bluuebunny/crossref_metadata_2025 huggingface dataset:
Programmable decade resistor
Authors: Duffy W. , Yin J. , Krakower J.
Published: March 2003

The design and construction of a programmable seven-decade resistor which interfaces with the IEEE 488 bus is described. Off-the-shelf commercial manually set decade units are modified for computer control. TTL logic circuitry is used to drive mercury-wetted reed relays which set the decades. The system controller is a Commodore PET (16K) personal computer.
dc discharge cell for laser optogalvanic spectroscopy
Authors: Webster Christopher R.
Published: March 2003

A dc electrical discharge cell for laser optogalvanic spectroscopy has been designed and tested. Signal optimization is achieved through the use of adjustable electrode positions and an orthogonal geometry between the probe laser and the discharge axis. Results are presented for visible dye laser and infrared diode laser studies of selected neutral, radical, and ion species.
Laboratory EXAFS spectrometer with a bent crystal, a solid-state detector, and a fast detection system
Authors: Tohji Kazuyuki , Udagawa Yasuo , Kawasaki Tsutomu , Masuda Kenji
Published: March 2003

A laboratory x-ray absorption spectrometer is described which consists of a Johansson-cut bent crystal, a rotating anode x-ray generator, and a fast SSD (solid-state detector). Because the SSD can completely discriminate the undesired reflections, contamination of the harmonics is avoided while maintaining a high-source voltage necessary for strong x-ray flux. Fast electronics equipment is employed to keep up with high-x-ray intensity. It is also possible to utilize higher-order reflections for high resolving power. The data of quality comparable to those obtained at synchrotron radiation facilities can be obtained in a comparable period of time. In addition, the determination of the absolute absorbance as defined is possible, which makes the problem of the background subtraction in EXAFS analysis easy.
Computer-based scanning system for electromagnetic dosimetry
Authors: Stuchly Stanislaw S. , Barski Mariusz , Tam Benjamin , Hartsgrove George , Symons Stephen
Published: March 2003

This paper describes an experimental system developed for the purpose of studying the distribution of electric field in lossy bodies. Ultimately, a map of the internal electric field intensity in a phantom model of the human body exposed in the near field of radio and microwave radiators is obtained. The field is sampled by a nonperturbing probe in a number of points under computer control using a system consisting of a microcomputer and a minicomputer. A description is given of the hardware and software components of the scanning system and the results of experimental evaluation of the performance of the system. For illustration the electric field distributions in simple configurations obtained experimentally are presented and compared with analytical results.
High-frequency temperature and pressure probe for unsteady compressible flows
Authors: Ng W. F. , Epstein A. H.
Published: March 2003

A 3-mm-diam, dual hot-wire aspiring probe is described which can simultaneously measure total temperature and total pressure in an unsteady high-speed gas flow. The probe consists of two coplanar constant temperature hot wires at different overheat ratios operated in a 1.5-mm-diam channel with a choked exit. Thus, the constant Mach number flow by the wires is influenced only by free-stream total temperature and pressure. The probe design is a compromise between the conflicting requirements of spatial resolution, frequency response, and angular sensitivity. The dc temperature accuracy of the probe is about 1% while the resolution is 0.3%. Frequency response of the present design is dc to 20 kHz.
Generalized response of chemiluminescence analyzers
Authors: Mehrabzadeh A. A. , O’Brien R. J. , Hard T. M.
Published: March 2003

The mass flow and chemical kinetic equations for a gaseous chemiluminescence (CL) analyzer are formulated and solved. The resultant equation can be used to predict the absolute response of the analyzer as a function of the sample flow rate, the sample gas pressure, the chamber pressure, the chamber volume, the mass flow rate and mole fraction of the reagent gas, and the rate constants of the relevant chemical processes. Thus, the equation allows optimization of these parameters. It is shown that for varying sample pressure the analyzer can be used to measure either concentration or mole fraction and that interfering reactions can sometimes be discriminated against by chamber pressure variation. The equations apply equally well to a flowing-liquid-phase CL analyzer, if the chemical mechanism considered is appropriate.
Spatial resolution in high-pressure xenon x-ray detectors
Authors: Tam K. C.
Published: March 2003

High-pressure xenon detectors used in medical x-ray scanning have high stopping power for x rays and high resolution, typically 1 mm for 50–150 keVP x rays. Industrial inspection calls for even higher spatial resolution at higher x-ray energies. The precision in localizing incident x-ray photons is limited by the spread of the primary electrons and other radiations produced by the x-ray photons in the detector. In this paper, the spatial resolution of the high-pressure xenon detector is determined by analytically modeling the interactions between the x-ray photons and Xe atoms, and calculating the spatial spread of the secondary radiation produced by the conversion electrons, bremsstrahlung, and fluorescent radiation. It is found that spatial resolution of the order of 100 μm is achievable for 320-keVP x rays in Xe at 75 atm. The spatial resolution determined in this way can be used in designing and calibrating gas detectors, and in estimating the contribution from all other experimental sources to the spatial spread of the detected signals.
Simple multiple-crystal x-ray spectrograph
Authors: Nagel D. J.
Published: March 2003

