bluuebunny/crossref_metadata_2025 huggingface dataset:
Hot stage and sample cell design for the solidification of transparent materials with and without forced convection
Authors: Kaukler William F.
Published: March 2003

A temperature gradient stage design for optical microscopy is described. Exceptional thermal stability is the major feature. The stage is used to study crystal growth phenomena occurring at the solid–liquid interface. The apparatus is designed to use transparent organic solutions as models for the study of metal-like solidification. The stage provides a controlled thermal environment for unidirectional solidification of low melting temperature materials. Freezing rate is regulated by mechanically sliding in the stage a thin glass cell containing the material being studied. Two cell assemblies are described. One type is used for convection-free and the other for controlled forced convection studies of the solidification interface.
Data logger based on a portable computer
Authors: Blackburn James A. , Vik S. , Saunderson H. , Stone M.
Published: March 2003

A portable multichannel data logger is described. The system utilizes a commercially available compact computer which is coupled to a single-chip voltmeter via a UART. Channel selection, under the direction of the computer, is performed by an analog multiplexer. Substantial data storage capabilities are provided by resident RAM within the computer.
Hydrostatic float polishing for wafer preparation
Authors: Hamaguchi Tsuneo , Kimura Masakazu , Egami Koji , Endo Nobuhiro
Published: March 2003

A new float polishing technique for wafer preparation has been developed. The technique employs a floating gap controlled by static pressure, and is useful for both planarization and damage-free surface preparation.
Direct reading fast microwave interferometer for ELMO Bumpy Torus
Authors: Uckan T.
Published: March 2003

A simple and inexpensive 4-mm direct reading fast (rise time∼100 μs) microwave interferometer is described. The system is particularly useful for density measurements on the ELMO Bumpy Torus (EBT) during pulsed operation.
Interfacing a HP-85 computer with a Sartorius microbalance
Authors: Lee H. E. , Prowse D. B.
Published: March 2003

A Sartorius 4431 microbalance has been interfaced to a HP-85 computer using serial parts normally used for a printer.
Computer-independent IEEE 488 interface between a Biomation 8100 and a microcomputer
Authors: Karnett M. P. , Clune T. R.
Published: March 2003

An interface to an IBM CS-9000 computer provides a substantial reduction in data collection time in time-resolved laser spectroscopy.
Large capacity As2 source for molecular beam epitaxy
Authors: Henderson T. , Kopp W. , Fischer R. , Klem J. , Morkoç H. , Erickson L. P. , Palmberg P. W.
Published: March 2003

Molecular beam epitaxy (MBE) is a crystal growth technique capable of growing ultrathin layered heterostructures for basic studies, and devices such as modulation doped field-effect transistors (MODFET’s), heterojunction lasers, heterojunction bipolar transistors (HBT’s), and superlattices. By using a dimeric arsenic source to grow GaAs and AlGaAs layers, the crystalline quality of these devices and structures may be improved, ultimately improving device performance. The design of a novel large capacity effusion cell (capable of producing about 700 μm GaAs growth) for cracking tetrameric arsenic into dimeric arsenic and the results of its use are described.
Pulsed laser-induced thermal desorption from surfaces: Instrumentation and procedures
Authors: Burgess D. R. , Hussla I. , Stair P. C. , Viswanathan R. , Weitz E.
Published: March 2003

Instrumentation and procedures for performing pulsed laser-induced thermal desorption experiments are described. The influence of various instrumental parameters on the measured desorption signals is discussed. Proper conditioning of the desorption flux is shown to be a critical factor for obtaining desorption signals undistorted by the finite pumping speed of the apparatus. Instrumental effects are illustrated using data for pulsed laser desorption of CO from clean copper surfaces.
Neutralization of multi-MeV light negative ions by plasma neutralizers
Authors: Hershcovitch A. I. , Johnson B. M. , Kovarik V. J. , Meron M. , Jones K. W. , Prelec K. , Grisham L. R.
Published: March 2003

A hollow cathode discharge fed plasma neutralizer has been built and was used to neutralize 3-MeV Li−, C−, and Si− ions. Initial results indicate that the performance of an unoptimized plasma neutralizer is better than gas stripping. Since hollow cathodes produce plasma targets with high efficiency, this type of plasma neutralizer can improve the overall efficiency of a neutral beam line.
Barium ion beam probe for magnetic field, diamagnetism, and space potential measurement in plasmas
Authors: Wickham M. , Fornaca S. , Lazar N. H. , Rynn N.
Published: March 2003

A diagnostic has been developed to simultaneously determine the magnetic field and space potential in fusion-like plasmas. Initial tests have demonstrated the ability to measure an absolute change of 17 G in the magnetic field strength; under the same test conditions a 6-V change in space potential could have been detected. The spatial resolution in these tests is a volume of 0.25 cm3. The magnetic field is determined by a measurement of the Zeeman resonance absorption pattern with a frequency scanning narrow-band laser of an energetic (<50 keV), low current (∼10 μA) barium ion beam. The laser is injected tangentially to the ion beam to take advantage of the narrow Doppler spread in the direction of the beam. Space potentials are determined by a measurement of the Doppler shift due to a change in beam energy E=E0−eφ. The diagnostic will be used initially on the TRW STM device to measure diamagnetic depression of the ELMO rings in STM.
Dynamic measurement of ultramicro amounts of gases with an ionization gauge
Authors: Graven W. M. , Gilmartin D. E.
Published: March 2003

