bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual chamber capillary viscometer for viscosity measurements of concentrated polymer solutions at elevated temperatures
Authors: Akkarachittoor Narayanan S. , Fricke Arthur L. , Small James D.
Published: July 2002

A dual chamber capillary viscometer (DCCV) has been designed and constructed to measure steady shear viscosity of concentrated polymer solutions at temperatures above the solution normal boiling point. Projected equipment capabilities are as follows: Shear rate: 102≤γ̇≤104 s−1, Viscosity: 10−1≤η≤104 Pa s, Temperature: 300 ≤T≤520 K. Equipment design and results using Newtonian viscosity standards and various Newtonian polymer solutions are presented. Viscosity results determined with Newtonian standards are within ±5% or better of the reported values and two different concentrated polymer solutions and a paper coating (a suspension of clay in a starch-water solution) were used to test the equipment capabilities over wide ranges of shear rate, viscosity, and temperature. The ranges of equipment capabilities tested to date are Shear rate: 300≤γ≤5500 s−1, Viscosity: 0.12≤η≤7.5 Pa s, Temperature: 299≤T≤399 K.
Study of the effects of photoelectron statistics on Thomson scattering data
Authors: Hart G. W. , Levinton F. M. , McNeill D. H.
Published: July 2002

A computer code has been developed which simulates a Thomson scattering measurement, from the counting statistics of the input channels through the mathematical analysis of the data. The scattered and background signals in each of the wavelength channels are assumed to obey Poisson statistics, and the spectral data are fitted to a Gaussian curve using a nonlinear least-squares fitting algorithm. This method goes beyond the usual calculation of the signal-to-noise ratio for the hardware and gives a quantitative measure of the effect of the noise on the final measurement. This method is applicable to Thomson scattering measurements in which the signal-to-noise ratio is low due to either low signal or high background. Thomson scattering data from the S-1 spheromak have been compared to this simulation, and they have been found to be in good agreement. This code has proven to be useful in assessing the effects of counting statistics relative to shot-to-shot variability in producing the observed spread in the data. It was also useful for designing improvements for the S-1 Thomson scattering system, and this method would be applicable to any measurement affected by counting statistics.
Dilution refrigerator for muon spin relaxation experiments
Authors: Cooke D. W. , Hoffer J. K. , Maez M. , Steyert W. A. , Heffner R. H.
Published: July 2002

The design, construction, and operational characteristics of a continuous 3He–4He dilution refrigerator specifically built for use in muon spin relaxation ( μSR) measurements at LAMPF are described in this paper. The refrigerator is unique in that it makes an angle of 30° with respect to horizontal—a requirement imposed by the previously existing physical constraints of the μSR spectrometer. Additionally, the refrigerator and associated gas handling units are portable so as to facilitate ease of movement into and out of the muon beam. Typical parameters describing refrigerator performance are 60-mK base temperature with 22-μW cooling capacity at 100 mK.
Simple particle injection system for laboratory burners
Authors: Beiting E. J. , Singh J. P.
Published: July 2002

The design of an easily constructed particle injection system for use with laboratory burners is presented. The particles are entrained in the flow using directed gas jets which are positioned in a standard glass flask. The characteristics of the system are evaluated using coal flyash particles in a 10-cm-long methane–air flame. Particle densities exceeding 104 cm−3 are attainable.
Automatic inspection device for locating microscopic inclusions in optical components
Authors: Marion J. E.
Published: July 2002

Automatic inspection of large optical components for the presence of microscopic metallic inclusions in the parts-per-quadrillion concentration range is performed by a simple device in which a Q-switched YAG laser is focused on a continuously scanned sample. Plasma emissions from inclusions are detected by a photomultiplier tube, whose output is monitored by a computer, which then generates an inclusion map. Rapid and reliable inspection of the large optical components required for a variety of high-energy systems is now possible.
Apparatus for electron-nuclear-double-resonance spectroscopy of matrix-isolated molecules: Application to the CH3 radical in solid argon
Authors: Weltner W. , Van Zee R. J.
Published: July 2002

An apparatus was built to enable electron-nuclear-double-resonance (ENDOR)/TRIPLE spectra to be measured of atoms and molecules isolated in solid rare-gas matrices at temperatures near 4 K. Its capability is demonstrated here by measuring the ENDOR spectrum of the CH3 radical in solid argon. The origin and shape of an observed ‘‘matrix ENDOR’’ line is also discussed.
Computer-aided photoelasticity used for stress measurements in polycrystal silicon ribbons
Authors: Chambonnet D. , Gauthier R. , Pinard P.
Published: July 2002

The brittleness of the polycrystal silicon ribbons is due to the residual stresses which appear in the material during the electron-powder-ribbon pulling process. We developed a new method for stress analysis based on combination of two techniques: classical infrared photoelasticity and modern digital image processing. The separation of principal stresses is achieved by means of a microcomputer: The sum of the principal stresses is determined which, combined with their differences, gives their values separately; by using these procedures it is possible to observe on a video analyzer the pseudocolor restoration of the stresses in the silicon ribbons. It may be noted that this method can be easily applied to other materials, such as InP for optoelectronic components.
Ultrahigh-vacuum apparatus for the preparation of thin metal bicrystals containing grain boundaries
Authors: Milkove K. R. , Sass S. L.
Published: July 2002

