bluuebunny/crossref_metadata_2025 huggingface dataset:
Hot-wire thermal precipitator with low inlet losses and low size selectivity
Authors: Kasper Gerhard
Published: March 2003

Thermal precipitators provide an independent method of measuring aerosol size distributions and concentrations for particles diameters below ≃ 5 μm. The original design by Green and Watson, using a single heated wire and two cover glasses as collector surfaces, was modified to reduce significantly the loss of fine particles by diffusion to the channel walls. Also, an inlet system for minimal particle losses is described. For the remaining losses a correction factor has been calculated. Deposit analyses carried out for monodisperse particles between 0.2 and 2 μm indicate a small degree of size selectivity.
Apparatus for creep rupture testing in high-pressure hydrogen at elevated temperatures
Authors: Yokogawa Kiyoshi , Fukuyama Seiji , Kudo Kiyokatsu
Published: March 2003

An apparatus has been developed for creep rupture testing in high-pressure hydrogen up to 49.1 MPa at elevated temperatures up to 873 K. The apparatus is designed to facilitate the measurement of the actual load on the specimen with an external load cell irrespective of axial load caused by high pressure in the vessel or friction at sliding seals where the pull rod enters the vessel. The exact strain of the specimen can be directly measured with an external extensometer. In addition, the specimen mounting assembly is also designed to simplify the installation and operation of the apparatus. Application of the apparatus to creep rupture testing of a low alloy steel in high pressure hydrogen at elevated temperature is briefly described.
High accuracy deconvolution method using spline functions
Authors: Deutsch Moshe , Beniaminy Israel
Published: March 2003

A spline-based deconvolution method for use with experimentally derived data is presented. The method is based on the fact that for a not too wide resolution function, if the original function is a piece-wise cubic, so is the convoluted function. The two functions have the same knots and their coefficients are related by a set of simple equations, so that once the values of the convoluted function, measured in the laboratory, are fitted by a piece-wise cubic spline and its coefficient are obtained, one is able to calculate the coefficients of the cubic function representing the desired, deconvoluted function. The novel features of the method, including the influence of the width of the resolution function, are fully discussed and results of its application to simulated data are presented. Results obtained for the same data with two other widely used deconvolution methods are also presented and the comparative merits and demerits of the methods are discussed. Our method proves to be stable and accurate, and to yield high quality results even in difficult cases with which the two other methods are unable to cope successfully.
Maintenance of constant carbon concentration during heat treatment of steel
Authors: Bradley J. R. , Abe T. , Aaronson H. I.
Published: March 2003

A previously described salt bath apparatus for high temperature heat treatment of steel is made more effective through replacement of Ca pellets by a dense graphite rod as the deoxidation agent and the compartmentalization of the salt bath to avoid contact between the steel specimens and the graphite. Carbon content changes during subsequent, lower temperature heat treatment in a lead bath are inhibited by enclosing each specimen in a pouch made from the same material and by solidified salt trapped within the pouch.
Electron flow through transverse magnetic fields in magnetic multipole arc discharges
Authors: Holmes A. J. T.
Published: March 2003

Magnetic multipole sources have been shown to produce very quiescent plasmas. As a result, the experimental measurements of the diffusion of electrons across transverse magnetic fields in the source show that it obeys the scaling laws generated by collisions of the long-range coulomb type. The absolute flux of electrons is compared with the theoretical value derived from a model of cross-field diffusion arising from coulomb collisions.
Multimixer far-infrared laser Thomson scattering apparatus
Authors: Park H. , Yu C. X. , Peebles W. A. , Luhmann N. C. , Savage R.
Published: March 2003

A detailed description of the design and calibration of a multimixer far-infrared scattering system for the study of collective plasma density fluctuations is presented. The apparatus permits either the determination of single-shot wave dispersion data or angularly resolved scattering data at multispatial locations during a single plasma discharge. Typical scattering data from spontaneously occurring low-frequency microturbulence as well as from kinetic Alfven waves (generated during ICRF heating) in the UCLA Microtor tokamak are presented.
High-resolution ν1 spectrum of propyne: Application of a microcomputer-controlled infrared-acoustic color center laser spectrometer
Authors: Kyrö E. , Lieb S. G. , Bevan J. W.
Published: March 2003