A nude ionization gauge adjacent to the closed ion-source chamber of a quadrupole mass spectrometer is a sensitive detector of the total amount of gas introduced for dynamic analysis. Linear relations between the amount of gas and the area of the ionization gauge pulse record were found for eight gases. For relatively unreactive gases, linearity extended to the smallest samples that could be detected, approximately 10−10 atm cm3. Validity of the dynamic method of analysis was established by demonstrating that the same response was obtained for pulsed and for continuous sample introductions from calibrated leak sources of each of the eight gases.
Design and operation of a 12.5-ns multichannel scaler
Authors: Bunn Thomas L. , Woodward W. Stephen , Baer Tomas
Published: March 2003

A fast multichannel scaler has been developed with a resolution of 12.5 ns and and a channel memory of 215 (32 768), yielding a timing range of 410 μs. The maximum cycle time of the instrument is 30 starts/s. Fast timing is achieved by the use of multiplexing and parallelism in data collection and transfer. When operating at the highest resolution, each channel is a 1-bit counter (flip-flop). The scaler is intimately interfaced to an 8-bit Z80 microcomputer. The characteristics of the scaler are ideal for ion time-of-flight measurements in multiphoton ionization experiments. The time resolution is illustrated with a photoelectron–photoion coincidence time-of-flight mass spectrum. In addition, the MCS is compared to a time-to-pulse-height converter/multichannel analyzer system by collecting random stop signals.
Velocity visualization in gas flows using laser-induced phosphorescence of biacetyl
Authors: Hiller B. , Booman R. A. , Hassa C. , Hanson R. K.
Published: March 2003

Visualization of a two-dimensional velocity field by means of laser-induced phosphorescence is demonstrated in a nitrogen flow at room temperature. A pulsed dye laser is used to excite seeded biacetyl molecules along a line in the flow. Two successive exposures of the emitted phosphorescence are recorded with an intensified 100×100 element photodiode array camera. Velocities are determined from the distance traveled in the time interval between exposures. Important factors in connection with the phosphorescence of biacetyl are discussed.
Fluorescence microscope to observe dynamical processes in monomolecular layers at the air/water interface
Authors: Lösche M. , Möhwald H.
Published: March 2003

An experimental setup is described to microscopically observe surfactant monolayers at the air/water interface. It basically consists of a film balance, incorporated into a fluorescence microscope, detecting the emission of dye probes. The apparatus is stable enough to observe dynamical processes over more than 5 h, with a spatial resolution of less than 2 μm and is sensitive enough to use probe concentrations as low as 0.1 mol%. Examples of surface textures appearing during lipid phase transitions demonstrate the good performance characteristics.
New soft x-ray emission spectrograph
Authors: Carson R. D. , Franck C. P. , Schnatterly S. , Zutavern F.
Published: March 2003

We have built a new soft x-ray emission spectrograph covering the photon energy range 20–800 eV. It incorporates toroidal holographic grazing incidence diffraction gratings and a position-sensitive photodiode array as a detector. The detector electronics are remote from the array which is under vacuum at nitrogen temperature, and features a double-correlated sampling scheme. The sample is excited with a Pierce-type electron gun using a quadrupole focusing lens. The performance of the instrument is described.
Adaption of a low-temperature x-ray Guinier diffractometer for use from 12 to 700 K
Authors: Ihringer Jörg , Appel Werner
Published: March 2003

With the application of a heater element to a cryostat of a low-temperature Guinier diffractometer and camera a working range from 12 to 700 K is achieved. The heating/cooling rates in the low-temperature range are from 0.5 to 160 K/h and in the high-temperature range from 0.5 to 600 K/h. The sample chamber can be either evacuated or filled with a gas up to a pressure of 0.2 MPa. To increase the accuracy of x-ray intensity measurements rotation of the sample is possible within the whole temperature range.
Voltage and current measurements on high power self-magnetically insulated vacuum transmission lines
Authors: Maenchen J. , Sheldon H. T. , Rondeau G. D. , Greenly J. B. , Hammer D. A.
Published: March 2003

Experimental corroboration of a variety of distinct measurement techniques for determining the voltage and current constituents at a vacuum diode termination of a high power (500 GW) vacuum transmission line operating in a self-magnetic-insulation regime is presented. The inherent difficulties of measuring driver and load parameters with electric field strengths in excess of 106 V/cm and vacuum electron flows comparable with the cathode conduction current have in the past been addressed by single nonverified measurement methods. In this work we perform multiple measurements and find agreement between B-dot and self-integrating Rogowski coil current diagnostics and consistency among the following voltage measurements: an equilibrium flow model calculation based on current flows, a time-resolved Thomson parabola, a resistive voltage monitor, a time-integrating Thomson parabola, and a Rutherford scattering time-of-flight system.
Fabrication of planar and cylindrical solid hydrogen pellets for laser interaction experiments
Authors: Guttman J. L. , Turnbull R. J.
Published: March 2003