An ultrahigh-vacuum apparatus for the preparation of thin metal bicrystals containing controlled grain boundaries at their midplane is described. The deposition of the thin epitaxial single-crystal films and their hot pressing together to produce the bicrystal in situ can be carried out using this equipment.
Transmission-line tunnel diode oscillator: A sensitive, fast, and flexible low-temperature detection system
Authors: Brisson John G. , Silvera Isaac F.
Published: July 2002

Tunnel diode oscillators (TDO’s) excel in high-resolution measurement of inductive and capacitive transducers at cryogenic temperatures. The transmission-line tunnel diode oscillator (TLTDO) discussed here combines the ease of construction of a discrete element TDO with the quick response times and immunity to stray reactances of the reentrant cavity TDO. Theory and design of four TLTDO’s are discussed. Two characteristic response times for TDO’s are discussed.
In situ magnetization loop tracer for thin-film growth
Authors: Haugdahl J. B. , Miller D. R.
Published: July 2002

A thin-film loop tracer is described which is straightforward to construct, rugged, has a sensitivity of at least 10−6 emu at fields to 3000 Oe, and a bandwidth of 1 megacycle. The device is readily adaptable for in situ ultrahigh-vacuum measurements.
Simple Bridgman anvil clamp-type high-pressure cell for x-ray powder diffraction up to 100 kbars
Authors: Jaya N. Victor , Natarajan S.
Published: July 2002

This note describes a simple Bridgman anvil clamp cell which has been developed, suitable for x-ray diffraction studies up to 100 kbar. A hydraulic press is used to develop the pressure and a pressure clamping method is used to maintain the pressure in the sample. The lattice parameters of NaCl and Al have been measured by employing MoKα radiation from a rotating anode x-ray generator to test the camera.
Time-of-flight Fourier electron spectrometer
Authors: Ascarelli G.
Published: July 2002

In this note, I would like to propose an electron spectrometer that would have the same advantages, with respect to its dispersive counterparts, as an optical or a NMR Fourier spectrometer has to its dispersive alternatives. As in the case of the other types of Fourier spectrometers, there will be a significant gain in the S/N ratio because of the multiplex advantage.
Angular scanning stage for glancing-incidence surface EXAFS
Authors: Jiang D. T. , Alberding N. , Seary A. J. , Crozier E. D.
Published: July 2002

In this paper a simple and inexpensive angular positioning apparatus is described which can be applied to measurements of x-ray reflectivity and extended x-ray absorption fine structure (EXAFS) at glancing angles of incidence. An efficient interactive alignment procedure is discussed and the performance of the device is given.
Anti-phase direct bonding and its application to the fabrication of InP-based 1.55 μm wavelength lasers on GaAs substrates
Authors: Okuno Y. , Uomi K. , Aoki M. , Taniwatari T. , Suzuki M. , Kondow M.
Published: July 2002

We propose anti-phase direct bonding and report on the first demonstration of its application to device fabrication. Cross-sectional observation by high-resolution transmission electron microscope showed that InP and GaAs wafers bonded at the atomic level and the misfit dislocations were localized at the bonding interface. Then InP-based 1.55 μm wavelength lasers were fabricated on GaAs. The performance of the lasers was approximately equal to that of the lasers formed by in-phase direct bonding. Moreover, stable operation was possible for more than 1000 h at 50 °C.
Methods for producing thin films of high-temperature liquids
Authors: Silva L. A. , Cutler M.
Published: July 2002

We describe the techniques we have developed to make micrometer-size films of liquid SexTe1−x alloys. Two approaches were employed. In the first, a vacuum-evaporated sample film and a surrounding evaporated gasket are sandwiched between two optical windows, and the sample is then melted to obtain the liquid. In the second, a drop of the sample liquid is compressed in a cavity between two windows. By varying the gasket thickness and the cavity depth, liquid films with thicknesses ranging from 0.3 to 25 μm were prepared with temperatures between 250 and 500 °C.
Ultrahigh-vacuum four-circle diffractometer for grazing incidence x-ray diffraction on i
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u MBE grown III-V semiconductor surfaces
Authors: Claverie P. , Massies J. , Pinchaux R. , Sauvage-Simkin M. , Frouin J. , Bonnet J. , Jedrecy N.
Published: July 2002

An ultrahigh-vacuum compatible four-circle diffractometer coupled to a molecular-beam epitaxy growth chamber has been designed to collect grazing-incidence x-ray diffraction (GIXD) spectra on in situ grown III-V semiconductor surfaces and interfaces. The unit is on line at the D25 bending magnet beam port of the LURE-DCI hard x-ray synchrotron-radiation facility (Orsay, France). Epilayer growth, surface processing, and diffraction data collection are performed without interruption of the ultrahigh-vacuum environment (in the low 10−10-mbar range) around the sample. The setup has been first applied to the determination of the atomic structures of GaAs(001) reconstructed surfaces. Results concerning the As-saturated c(4×4) phase are presented together with preliminary information on the As-stabilized 2×4 reconstruction.
Operation of a TFTR ion source with a ground potential gas feed into the neutralizer
Authors: Kamperschroer J. H. , Dudek L. E. , Grisham L. R. , Newman R. A. , O’Connor T. E. , Stevenson T. N. , von Halle A. , Williams M. D. , Wright K. E.
Published: July 2002

