to glass lamps has been developed. The resulting seals have good vacuum properties and can be cooled to cryogenic temperatures while maintaining their vacuum integrity. The technique uses dual, indium O rings to provide a vacuum seal for a LiF window on a resonance lamp. It is appropriate for resonance lamps that produce line spectra. LiF crystals must be cooled to transmit Lyman-β radiation that can optically pump atomic hydrogen. This indium seal has other applications such as windows for VUV lasers. Details of the construction, assembly, and performance of the seal are described. A discussion of the merits and applications of the window seal is presented.
Modification of Ithaco model 391A lock-in amplifier for use in the high- dynamic-range mode at the frequency range from 60 to 120 kHz
Authors: Maeda Shiro , Shindo Yohji
Published: July 2002

The GREEN plug-in cards set of Ithaco model 391A lock-in amplifier has been modified to carry out measurements in high dynamic range at the frequency range from 60 to 120 kHz.
Time-of-flight laser mass spectrometer for gas analysis in a collisional regime
Authors: Montone A. , Morales P. , Nardi A.
Published: July 2002

We have built and tested a new type of time-of-flight mass spectrometer for measurements of fragmentation processes in a collisional regime. Preliminary test results are given for triethylamine.
A new VUV beamline BL-19 for undulator radiation at the Photon Factory
Authors: Kakizaki A. , Soda K. , Fujisawa M. , Suga S. , Mori T. , Watanabe Y. , Ishii T. , Taniguchi M. , Ikezawa M. , Suzuki S. , Sugawara H. , Kamiya Y. , Miyahara T. , Tanaka K. , Kato H. , Ito K. , Yagashita A. , Satow Y. , Kosuge T. , Sato S. , Asaoka S. , Kanaya N.
Published: July 2002

A new VUV beamline at the Photon Factory ring that is designed to accept radiation emitted from an undulator is described. The characteristics of the undulator and all parts of the beamline; a front end, a mirror system, and two monochromators, are described in detail. The characteristics of optical elements in the beamline are also shown.
Photon beam position monitor
Authors: Izumi T. , Nakajima T. , Kurihama T.
Published: July 2002

A highly sensitive beam position monitor has been designed for use with synchrotron radiation sources. This beam position monitor consists of two gas-flow ionization chambers having three parallel plate conductors. The incident beam is divided by a central plate. Therefore, a displacement of the beam position is detected with the two outside ionization chambers. The position monitor was tested at the BL6Cl beamline of the Photon Factory (PF). The results show a good performance.
Beryllium window assembly for the 53-pole wiggler beamline at the Photon Factory
Authors: Sato Shigeru , Asaoka Seiji , Nagakura Ichiro , Kanaya Noriichi
Published: July 2002

The performance of a beryllium window assembly which is exposed to large heat loads due to intense photon flux form a 53-pole multipole wiggler is described. Six graphite foils were designed to have a thickness of 0.14 mm each in order to reduce the thermal loads at two 0.2-mm-thick beryllium windows so that the beryllium windows could withstand the high thermal stress caused by a peak power density of 3.2 kW/mrad2 from the wiggler. The beryllium windows are located at the downstream side of the graphite foils and transmit x-ray components to an experimental station. The maximum temperature rise measured at the beryllium windows under a total synchrotron radiation power of 7.75 kW at 300 mA of stored beam current was 180 °C. No visual damage was observed.
Status report on the synchrotron radiation source ‘‘SIBERIA’’ at the I. V. Kurchatov Institute of Atomic Energy
Authors: Stepanov E. P.
Published: July 2002

The 450-MeV electron storage ring SIBERIA-1 with 100-mA stored beam current was put into operation at the I. V. Kurchatov Institute of Atomic Energy in 1983. In 1984 a 3-pole superconducting wiggler was placed in the storage ring, which produced SR beams with a critical wavelength 21 Å. Investigations of phosphor-crystal and high-temperature superconductor luminescence, VUV-spectrometry of wide-band dielectrics, photoelectron spectroscopy of HTSC, etc. are being carried out. A 2.5-GeV 100-mA electron storage ring, SIBERIA-2, is now under construction.
Calculation of undulator radiation spectral and angular distributions
Authors: Walker R. P.
Published: July 2002