A system is described for fabricating both planar and cylindrical solid hydrogen pellets. The target geometry is determined by the geometry of interchangeable target molds. Planar targets fabricated with this system have dimensions of 3.0×3.0 mm with thicknesses ranging from 0.13 to 0.60 mm, and cylindrical targets were 1.0–3.0 mm in length with diameter of 0.80 mm.
Modular twin bus microprocessor system for laboratory automation
Authors: Newcome B. H. , Enke C. G.
Published: March 2003

This modular microprocessor system can be used to create a wide range of custom-tailored computer systems out of a standard set of active modules. New modules can be easily incorporated into the system as the requirements of the instrumentation change and as improved integrated circuits become available. A unique feature of this system is the existence of two sets of bus traces on the mother board. The second bus can be used as an extension of the system bus, an interprocessor but in a distributed processing system, a hardware driven peripheral bus, or the system bus of a second microprocessor. The second bus is shown to add substantially to the versatility and power of the system. The second bus also provides the means by which a single processor system can be upgraded into a distributed processor network without making the special interfaces designed for the single processor obsolete.
Application of a solid-state image sensor to optical profile measurement of intense neutral beams
Authors: Okumura Y. , Akiba M. , Mizuhashi K.
Published: March 2003

A compact optical beam profile monitor using a solid-state image sensor for detection of the center axis and the divergence of a high-power neutral beam is described. The monitor has high spatial resolving power and good reliability.
Low-power, low-weight, and high-sensitivity powder diffractometer for microgram samples
Authors: Bæcklund J. , Bæcklund P.
Published: March 2003

A low-power diffractometer with a microfocus x-ray tube with the focus on its window is described. X-ray paths are kept short and the whole of the diffracted cone enters the detector, which leads to an improved sensitivity as compared to conventional instruments. For the most intense quartz line, sensitivities of 920 counts per second per microgram have been obtained at a tube power of 1.25 W and Cr radiation. Specimens of less than 50-ng quartz can be detected. The low power results in low weight, less than 20 kg, thus allowing the instrument to be portable.
Closed-flow, thermostatable titration vessel for spectrophotometric measurements
Authors: Olsson Lars-Fride
Published: March 2003

A titration vessel with a built-in closed-loop flow system connected to a flow-through spectrophotometric absorption cell has been designed and tested. No pump is necessary; the flow is actuated when the solution is stirred.
Gated Raman spectroscopy (GRAS): A new experimental approach for the measurement of Raman signals of particles in suspension
Authors: de Grooth B. G. , de Mul F. F. M. , Greve J.
Published: March 2003

A new technique for the measurement of Raman spectra of small particles in suspension, such as biological cells, is described. The particles flow through a rectangular glass capillary mounted at the sample position of a laser Raman microspectrometer. The measuring volume inside the glass capillary is comparable to the volume of the particles. The elastic forward light scattering of the laser beam by the particles is used to monitor the presence of a particle in the measuring volume. Photon pulses from the Raman detector are counted only when a particle is inside the measuring volume. In this way the background signal caused by the suspending medium is suppressed, thus allowing measurement at very low particle concentrations. The technique, which is called gated Raman spectroscopy (GRAS) combines features such as: efficient light collection, suppression of background, and the possibility to use high laser powers. A great advantage is that this technique can be used for the study of (living) biological cells under physiological conditions. The GRAS technique is demonstrated with polystyrene particles and with unicellular algae chlorella vulgaris.
Keyed-powder gun for the oblique-impact shock study of solids in several 10 s of GPa region
Authors: Mashimo Tsutomu , Ozaki Shinobu , Nagayama Kunihito
Published: March 2003

Experimental equipment for the precise oblique-impact shock study of solids in several 10 s of GPa region was developed. A powder gun with a keyed launcher (keyed-powder gun), which is capable of accelerating projectiles of 20–40 g in weight without rotation to velocities of even greater than 2 km/s, was produced for the first time. The gun has a double-wall structure launcher with a key whose muzzle shape resembles an old moon (basic bore diameter is 27 mm). Measurement of projectile velocities in the launcher by the reflected-light method, including a logic trigger circuit for shock-wave measurements, is combined with this gun. It was confirmed that the parallel-plate impact experiment (normal type or oblique type), in which the tilt angle of parallel plates is less than 0.18° could be performed, allowing precise measurements of impact velocity and shock-wave data by electrical and optical methods. Further, the keyed-powder gun should find other widespread applications, e.g., for hypervelocity-aerodynamic simulation study.
Simple high-temperature thermal diffusivity apparatus
Authors: Wood C. , Zoltan A.
Published: March 2003

A simple and inexpensive thermal diffusivity apparatus is described for measurement up to1600 K. The novel features of the apparatus include a light pipe, a long furnace, and a differential thermocouple. A low heat-load sample holder for clamping the sample in a vertical position is also described. The results of measurements on AXM-5Q graphite are reported.
Effect of gas composition on the response of a thick-source alpha particle gas densimeter
Authors: Fjeld Robert A. , Johnson Randall M. , McFarland Andrew R.
Published: March 2003