The design of a compact x-ray spectrograph most useful in the 0.5–50-keV region is described. Although developed primarily for plasma emission measurements it may also be useful for spectroscopy of other bright x-ray sources, such as synchrotron radiation from storage rings.
Ultrahigh vacuum arc method to form thin refractory metal films
Authors: Kanayama Michio , Igarashi Yuichiro
Published: March 2003

A practical means has been established for starting a discharge between refractory metal electrodes in ultrahigh vacuum and to sustain it stably for a long time. Thin single-crystal films were thus obtained. Unlike what is done in the sputtering method, no inert gas is used here. The emission of gaseous particles in the present method occurs due to plasma power, the particles having, therefore, an appreciable amount of kinetic energy. This fact distinguishes it from the E-gun method, in which evaporated particles are not energized. We present, as an example, the results obtained when applying the method to tungsten. The gas supply that sustains the plasma state comes from the melting surface of two rod-shaped electrodes surrounded by a helical filament. The arc-type discharge, easily starts by applying an input voltage of only about 1.5–2.5 kV between the electrodes while simultaneously bombarding them with electrons emitted from the filament, and is electrically controlled by a load resistance and a servo mechanism continuously adjusting the gap between the consuming electrodes. A stationary discharge is, therefore, attained. Starting voltages are quite reproducible and depend little on the gap length, provided that this last parameter is less than about 2 mm. The discharge, closely related to both discharge power and gap length, is of practical use only within a stable region. Excessive power supply produces splashing of the electrodes, while insufficient power results in the disappearance of the discharge. The evaporation rate depends on the power of the plasma column. Effects due to partial pressure of materials other than that of rods are sufficiently eliminated by the ultrahigh vacuum system.
Instrumentation for incremental voltage step electrochemical measurements
Authors: Thompson A. H.
Published: March 2003

A new electrochemical instrument is described that permits the rapid and precise measurement of electrode parameters of reaction. The described techniques, previously called electrochemical potential spectroscopy, are particularly valuable in studying solid-state reactions and phase transitions and are generally useful whenever approximations to equilibrium data are required on slow processes. The instrument may also be viewed as a general purpose instrument for measurement of electrical capacitance. It automatically measures the voltage–composition– current–time relations on an electrochemical cell by systematically stepping the voltage through a series of programmed constant voltage steps. The instrument is designed for three-electrode measurements and has been fully developed and tested on a large number of electrochemical systems. Three commercial lithium cells are measured to illustrate the method, its time saving advantages, and its weaknesses. Comparison is also made to open circuit data collected on Li–V2O5. Three electrode measurements are reported elsewhere.
Measurement of thermal conductivity and contact resistance of paper and thin-film materials
Authors: Sanders D. J. , Forsyth R. C.
Published: March 2003

A new thermal conductivity cell is described which can be used to measure the bulk thermal conductivity and the thermal contact resistance of paper and other thin-film materials. The cell incorporates a hydraulic piston which can apply pressures up to 1700 psi to the sample which is situated between the optically flat end faces of two brass columns. By measuring the thermal resistance of paper samples of various thicknesses, it is demonstrated that a pressure of 1700 psi effectively eliminates the thermal contact resistance. By comparing measurements at zero and maximum applied pressure, both the bulk conductivity and the contact resistance can be calculated. This is illustrated with several types of paper. In all cases, there is a qualitative correlation between the measured contact resistance and the surface roughness of the sheet. The technique can also be used for thin polymer films, and for layered structures such as the ink donor films used in thermal transfer printing.
Simple absolute calibration method using laser sources for pulsed spectroscopic applications in the visible and UV
Authors: Döbele H. F. , Rückle B. , Vielemeier B.
Published: March 2003

A diffuser system is used to scatter the radiation of a suitable laser beam isotropically into the acceptance angle of spectroscopic detection systems. In connection with a laser energy meter, absolute calibration can be performed.
Metastable ion beam fractions measured for different ion sources
Authors: Hofer W. , Vanek W. , Varga P. , Winter H.
Published: March 2003

Metastable fractions of singly charged ion beams extracted from different ion sources have been determined by measurement of secondary electron spectra which result from slow ion-induced potential emission from a well-defined solid surface. Data are presented for Ar+, Kr+, Xe+ beams produced by a NIER-type electron impact source, a ‘‘COLUTRON’’-type low-pressure arc plasma source, and a ‘‘DUOPLASMATRON’’-type magnetically compressed arc plasma source, respectively. The measured metastable fractions are accurate within 25%, and their dependence on various ion source parameters can be well explained with a simple model of metastable ion production and loss kinetics.
Apparatus for the continuous analysis of residual stresses in proximity to metallic surfaces
Authors: Solina A. , Bulckaen V. , Paganini L.
Published: March 2003

The following paper deals with a new apparatus for the continuous measurement of residual stresses (both at the surface and in the underlying strata) in variously treated metal disks (carburizing, shot peening, nitriding, surface hardening, ion implantation, etc.). The thickness of stressed analyzable strata can vary by fractions of a μm up to 1 mm. It should be noted that for a thickness of less than 10 μm there is no alternative analysis process. Typical examples of stress analysis using this new apparatus are reported.
Fully automatic apparatus for the determination of doping profiles in Si by electrical measurements and anodic stripping
Authors: Galloni R. , Sardo A.
Published: March 2003