Development of a microcomputer-controlled infrared-acoustic color center laser spectrometer capable of scanning in 100 cm−1 sections over the wavelength range 2.2–3.3 μm with a resolution of 0.01 cm−1 (300 MHz) is reported. Application of the spectrometer to investigation of the ν1 spectrum of propyne is demonstrated.
Construction and testing of a high-pressure joule-heating temperature-jump apparatus
Authors: Doss R. , van Eldik R. , Kelm H.
Published: March 2003

This paper describes the construction and testing of a high-pressure joule-heating temperature-jump apparatus for the study of fast reactions in solution at pressures up to 2 kbar. Important features are: a liquid pressurizing medium; a Teflon membrane pressure transmitting device; a constant, pressure independent, electrode distance. The Co(II)-PADA reaction was used to test the system, and the results are in good agreement with earlier reported data.
Automated spectrometer for pressure measurement using ruby fluorescence
Authors: Whitmore J. E. , Bruzzone C. L. , Ingalls R.
Published: March 2003

A scanning fluorescence spectrophotometer intended for measurement of the ruby R1 lines in a high-pressure diamond anvil cell is described. A rigid framework supports the electronic and optical components and an XYZ translation stage to hold the pressure cell. Innovations include a digital monochromator scan controller, the automatic placement of tick marks on the recorder output at 0.1 nm intervals, and light detection with a photodiode. The unit is compact, weighs 50 kg, and requires only a chart recorder for operation as an automated high-pressure measurement station. These features allow easy shipment and reassembly at remote experimental sites.
Large-area, high-sensitivity heat-flow sensor
Authors: Klems J. H. , DiBartolomeo D.
Published: March 2003

A heat-flow sensor based on ac resistance thermometry and utilizing synchronous detection is described. The sensor design permits large-area sensors to be constructed economically. Calibration of an initial 0.09 m2 prototype yielded a linear response with a sensitivity of (37.610.01) mV(W/m2)−1. The minimum detectable heat flux is no larger than 0.08 W/m2.
Waveguide laser using a curved grating
Authors: Sielmann H. , Waksberg A.
Published: March 2003

A curved grating was introduced into the cavity of a glass tube waveguide laser. This replaces the commonly used lens–flat grating configuration and facilitates the operation of the laser system. Several positions of the grating are possible and allow the design of a more compact cavity. The performance is comparable to that of conventional cavities.
High-current analog switches
Authors: Last Thomas A.
Published: March 2003

Two high-current analog switches are described. One is based on a JFET (junction field effect transistor) and the other on a VMOS (vertical metal oxide semiconductor) field effect transistor. The JFET switch has an input voltage and current range of ±10 V and ±350 mA, respectively, with a channel resistance of 3 Ω. The switch exhibited turn-on and turn-off times of 250 and 150 ns, respectively, for a positive 9 V signal (180 mA load current). The switch off-state leakage current was less than 1 nA. The VMOS switch has an input voltage and current range of ±10 V and ±750 mA, respectively, with a channel resistance of 5.5 Ω. The turn-on and turn-off times for the VMOS switch were 600 and 200 ns, respectively, for an input voltage of 9 V (360 mA load current).
Pneumatic driver for diamond anvil cells
Authors: Webb Alan A. , Qadri Syed B.
Published: March 2003

Use of Bassett-style diamond anvil cells in a remote environment is inconvenient since they must be accessed for each change in pressure. A simple pneumatic driver, however, has been designed and built which permits remote operation.
Comparison of two types of antennas for plasma heating
Authors: Roychowdhury U. K. , Venugopalan M. , Pool M. L. , Graham Robert
Published: March 2003