The results of a theoretical and experimental study of the effect of gas composition on the response of a thick-source alpha gas densimeter are presented. A mathematical description of gauge response is developed and used to predict the response of a Po-210 densimeter. Gauge response is measured for pure gases (He, CH4, N2, CO2, Ar) and gaseous mixtures having densities between 0.3 and 1.3 kg/m3. Qualitative predictions of the dependence of gauge response on gas composition, based on heuristic arguments, are borne out experimentally and theoretically. For a given density, response increases with increasing atomic number, and decreasing ratio of atomic number to atomic weight. The effect of gas composition on gauge response is more pronounced for low Z gases than for high Z gases. The presence of hydrogen in a gas sample significantly decreases gauge response. Theoretical predictions show very good agreement with experimental measurements. The total uncertainty in gauge response is calculated for gases having atomic numbers near Z=7. For a 2% uncertainty in average atomic number, the uncertainty in the density measurement is less than 2.5% at a density of 1 kg/m3.
Dual junction field effect transistor as a comparator of small currents
Authors: Janka K.
Published: March 2003

In certain applications a picoampere-range current comparator with a wide range of input currents is needed. This paper presents a simple current comparator realized using gate-source and gate-substrate junctions of a dual junction field effect transistor (JFET) as current-to-voltage converters to control the circuit. Measurements using an AD 833A JFET have been carried out with input currents in the range 0.1–100 pA and drain voltages in the range 100 mV–10 V.
Measurement of thermal conductivities of glassy-metallic ribbons at low temperatures
Authors: Cotts E. J. , Anderson A. C.
Published: March 2003

Thermal transport can be measured in samples of low thermal conductance using a carbon chip as both heater and thermometer.
Design of an irradiation cell for multiphoton decomposition experiments
Authors: Evans D. K. , Nicol G. R. , Back R. A.
Published: March 2003

An irradiation cell is described which uses a flowing transparent gas to confine an absorbing gas to a region well away from the cell windows. The cell design allows use of a focused laser beam of high fluence avoiding laser damage to the cell windows and yet gives a nearly uniform beam profile in the region filled by the absorber gas.
Velocity analysis of on-axis cesium atoms by the time-of-flight method
Authors: Heindorff T. , Fischer B.
Published: March 2003

Time-of-flight distributions of cesium atoms effusing from the near-ideal orifice of an oven have been measured for Knudsen numbers ranging from 1 to 370. The apparatus consisting of a single-disk chopper and a single-ion counting detector is described. The experimental results are compared with theoretical data computed by using the free-molecule flow model. Experiment and theory are in good agreement. An error analysis is carried out. Deviations from the results of other studies are discussed. The influence of the scattering of cesium atoms by residual gas particles is demonstrated by a distorted distribution curve.
Tunable subnanosecond pulses from short cavity dye laser systems pumped with a nitrogen-TEA laser
Authors: Scott Gary W. , Shen Stanley Gao-Zhi , Cox A. J.
Published: March 2003

The performance of a laser system consisting of piezoelectrically tunable short cavity dye lasers pumped with a nitrogen-TEA laser is presented. The design and construction details of the nitrogen laser are given, and its pulse energy and pulse duration under various operating conditions are presented. Typically, UV pulses (337 nm) from the N2 laser had energies of 80 μJ and durations of 600 ps. The shortest dye laser pulses measured were about 90 ps at 600 nm.
Subnanosecond waveform analysis in the presence of fading by means of a random sampling technique
Authors: Docchio F. , Ramponi R. , Zaraga F.
Published: March 2003

The measurement of fast fluorescence waveforms with a traditional sequential sampling technique results in an inaccurate determination of the fluorescence decay time(s) in the presence of fluorescence fading. This paper describes a random sampling technique that overcomes this difficulty. A suitable software for random sampling and averaging has been developed for a subnanosecond pulsed-laser microfluorometer. Details of the random sampling routine are presented. The advantages of the random sampling technique as opposed to sequential sampling are discussed mathematically, and results of computer simulation for the two methods are shown.
Fast, self-compensating spectral-scanning ellipsometer
Authors: Muller Rolf H. , Farmer Joseph C.
Published: March 2003

The advantages of rapid spectral scanning have been combined with the inherent accuracy of the compensating ellipsometer operated in the polarizer-compensator–sample-analyzer configuration. Wavelength is scanned over the visible–UV (370–720 nm) at a maximum rate of 114 nm/s by rotating a continuously variable interference filter. A three-reflection Fresnel rhomb serves as the achromatic quarter-wave compensator. A microcomputer is used to collect spectroscopic measurements, perform instrument calibrations, digital filtering, and data interpretation.
Intelligent microcomputer interface for continuous registration and storage of spectra by photon counting
Authors: Wittig B. , Rohrer F. , Zetzsch C.
Published: March 2003

Based on an APPLE II microcomputer a low-cost counting system for digital recording of high-resolution spectra has been developed. The pulses originating from a photomultiplier are converted into TTL pulses by a commercial amplifier discriminator and are fed to a homemade 30-MHz BCD-counter with variable gatewidth (between 10 μs and 8 s). An interface incorporating a 256-byte buffer makes the information compatible with the 16-bit parallel port of the microcomputer. Simultaneous registration and storage of the counts during the gate width can be performed at speeds up to 250 words of 32 bits each per second. Software suitable for recording the count rates, for simultaneous storage on floppy disk, and for subsequent evaluation on the graphic display of the microcomputer is described. The software can easily be adapted to other applications, e.g., gas chromatography, nuclear-magnetic resonance, or mass spectroscopy.
Experimental setup for the study of the optical transmission of cesium up to 1500°C
Authors: Leycuras André , Rous Jean
Published: March 2003