A completely automatic, computer-controlled apparatus for the determination of doping profiles in silicon has been set up. Doping is determined by resistivity and Hall measurements associated with the subsequent removal of controlled thin layers of material. Anodic oxidation and subsequent oxide stripping by chemical etching has been chosen as the most controllable peeling technique. Electrical measurements are automatically detected and both carrier concentration and mobility values are plotted versus depth. A set of empirical parameters are provided to fit mobility-concentration data for P, B, and As available in the literature, with analytical expressions. In this way, comparison with experimental values detected in the profiling operation can be readily made and information on the presence of lattice imperfections can be obtained. A new technique for sample preparation, which uses an ultrasonic drill for mesa etching the van der Pauw pattern, is also described. With this apparatus the critical and time wasting operation of electrical activity profiling becomes a powerful method of standard analysis.
Apparatus for simultaneous temperature and heat-flow measurements under transient conditions
Authors: Leclercq D. , Thery P.
Published: March 2003

In this paper, it is shown how a heat-flow transducer and a digital electronic unit can be used together for simultaneous measurements of heat flow and temperature. The electrical output of the sensor consists of a voltage generator (whose open circuit voltage is proportional to the rate of the heat flow to be measured). The electrical output of the sensor acts as a single battery and metallic resistors were disposed between the terminals. The open circuit voltage is proportional to the rate of heat flow to be measured. The value of the resistor is controlled by temperature. The procedure for simultaneously measuring heat flow and temperature is made straightforward by including a balanced Wheatstone bridge driven by an ac carrier as an integral part of the design. To solve the difficult problem of precise detection and maintenance of the balance, the classical Wheatstone bridge configuration has been slightly modified by adding a capacitor to smooth the phase variations around the balance. The discrete time feedback loop used for automatically balancing the bridge includes a digital integrator which sums the phase errors and provides the required voltage. As a result, temperature measurements were made with a linearity better than 1% in the measuring range and the digital readout is obtained with a rise time of 10 ms.
New radiant heater for zone melting intermediate melting-point materials
Authors: Bylander E. G. , Best A. B.
Published: March 2003

A radiant zone heater based on molybdenum disilicide wire and a machinable alumina support/reflector is described for use with materials with liquidus temperatures in the range of 600 ° and 1200 °C.
Electrode material for high-temperature oxygen partial pressure electrochemical sensors: Strontium-doped lanthanum chromite
Authors: Barbi Giovanni B. , Casiraghi Andrea , Mari Claudio M.
Published: March 2003

The electrochemical behavior of 20% strontium-doped lanthanum chromite (SDLC), deposited onto a 8% yttria-stabilized zirconia (YSZ) solid electrolyte, has been investigated. The electromotive force developed across the interface SDLC/YSZ and a Pt/YSZ reference at 0.21 atm (air) corresponds to the Nernst theoretical relationship. This behavior has been tested between 700° and 1000 °C in the ranges 100–10−5 and 10−13–10−20 atm of oxygen, the lower pressures by the equilibrium of carefully calibrated steam and hydrogen mixtures. Although not demonstrated, it is probable that the oxygen pressure range of applicability of this mixed oxide electrode covers the entire field of pure ionic conductivity of any zirconia-base electrolyte. The fair agreement between the measured values and the theoretical emf values, the resistance of the electrode layer to scaling, as well as its good thermodynamic stability, suggests SDLC as a possible alternative to platinum in high-temperature oxygen pressure sensors.
Improved constant current ballast
Authors: Rosenthal Louis A.
Published: March 2003

Significant improvements in a constant current ballast circuit to provide linear programmed current control at levels up to 5 A, with minimum voltage drop, can be realized.
On centering of lenses during cementing
Authors: Mudholkar V. M. , Sharma G. K.
Published: March 2003

An apparatus has been designed for direct viewing of centering errors in cemented doublets. The centering errors can be corrected in situ during cementing. This enables easy rectificiation and is applicable both to thermoplastic and thermosetting cemented lens systems. Multiple lenses can also be easily centered and cemented using this apparatus.
Porous tungsten relativistic electron beam cathodes compared with carbon cathodes
Authors: Matsuzawa Hidenori , Kanai Hisashi
Published: March 2003

Porous tungsten cathodes have electron emission characteristics similar to those of plain carbon cathodes, and carbon cathodes with many grooves on the front surface and with silicon resin coating on the lateral surface are superior in emission current to plain carbon cathodes by a factor of 50%.
Magnetic-field-free vapor furnace for photoelectron spectroscopy. I. Temperatures up to 900 K
Authors: Schönhense Gerd
Published: March 2003

A vapor furnace producing stable atomic and molecular beams for photoionization experiments is described. During operation the furnace causes no detectable magnetic stray field because it is heated by a stream of hot air. Thus angle- and energy-resolved measurements of photoelectron spin polarization could be done at a kinetic energy as low as 0.5 eV. The high temporal stability of the target beam is demonstrated by means of an angular distribution measurement with mercury atoms.
Electron microscope grid holders for a multipurpose specimen stage
Authors: Warble C. E.
Published: March 2003