TFTR long pulse ion sources have been operated with gas fed only into the neutralizer. Gas for the plasma generator entered through the accelerator rather than directly into the arc chamber. This modification has been proposed for tritium beam operation to locate control electronics at ground potential and to simplify tritium plumbing. Source operation with this configuration and with the nominal gas system that feeds gas into both the ion source and the center of the neutralizer are compared. Comparison is based upon accelerator grid currents, beam composition, and neutral power delivered to the calorimeter. Charge exchange in the accelerator can be a significant loss mechanism in both systems at high throughput. A suitable operating point with the proposed system was found that requires 30% less gas than used presently. The extracted D+, D+2, and D+3 fractions of the beam were found to be a function of the gas throughput; at similar throughputs, the two gas feed systems produced similar extracted ion fractions. Operation at the proposed gas efficient point results in a small reduction (relative to the old high throughput mode) in the extracted D+ fraction of the beam from 77% to 71%, with concomitant changes in the D+2 fraction from 18% to 26%, and 6% to 3% for D+3. The injected power is unchanged, ∼2.2 MW at 95 kV.
An optical high pressure cell with spherical sapphire anvils
Authors: Takano Kaoru J. , Wakatsuki Masao
Published: July 2002

An optical high pressure cell has been constructed of spherical sapphire anvils (9.53 mm in diameter). The anvil has a small flat compression face (1.5 mm or 2.5 mm in diameter), which is perpendicular to the crystal c axis. Pressure is generated using a gasket, typically made of phosphorus bronze. A maximum pressure of 12.6 GPa was generated at room temperature in a liquid pressure medium. Pressures up to 10 GPa have been generated stably without appreciable damage of the anvils. The capability of optical observations for a photon energy region up to 6.4 eV was confirmed with this anvil, at high pressure. An advantage of the spherical anvil is ease in production.
The design and application of a microfoil tensile test apparatus for monitoring the degree of ultraviolet degradation of polymers
Authors: de Bruijn J. C. M. , Meijer H. D. F.
Published: July 2002

A microfoil tensile test apparatus has been developed to determine the tensile strength of thin slices cut from the surface of uv-degraded plastic products. It will be shown that it is possible to obtain data on the degree and depth of ultraviolet degradation in polypropylene copolymer and high-density polyethylene with the microfoil tensile test apparatus and to relate this to the impact resistance. The results are in agreement with the results determined by infrared spectroscopy but are obtained in less time and more accurately. The influences of sample preparation and geometry, elapsed time after microtoming, and method of processing on the tensile strength, will be discussed.
Noncontact monitoring of liquid surface levels with a precision of 10 micrometers: A simple ultrasound device
Authors: Wang Yicheng , Mingotaud C. , Patterson L. K.
Published: July 2002

A simple inexpensive device has been designed to measure the position of a flat surface to an accuracy of ±10 μm and has been applied to monitor water levels in studies of spread monolayers at the air-water interface. This instrument provides for determination of surface location in a range intermediate between those accessible by physical methods and those requiring the much more expensive and difficult techniques of interferometry. This technique utilizes a sound transmitter operating at 45 kHz and simple microphones coupled to phase-shift measurements via a phase-to-voltage converter.
Liquid helium level detector
Authors: Quine Richard W. , Eaton Sandra S. , Eaton Gareth R.
Published: July 2002

A simple mechanical and electrical design is presented for a small probe for monitoring the level of liquid helium in experimental apparatus or storage Dewars.
Low cost quadrature signal resolver
Authors: Legg Jeff , Phelps Larry
Published: July 2002

The details of an inexpensive, flexible quadrature signal resolver are given. The unit employs inexpensive embedded controller technology and is suitable for use with linear or rotary encoders. The unit is easily programmed to perform a variety of quadrature signal analysis/decoding functions and is particularly suited to special applications that are not addressed by manufacturers.
A compact coaxial electrical feedthrough for use up to 400 MPa
Authors: McNamee M. J. , Wawersik W. R. , Shields M. E. , Holcomb D. J.
Published: July 2002

Acoustic emission (AE) measurements coupled with source locations of AE are an important tool for monitoring the evolution of microcracking during the deformation of pressure-sensitive brittle materials. Successful resolution of acoustic emission signals, however, requires the transmission of low-amplitude (tens of microvolts), high-frequency (1 MHz) electrical signals. To accomplish this under hydrostatic pressure, AE signals must be transmitted along coaxial cables and through coaxial electrical feedthroughs from the inside to the outside of pressure vessels. The need for multiple, isolated feedthroughs in relatively small pressure vessels led to the development of the coaxial electrical feedthroughs as shown.
Demonstration of a novel wide-band optical signal generator by deep phase modulation in a fiber coupler
Authors: Chien Pie-Yau , Pan Ci-Ling
Published: July 2002

A simple method for wide bandwidth optical signal generation has been realized by applying a deep phase modulation signal in a fiber coupler which acts as an all-fiber Michelson interferometer. The output of the interferometer displays a discrete spectrum with a nearly leveled output and frequency bandwidth up to a hundred times that of the frequency of the modulation signal. In this first demonstration, we have generated frequency components up to 4 MHz (with external modulation) and 50 MHz (by direct modulation of the laser diode) respectively. Multigigahertz operation is possible in the future with wideband integrated-optic phase modulators.
Phase-space measurement of a beam with a Maxwellian transverse velocity distribution by a finite-width slit
Authors: Rhee M. J. , Schneider R. F.
Published: July 2002