The validity of an approximation used in the derivation of the standard analytic formula for the radiation produced by an ideal undulator is examined. Efficient algorithms for calculating the spectral and angular distributions including the effect of electron beam emittance are described. Results from a computer program that allows a number of different calculations to be performed with a range of approximations are presented.
Sandia Super-EBIS
Authors: Schmieder R. W. , Bisson C. L. , Haney S. , Toly N. , Van Hook A. R. , Weeks J.
Published: July 2002

The Sandia Super-EBIS is a state-of-the-art electron-beam ion source designed to produce extracted beams of ions up to U82+ at energies below 1 keV/Q for use in beam-target experiments. It is built around a 1-m-long superconducting solenoid and an electron gun rated up to 80 kV. All aspects of the design have been optimized for efficient extraction of the ions and their transport to the target.
Development of an advanced ‘‘volume’’ H− source for neutral beam application
Authors: Leung K. N. , Anderson O. A. , Chan C. F. , Cooper W. S. , DeVries G. J. , Hauck C. A. , Kunkel W. B. , Kwan J. W. , Lietzke A. F. , Purgalis P. , Wells R. P.
Published: July 2002

Based on recent experimental results made on the large and small multicusp volume H− sources, a new multicusp source has been designed to generate high-brightness H− or D− beams for high duty factor or dc operations. Cesium will be introduced into the source plasma to enhance the H− output current. Arrangements for reducing the electrons as well as capturing them in the preaccelerator electrodes will be incorporated into the new source geometry.
The energy component analyzer and spectrum analysis of end-loss ions in a tandem mirror
Authors: Ishii K. , Ohkawara H. , Maeda Y. , Katanuma I. , Yatsu K. , Miyoshi S.
Published: July 2002

Features of the electrostatic energy analyzer of a cylindrical type are described with the aim of measuring the end-loss ions in the tandem mirror GAMMA 10. The analyzer provides us with information about ion density distributions in a loss-cone region of velocity space as well as plug potential in the tandem mirror. Application of the analyzer to the tandem mirror experiments and the energy spectrum analysis are discussed.
Data acquisition and signal processing using a laptop personal computer
Authors: Imaino W. , Munce C. , Yerry M. , McDonald N. , Tran N.
Published: July 2002

This article describes a battery-operated system, consisting of a laptop personal computer, peripheral electronics, and associated software programs, that allows for flexible data acquisition and conditional signal processing. The design of a data acquisition system around a laptop computer contains many challenges not encountered in conventional PC-based systems. The focus of this article is on those aspects of the peripheral electronics that are implemented specifically to minimize power consumption in a battery-operated environment, take advantage of the particular features of our laptop, and provide the greatest possible signal processing flexibility and capability. The use of this system in an experiment to detect bearing defects by acquiring and processing the signal from an accelerometer is described. The application employs a vibration envelope detection scheme along with the full flexibility designed into the peripheral electronics to provide a quite sophisticated tool for monitoring the health of a bearing.
A simple device for preparing small area junctions for inelastic electron tunneling spectroscopy and for other four point junctions
Authors: Gauvin Serge , Leblanc Roger M.
Published: July 2002

A sample holder with an adjustable mask area (4 mm2 to less than 0.01 mm2) for vacuum metal deposition at low temperature is reported. This simple system is designed for inelastic electron tunneling spectroscopy but can be used for various kinds of four point junctions. The design allows for easy dismantling and cleaning of the device.
A simple relative laser power meter
Authors: Radak Bojan B. , Radak Branislav B.
Published: July 2002

A simple relative laser power meter was designed and built according to the principles of the ‘‘pedestal’’ calorimeter. The principles and specific details of the construction are given. The time response was measured and characterized by the time constants of the heating (‘‘laser on’’) and cooling (‘‘laser off’’) of the receiving element. The time constants were 1.46 s for heating and 1.34 s for cooling.
Automated, differentially pumped, mass-spectrometer sampling system
Authors: Little Jon C. , Gordon Lloyd B.
Published: July 2002