An experimental setup for the study of the optical transmission in cesium up to its critical point is presented. The cesium is contained in a niobium cell with long sapphire windows. This cell is heated in a high-pressure vessel. The transmission spectra of the cesium, a few microns thick, is measured by means of a lock-in amplifier with a chopped xenon arc source. Spectra have been obtained with cesium up to 1500 °C and 11 MPa. Some improvements for higher temperatures are suggested.
High-resolution spectrometer for spin-polarized electron spectroscopies of ferromagnetic materials
Authors: Raue R. , Hopster H. , Kisker E.
Published: March 2003

A UHV apparatus for spin-polarized electron spectroscopies with high energy and angle resolution (ΔE=100 meV, ΔΘ=±3 °) is described. The energy dispersive element is a 180 ° hemispherical analyzer. Spin polarization is measured by a Mott detector (100 kV) whose efficiency is increased by employing multidetectors. The transmission of the electron optical system is optimized. An electron gun or an UV resonance lamp can be used as excitation sources. The performance of the setup is demonstrated by measurements of the spin polarization of electron-excited secondary electrons and spin-polarized energy-and angle-resolved photoemission spectra from Ni(110).
Electromagnetic squeezer for compressing squeezable electron tunneling junctions
Authors: Moreland John , Hansma P. K.
Published: March 2003

The resistance of squeezable electron tunnel junctions (SET junctions) can be adjusted with an electromagnetic squeezer. For junctions immersed in liquid helium, the resistance is stable to approximately 0.1%. This stability is sufficient for measurements of superconducting energy gaps and for superconducting phonon spectroscopy out to 50-mV applied bias. Increased stability, especially at higher biases, will be necessary for inelastic electron tunneling spectroscopy.
Design and construction of a digital temperature controller for use in surface studies
Authors: Engstrom J. R. , Weinberg W. H.
Published: March 2003

An optimal crystal temperature control scheme is proposed which utilizes a minicomputer as the controller element. The controller design is based on standard frequency response techniques applied to an accurate and readily characterizable physical model. Specific control strategies for the production of both linear and step-function temperature profiles, commonly employed in surface studies, are presented and evaluated.
Application of fast Fourier transformation in thermoluminescence thermogram reconstruction
Authors: Pla C. , Podgorsak E. B.
Published: March 2003

A thermoluminescence (TL) thermogram reconstruction technique based on fast Fourier transformation (FFT) techniques is presented. Only the first few terms of the real and imaginary ‘‘frequency arrays,’’ representing the thermogram in the frequency domain, are used for thermogram reconstruction by an inverse transformation. A method to determine the optimum number of FFT terms is discussed and a reconstruction study performed on six commonly used TL materials.
Fast and continuous cross-correlation measurements of a double synchronously pumped mode-locked dye laser system
Authors: De Mazière M. , Bouwen A. , Schoemaker D.
Published: March 2003

The use of commercially available autocorrelators for generating continuous and fast display of cross correlations as well as autocorrelation traces is demonstrated for a double synchronously pumped mode-locked dye laser, emitting at two different wavelengths. We show how the average relative time delay between both pulse trains can be read directly on a picosecond time scale. As such, this technique extends the monitoring capabilities of these devices.
Characteristics of electron multipliers in the detection of alkali ions
Authors: Haq Faizan Ul
Published: March 2003

Results are presented showing the gain of electron multipliers EMI 9603-B and EMI 6260 as a function of their multiplying dynode voltage, ion input current, and ion accelerating voltage for Li+, Na+, K+, Rb+, and Cs+ ions. The high sensitivity of the particle multipliers for very low ion currents (∼10−14 and 10−10 A) and their potentialities for mass discrimination of different alkali ions have been discussed.
Instrumentation for magnetically confined fusion plasma diagnostics
Authors: Luhmann N. C. , Peebles W. A.
Published: March 2003

Recent progress in magnetically confined plasma research has brought the goal of controlled thermonuclear fusion within reach. Simultaneously, the increased size, temperature, and density of these devices has resulted in rapid changes in diagnostic techniques. In this article, recent developments in instrumentation are reviewed together with trends for the future. The topics discussed include far-infrared laser interferometry and polarimetry, ruby laser television Thomson scattering, excimer and Nd-glass laser scattering, ion temperature determination via large-α scattering with FIR and CO2 lasers, collective scattering, Schottky diode mixer technology, synchrotron radiation diagnostics and imaging, ion beam probes, x-ray diagnostics and imaging, neutron diagnostics, resonance fluorescence scattering, ultraviolet diagnostics, and internal magnetic field measurement.
Measurement of electrical conductivity and thermopower of liquid semiconductors
Authors: Rasolondramanitra H. , Cutler M.
Published: March 2003

A fused-quartz cell with graphite electrodes, suitable for measurement of corrosive liquids at high temperatures is described. Experimental procedures that reduce errors and facilitate the measurement, which are made possible by computer-controlled automation of the measurement, are also discussed.
New method of measuring vibration amplitudes of quartz crystals
Authors: Wimmer L. , Hertl S. , Hemetsberger J. , Benes E.
Published: March 2003