The ability of a quadrupole coil, an antenna, of new design for the production of high-energy protons in a plasma has been compared experimentally with that of a conventional wraparound coil. The energies of the protons in the escape cone of a magnetic bottle were measured by a Faraday cup. The antennas were placed alternately midway between the two solenoids and operated in resonance under similar conditions. Proton energies of 380 eV were attained with the new quadrupole coil, a value more than twice that obtained by the wraparound coil. Thus, the new coil is judged superior for the purpose of ion cyclotron resonance heating.
Dilatometry at low temperatures
Authors: Ackerman D. A. , Anderson A. C.
Published: March 2003

A dilatometer has been constructed for the routine measurement of thermal expansion coefficients in the temperature range of 0.1–10 K. Using a SQUID detector, the dilatometer provides a resolution of 2×10−4 Å. As a test of this apparatus, the linear thermal expansion coefficient of high-purity copper has been measured between 0.2 and 9 K.
High-precision tunable infrared reflectometer
Authors: Cem Gokay M. , Harding K. , Loomis J. , Marcheski J.
Published: March 2003

This report describes a double-bounce reflectometer operating between 1 and 4 μm. This reflectometer uses the Nernst glower as a source in conjunction with a liquid N2-cooled InSb detector. Data collection was best accomplished with a noise eliminating sample-and-hold system and a low-noise straight ac amplifier in conjunction with a computer. The reflectometer was evaluated using two samples with different metallic coatings, one aluminum and the other gold. Average absolute reflectance values of 95.059±0.025% for the aluminum sample and 98.088±0.017% for the gold sample were obtained at 3.79 μm at 45° incidence angle. The precision of the reflectometer was better than 0.03% for measurements made over a period of several days.
Zero-field pulsed spin echo spectrometer for the study of ferromagnetic materials
Authors: Chaughule R. S. , Gupta L. C.
Published: March 2003

Complete description of a pulsed nuclear-magnetic-resonance spectrometer operating in the frequency range 100–600 MHz is presented. The spectrometer is suitable for investigating hyperfine fields in ferromagnetic materials and has some novel features. High sensitivity, simplicity of operation, and ease of tuning over the entire frequency interval are some significant characteristics of the spectrometer.
Slot-effect electrometers with monopolar electrets
Authors: Jefimenko Oleg D. , Abazi Alajdin
Published: March 2003

Slot-effect electrometers with monopolar electrets as active elements are, in several aspects, superior to similar electrometers with bipolar electrets. In particular, the sensitivity of electrometers with monopolar electrets does not depend on the electret thickness and on the electret–electrode gap. Therefore, monopolar foil electrets can be used in such meters, and the electrometers can be constructed with less precision than when bipolar electrets are used. Two prototype electrometers are described: one with a disk-shaped electret, the other with a cylindrical electret. The sensitivity of the former is 1000 V or 10−7 C per full-scale deflection, that of the latter is 100 V or 10−9 C per full-scale deflection.
Precision spinning drop interfacial tensiometer
Authors: Seeto Y. , Scriven L. E.
Published: March 2003

An improved instrument is described for precise measurement of interfacial tension by means of a spinning drop in gyrostatic equilibrium. Vibrations which can interfere with gyrostatic equilibrium are greatly reduced and bearing heating artifacts are avoided. Sample holders of biprecision tubing permit determination of the drop magnification factor to be replaced by measurement of the liquid refractive index, which is much more precise. Other improvements and cost effective features are described. Systematic errors are analyzed. They increase from 2% as tension drops below 10 mdyn/cm (10−5 N/m), but decrease from 1% for tensions exceeding 0.08 dyn/cm (8×10−5 N/m), in typical circumstances.
Slow-scan silicon-intensified target-TV x-ray detector for quantitative recording of weak x-ray images
Authors: Gruner Sol M. , Milch James R. , Reynolds George T.
Published: March 2003