In this article improved grid holders for use in a multipurpose electron microscope stage are described. Two models, made from copper, bronze, or brass, both allowing cooling and tilting, provide either (1) a heating capability with the grid in a strip configuration or (2) a full-circle grid without the heating facility. The mechanical stability, electrical, thermal, and anticontamination characteristics, and tilt movements are excellent.
Dust concentration measurement probe using beta attenuation
Authors: Slezak S. E. , Buckius R. O.
Published: March 2003

A small probe utilizing the attenuation of the beta emissions from promethium-147 has been constructed and calibrated for measuring the suspension concentration of dusts in the range of 0.1 to 2.0 kg/m3. The absorption of beta particles (negatively charged electrons) is related to the amount of matter through which the particles pass. The probe discussed here measures the beta absorption through a 3.8-cm path length at sample rates up to 20 samples per second. The small size of the probe (16 cm overall) allows real-time in situ local measurements of the suspension of a dust. The basic theory of operation and details of the probe operation are presented. Data from the probe for use in dust flammability experiments are also presented.
Apparatus for measurements on the fragmentation of MeV molecular-ion beams
Authors: Zabransky B. J. , Cooney P. J. , Gemmell D. S. , Kanter E. P. , Vager Z.
Published: March 2003

An apparatus for the study of the fragmentation of MeV molecular ions is described. The system permits high-resolution measurement of the joint distribution in energy and angle for fragment ions of selected charge and mass. Two movable detectors allow the study of spatial and temporal correlations among up to three fragments resulting from a single dissociation event. All experimental parameters are monitored, controlled, displayed, and recorded by a computer system that uses a linked network of four processors. Real-time, computer-generated color graphics are employed to give a visual rendition of the relation between the detector positions and the trajectories of outgoing fragments.
Cantilever and capacitor technique for measuring dilatation
Authors: Primak William , Monahan Emmet
Published: March 2003

The relationship of EerNisse’s technique for measuring small dilatations caused by irradiation with short-range particles, which utilizes a metallized thin plate mounted as a cantilever below whose free end an electrode is placed (forming a capacitor), to a photoelastic technique and to an interferometric technique are derived. The effects of stray capacitance, the fringing field of the capacitor, the clamping stress on the cantilever plate, the electrical resistance of the metallic coating, the charging of the tank circuit of which the capacitor is an element, the flange bolting stress, and the beam heating are assessed, and examples of the manner in which they contaminate the data are given.
Fast, two-channel analog-to-digital converter for DEC microcomputers
Authors: Wicke Brian G.
Published: March 2003

A circuit is described which provides fast acquisition of two analog signals by the Digital Equipment Corporation family of LSI 11, 11/2, and 11/23 microcomputers. This circuit digitizes each signal with 12 bits of resolution and stores the results directly in microcomputer memory via direct memory access. Real-time data-acquisition speeds up to three microseconds per pair of signals may be obtained.
High-concentration H2+ or D2+ ion source
Authors: Ehlers K. W. , Leung K. N.
Published: March 2003

The characteristics of a multicusp source that can produce a H2+ or D2+ ion fraction greater than 80% is described.
Improvements of the performance of triple hot wire probes
Authors: Andreopoulos J.
Published: March 2003

Two specific problems associated with a triple hot wire probe are discussed and analyzed here, namely, the problem of nonorthogonality of the three wires and the variation of the directional sensitivity coefficients k2 and h2 with the pitch and yaw angles. Both problems can cause significant errors in the measured turbulence quantities. In particular, v̄2 and w̄2 can be drastically affected. The present results confirm that v̄2 and w̄2 can be measured rather inaccurately with a triple wire, if  ‘‘overall’’ values of k2 and h2 are used, where ‘‘overall’’ denotes a mean integral value over a wide range of angles. It was found here that if these coefficients, in particular h2, are left to vary with the angles, v̄2 and w̄2 can be measured more accurately. It is strongly recommended to take this effect into account when high-velocity fluctuations are expected. Two numerical schemes have been proposed as remedies to these problems. They were found to work effectively although the data processing time is significantly increased. It is believed that these algorithms improve the performance of a triple wire, and can be applied to any three-dimensional flow with high turbulence level for which the mean velocity vector is unknown beforehand.
Simple corrections for the temperature sensitivity of hot wires
Authors: Tavoularis S.
Published: March 2003

Measuring errors due to hot-wire temperature sensitivity are expressed in terms of measurable parameters. Examples show that such errors can be significant, often excessive.
High-resolution third-sound resonator
Authors: Ellis F. M. , Hallock R. B.
Published: March 2003

A third-sound helium film resonator using a capacitive thickness detector suitable for high-resolution studies of third sound in 4He and 3He–4He mixtures is described. The sensitivity to changes in the helium film thickness is observed to be ≂0.1 pm.
Improved system for measuring the writing speed of sweeping image cameras
Authors: McQueen R. G.
Published: March 2003