A numerical method is presented of finding the rms width and the height of a Maxwellian transverse velocity distribution from an experimentally obtained beamlet profile formed by a finite-width slit. The results are also least-squares fit to polynomials that can be very conveniently used in actual data analyses.
Heterodyne technique for potential modulation differentiation
Authors: Almeida F. J. D. , Morra R. M. , Willis R. F.
Published: July 2002

A potential modulation differentiation technique which uses heterodyne modulation is presented. The second derivative I″(V) of the collected current I(V) is obtained by modulating the voltage V using two synchronized signals with angular frequencies Kω0 and (K − 1)ω0, K≫1, and detecting the component of the collected current with angular frequency ω0. This technique eliminates problems caused by stray capacitively coupled signals and harmonic distortions produced by the signal generator and the preamplifiers. It can be applied to techniques in which the desired signal is the second derivative of the collected current, such as retarding field Auger electron spectroscopy, appearance potential spectroscopy, and work-function measurements. Auger spectra obtained using a multigrid retarding field analyzer and the proposed modulation technique show that only three grids are needed rather than the four grids required in the conventional experimental setup. Furthermore, there is no need for resonant filters or neutralization (bridge) amplifiers, and the high dynamic range commercial lock-in amplifier can be replaced by a circuit based on a single chip.
Neutron calibration for the FRX-C/LSM magnetic compression experiment
Authors: Chrien R. E.
Published: July 2002

Neutron source strength and yield from field-reversed configurations have been measured in the FRX-C/LSM magnetic compression experiment using plastic scintillators, indium activation samples, and moderated rhodium activation counters. The calibration of these neutron detectors is complicated by the changing shape and position of the plasma and by the presence of the massive aluminum compression coils. The overall uncertainty in the neutron measurements is estimated to be 45%.
The high-frequency oscillation of current and voltage in a plasma-focus discharge device
Authors: Sato Toshihiko , Ochiai Isao , Kato Yasuo , Murayama Seiichi
Published: July 2002

The presence of a high-frequency (≳6 MHz) oscillation in the discharge current and voltage of a plasma-focus device is found experimentally and is explained by using equivalent circuit analyses. The occurrence of such an oscillation is attributed to the excitation of the resonant oscillation in the discharge circuit. It is also shown that the high-frequency response of the driver circuit, which consists of a capacitor bank and cables, plays an important role in determining the high-frequency behavior of the discharge current and voltage.
PC network based data acquisition system for the MT-1M tokamak
Authors: Zoletnik S. , Kálvin S.
Published: July 2002

An IBM PC compatible computer network based data acquisition system for the small tokamak MT-1M is described. The network operating system is DECnet-DOS and the computers are connected by a thin wire ethernet cable. The tokamak measurement system is divided into subsystems which enable fast modular reconfiguration of the system. Every subsystem can manage its own data and can access data of the other subsystems as well.
Visible light tomography using an optical imaging system
Authors: Ingesson L. C. , Koning J. J. , Donné A. J. H. , Schram D. C.
Published: July 2002

A system for tomography in the wavelength range 200–1100 nm has been designed for the Rijnhuizen Tokamak Project (RTP). The plasma is viewed from five directions in one poloidal plane with a total of 80 detectors. An optical imaging system consisting of two spherical mirrors for each viewing direction is used to combine a good spatial resolution (1 cm, the minor radius of RTP being 17 cm) with a sufficiently high signal level for the fast electronics (200 kHz). Because of the complexity of the imaging, implementation of the system into common tomography codes is not straightforward. Ray tracing is used to calculate the contribution of the local emissivities in the plasma to the measured signals of the various detectors.
Atomic modeling and spectroscopic diagnostics (invited)
Authors: von Hellermann M. G. , Summers H. P.
Published: July 2002

Atomic reaction models provide the link by which quantitative diagnostic comments on plasma behavior and parameters may be made from spectral observations of emission by ions in the plasma. This paper reviews progress in this area with emphasis on impurity species in magnetic confinement fusion plasmas. A systematic approach based on generalized collisional-radiative theory is adopted and items discussed include spectroscopy of edge and divertor environments, beam emission, and charge exchange spectroscopy. Case studies are based on experience at the JET Joint European Torus Experiment.
Calibration of CR-39 for detecting fusion neutrons
Authors: Collopy M. T. , Carpenter P. , Harmon C. D. , Vandenberg J. , Cooper G. W. , Ruiz C. L. , Reyes P. , Stygar W. A. , Schmidlapp A. , Malbrough D. J. , Becker R.
Published: July 2002