The construction and performance of a two-dimensional x-ray detector is described. X-rays are detected as scintillations in a thin phosphor screen which is fiber-optically coupled to a cooled SIT vidicon TV camera tube. The x-ray image is analog integrated on the vidicon target during an exposure period; afterwards, the x-ray signal is gated off and the target is read via a slow-scan, low-noise readout in a 256×256-pixel raster. Test data are presented on the performance of a detector based on an 80-mm SIT tube. The device is shown to be a quantitative, quantum-limited detector suitable for recording x-ray diffraction patterns over a wide range of x-ray intensities. The detector is shown to be especially suited for high count-rate applications. Current applications of the detector are described.
Digital data-acquisition system and mode analysis of magnetohydrodynamic instabilities in a noncircular tokamak
Authors: Tsuji Shunji , Toyama Hiroshi
Published: March 2003

A microcomputer-based data-acquisition system has been developed to investigate large scale magnetohydrodynamic (MHD) instabilities in a noncircular tokamak, TNT-A. Two pairs of multiplexers, sample and hold amplifiers, and fast AD converters, together with DMA data transfer, allow the system to support fast multichannel data acquisition (sampling time≂1.3 μs). Spectral analysis of poloidal magnetic field fluctuations gives mode numbers and the relative level of instabilities. A least-squares method has been devised to identify poloidal mode numbers, while taking into account the effects of noncircularity and displacement of the plasma column. This method proved to be effective for a noncircular tokamak and it enables us to check mode mixing between different frequencies.
Two methods for absolute calibration of dynamic pressure transducers
Authors: Swift G. W. , Migliori A. , Garrett S. L. , Wheatley J. C.
Published: March 2003

Two techniques are described for absolute calibration of a dynamic pressure transducer from 0 to 400 Hz in 1-MPa helium gas. One technique is based on a comparison to a mercury manometer; the other is based on the principle of reciprocity. The two techniques agree within the instrumental uncertainties of 1%.
Technique for producing uniform small droplets by capillary waves excited in a small meniscus
Authors: Jonsson Haflidi , Vonnegut Bernard
Published: March 2003

The vibration caused by tapping a small liquid-filled glass capillary causes small droplets to be ejected from the meniscus in its open end. This phenomenon serves as the basis for an apparatus capable of producing uniform water droplets in the size range from 3–150 μm diameter. The electric charge of the droplets can be controlled by electrostatic induction at their point of formation.
Biomagnetic instrumentation
Authors: Romani Gian Luca , Williamson Samuel J. , Kaufman Lloyd
Published: March 2003

We present a review of recent developments of the instrumentation for measuring magnetic fields emanating from the human body and other biological systems. The techniques for using various types of field sensors in shielded and unshielded environments are described, with special attention paid to recent advances in the application of SQUID systems. We also outline the present technical frontiers and point to avenues along which further improvements in performance are desirable.
Improved instrumentation for measuring the magnetic field of cellular action currents
Authors: Wikswo John P.
Published: March 2003

The instrumentation for measuring the magnetic field associated with the action potential in isolated nerve bundles has been improved to the extent that measurements can now be made in a typical laboratory without magnetic shielding. The superconducting magnetometer is operated in a liquid-helium storage Dewar so that transfers of liquid helium are no longer required. A power-line trigger circuit is used to minimize the interference of 60 Hz noise and its odd harmonics. A compensation circuit has been developed to correct, in real time, for the high-pass characteristics of the magnetometer. As a result of these improvements, it is possible to observe action currents as small as 0.1 μA in a 1.0-Hz to 1-kHz bandwidth without signal averaging.
Apparatus for subjecting living cells to fluid shear stress
Authors: Bussolari Steven R. , Dewey C. Forbes , Gimbrone Michael A.
Published: March 2003

This apparatus subjects cultured cell specimens to controlled levels of fluid shear stress in vitro. The cone-plate geometry permits long term (≳7 days) investigation of the effects of external fluid forces on living cells.
Miniature, sealed TEA-CO2 lasers with integral semiconductive preionization
Authors: Pace Paul , Mathieu Pierre , Cruickshank James
Published: March 2003