The design, construction, and testing of an automated gas sampling system for a quadrupole mass spectrometer on a process chamber with a wide pressure range is described. A set of two parallel stepper-activated vacuum valves are used to vary the amount of gas admitted into the mass spectrometer chamber. One valve is a standard low-conductance leak valve to allow the sampling of high pressures (760 down to 10−2 Torr). The other valve is a specially designed high-conductance valve to allow the sampling of lower pressures (1×10−2 down to 2×10−5 Torr). The computer-controlled sampling system automatically adjusts the position of the valves to provide the proper leak rate so that the mass spectrometer can continuously monitor a process chamber with a time varying pressure between 760 and 2×10−5 Torr. This provides a constant pressure at the mass spectrometer sensing head, despite the varying process chamber pressure. No commercially available mass spectrometer system was found which was able to automatically monitor the gas composition in a process chamber with such time varying pressures. The principles of operation are presented along with calculations of the gas flow and the control equations.
A condenser objective lens with asymmetric polepieces to facilitate the extraction of secondary and Auger electrons
Authors: Bleeker A. J. , Kruit P.
Published: July 2002

A new condenser objective lens for a scanning transmission electron microscope especially designed for through-the-lens extraction of secondary and Auger electrons is presented. The optimal axial field to extract the secondary and Auger electrons is a field that falls off as 1/z2. This field form has been realized by a new lens design with one sharp polepiece and a second, carefully shaped, polepiece. This polepiece consists of two magnetically separated parts. The bore in this polepiece measures 20 mm while the working distance is 10 mm. The spherical aberration on the condenser side is 2.5 mm for an acceleration voltage of 125 kV while, with the same lens excitation, the projector side spherical and chromatic aberrations are 1.1 and 1.5 mm, respectively. All (Auger) electrons with an energy up to 1000 eV emerging from the specimen can be concentrated in a disk of 4.2 mm and a maximum opening angle of 6° for further energy analysis.
Direct imaging of x rays with a CCD using hardware processing
Authors: Mayer R.
Published: July 2002

This study investigated the direct imaging of low intensity x-rays by a room-temperature charge coupled device (CCD). Commercial CCD evaluation kits read out the information and provided initial processing of the data. The extraction of the signal from noise was achieved using NIM modules rather than by storing and numerically analyzing the data. Due to the fast processing at standard TV rates, the storage of the data required conversion of the signal from a timing to a pulse height analysis (PHA) spectrum. The tested CCDs were found to have lower efficiency relative to the proportional counter for the range of photon energies (1.5–8.0 keV) studied but had higher spatial resolution than gas-filled position-sensitive detectors. Application of CCDs for x-ray energy dispersive detectors is described.
Experiments with high-voltage insulators in the presence of tritium
Authors: Grisham L. R. , Falter H. , Causey R. , Chrisman W. , Stevenson T. , Wright K.
Published: July 2002

During the final deuterium-tritium phases of the TFTR and JET tokamaks half of the neutral injectors will be used to produce tritium neutral beams to maintain an equal mix of deuterium and tritium in the core plasma, and such requirements may also occur in future devices. This will require that the voltage hold off capabilities of the high voltage insulators in the accelerators be unimpaired by any charge buildups associated with the beta decay of adsorbed layers. We report tests in which we measured the drain currents under high dc voltage of TFTR and JET accelerator insulators while they were successively exposed to vacuum, deuterium and tritium. There did not appear to be any substantial reduction in hold-off capability with tritium, although at some voltages there was a small increase in the leakage current. We also compared the breakdown properties of a plastic tubing filled with deuterium and then tritium at varying pressures, since such tubing has been considered as a high-voltage break in the gas feed system for TFTR, and the presence of large numbers of electron-ion pairs might lead to enhanced Paschen breakdown. We found no significant differences in the behavior for the geometry used.
Influence of the propellant flow on the performance of diaphragm operated gas guns
Authors: de Icaza M. , Renero C. , Prieto F. E.
Published: July 2002

Many different properties of matter under shock wave loading can be studied through the use of gas-gun accelerated projectiles. Knowledge of the motion of the projectile, and in particular of its velocity, is thus of prime importance. This motion depends upon the sudden release of a compressed gas confined in a breech. The corresponding firing mechanism is a geometrical restriction to the flow of the accelerating gas behind the projectile. In this article a theoretical expression is obtained to take into account this restriction, and is applied to the case of the diaphragm type of firing mechanism. Two conditions are imposed to the one dimensional and isentropic flow at the diaphragm zone: the continuity of the fluid flow (density times velocity times cross section) and the continuity of force (pressure times cross section). The theoretical expression obtained can be expressed in term of upper and lower bounds. A comparison with experimental results, obtained in our laboratory, is carried out, showing that they systematically fall around the upper bound. The reasons for this behavior are discussed and a useful rule to design the firing mechanism is suggested.
Displacement sensor for a gravitational redshift experiment with 67Zn Mössbauer resonance
Authors: Ikonen E. , Seppä H. , Potzel W. , Schäfer C.
Published: July 2002