A new system has been developed for determining the writing speed of sweeping image cameras. In this system the time intervals between light pulses from the image of a small objective slit as seen by a photomultiplier tube through a pair of slits at the object plane are measured by a time interval meter. Several features of this system allow the writing speed of an individual measurement to be determined to better than a tenth of a percent so that very precise corrections can be determined for nonideal behavior of the camera’s optical system.
Matrix formalism for uncertainty analysis
Authors: Smith Donald L.
Published: March 2003

A convenient, versatile matrix formalism for uncertainty analysis is discussed, and the concepts are illustrated numerically by means of their application to a hypothetical robot apparatus. The importance of uncertainty correlations is emphasized in this treatment which is based upon well-known statistical laws that govern experimental observations.
Field emission ion source of molecular cesium ions
Authors: Helm H. , Möller R.
Published: March 2003

Molecular cesium ions are formed by field ionization from a liquid-cesium droplet suspended on a tungsten needle. An ion beam containing typically 87% Cs+, 10% Cs+2, 2% Cs+3, and 1% heavier molecular ions Cs+n (n>3) can be extracted from the liquid surface. We identified molecular ions in the beam up to Cs+9 by photodissociation with a krypton ion laser. The source operates with reliable long-term stability and shows a conversion efficiency of liquid metal into gas-phase ions of >25%.
Electrically triggered multimodule KrF laser system with narrow-linewidth output
Authors: McKen D. C. D. , Fedosejevs R. , Arnfield M. , Tomov I. V. , Domier C. , Offenberger A. A.
Published: March 2003

A narrow-linewidth multimodule KrF discharge laser system is described which is designed to be the front end of an electron-beam pumped amplifier–Raman compressor high-power UV laser facility. The discharge laser system consists of an intracavity triple étalon-narrowed master oscillator followed by an injection-locked slave oscillator and two single-pass amplifiers. The master oscillator has 30 cm of gain length while the three remaining devices utilize 90 cm of gain length. The units are electrically triggered from a high-voltage multitrigger pulse generator. The pertinent electrical parameters have been determined and are reported. Narrowband output (0.1 cm−1) of 1.6 J can be obtained in 20-ns FWHM pulses. The small signal gain and saturation intensity of the 90-cm amplifier modules were measured giving values of 0.115 cm−1 and 1.7 MW/cm2, respectively.
Grazing-incidence differential-reflectance method for explicit determination of the complex dielectric function of an isotropic absorbing medium
Authors: Azzam R. M. A.
Published: March 2003

Measurement of the small angles of grazing incidence (between the light beam and the surface), θ=θp and θ=θs, that are required to decrease the intensity reflectances of a planar surface of an absorbing isotropic medium for the parallel ( p) and perpendicular (s) polarizations, respectively, from 1 (at θ=0) to 1−γ, where γ is a small predetermined reflectance loss (γ≲0.1), permits simple, explicit, and direct determination of both the real and imaginary parts of the complex dielectric function of the medium at the wavelength of the incident monochromatic radiation.
Laser beam spatial profile analysis using a two-dimensional photodiode array
Authors: Knudtson J. Thomas , Ratzlaff Kenneth L.
Published: March 2003

A system for the spatial characterization of a laser beam using an optoelectronic imaging device is described. A two-dimensional photodiode array interfaced to a small computer is used to obtain the image of the beam’s cross section; the peak position, peak intensity, and Gaussian peak width can then be computed and displayed. Details of the array interface, the graphics, and the data-processing algorithm are provided.
Protection of large capacitor banks
Authors: Sprott J. C. , Lovell T. W.
Published: March 2003

Large capacitor banks, as used in many pulsed plasma experiments, are subject to catastrophic failure in the event of a short in the output or in an individual capacitor. Methods are described for minimizing the damage and down time caused by such a failure.
Temperature determination of freely rotating bodies
Authors: Weller A.
Published: March 2003

A new approach for the determination of the temperature of rotating bodies is described, which makes use of the fact that the sample is rotating with virtually no friction. The basic principle is that a temperature change causes thermal expansion, and hence a change in the moment of inertia which, due to conservation of angular momentum, results in a change of rotational frequency. The method was used to determine the temperature of a magnetically suspended cylinder of pure iron within ±5 K while cooling down from 800 to 300 K. The contact-free suspension is ideally suited to study the radiative interaction of the sample with its environment. It is shown that on the basis of the Stefan–Boltzmann equation the time constant of radiation exchange and the emissive power of the sample can be evaluated. From the results of these investigations the measuring limit of a spinning rotor vacuum gauge due to temperature fluctuations can be estimated.
High repetition rate subnanosecond gated photon counting
Authors: Alfano A. J. , Fong F. K. , Lytle F. E.
Published: March 2003

A gated photon counting instrument which is capable of operation at the full 100-MHz repetition rate of mode-locked ion lasers is described. This instrument provides a high throughput alternative to more complex and costly instrumentation commonly used in time-correlated single photon counting. Applications to the measurement of subnanosecond fluorescence lifetimes at a 96.8-MHz laser repetition rate and to the reduction of matrix quenching effects in fluorometry at a 5-MHz laser rate are presented.
Development of a totally computer-controlled triple quadrupole mass spectrometer system
Authors: Wong Carla M. , Crawford Richard W. , Barton Victor C. , Brand Hal R. , Neufeld Kenneth W. , Bowman James E.
Published: March 2003