A novel excitation technique is presented for TEA-CO2 lasers. A homogeneous self-sustained discharge is obtained with preionization provided through semiconductive plates. The laser can operate in a sealed configuration using a room-temperature catalyst. Details of the construction and operating characteristics are given. Emphasis has been placed on simple and efficient construction in a compact device.
Production of 75-keV, 70-A, 10-s ion beams
Authors: Akiba Masato , Araki Masanori , Horiike Hiroshi , Ito Takao , Kawai Mikito , Kuriyama Masaaki , Kitamura Shigeru , Matsuda Shinzaburo , Matsuoka Mamoru , Mukaida Hidetoshi , Oguchi Yoshiaki , Ohara Yoshihiro , Ohga Tokumichi , Ohtsuki Hiroshi , Okumura Yoshikazu , Shibanuma Kiyoshi , Shibata Takemasa , Shirakata Hirofumi , Tanaka Shigeru
Published: March 2003

High-power long pulse ion sources were fabricated and tested at a prototype injector unit for JT-60. Ion beams of 70 A at an energy of 75 keV were extracted repeatedly for up to 10 s. The heat loadings to each grid were within our design values and each grid turned out to be thermally stable during 10 s pulse. The neutral beam power deposited to the beam target was over 1.43 MW, which corresponds to the design value of the JT-60 neutral beam injector. The e-folding half-width beam divergence angle was about 1.0° at optimum beam current and a proton ratio of about 80% was obtained. It was also confirmed that other beam line components, such as the ion beam dump and the cryopump, were sufficiently reliable.
Discharge treatment technique of breaking alternate fingers of an interdigital transducer
Authors: Singh Awatar
Published: March 2003

This note reports a new technique of breaking alternate fingers of an interdigital transducer that is made of just one metal. The technique is based on the discharge treatment of the film. Various advantages of the technique are also pointed out.
Improved evaporation geometry for powdered materials
Authors: Singh Awatar
Published: March 2003

This note reports the design of an improved evaporation geometry for the deposition of thin films of powdered materials. The geometry makes use of the fact that if the powdered material is heated in a chamber covered with two perforated strips with perforations misaligned, the paths for particle ejection are eliminated and reproducible pin-hole free film deposition is observed. The geometry is found to be compatible with other materials which do not react with the source boat construction material.
Versatile facility for shaping hard and brittle materials
Authors: Deutsch Moshe
Published: March 2003

A simple-to-construct attachment for a conventional wafering machine is described. The attachment incorporates an ultra-high-speed air turbine with a diamond needle cutting tool, and turns the wafering machine into a versatile milling machine for hard and brittle materials.
Dispersion electron spin resonance with the loop-gap resonator
Authors: Hyde James S. , Froncisz W. , Kusumi Akihiro
Published: March 2003

The loop-gap resonator, a novel microwave lumped-circuit structure, when used as a sample resonator in electron-spin-resonance spectroscopy, permits the direct detection of dispersion signals with greatly decreased demodulation of the FM noise that originates in the microwave oscillator. The improvement arises from two factors: 65 times higher energy density for a given input power and 12 times lower resonator Q compared with a typical cavity resonator. The signal-to-noise ratio for the dispersion signal of DPPH is predicted to be improved by a factor of 12×65=780; experimentally a factor of 700 was realized.
High-temperature, multihole SQUID sensor
Authors: Zarembiński Stefan , Kachniarz Jakub
Published: March 2003

A report is given on the preparation of a high-temperature SQUID sensor by coating a niobium sensor with a Nb3Sn layer superconducting at approximately 18 K. It seems that a similar technique could make it possible for a SQUID sensor to work at even higher temperatures (e.g., 20 K for GaxNb1−x or 23 K for Nb3Ge layers).
Note on decreasing the bandwidth of frequency-selective feedback amplifiers
Authors: Kiess E. M.
Published: March 2003