A displacement sensor was constructed to monitor the motion of a piezoelectric Doppler velocity transducer in a gravitational redshift experiment with 67Zn Mössbauer resonance. The sensor uses a dc superconducting quantum interference device (SQUID) to detect small displacements of a permanent magnet. To meet the stringent requirements of the redshift experiment, the magnetic flux gradient and the pickup coil of the sensor are designed in such a way that the SQUID flux noise of 7 × 10−6 Φ0/√Hz corresponds to a displacement resolution of 6 × 10−14 m/√Hz. However, resolution up to 3 × 10−15 m/√Hz in the frequency band of 20–20 000 Hz is demonstrated. The linearity of the displacement sensor and the piezoelectric transducer are considered in detail and the resulting uncertainties associated with the Doppler modulation in the Mössbauer experiment are evaluated.
Fourier analysis through geometrically represented signal voltages
Authors: Levine Robert Y. , Zatet Mohamed
Published: July 2002

A new approach to electro-optical signal modulation is proposed based on the geometrical representation of signal voltages. In the forward biased implementation an assembly consisting of a deposited meander pattern, sinusoidal mask, and microchannel plate (MCP) is shown to perform one-dimensional Fourier analysis. The sinusoidal mask is shown to modulate a biasing voltage pulse as is traverses the meander pattern. In this paper the MCP gain and signal-to-noise models are combined with signal sampling criteria to obtain constraints on the assembly dimensions and biasing voltages. It is shown that a 0.5 mm square meander, coupled with mask wavelengths of order 10 mm, is sufficient to measure about 10 Fourier components of a 400 ps pulse with peak voltage of order 10 V. Experimental issues which have arisen in the course of testing the concept are discussed.
Thermal lens technique for sensitive kinetic determinations of fast chemical reactions. Part I. Theory
Authors: Franko Mladen , Tran Chieu D.
Published: July 2002

The thermal lens effect can be successfully explained by use of the presently available theories. However, the existing theories fail for cases where the sample concentration changes with time, i.e., when the sample undergoes a chemical reaction. The objective of this work is to demonstrate that the thermal lens technique can be used for the sensitive kinetic determination of fast chemical reactions. It is systematically approached from two different directions: the theoretical aspect which is described in this paper and the experimental section which will be reported in the following paper. Specifically, novel theories which are based on the parabolic as well as the aberrant model have been derived to describe the thermal lens signal for cases where the sample concentration changes with time. Based on the developed theories, computer calculations were then performed to simulate conditions for various chemical reactions. It was found that in all cases, both of the developed (parabolic and aberrant based) theories can be used successfully to determine not only the order of the reaction but also the reaction rate constant.
Physics and technology of high brightness sources−The future (invited)
Authors: Kulipanov G. N. , Mezentsev N. A. , Skrinsky A. N.
Published: July 2002

Various trends in the development of high brightness synchrotron radiation sources are reported. The ways of increasing the brightness whose choice is governed by the compromise between users, machine, and economic requirements, are discussed. The experimental and technological possibilities of new families of storage rings that are being designed and constructed in different countries are compared. The physical and technical problems associated with the creation of such storage rings are treated.
Modification of a commercial microwave oven for applications in the chemical laboratory
Authors: Pougnet M. A. B.
Published: July 2002

A commercial microwave oven has been modified for laboratory applications. The modifications include the lining of the cavity with polypropylene, the use of a polypropylene turntable, incorporation of inlet and outlet ports, and the use of an extraction system to purge the oven’s cavity.
Frequency stabilization of a multimode high-power He-Ne laser
Authors: Yokoyama Shuko , Araki Tsutomu , Oshio Takanori , Suzuki Norihito
Published: July 2002