A totally computer-controlled triple quadrupole mass spectrometer (TQMS) is described. It has a number of unique features not available on current commercial instruments, including: complete computer control of source and all ion axial potentials; use of dual computers for data acquisition and data processing; and capability for self-adaptive control of experiments. Furthermore, it has been possible to produce this instrument at a cost significantly below that of commercial instruments. This triple quadrupole mass spectrometer has been constructed using components commercially available from several different manufacturers. The source is a standard Hewlett-Packard 5985B GC/MS source. The two quadrupole analyzers and the quadrupole CAD region contain Balzers QMA 150 rods with Balzers QMG 511 rf controllers for the analyzers and a Balzers QHS-511 controller for the CAD region. The pulsed-positive-ion-negative-ion-chemical ionization (PPINICI) detector is made by Finnigan Corporation. The mechanical and electronics design were developed at LLNL for linking these diverse elements into a functional TQMS as described. The computer design for total control of the system is unique in that two separate LSI-11/23 minicomputers and assorted I/O peripherals and interfaces from several manufacturers are used. The evolution of this design concept from totally computer-controlled instrumentation into future self-adaptive or ‘‘expert’’ systems for instrumental analysis is described. Operational characteristics of the instrument and initial results from experiments involving the analysis of the high explosive HMX (1,3,5,7-Tetranitro-1,3,5,7-Tetrazacyclooctane) are presented.
Construction and calibration of a four-beam source for the preparation of rare-gas diluted metal–hydrogen films
Authors: Ludwig R. , Micklitz H.
Published: March 2003

We present a unit which enables us to evaporate two different metals, rare gas, and atomic or molecular hydrogen at the same time onto a substrate held at a temperature of about 5 K. The deposition rates of the metals and the rare gas are measured by a quartz oscillator. The hydrogen deposition rate is calibrated by using the H-concentration dependence of the superconducting transition temperature in Pd–H and Al–H, known from ion-implantation experiments.
Beam-splitter mount for efficient monitoring of mode-locked and synchronously pumped cw lasers
Authors: van Hoek A. , Visser A. J. W. G.
Published: March 2003

Monitoring the optical pulses from mode-locked and synchronously pumped continuous wave (cw) lasers, reference beams are taken from the main beams with beam splitters. Depending on the angle with respect to the incident beam and the direction of the rotation axis of the beam splitter, light fractions of different polarizations can be selected. Based on practical and theoretical considerations an alternative beam-splitter mount has been designed which efficiently utilizes the available optical power.
Acoustic wave calibration for CO2 laser scattering experiments
Authors: Valley J. F. , Slusher R. E.
Published: March 2003

An acoustic wave technique is described which provides an absolute calibration of the amplitude of the light scattered from a CO2 laser beam at near-forward angles by fluctuations in plasmas or other media. This technique also provides a direct measure of the wavelengths of fluctuations that can be resolved by CO2 laser light scattering. Using simple vibrating membranes, acoustic waves with wavelengths from a few millimeters to several centimeters can be generated with accurately measured amplitudes. Laser scattering from these waves verifies that wavelengths as long as 2 cm can be resolved with small-angle CO2 laser scattering. For the case of heterodyne detection, calibration of the scattered wave amplitudes is obtained to within ± 20%.
Spatial filtering of backscattering signal in optical fibers
Authors: Biet M.
Published: March 2003

Reducing the front face echo is one of the major problems encountered in backscattering measurements of optical fibers. A simple method is proposed in order to eliminate completely this unwanted signal for both multimode and single-mode fibers. The setup is very simple and no special preparation of the fiber is needed. The insertion losses of the filtering device are very low and the detector is protected against direct reflections. In the case of multimode fibers a selective analysis of the backscattered signal can be performed.
High-temperature calorimeter for the measurement of vapor pressure and enthalpy of vaporization
Authors: Natarajan G. , Viswanath D. S.
Published: March 2003

An adiabatic calorimeter for the simultaneous measurement of enthalpies of vaporization and vapor pressures of certain coal chemicals is described. The calorimeter was tested using benzene for which accurate experimental data exists in the literature. Benzene is one of the substances recommended by IUPAC as a reference substance for calorimetric studies. The uncertainty in the benzene data is ±5 J/mole in the temperature range of 350 K (very close to the boiling point) to 480 K (around 0.85 times the critical temperature). Both vapor pressure and enthalpies of vaporization of benzene showed excellent agreement with the available literature data.
Simple apparatus for concentration determinations in binary-gas mixtures
Authors: Brooks J. S. , Hallock R. B.
Published: March 2003

A sound resonator is described which allows concentration measurements in binary-gas mixtures. The apparatus is particularly useful for relative measurements between a mixture and a pure gas.
Reactive scattering cell for atomic hydrogen and deuterium
Authors: Park J. T. , Redd E. , Kvale T. J. , Rille E.
Published: March 2003