A new method is presented to measure in-plane vibration amplitudes of the order of some 10 nm. The measurement system utilizes the speckle effect and consists of only a few mechanical components. The evaluation is done by a microcomputer. The whole system is insensitive to environmental noise. The method has been applied to investigate the amplitude distribution of plano-convex AT-cut quartz crystals as they are commonly used in thin-film thickness monitors.
Use of PVC for replicating submicron features for microelectronic devices
Authors: Katzir A. , Vratny F.
Published: March 2003

Microelectronic devices consist of features whose sizes are nominally less than 1 μm. Features of the same size appear also on the x-ray masks used for processing the devices. For nondestructive testing of various structures it is useful to replicate the mask or circuit using a polymer layer. The replica can then be checked in a scanning electron microscope (SEM) for faults or problems in processing. It was found that PVC replication could faithfully reproduce features as small as 0.25 μm.
Direct comparison of performances of TOF atom-probe FIM in the linear and energy-compensated mode
Authors: Murakami Kenji , Adachi Toshiyuki , Kuroda Tsukasa , Nakamura Shogo
Published: March 2003

A direct comparison of the performances of the time-of-flight (TOF) atom-probe mass spectrometer in the linear and the energy-compensated mode has been carried out using our newly constructed combined-type TOF atom-probe field ion microscope. The detectability and the mass resolution were measured using the W(011) plane and the Mo(011) plane, respectively. The results suggest that in the energy compensated-type mass spectrometer, the use of an einzel lens for focusing the ion beam (called a ‘‘focusing energy compensated-part’’ in the text) is an effective way to increase the transmittance of ions through the deflector system without lowering mass resolution. It is suggested that this type of TOF atom probe is the best.
Personal computer-based automatic measurement system applicable to deep-level transient spectroscopy
Authors: Chang C. Y. , Hsu W. C. , Uang C. M. , Fang Y. K. , Liu W. C. , Wu B. S.
Published: March 2003

A simple, low-cost, and flexible personal computer-based automatic measurement system used for deep-level transient spectroscopy (DLTS) is developed and implemented. An IEEE-488 interface bus is designated for communication between the personal computer and instruments. This configuration provides advantages in ease of operation and quick set up, especially for the purpose of data acquisition and processing. In general, the system can be applied to any programmable measurement automatic configuration. A linear least-square regression method is used to process the Arrhenius plot and to determine the activation energy. The DLTS signal and the Arrhenius plot are plotted and displayed during one thermal scan. A new DLTS computation algorithm has also been employed.
Mirror electrode for laser initiated discharge channels
Authors: Gilgenbach R. M. , Horton L. D.
Published: March 2003

A reflecting waxicon has been demonstrated to generate long, smooth, CO2 laser induced breakdown plasmas in atmospheric pressure gases including nitrogen, argon, and air. A waxicon or compound axicon is a mirror consisting of two concentric cones which form a W-shaped cross section. The protruding central cone of the waxicon also functions as an electrode for laser guided electrical discharges. In contrast to conventional mirrors, this waxicon design produces nearly uniform laser intensity in a fixed length of breakdown plasma. The length of the laser induced breakdown plasma has been measured as a function of incident laser power and agrees well with predictions of a ray tracing code.
Saturated absorption in a molecular gas mixture to find line frequencies
Authors: Tabosa J. W. R. , Leite J. R. Rios
Published: March 2003

Saturated abosorption on a low-pressure mixture of CO2 and CH3OH inside a hot cell is used to demonstrate how the frequencies of molecular infrared transitions in near coincidence with a CO2 laser emission can be obtained with sub-Doppler resolution.
Cylindrical spinner and speed controller for magic angle spinning nuclear magnetic resonance
Authors: Lee James N. , Alderman D. W. , Jin Jiang Yi , Zilm Kurt W. , Mayne Charles L. , Pugmire Ronald J. , Grant David M.
Published: March 2003

A new design for a cylindrical spinner suitable for magic angle spinning nuclear magnetic resonance (NMR) is described. The rotor has a large sample volume (0.66 cm3) and is capable of spinning speeds from 500 Hz to 5 kHz at drive gas pressures below 50 lb/in.2. The rotor is completely supported by gas bearings. Axial positioning is provided by the rotor’s T shape, leaving the bottom surface available for a photoelectric tachometer. The coil is wrapped on a form machined into the outer surface of the stator, producing a high filling factor. Also described is an instrument which controls the spinning speed of such a rotor to ±0.6 Hz around a set speed in the range of 3–4 kHz. The rotor’s speed is determined by means of a photoelectric tachometer. The instrument then compares this measured speed to the desired value and adjusts the gas flow to the rotor to correct any difference.
Errors due to field nonuniformity in vibrating sample magnetometry
Authors: Kerchner H. R. , Sekula S. T. , Thompson J. R.
Published: March 2003

In a vibrating sample magnetometer the signal contains a spurious component due to the ac magnetization induced in the sample as it vibrates in an imperfectly uniform dc magnetic field. In high-conductivity and superconducting samples, the spurious signal may be larger than that due to the dc magnetization. A quantitative analysis is given, and measurements made in an uncompensated solenoid are compared with those made in a fourth-order solenoid.
Ion scattering spectrometry in a commercial scanning Auger microprobe
Authors: Liu Zhixiong , Reed David A.
Published: March 2003