We have measured the efficiency (tracks per incident neutron) of pure CR-39 for detecting DD and DT neutrons. Neutrons having average energies of 2.9 MeV (DD) and 14.8 MeV (DT) were produced by a 200-keV electrostatic accelerator and the neutron yields were measured using the associated particle counting technique. All CR-39 samples irradiated by DD or DT neutrons were etched for 2 h in a 70°, 6.25-N_ NaOH bath. For bare CR-39, the efficiencies for detecting 2.9- and 14.8-MeV neutrons were found to be (1.3±0.4)×10−4 and (5.0±1.8)×10−5, respectively. We also investigated using CR-39 and polyimide as proton radiators. For detecting 2.9-MeV neutrons, the radiators had no significant effect on efficiency; but for detecting 14.8-MeV neutrons the polyimide radiator increased the efficiency to (7.8±2.8)×10−5.
Thermoregulated fiber-optic probe validation for temperature determination in spite of radiation disturbances
Authors: Ciaurriz C. , Hernandez D. , Olalde G. , Devilliers C. , Salle M.
Published: July 2002

A methodology has been developed for measuring surface temperatures at high temperature in highly hostile environments, in spite of material thermoradiative properties and radiation interferences. The measurement technique is bichromatic optical pyrometry. The radiometer is connected to a fiber-optic probe coupled with a reflecting hemisphere head. When reducing the distance between probe and target, the correction on measured temperature improves but meanwhile the thermal disturbance on target increases. The purpose of this work consists in a complete analysis of this process. Experiments were performed on platinum and graphite. The samples were submitted to high flux obtained from concentrated solar energy or Joule effect. The measured temperatures are analyzed to get meaningful temperatures and thermal disturbances variation versus the distance between probe and target at various temperature levels. Experimental and theoretical results are compared. Temperature evolutions are concordant with literature emissivity data. As for thermal disturbance, the concordance is very good at an optimal distance of 1 mm, somewhat worse at longer distances and worse at very short distances. Nevertheless, these first tests results and simulation prove that great confidence could be accorded to this methodology provided other experiments and calculation with different boundary conditions are performed.
Extension of the energy range of the moveable fast ion probe on TFTR
Authors: Darrow D. S. , Boivin R. L. , Zweben S. J.
Published: July 2002

The range of detectable energies of the moveable fast ion probe on TFTR has been extended by the removal of a 3-μm Al foil across its entrance aperture. This foil formerly stopped hydrogenic ions with energies below 300 keV, and helium ions with energies below 900 keV. The new arrangement allows detection of neutral beam ions (100-keV D+) at toroidal fields between 1 and 5 T. Data typical of the probe’s enhanced performance are shown.
A high speed data acquisition and processing system for real time data analysis and control
Authors: Ferron J. R.
Published: July 2002

A high speed data acquisition system which is closely coupled with a high speed digital processor is described. Data acquisition at a rate of 40 million 14 bit data values per second is possible simultaneously with data processing at a rate of 80 million floating point operations per second. This is achieved by coupling a commercially available VME format single board computer based on the Intel i860 microprocessor with a custom designed first-in, first-out memory circuit that transfers data at high speed to the processor board memory. Parallel processing to achieve increased computation speed is easily implemented because the data can be transferred simultaneously to multiple processor boards. Possible applications include high speed process control and real time data reduction. A specific example is described in which this hardware is used to implement a feedback control system for 18 parameters which uses 100 input signals and achieves a 100 μs cycle time.
Electrical properties of Si1−xCx alloys and modulation doped Si/Si1−xCx/Si structures
Authors: Faschinger W. , Zerlauth S. , Bauer G. , Palmetshofer L.
Published: July 2002

We report electrical properties of undoped and Sb-doped Si1−xCx alloys grown by molecular beam epitaxy. Nominally undoped alloy layers exhibit electron background levels of 4×1016 cm−3 with a mobility above 30 000 cm2/V s at low temperatures. The layers can be doped with Sb at low growth temperatures, and the carrier concentrations and mobilities obtained are comparable to similarly doped Si layers. Modulation-doped Si/Si1−xCx/Si structures with the modulation doping in the Si layer close to the surface exhibit enhanced electron mobilities with peak values of about 10 000 cm2/V s, indicating that Si1−xCx strained on a silicon substrate forms an electron channel. From the saturation carrier concentration at low temperatures, the electron barrier between Si and Si0.98C0.02 is estimated to be about 150 meV. In lightly doped channel structures carrier freeze-out at low temperatures is observed, indicating a relatively high defect density in the channel.
Apparatus for producing ultraclean bicrystals by the molecular beam epitaxy growth and ultrahigh vacuum bonding of thin films
Authors: Amiri-Hezaveh A. , Balluffi R. W.
Published: July 2002

An apparatus has been designed and constructed which is capable of growing single-crystal thin films and then bonding them together face-to-face to produce bicrystals under ultrahigh vacuum (UHV) conditions. The films are grown in molecular beam epitaxy (MBE) system capable of growing well-characterized single-crystal thin films of metals, semiconductors, and high Tc superconductors. It has the unique capability to perform multiple processing steps on a substrate within a continuous 10−11 Torr (base pressure) UHV environment. The system is computer controlled and whole-growth sequence parameters can be readily programmed. This design allows the manufacture of films of new structural materials and the ability to change layer type or composition within atomic monolayer dimensions. The MBE chamber is connected to a surface analytical and bonding chamber into which the grown films can be transferred, characterized, and bonded together at controlled misorientations. The bonding operation is carried out in a 10−10 Torr UHV environment, assuring cleanliness of interfaces. The system has the potential to produce a wide variety of new homophase and heterophase bicrystals containing interfaces in a form suitable for further study.
Low-temperature metal-oxide-semiconductor field-effect transistor preamplifier
Authors: Imai Jim , Flores Ruben
Published: July 2002