A design for a high-temperature reactive scattering cell for atomic hydrogen and atomic deuterium is described. At approximately 2700 K a dissociation of the molecular target species of over 95% has been obtained. The lifetime of 340 h of operation is sufficient for precision, long-time, differential cross-section measurements.
Improved x-ray collimation system for diamond-anvil high-pressure cells
Authors: Schiferl D. , Olinger B. , Livingston R.
Published: March 2003

An improved x-ray collimation system for diamond-anvil high-pressure cells is described. The usual practice of mounting the collimator directly in the diamond-anvil cell is not followed. Instead, the collimator is mounted and aligned in a fixture which can be removed from the diamong-anvil cell. The end of the collimator furthest from the sample can be fitted with a set of removable plugs, each with a different aperture. This collimation system is easily aligned, can be removed from the high-pressure cell with no loss of alignment, and is inexpensive to construct.
Absorbance corrections in self-adjusting, variable path-length-diameter, high-pressure cells
Authors: Byrne Robert H.
Published: March 2003

Optical cells which maintain both constant diameter and constant internal mass during pressurization also maintain constant molar cross section (moles/cm2). In the recent article of le Noble and Schlott, ‘‘All quartz optical cell of constant diameter for use in high pressure studies,’’ the authors erroneously assume that the diameter of their constant internal mass, syringe-type cell is constant during pressurization [W. J. le Noble and R. Schlott, Rev. Sci. Instrum. 47, 770–771 (1976)]. In contrast to the authors’ principal conclusion, cell corrections are required in using the cell of their design. The corrections required to compensate for pressure-induced variations of molar cross section allow accurate employment of le Noble and Schlotts’ useful cell design.
High magnetic field, large-volume magnetic multipole ion source producing hydrogen ion beams with high proton ratio
Authors: Okumura Yoshikazu , Horiike Hiroshi , Mizuhashi Kiyoshi
Published: March 2003

In order to enhance the proton fraction in hydrogen ion beams, a high magnetic field, large-volume magnetic multipole ion source has been designed and tested. The plasma source is made of a water-cooled rectangular copper chamber, which is surrounded by a set of mild steel strips and samarium–cobalt magnets arranged in a continuous line-cusp geometry. The magnetic field at the inner wall surface is 2.7 kG. This strong magnetic field enables us to enlarge the chamber volume without increasing the ion loss area. Large plasma volume and small ion loss area increase the ion confinement time and enhance the proton yield. The proton fraction in the beams, as measured by both a magnetic momentum mass analyzer and a optical spectrometer, is found to be more than 90% at an ion beam current of 28 A ( j=250 mA/cm2). This source is also operated with a weak magnetic field (∼0.6 kG) by replacing the samarium–cobalt magnets with AlNiCo magnet, in which case the proton fraction decreases to 80%. These experimental values are in good agreement with the values predicted by a simple scaling equation of the proton ratio on the plasma volume and the ion loss area.
Low-dissipation support for a gravitational radiation antenna
Authors: Karim Munawar
Published: March 2003

We describe a support for the University of Rochester gravitational wave detector. The support is a two-stage filter with springs made of aluminum and a brass intermediate mass. With this support we have measured a mechanical quality factor for the fundamental mode of a 200-kg aluminum cylinder of 2.2×107 at 2302 Hz at 4.2 K. The filter attenuates vibrations by −130 dB at this frequency.
High temperature Hall-effect apparatus
Authors: Wood C. , Lockwood A. , Chmielewski A. , Parker J. , Zoltan A.
Published: March 2003

A high-temperature Hall-effect apparatus is described which allows measurements up to temperatures greater than 1200 K using the van der Pauw method. The apparatus was designed for measurements on refractory materials having high charge carrier concentrations and generally low mobilities. Pressure contacts are applied to the samples. Consequently, special contacting methods, peculiar to a specific sample material, are not required. The apparatus has been semiautomated to facilitate measurements. Results are presented on n- and p-type silicon.
Digital data-acquisition system for measuring the free decay of acoustical standing waves in a resonant tube
Authors: Meredith Roger W. , Zuckerwar Allan J.
Published: March 2003

A low-cost digital system based on an 8-bit Apple II microcomputer has been designed to provide on-line control, data acquisition, and evaluation of sound absorption measurements in gases. The measurements are conducted in a resonant tube, in which an acoustical standing wave is excited, the excitation removed, and the sound absorption evaluated from the free decay envelope. The free decay is initiated from the computer keyboard after the standing wave is established, and the microphone response signal is the source of the analog signal for the A/D converter. The acquisition software is written in assembly language and the evaluation software in basic. This paper describes the acoustical measurement, hardware, software, and system performance and presents measurements of sound absorption in air as an example.
Device for loading thin wires in a vacuum
Authors: Kania D. R.
Published: March 2003

A simple device has been developed to load thin (25 μm in diameter) wires in vacuum for an exploding wire plasma system. Wires may be loaded with high reliability, straight, and accurately positioned. An improvement in the reproducibility of the wire explosion results and is attributed to the ability to repeatedly form the electrical contacts between wire and electrodes.
High heat flux target for intense neutron source
Authors: Bacon F. M. , Cowgill D. F. , Hickox C. E. , Walko R. J. , Subia S. R. , Riedel A. A.
Published: March 2003