The Q of a tuned feedback amplifier can be increased by increasing the impedance of the input circuit. The quantity gain times input impedance divided by Q is found to be constant. An experimental value Q in excess of 3000 was obtained.
Measurement set for optical fiber loss spectra
Authors: Stone J. , Earl H. E. , Derosier R. M.
Published: March 2003

A set for measuring optical-fiber loss spectra is described. The set consists of a tungsten halogen lamp, a monochromator, a Si or InGaAs detector, and novel data processing instrumentation. Fully resolved spectra are obtained from the visible to 1.7 μm with an accuracy of 0.1 dB for both single-mode and multimode fibers.
External generation of gate delays in a boxcar integrator—Application to deep level transient spectroscopy
Authors: Kosai K.
Published: March 2003

A simple and easily installed modification is described which upon application of external pulses causes the undelayed opening of the gates in the signal processing modules of a Princeton Applied Research Model 162 boxcar integrator. This allows the timing for the aperture delays to be done externally with digital circuitry, thus simplifying the setting of time parameters in deep level transient spectroscopy (DLTS) measurements, as well as giving increased time accuracy, stability, and easier interfacing to a computer. A second circuit is also described which, when used with a modified 162, permits double correlation DLTS to be performed with one, instead of two, instruments.
Microwave sputtering system for the fabrication of thin solid films
Authors: Kato I. , Card H. C. , Kao K. C. , Mejia S. R. , Chow L.
Published: March 2003

A new microwave-plasma sputtering method has been developed for the fabrication of thin solid films. One advantage of this method is that the substrate is not exposed to the plasma which can be made very uniform and confined in a predetermined region. It is, therefore, possible to fabricate uniform solid films over a large area and for a wide range of film thicknesses on low melting-point substrates. Amorphous selenium films fabricated on a glass substrate or a polyethlene sheet are found to be very uniform in thickness, structure, and optical constants over a large deposition area.
Fast computer-controlled mirror system for intensity measurements in low-energy electron diffraction
Authors: Berndt W.
Published: March 2003

A plane mirror rotatable about two orthogonal axes has been developed for imaging low-energy electron diffraction (LEED) spots into a photometer tube. The mirror is driven by stepping motors and controlled by a PDP 11 computer. Using a sequence of primary-beam energy values in steps of 2 eV the acquistion time for the normalized intensity data from one diffraction beam between 30–200 eV takes approximately 10 s.
Construction and performance of a simple multishielded Dewar
Authors: Lin Li-He , Gasparini Francis M.
Published: March 2003

We have constructed a multishielded Dewar which we have tested at nitrogen and helium temperatures. The Dewar is of extremely simple design, requires no special insulating materials, and attains excellent performance. With an arrangement of 20 shields we have obtained evaporation rates of 5.6 and 3.0 liquid cm3 per hour for liquid helium and nitrogen, respectively. We report measurements of temperature distributions and evaporation rate as a function of the number of shields.
Multichannel switch triggered by low-voltage auxiliary discharges
Authors: Cohn D. B. , Long W. H. , Stappaerts E. A. , Plummer M. J. , West J. B.
Published: March 2003

A railgap has been developed which is triggerable by either corona or spark discharges. Trigger voltage and energy were 15 kV and 20 mJ, respectively. The switch was successfully tested over the range 15–35 kV, providing a channel spacing of about 1/cm.
Computer-controlled plasma emission spectroscopy
Authors: Etemadi K. , Pfender E.
Published: March 2003

A mirror system, consisting of a rotating mirror and a pair of coupled stepping mirrors, is used in conjunction with computer control of data acquisition followed by computer reduction of the data for a quick determination of plasma properties.
Mechanical filter for the suspension of gravitational wave antennas
Authors: Coccia Eugenio
Published: March 2003