This reliable, high input impedance, unity gain metal-oxide-semiconductor field-effect transistor preamplifier is an improved design for cryogenic applications. The high input impedance is well suited for applications involving capacitive transducers. This circuit is directly immersible in liquid helium and thereby reduces the noise and spurious pickup associated with remotely located preamplifiers. In addition, the circuit utilizes easily available commercial parts which will reduce cost and the need to order nonstandard components.
Channeled spectrum liquid refractometer
Authors: Podoleanu A. Gh. , Taplin S. R. , Webb D. J. , Jackson D. A.
Published: July 2002

We describe an experimental demonstration of a novel technique for liquid refractometry. A channeled spectrum is produced from an optical beam generated by a diode laser operating below threshold by intercepting half of the beam with a liquid cell. The spectrum is analyzed using a grating and a linear CCD array and provides information on the refractive index of the liquid. The experimental results show that accuracies of better than 0.3% in the index may be obtained with the present method.
A system for the measurement of near-surface magnetic properties
Authors: Tejedor M. , Rubio H. , González M. , Elbaile L. , Iglesias R.
Published: July 2002

The transverse magneto-optical Kerr effect is employed for the measurement of in-plane surface magnetization. An automatic and computerized system is used for the detection of the field that acts on the surface in samples that do not have a negligible demagnetizing factor. The demagnetizing field due to the bulk is corrected, obtaining the true magnetization process of the surface.
Producing diamond anvil cell gaskets for ultrahigh-pressure applications using an inexpensive electric discharge machine
Authors: Lorenzana H. E. , Bennahmias M. , Radousky H. , Kruger M. B.
Published: July 2002

Small holes are drilled in diamond anvil cell gaskets to contain and pressurize samples. As high-pressure technology pushes the multimegabar regime, smaller-tipped diamond anvils are being increasingly utilized. Consequently, well-centered holes with diameters smaller than 100 μm need to be routinely produced in these gaskets made of exceedingly hard metals. We describe the construction of an inexpensive electric discharge machine that can drill metals with holes as small as 25 μm in diameter. This method of drilling is easy to use, far less expensive than other commonly used techniques, and has the advantage of being effective on extremely difficult to machine metals such as rhenium.
Improvement of the gas efficiency in a microwave plasma cathode type oxygen ion source
Authors: Miyake Koji , Mikami Takashi , Tahara Hideaki , Ogata Kiyoshi , Matsubara Yoshio , Nogawa Shuichi , Ishikawa Junzo
Published: July 2002

A microwave plasma (MP) cathode for ion sources has advantages of a long lifetime for reactive gas, and a capability of a high-current electron emission of several amperes. This article describes a new MP cathode, in which a convergent magnetic field is formed at an electron emitting aperture in order to improve the working gas efficiency, that is the decreasing of the gas flow rate (Qeff) to obtain the electron emission current of 1 A. By applying a magnetic field (∼3 kG), the Qeff was decreased to 1/5 to 1/10 of that in the conventional MP cathode, and a high current of oxygen ion beam of 62 mA in a high vacuum (1.8×10−5 Torr) system was successfully obtained. Further improvements are expected by changing various parameters.
Plasma sputter multicusp negative/positive ion source with ECR discharge
Authors: Takagi A. , Mori Y.
Published: July 2002

A plasma sputter type of negative and positive ion source with electron cyclotron resonance (ECR) discharge has been developed at KEK. The ECR discharge was produced by a 2.45 GHz microwave source. In this ion source, negative heavy ions are produced at the surface of the metal which is placed in a Xe gas plasma confined in a cusp magnetic field. Positive ions are generated by ionizing of sputtered neutral atoms in the ECR discharge. The microwave is introduced into the source through a sputter target using a waveguide type of microwave transformer.
Beam combiner for transient phenomena measurement in the JT-60 Thomson scattering diagnostic
Authors: Yoshida H. , Naito O. , Yamashita O. , Kitamura S. , Nagashima A. , Matoba T.
Published: July 2002

A beam combine method of two ruby lasers has been developed for the JT-60 Thomson scattering system, that is mainly composed of a polarizer plate and a Faraday rotator. By this method we have achieved a minimum time interval of 2 ms between the two laser pulses homogeneously combined. Also a high energy transmission of more than 95% has been attained. As a result, transient phenomena measurement can be available especially for pellet-injected plasmas by using the Thomson scattering system. The beam combine method applied to JT-60 is very attractive in terms of upgrading a Thomson scattering system to a high repetition diagnostic without any essential change of the existing equipment, and has been working with no serious trouble since 1989. The application of this method to a multilaser system with three or more lasers is also discussed for the practical purpose of improving a repetition rate of high power pulsed laser.
A new confocal stigmatic spectrometer for micro-Raman and microfluorescence spectral imaging analysis: Design and applications
Authors: Feofanov A. , Sharonov S. , Valisa P. , Da Silva E. , Nabiev I. , Manfait M.
Published: July 2002