A scanning Auger microprobe (SAM) equipped with a cylindrical mirror analyzer and noncoaxial ion gun has been adapted for ion scattering spectrometry (ISS). An optimally designed movable entrance aperture limits the scattering angle, providing high mass resolution and good sensitivity. Much of the electronics of the original SAM is employed for ISS, and switching the mode of operation is easily accomplished. The critical part of the apparatus is the entrance aperture, and its design is discussed in detail.
Ion thinning apparatus for the preparation of transmission electron microscopy specimens using new-type ion guns
Authors: Yoshida Kentaroh , Yamada Takashi
Published: March 2003

An ion thinning apparatus for the preparation of transmission electron microscopy (TEM) specimens was constructed using new-type cold cathode ion guns. The gun was specially designed for this purpose and has a movable central cathode rod. The rod is used to stabilize the discharge inside the gun when the pressure is high and to stimulate it when the pressure is low. The gun has no consumable parts within it and operates stably for more than 300 h. The thinning apparatus operates well at a vacuum of 3×10−5 to 1×10−4 Torr and gives argon-ion beams of 5 kV, 0.8 mA, with a maximum density of 0.25 mA/cm2. A few examples of the preparations and the observations are also described for the specimens of some rock-forming minerals and human teeth.
Calibration of a three-element hot-wire anemometer
Authors: Skinner G. T. , Rae W. J.
Published: March 2003

A fast method of calibrating a three-component hot-wire probe in a computer-controlled digital anemometer system is presented.
Channel multiplier compatible materials and lifetime tests
Authors: McComas D. J. , Bame S. J.
Published: March 2003

Certain materials useful in space sensor construction were tested for their noncontaminating compatibility with channel electron multipliers. Gain profiles indicate that the materials tested do not adversely affect the lifetimes of the multipliers. These materials are, therefore, shown to be safe for use with channel electron multipliers in space instrumentation even for the most stringent long lifetime mission requirements. The tests indicate that the multipliers which are to be flown on an extended space mission will have adequate lifetimes to return satisfactory data throughout the entire mission.
Thyratron-switched N2 atmospheric-pressure oscillator, low-pressure amplifier laser system
Authors: Docchio F. , Magni V. , Ramponi R.
Published: March 2003

The article presents the results of experimental investigation on an atmospheric-pressure N2 oscillator low-pressure N2 amplifier system. This system gives pulses of a duration of about 0.8 ns, with 800-kW peak power, and good (±3%) stability. The parameters affecting the oscillator–amplifier operation are discussed with the aim of optimizing system performances.
Directional pressure probe
Authors: Samet M. , Einav S.
Published: March 2003

In many complex flow fields, such as those encountered in combustion chambers, swirl atomizers, gas separators, and turbomachines, the mean-flow direction is not well known. However, quite often the experimental determination of the three-dimensional, steady-state characteristics of these flows is required. One of the most suitable instruments for measuring mean-flow values in such situations is the directional pressure probe. Presented in this paper are the results of a program to construct, calibrate, and employ a special type of directional pressure probe which is called: five-tube pressure probe or 5TPP. Topics such as calibration techniques, various sources of errors, and correction procedures are discussed in detail. Preliminary tests, which included measurements in the initial region of a turbulent jet in a coflowing stream, have shown fair agreement between the measurements of velocity with a 5TPP and with a standard hot-wire probe.
Liquid velocity measuring system with two delay line oscillators
Authors: Urabe Heijiro , Toda Kohji
Published: March 2003

A method using two delay line oscillators is described for measuring the flow velocity of a liquid. Each of the delay line oscillators is composed of two interdigital transducers on one surface of a piezoelectric plate, and an amplifier. The transducer operates as a sound beam radiator or a detector at a liquid–solid interface. The liquid velocity is estimated from the oscillation frequencies of two delay line oscillators. Experimental results confirming the operation principle of the method are satisfactory for water velocity measurement.
Processor operated correlator with applications to laser Doppler signals
Authors: Bisgaard C. , Johnsen B. , Hassager O.
Published: March 2003

A 64-channel correlator is designed with application to the processing of laser Doppler anemometry signals in the range 200 Hz to 250 kHz. The correlator is processor operated to enable the consecutive sampling of 448 correlation functions at a rate up to 500 Hz. Software is described to identify a Doppler frequency from each correlation and the system is especially designed for transient flow signals. Doppler frequencies are determined with an accuracy of about 0.1%.
Single axis photoelectronic autocollimator
Authors: Luther Gabriel G. , Deslattes Richard D. , Towler William R.
Published: March 2003

Several single axis, diffraction limited, monolithic autocollimators, capable of resolving less than 10−3 arc s have been designed and built. Their features include small size, lightweight, ruggedness, and ease of operation. Construction features and performance levels are given.
Calibration of ac susceptometer for cylindrical specimens
Authors: Goldfarb R. B. , Minervini J. V.
Published: March 2003