We discuss here the design of a new suspension for Weber-type gravitational wave antennas. The suspension consists of cantilever beams and operates as a mechanical filter for the external mechanical noise. The attenuation of the filter and the stresses applied on the antenna are computed and verified experimentally. When the filter is optimized, the attenuation depends on the value of an angular frequency, ωc, characteristic of the material of the beams. Attenuation of the order of 10−6–10−7 can be obtained at 1 KHz for a 1000-kg antenna using materials with good anelastic behavior such as Al 5056 and Ti 64.
Detection efficiency of a heavy ion time-of-flight spectrometer with thin carbon foils in the start detector
Authors: Stüdemann W. , Wilken B.
Published: March 2003

We report measurements of the effect of heavy-ion scattering due to the passage through carbon foils with thicknesses of 4.5, 6.7, and 16.9 μg/cm2 in a wide energy range. For comparison of the results with theoretical predictions the actual foil thicknesses were determined by scaling energy loss measurements with tabulated stopping powers. Using these thicknesses the measurements in general agree well with theory. However, particularly for the 4.5 μg/cm2 foil, significant deviations from the specified thickness have been found very likely due to additional cover layers. The results are used to determine the loss in detection efficiency for low-energy heavy ions in instruments based on the time-of-flight method with thin carbon foils acting as converters for secondary electrons.
Zinc selenide window for transmission of CO2 laser radiation into moist gas at elevated pressures
Authors: Nelson Lloyd S. , Duda Patricia M.
Published: March 2003

A zinc selenide window transmitted cw CO2 laser radiation into a chamber that contained a gaseous mixture of Ar–O2–H2O at pressures up to 1.05 MPa above local atmospheric pressure. There were no changes in the appearance of the window after extended service, even though it often became visibly fogged by condensed water vapor.
Simple magnetic technique to locate a moving part in a high-pressure vessel with moderate precision
Authors: Laporte P. , Leycuras A.
Published: March 2003

We present a simple magnetic following of the displacement of a moving part under a fluid high pressure. The advantages of the system are its low cost, versatility, minimal maintenance, and a precision of a few tenths of a millimeter.
Comments on ’’Voltage and current sensors for a high-density Z-pinch experiment’’
Authors: Drouet Michel G.
Published: March 2003

Improvements to the current sensor using a pickup soil are proposed. In this way the Ohmic voltage drop is avoided, the sensitivity is increased, and the measuring circuit is isolated from the high-current circuit.
New digital photoelectric correlator
Authors: Friberg S. , Andersen J. , Mandel L.
Published: March 2003

A simple electronic correlator for two-time photoelectric correlation measurements has been developed. It functions by registering the distribution of time intervals between pairs of photoelectric pulses. Its basic elements are a clock that is started by the first pulse and is used to digitize the time intervals, a pair of fast counters for counting subsequent pulses, and a set of data registers. The pulses are directed to one or the other counter alternately at regular clock intervals. The operation of the correlator is described and tested by measurements of a randomly modulated light source.
Balloon-borne scanning spectrometer system for atmospheric extinction studies in the 350–1100 nm spectral region
Authors: Thompson Dennis A. , Pepin Theodore J. , Lane Royce W. , VanBaalen Jeffrey , Bauer III Henry R.
Published: March 2003

We have developed a scanning spectrometer system capable of being flown in high-altitude balloon studies of the earth’s atmosphere. Primary characteristics of the instrument are small size, large operative wavelength range (350–1100 nm), high-data density (151 data samples across each spectral scan and each scan completed in approximately 10 s), and real-time data telemetry to ground. We also developed and utilized a computer software package to provide a real-time monitor of balloon gondola and instrument performance. Software reliability was enhanced by proof of correctness techniques.
Contactless magnetoresistance measurements with a rotating sample magnetometer
Authors: Flanders P. J. , Fischer J. E.
Published: March 2003