A new instrument was developed permitting confocal spectral imaging technique to be carried out with a lateral resolution ∼0.3 μm and an axial resolution ∼1.0 μm for specimen areas ranging from 5×5 to 150×150 μm. The modular Raman/fluorescence spectrometer was equipped with a CCD camera, microscope, motorized sample stage, and the confocal entrance chamber. A system of galvanometer controlled mirror scanners equipped the confocal entrance chamber, allowing spectra to be accumulated up to several hundreds of points of sample in parallel, with adjustable spectral and spatial resolution. Stray light rejection property of the Raman spectrometer provides the possibility of the Raman spectral image to be recorded in the low frequency domain. A software was developed to control image accumulation, creation, and treatment. The methods of spectral analysis being applied to a multidimensional set of spectra permit the multiform spectral images to be created. In order to create these images, the different spectral parameters and their combination can be used, namely: intensity of characteristic bands and their ratios, width of spectral bands, and shift of band frequencies. The decomposition algorithms can be applied to two-dimensional (or three-dimensional) images to deconvolute the overlapped spectra of sample components or to analyze the subtle spectral differences. The three-dimensional performance of the instrument was analyzed in the particular examples of microfluorescence study of matrices for piezoelectric elements production, micro-Raman investigation of fluid inclusions in mineral, micro-Raman mapping of polymeric materials, and microfluorescence analysis of drug interaction with living cancer cells. It is shown that the spectrometer is suitable for a wide range of applications in mineralogy, material research, solid state physics, biophysics, cellular biology, and medicine.
Installation and operation of the LNLS double-crystal monochromator at CAMD
Authors: Schilling Paul J. , Morikawa Eizi , Tolentino Hélio , Tamura Edilson , Kurtz Richard L. , Cusatis Cesar
Published: July 2002

A new x-ray beamline has been installed at CAMD utilizing a two-crystal monochromator designed and built at LNLS. The beamline will operate in the 2–18 keV range using up to 4 mrad of dipole radiation from the CAMD storage ring. The monochromator maintains a fixed exit beam and fixed positions of the beam on the two crystals using mutually perpendicular elastic translations. With the ring operating at 1.5 GeV and 160 mA, Si(220) crystals will provide a flux of ∼3(109) photons/s/mrad at 8 keV, with an energy resolution ΔE<2 eV, to the experimental hutch. The beamline is equipped with an EXAFS endstation and will also be used for other x-ray applications at CAMD. First results are presented.
High-resolution spectroscopy of the D i
i
i–D divertor region
Authors: Tugarinov S. , Brooks N. H. , Buzhinskij O. , Parker C. , Pulinetz T. , Skvortzova A. , Trofimenko V.
Published: July 2002

The results of spectral measurements in the D iii–D divertor region, carried out using a high-resolution spectrometer and a survey spectrograph developed at the TRINITI Laboratory, Russia are presented in this report. Observations were made along a vertical chord passing through the X point and intersecting the divertor floor at the major radius of the V1 ports. The high-resolution spectrometer is designed for simultaneous measurements along eight spatial chords with a time resolution of 7 ms. Each of the eight spectra is dispersed over 512 pixels on an intensified charge coupled device (CCD) detector. 768 frames of data are recorded directly to RAM memory of a PC computer during every discharge. High optical throughput is achieved simultaneously with high spectral resolution; the instrument has an f/number of 3 and a spectral resolution of 0.025 nm. The spectrometer can also operate in survey mode, recording a spectral region of 13 nm with 0.1-nm resolution. Using Doppler broadening of spectral lines, the temperature of deuterium atoms and of C ii and C iii was obtained for L, H, and ELMing H-mode regimes in D iii–D. Using the survey spectrograph, photographic exposures of divertor plasma radiation were obtained spanning the spectral ranges 340–424 and 486–848 nm, in second and first orders of the grating, respectively. The spectrograph is stigmatic and has an f/number of 3.
Visible spectroscopy of the JET pumped divertor using coherent optical-fiber bundles
Authors: Morgan P. D. , Wilson C. H.
Published: July 2002

Visible spectroscopy will be one of the key diagnostics in the study of the performance of the new JET pumped divertor. Images of the divertor plasma are obtained using a periscope and coherent optical-fiber bundle. A CCD camera records the images, using a filter to isolate the required spectral feature. The system covers the wavelength range 400–800 nm, has spatial resolution 8 mm, can detect the continuum level for all foreseen plasma operation, and has temporal resolution of up to 6 ms.
A pellet ablation diagnostic system for the RFX reversed field pinch
Authors: Garzotti L. , Innocente P. , Martini S. , Pasqualotto R. , Scarin P. , Valisa M.
Published: July 2002

In view of the installation of a multiple pellet injector on the RFX experiment, an integrated diagnostic system has been designed to monitor the pellet behavior in the plasma. The evidence in the reversed field pinches (RFPs) of large poloidal and toroidal pellet deflections along magnetic field lines due to asymmetric ablation, calls for a 3D system with good space and time resolution. Two arrays of Hα detectors will view the trajectories of the pellets from below and from behind and a digital charged coupled device (CCD) camera will view the injection poloidal section from a tangential viewpoint. The two systems will allow the complete determination of the time-resolved trajectory of each pellet. The space integrated Hα emission rate will be measured by a large angle detector and by a space integration of the CCD camera measurement.
Z
eff profiles measured by visible and soft x-ray bremsstrahlung arrays in TFTR (abstract)a)
Authors: Park H. , Adler H. , Hill K. W.
Published: July 2002