A high-power, frequency-stabilized laser source is required for an atomic force microscope which uses interferometric techniques to obtain distance measurements with picometer resolution. For this purpose, the oscillation frequency of a 10 mW multimode He-Ne laser was stabilized using a new technique. Optical interaction between the longitudinal modes synthesizes intermode beats. Frequency of the intermode beat signal changes periodically with respect to cavity thermal expansion. This phenomenon is explained by the concept of ‘‘frequency pulling.’’ The secondary beats synthesized by the interaction between the intermode beat signals also change due to frequency pulling. The relation between the secondary beat of an intermode beat frequency and the laser cavity length is utilized for the stabilization of laser frequency. The change in the frequency of the secondary intermode beat is employed as the feedback signal to control the length of the cavity of the laser. To detect the frequency change in the secondary beat signal, a simple microwave electronics circuit was designed. An excellent frequency stability (instability: ±2 parts in 108) and high-power laser output were obtained successfully using this simple technique.
A coincidence system for studying collisional ion dissociation: Application to H+3 in He
Authors: de Urquijo J. , Alvarez I. , Domínguez I. , Cisneros C. , Martínez H.
Published: July 2002

A simple coincidence circuit has been built and attached to conventional pulse counters to obtain the energy distribution of the coincident ion pair arising from the three-body polar dissociation process H+3+He→H++H++H−. The coincidence circuit is based on TTL components and a solid-state delay line. A method to derive the true coincidence H+–H− energy distribution is described, from which properties such as the inelastic energy loss and angle of proton ejection can be obtained.
UHV optical window seal to conflata) knife edge
Authors: Noble A. , Kasevich M.
Published: July 2002

We report a bakeable vacuum seal between glass blanks and a stainless-steel conflat vacuum port without leaks at the 10−10 atm cm3 s−1 level. The seal permits true optical windows, both flat and coated, to be economically used in ultrahigh-vacuum applications
Design and construction of a high-precision computer-controlled monochromator
Authors: Golnabi H.
Published: July 2002

A high-precision, computer-controlled monochromator of modest cost is described. The folded sine bar is used for the grating drive that provides high linearity even for large scanning angles. With a 200 steps/turn stepper motor and 600 grooves/mm grating, the minimum step size in first order is 0.05 nm, which can be further reduced. Over the 300–750 nm range, a bandpass better than 0.1 nm and a reproducibility of ±0.05 nm can be achieved. The stray light rejection of 8.9×10−7 at 5.5 nm from the laser line is remarkable for this single grating instrument. Its performance promises to be an important tool for most forms of laser spectroscopy.
Ion beam generation from a thermal contact-ionization plasma source
Authors: Katsumata I. , Yamasaki M. , Murakami K. , Fujimoto M. , Tsukahara H. , Nanjo Y. , Yoshimura H.
Published: July 2002

The ion beams are produced by a cylindrical thermal contact-ionization plasma source with an electrostatic lens system. The source plasma is produced at the inside surface of a 5-mm-diam 20-mm-long Re foil cylinder protected with a W cylinder. The surface is heated up to 3000 K by electron bombardment. The material to be ionized is fed to the surface through a guide pipe from a reservoir. Generation of all alkaline metal ions have been tested and a beam current of hundreds of μA is obtained. The efficiency for Li+ production is 30%, while that for Cs+ is nearly 100%. Alkaline earth ion beams, except Mg, are generated. A current of Ba+ up to 200 μA is obtained, while a Tl+ beam of over 200 μA is achieved. Halogen negative ion beams, except F−, of the order of 10 μA are also obtained when alkali halides are used. Attempts to extract Li− from the source are also being made.
Doppler-shifted neutral beam line shape and beam transmission
Authors: Kamperschroer J. H. , Grisham L. R. , Kokatnur N. , Lagin L. J. , Newman R. A. , O’Connor T. E. , Stevenson T. N. , Halle A. von
Published: July 2002

Analysis of Doppler-shifted Balmer-α line emission from the Tokamak Fusion Test Reactor’s (TFTR) neutral beam injection systems has revealed that the line shape, which is a direct measure of the velocity distribution function, is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the wide-divergence part of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e-divergence of 1.3° (based on fits to the beam shape on the calorimeter), the wide part has a divergence of 6.9°. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9°. Up to now, most fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of ∼75%, a value in rough agreement with predictions of the two Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An additional factor in determining the power density at the surface of beam absorbers is the angle at which the particles arrive. Angles are different for particles emitted from different locations on the ion source. To treat this situation, the average angle of incidence is calculated. For beam loss at the exit of the neutralizer, the average angle of incidence is 2.2°, rather than the 4.95° subtended by the center of the ion source. This average angle of incidence is found to be a function of beam divergence.
Analysis of a flexible surface-coil-type resonator for magnetic resonance measurements
Authors: Hirata Hiroshi , Iwai Hisako , Ono Mitsuhiro
Published: July 2002