A 200-kV, 200-mA deuterium ion accelerator has been developed to simulate the operation of an intense neutron source for use in cancer therapy. The thin-film ScD2 target for the neutron source is supported on a water-cooled copper substrate designed to dissipate 40 MW/m2 at a surface temperature of 450 °C. This paper describes the theoretical and experimental analysis of the target and the postmortem analysis of a target after 140 h of operation at power densities exceeding 40 MW/m2. Cooling channel erosion due to nucleate boiling of the cooling water was shown to be the life-limiting feature of the target design.
High-pressure multimode resonator system for high microwave frequencies up to 215 GHz
Authors: Bridges Frank , Ready Steven , Morgan Michael
Published: March 2003

A high-pressure (P<3.6 kbar) multimode resonator system suitable for low-temperature (4.2 K) microwave measurements over a wide range of frequencies (21–215 GHz) is described. A simple reflection spectrometer is used for low frequencies (<50 GHz). At higher frequencies, an unusual transmission resonator scheme is used which requires only one microwave window.
Rotating disk valve for use in a differentially pumped gas system
Authors: Bonin Keith D. , McIlrath T. J.
Published: March 2003

Transmitting materials that can support reasonable pressure differentials and high laser intensities are not available in the extreme ultraviolet (XUV) spectral region below 100 nm. The present rotating disk system is designed to provide a clear aperture for XUV radiation on a pulsed basis while minimizing gas loss due to differential pumping. A comparison of the rotating disk valve and recent applications of pulsed supersonic nozzles to the generation of coherent radiation in the XUV by nonlinear laser mixing in gases is made. In an experimental setup designed to generate coherent XUV light near 92.3 nm in krypton, the rotating disk resulted in a gas savings of about a factor of 9 over an open aperture of the same size.
Apparatus for measuring time intervals of the beating rhythm of cultured cardiac cells
Authors: Kobayasi Syoyu , Goshima Kiyota
Published: March 2003

A simple and reliable system measuring the time intervals of periodic variations in intensity or shape of video images is described. This system was applied to the measurement of the statistics of beating intervals of cultured cardiac cells.
Simple inductive displacement transducer
Authors: Velayudhan C. , Bundell J. H.
Published: March 2003

A simple variant of the conventional methods of displacement measurement based on differential inductance variation is described. The theory of the transducer and an operational amplifier method of finding the difference between two oppositely varying inductances are presented. The major limitations of the method on linearity, sensitivity, and stability are discussed. A brief comparison with the well-known bridge methods is given. The prototype instrument has a dc output whose amplitude is proportional to the displacement and whose polarity indicates the direction of displacement. It has a sensitivity of 50 mV/μm, resolution of about 0.08 μm, and a maximum nonlinearity error of about 2% for a displacement range of ±100 μm. An application of the transducer system in the measurement of the reaction torque of a rotating machine delivering or receiving power is also given.
Thermal anchors for electrical leads to cryogenic experiments in an ultrahigh-vacuum environment
Authors: Nicoli V. M. , Naugle D. G.
Published: March 2003

Conveniently demountable thermal anchors made with single-crystal sapphire plates and cylinders suitable for use in an ultrahigh-vacuum environment with electrical leads from room-temperature instrumentation to experiments at liquid-helium temperatures are described.
Automatic dispensing of liquid nitrogen in submilliliter doses
Authors: Milner C. J.
Published: March 2003

Well-controlled doses of 0.2 to 0.5 ml of liquid nitrogen are delivered, on electrical signal (not more than once per 5 s), as fills of a miniature bucket raised by an automatic hoist. The bucket is lifted, brimming, from the storage flask and then moved sideways until over the receiver. At this point, a steel ball, which has been resting in and sealing a drain hole in the bucket, is lifted from its seat by a magnet fixed alongside the (now descending) bucket. Design features are outlined: some alternative designs, valving liquid through a short drain tube fixed in the storage flask, are briefly reviewed. In tests the device delivered 74 g (approx. 260 doses) during 63 min, the loss by evaporation meanwhile being 11 g from the bucket, implying a transfer efficiency of 87%. An indirect measure indicated the dose sizes as 354±10 μl approximately.
Method for measuring the refractive index of transparent solids
Authors: Bass Jay D. , Weidner Donald J.
Published: March 2003

A method for determining the refractive indices of transparent isotropic or anisotropic solids is presented. The method utilizes null position measurements of light deflected by a sample immersed in a liquid of known index. Measurements of absolute deflection angles are not involved. Natural crystal growth faces, even at right angles, can serve as prism faces, thus eliminating the need for extensive surface preparation. Consequently, this method is particularly well suited for measuring the refractive index of small samples with high indices. Using a simple refractometer, results were obtained for two biaxial and one isotropic material with high refractive indices: Ni2SiO4 with the spinel structure (maximum dimension of 0.12 mm), Ni2SiO4 (olivine structure), and GdAlO3 (perovskite structure). Uncertainties of less than 0.1% are obtained from visual observations of the refracted light. Increased accuracy is possible by improving the calibration of the immersion liquid refractive index and the detection system.