The Zeff profiles from the tangential array of visible bremsstrahlung (VB) emission (5235 Å) have shown several interesting features in TFTR. The observed Zeff profile was flat during the ohmic phase and hollow during the neutral-beam heating phase. In order to crosscheck the measured Zeff profiles from the VB array, a poloidal array which measures bremsstrahlung emission in the soft x-ray region has been analyzed. The analysis of array measurements in the two different spectral regions was performed on the same geometry determined from the Abel inversion of the electron density (interferometry). The two independent measurements of Zeff profiles have been consistent with each other for most of the discharges in TFTR. However, in a discharge where the two measurements are inconsistent, the Zeff profile deduced from the VB array indicates some degree of problems. In this paper, the detailed analysis of the bremsstrahlung array (both poloidal and tangential) measurements is presented. Particularly, the effects of geometry in the inversion process, such as a poloidal elongation of flux surfaces, are investigated.
Streaked laser absorption measurements of density and temperature profiles in a high density Z pinch
Authors: Yadlowsky E. J. , Settersten T. B. , Hazelton R. C. , Moschella J. J. , Spanjers G. G. , Apruzese J. P. , Davis J.
Published: July 2002

A nonresonant laser absorption technique is described for studying the density and temperature profiles in a high density z-pinch discharge. A long pulse (700-ns) dye laser backlights the pinch and a streak camera records the transmitted laser intensity. Spatially and temporally resolved absorption coefficients are inferred from the fractional transmission through the plasma. The measured values are related to plasma density and temperature profiles using theoretical calculated absorption coefficients and equations of state. The results demonstrate the fine spatial resolution that can be obtained with this technique, reveal a complex radial structure in z-pinch discharges not observable in emission light streak photographs, and establish the practicality of using the technique to evaluate and benchmark theoretical model predictions.
The summary database system for the RFX reversed field pinch experiment
Authors: Innocente P. , Klare K.
Published: July 2002

The RFX Summary Database System contains the most important experimental data, and provides tools to collect and insert the data and to interactively study their dependence. It was developed to allow a fast search for shots with given characteristics for follow-up, detailed shot analysis, and study of the scaling laws of the RFX plasmas. The database uses the Rdb/VMS relational database and is accessed using Structured Query Language syntax. A program automatically inserts the most important data for each shot while the users can access the database with their own programs using high-level routines. An Interactive Data Language interface to the database allows the users to interactively insert and extract data from the database, combine, or modify the data as they want, plot and fit the extracted or computed data, and perform general multiple regression analysis.
A low-energy low-density electron beam diagnostic for large amplitude relativistic plasma waves
Authors: Williams R. L.
Published: July 2002

The interactions of a low-energy electron beam that is injected perpendicularly through a large amplitude relativistic plasma wave are considered computationally. As the beam passes through the electrostatic fields of the plasma wave, its transverse profile becomes distorted. The amount of distortion provides information on the magnitude of the electrostatic field, as shown by particle trajectory simulations. The sensitivity and advantages of this low-energy beam diagnostic are compared with that for a relativistic electron beam diagnostic. The limit on the beam density required to prevent the growth of two stream instabilities is addressed. Implications for the use of this method as a diagnostic for ultrahigh-gradient plasma wave accelerators are discussed.
Summary of 12th international ECRIS workshop [1995] (invited)a)
Authors: Sekiguchi M.
Published: July 2002

The 12th international workshop on electron cyclotron resonance ion sources (ECRIS), held on 25–27 April 1995, is summarized from the following points of view: (1) steady improvement of performance, (2) better understanding of the physical processes upon which ECR ion sources are based, (3) active pursuit for better performance by using higher magnetic field and devising new technologies, and (4) expanding application of ECRIS for highly charged ions. The upper limit of performance has not been foreseen and further improvement can be expected.
Adapting a high-precision angle encoder to use in ultrahigh vacuum
Authors: Haas E. de , Barsingerhorn W. , van der Veen J. F. , Sturre J.
Published: July 2002

Minor modifications to a commercially available angle encoder which normally operates in air make it suitable for use in an ultrahigh-vacuum environment. Its compact design is expected to lead to a wide range of applications in surface science instrumentation.
Distinction between DD and DT neutrons in the TFTR neutron collimator
Authors: Bitter M. , Johnson L. C. , Ku Long-Poe , Roquemore A. L. , Goeler S. von
Published: July 2002

A difficult part of the analysis of the neutron collimator data is the distinction between contributions from DD and DT neutrons. This is important for the majority of TFTR discharges, which use neutral deuterium heating beams and relatively small amounts of tritium. At present, the DT-neutron contribution is determined from a comparison of the chord-integrated neutron collimator data with measurements of the DT-neutron source strength from general wide-angle detectors, using an iterative computational method. A more satisfactory solution should be obtained with detectors that measure the contributions from DD and DT neutrons, and gamma radiation, directly. Pulse-shaping techniques are insufficient, since the detectors in the neutron collimator are operated in current mode. The presently used data analysis is described and the concept of a new multilayered plastic detector that makes use of the differences in the attenuation of the various radiation components is presented. The dimensions of the detector are based on calculations of the attenuation for the expected neutron energy spectrum.