This paper presents a method for analyzing the sensitivity of a flexible surface-coil-type resonator (FSCR). It first describes the configuration and the operation principle of the FSCR and then a method for estimating relative sensitivity of the FSCR. In this estimation, the quality factor and the filling factor of the FSCR are formulated because the strength of electron spin resonance (ESR) signals is proportional to the product of these factors. Finally, this paper reports experiments, measuring the ESR spectra of 1,1-Diphenyl-2-picrylhydrazyl powder, confirming the validity of the proposed method.
Flow injection system for the scanning tunneling microscope
Authors: Noll J. D. , Van Patten P. G. , Nicholson M. A. , Booksh K. , Myrick M. L.
Published: July 2002

A flow injection scanning tunneling microscopy (FISTM) system is described and characterized which permits observation of surface chemical processes. This modification to a standard scanning tunneling microscope consists of a peristaltic pump attached via a manual HPLC-type flow injector to a constant-volume sample cell. Images recorded as fluids continuously exchange in the cell are reported. Evidence supports that analytes are transported into the tip region through a stagnant fluid domain by diffusion from the adjacent, circulating bulk solution. Electrochemical measurements of the exposed tip surface area and rates of diffusion of analytes are presented and interpreted. Erosion of contaminants on a gold surface exposed to hydrogen peroxide was observed using FISTM, and these results are presented.
An optical tracking device for recording the three-dimensional paths of flying birds
Authors: Tucker Vance A.
Published: July 2002

This paper describes a portable tracking device (TD) that records sequential, three-dimensional positions of an object as it moves through space. The operator manually tracks the object through a tripod-mounted, optical rangefinder at ranges of 250 to 5,000 m, and adjusts a thumbwheel to keep two images of the object in alignment. The rangefinder has a 1-meter base and rotates around horizontal and vertical axes. The rotations of the rangefinder and thumbwheel turn the shafts of three digital resolvers that connect to the parallel port of a portable microcomputer. The computer reads all three resolvers in 0.001 second, averages the data over 1 second, and stores the averages in memory. At the end of a track, the computer writes the data to a disk file for later analysis. The TD was designed to track birds (or similar objects) flying in natural conditions. The accuracy of the TD varies with range and depends on the skill of the operator. A point in space measured by the TD is the center of an approximately cylindrical confidence volume that contains the object 95% of the time. The length of the cylinder, measured along the cylinder axis, coincides with the line of sight of the rangefinder. An experienced operator can keep a flying bird within a confidence volume that is 3 m in diameter and 3 m long at a range of 250 m. As range increases, diameter and length increase in proportion to range, and range squared, respectively. The length of the confidence volume is 42 m at 1,000 m and 167 m at 2,000 m.
Bipolar high voltage dc supply for deflecting charged particle beams
Authors: de Urquijo J. , Alvarez I. , Cisneros C.
Published: July 2002

We report on the design of a regulated bipolar power supply with a continuously variable output range of ±2.4 kV. A simple 0–9 V control circuit allows the simultaneous operation of two ±5 kV regulated power supply modules coupled to a passive resistive adder. This arrangement eliminates the need of polarity inversion. Excellent linearity, very low ripple, and high regulation over the whole range were obtained.
Fiberoptic evanescent wave infrared spectroscopy of gases in liquids
Authors: Bunimovich D. , Belotserkovsky E. , Katzir A.
Published: July 2002

Silver halide optical fibers were used as attenuated total reflection elements for infrared evanescent wave spectroscopy of gases in liquids. The evanescent wave absorption spectra of chlorodifluoromethane (Freon-22) and carbon dioxide gases (CO2) in water were studied and the dependence on vapor pressure of the gas and temperature was investigated. Absorption peaks were easily traced and correlated well with those in the literature. The use of the infrared (IR) fibers in the fiberoptic evanescent wave spectroscopy system bypasses the difficulty of ordinary IR spectroscopy related to the strong IR absorption of most liquid solvents, and provides a flexible, easy, and inexpensive way of determining the presence and concentration of gases in liquids to within about 5% accuracy.
State selection of O+(4So,2Do,2Po) using resonance dissociative charge transfer of He+(Ne+, Ar+)+O2 and radio frequency multipole ion guide techniques
Authors: Li X. , Huang Y.-L. , Flesch G. D. , Ng C. Y.
Published: July 2002