The absolute magnetic susceptibility of cylindrical specimens is obtained with an ac susceptometer whose calibration is based on a calculation of mutual inductance. An axially magnetized cylinder is modeled as a solenoid of the same size. The mutual inductance between such a solenoid and a pickup coil of arbitrary dimensions is computed. The susceptibility is then a function of the mutual inductance, the cylinder length, the magnitude and frequency of the ac magnetizing field, and the voltage induced on the pickup coil. Demagnetization factor and eddy-current effects are considered, an example is given, and pickup coil compensation is discussed. Other calibration methods are also presented.
Hot-stage for i
n s
i
t
u operation of a battery in a scanning electron microscope
Authors: Singh R. N. , Ettinger R. H. , Lewis N.
Published: March 2003

A hot-stage assembly has been designed, built, and operated inside a scanning electron microscope to observe and study the electrode–electrolyte interface behavior of a sodium–sulfur cell. This device has demonstrated the possibility of direct observation of the sodium evolution process onto the surface of a sodium beta″-alumina electrolyte. The results illustrated the wetting behavior of liquid sodium with the electrolyte surface and the dynamic behavior of liquid sodium evolution processes.
Electrohydraulic gas sampling valve
Authors: LoRusso J. A. , Lavoie G. A. , Forgacs R. L. , Jeryan R. A. , Errante J.
Published: March 2003

An electrohydraulically actuated gas sampling valve is described for use in reciprocating IC engine combustion studies. The design objectives achieved include: short sampling interval, 0.4–1.0 ms; variable valve lift range, 0.01–0.3 mm; and large sealing force capability to retain a gas tight seal when the valve is closed. The present configuration has flush seating geometry of the valve stem to valve seat to permit accurate boundary layer probing without perturbation of the sample region before the time of sampling. When coupled to a gas chromatograph or another measurement device, species concentrations can be measured at various times in the combustion cycle. Use of the valve in engine combustion studies has provided new experimental insight indicating that flame-wall quenching is not an important contributor to exhaust hydrocarbon emissions as once believed.
Core-level electron–electron coincidence spectroscopy
Authors: Haak H. W. , Sawatzky G. A. , Ungier L. , Gimzewski J. K. , Thomas T. D.
Published: March 2003

Two electron-spectrometer systems designed for electron–electron coincidence spectroscopy are described. One, based on two hemispherical analyzers and x-ray excitation, is especially suited for Auger-photoelectron coincidence spectroscopy (APECS) of solids and surfaces. The other, using a cylindrical mirror analyzer, a hemispherical analyzer, and electron-beam excitation is designed for near-dipole (e, 2e) spectroscopy of gaseous samples. Typical results obtained with these instruments are presented.
Broadband, high-power, millimeter-to-centimeter spectrometer
Authors: Mako F. , Pasour J. A. , Roberson C. W. , Lucey R.
Published: March 2003

A simple spectrometer is described for directly measuring both a high electric field (0.1–100 kV/cm) and wavelength over a broadband (0.1–10 cm). The combination of interference and gas breakdown are utilized in measuring the electric field and wavelength. Electron diffusion and the characteristic breakdown relation limit resolution of submillimeter wavelengths by requiring very high electric field (>100 kV/cm).
Surface fluctuation spectroscopy: A novel technique for characterizing liquid interfaces
Authors: Shih L. B.
Published: March 2003

Surface fluctuation spectroscopy is a dynamic light scattering technique which involves the detection of thermal fluctuations (capillary waves) that cover every liquid interface. The advantages of this technique over conventional mechanical methods are discussed. The signal resolution and precision are improved by using a grating heterodyne technique coupled with a digital correlator. Detailed calculations showed that, for the measured power spectrum (the Fourier transform of the correlation function) to take the Lorentzian shape, it is necessary that certain optical conditions be met. These conditions are demonstrated with experimental data collected for ethanol at the ambient temperature as a function of the wave number. Once the optical parameters are adjusted correctly, the experimental results show excellent agreement with the literature values. We have also demonstrated that, using microcomputer technology, the entire system can be automated. The instrument is easy to operate and can be used either for research purposes or on a routine basis. The implication of this instrument as a powerful analytical tool for a wide spectrum of liquid interfaces is also discussed.
Versatile temperature controller for the investigation of surface phenomena
Authors: Stroscio Joseph A. , Richter Lee J. , Ho W.
Published: March 2003

The design, construction, and performance of a stable temperature controller specifically built for surface studies is described. The controller can be operated either manually as an independent unit or automatically while interfaced to a digital signal analyzer, a computer, or an external programmer. Problems arising from the magnetic field generated by sample heating current are eliminated, allowing detailed studies of surface phenomena by electron spectroscopies over a wide range of temperatures and electron energies.
Isolation and inversion transformers for nanosecond pulses
Authors: Yamazaki Hatsuo , Homma Akira , Yamaki Shin’ichi
Published: March 2003

In the transmission-line approach to the design of transformers, a harmful mode of signal propagation that inevitably appears outside the transmission line has to be taken into account. The effect of this mode upon the output signal was studied theoretically and experimentally using a simplified model. With respect to the use of ferrite beads for suppressing the effect of this mode, a simple rule was derived for their effective use. According to the result obtained, isolation and inversion transformers were made for a test. The result of the test is given.
Construction of a low-noise, 16-bit, digital-to-analog converter interface for Apple computers
Authors: Benassi R. , Takatani S. , Chung Y. W.
Published: March 2003

The details of a relatively low-cost, low-noise, 16-bit interface between a digital-to-analog converter and an Apple II computer are presented.