By controlling the collision energies for dissociative charge transfer collisions of He+(Ne+,Ar+) +O2 in a rf octopole ion guide gas cell, and by applying appropriate effective ion trapping potentials to the rf octopole ion guide, we show that state-selected O+(4So), O+(2Do), and O+(2Po) reactant ion beams with high purities and usable intensities can be prepared for scattering experiments. This experimental scheme, which makes possible the enrichment of an ionic species with a lower kinetic energy distribution in a rf multipole ion guide, should be useful for state selection of other excited atomic ions by using appropriate dissociative charge transfer or dissociative photoionization processes.
Magnetic resonance spectral reconstruction using frequency-shifted and summed Fourier transform processing
Authors: Clark W. G. , Hanson M. E. , Lefloch F. , Ségransan P.
Published: July 2002

A novel method of Fourier transform spectroscopy of the transient signals from wide, inhomogeneously broadened magnetic resonance spectra is described and analyzed. It has the advantages of high resolution, high sensitivity, and freedom from the distortions introduced by the finite amplitude of the pulsed rf magnetic field and the finite bandwidth of the receiving system. It consists of recording the transient signal at a series of magnetic fields, shifting the frequency of the transient by the corresponding field step for each point, and summing the corresponding Fourier transformed signals. Although the primary emphasis is on pulsed NMR, the analysis also applies to pulsed ESR. Criteria for the range and step interval of the magnetic field variation are discussed. The accuracy and sensitivity of the method are compared with earlier methods of spin echo spectroscopy. A description of the corresponding measurement of NQR, NMR, and ESR spectra obtained by stepping the frequency of the spectrometer is also presented.
Design of the cell and gas-handling system for the x-ray absorption study of supercritical fluid material
Authors: Murata T. , Nakagawa K. , Kimura A. , Otoda N. , Shimoyama I.
Published: July 2002

A cell and gas-handling system of the supercritical material for x-ray absorption measurement are designed. The cell was made of stainless steel with a pair of Be windows of 3 mm thickness. The x-ray path can be controlled by changing the distance between two Be windows. Electric cartridge heaters are embedded in the cell to control the temperature. With this system we have studied the supercritical state of CF3Br, whose critical point is 67 °C and 39.1 atm. The results of x-ray absorption fine structure measurements for Br K edge for gaseous, liquid, and supercritical states of this material are presented together with the performance of the gas-handling system.
Application of piezoelectric stress gauges to the measurement of pulsed ion and neutral beam power density (abstract)a)
Authors: Hanson D. L. , Cuneo M. E. , Stygar W. A.
Published: July 2002

Fast-response piezoelectric stress gauges are potentially useful in a number of plasma physics diagnostic applications, but have received only limited development in this direction. Principal applications include the measurement of pulsed photon, electron, ion,b) and neutral beam power, and magnetic pressure.c) We will discuss the use of X-cut quartz and PVDF piezoelectric polymer stress gauges for measurement of ion power density on ion diode experiments. In our present work on the PBFA accelerator, we are attempting to quantify the ion and neutral particle flux in a parasitic beam which limits power coupling to the primary ion beam for light ion ICF experiments. Stress gauge data and hydrocode calculations related to this problem will be presented.
The electron-beam ion source ‘‘Krion-S’’ performance in LHE (abstract)
Authors: Ovsyannikov V. P. , Kalagin I. V. , Kovalenko A. D. , Romanov Yi. I. , Kultashev O. K.
Published: July 2002

The design of the electron-beam ion source (EBIS) ‘‘Krion-S’’ on the high voltage (HV) platform of the preinjector of the LINAC LU-20 and some results of accelerating argon and krypton ions up to 5 Mev/u are presented. The gas mixing (working gas and Ne) by original technology has been used for the ‘‘ion cooling’’ procedure. The cryogenic ionizator Krion-S is used as an ion source for multicharged ions with mass charge ratio band 0.35–0.5 at the accelerating facility ‘‘NUCLOTRON’’ of the Laboratory of High Energies (LNE) JINR in Dubna.