We describe an eddy current moment detection technique designed to measure the magnetoresistance of a conducting sample rotating in a dc magnetic field. No contacts are required, and measurements vs temperature and magnetic field are straightforward. Signal components are detected at even multiples of the rotation frequency. Both small-signal (Δρ/ρ0<0.5) and large-signal (Δρ/ρ0≳0.5) analyses are presented. The detection limit is ∼10−2. Applications of the method are given for graphite and its intercalation compounds.
Portable magnetic field dosimeter with data acquisition capabilities
Authors: Fujita T. Y. , Tenforde T. S.
Published: March 2003

Design concepts, engineering specifications, and performance test results are presented for a compact magnetic field dosimeter that is suitable for monitoring personnel exposures to steady-state and time-varying magnetic fields. The battery-operated dosimeter contains thin-film Hall sensors that record the magnetic induction (B) along three orthogonal axes. The Hall generators are operated in a pulsed mode, and the time rate of change of the magnetic induction (dB/dt) is determined for values of B recorded during consecutive sampling intervals (typically 75 ms). The pulsed mode operation also serves to reduce battery consumption. The dosimeter contains a programmable microprocessor-based logic circuit and 4096 12-bit words of permanent and random-access memory. Stored parameters include: (1) average values of B and dB/dt during a preset time interval (typically 5 min); (2) peak values of B and dB/dt during the preset interval; and (3) the number of times that specified threshold levels for these parameters are exceeded. An audible alarm is activated when B or dB/dt exceeds a specified threshold level. Sensitivity factors and threshold levels can be loaded into the dosimeter from a bench-mounted programmable calculator, which is also used at the end of each workday to record and process data stored in the dosimeter’s random-access memory.
High-temperature EPR cavity for application of uniaxial stress
Authors: Berlinger W.
Published: March 2003

A high-temperature EPR (K-band) system is described which allows uniaxial stress single-crystal work. The force perpendicular to the magnet plane ranges up to 35 kp, and the maximum temperature is 1300 K with a stability of ±1 K.
Low-speed heat-pulse anemometer
Authors: Skinner G. T. , Dunn M. G. , Hiemenz R. J.
Published: March 2003

A method of extending the low-speed limit of a heat-pulse anemometer has been developed and embodied in a portable microprocessor-based instrument. The objective was to produce an inertialess anemometer for the measurement of ventilating air flows in mining operations.
Jitter debugging two laser experiments
Authors: Rayner D. M. , Hackett P. A. , Willis C.
Published: March 2003

A method to overcome the problem of timing jitter in two laser experiments is described. The technique involves the use of a time-to-pulse height converter to measure the interpulse separation and a data acquisition system capable of recording this and other experimental parameters on a shot-to-shot basis. The method is estimated to be useful in measurement systems with resolution down to 10 ps.
Selective removal of F2 impurity from NF3/Xe/Ne, XeF laser mixtures
Authors: Mandl A. , Slater R. , Appel C. H.
Published: March 2003

It is shown that a titanium filled reactor can be used to selectively remove the F2 impurity that builds up in a XeF laser. The reactor can be operated in a temperature regime that is compatible with optimal XeF laser performance.
Technique for measuring the motions of the internal surface of deforming thick-walled structural shells
Authors: Watson J. L.
Published: March 2003

An optical method has been developed for measuring the deformation and deformation rates of thick-walled structural shells subjected to impact. The technique uses a field lens to image features of the internal surface which are not readily visible and uses collimated light from a distant source to illuminate the shell’s internal surface. A Model 189 Beckman and Whitley (Cordin) framing camera was used to record shell surface positions as functions of time.
Improved changeover time between regular and GC–IR on the Digilab FTS-15B
Authors: Stewart James F. , White F. Tom , Battiste David R.
Published: March 2003

The time needed to change from regular to GC–IR (gas chromatography–infrared spectroscopy) operation on the Digilab FTS-15B Fourier transform infrared spectrometer has been reduced by 40–45 min. First, a single-pole double throw switch connected to the detector selection circuitry on the signal board was mounted in the sample compartment. Second, a 1-in.-diam hole was cut into the top of the purge cover above the position of an operational amplifier that is used to adjust the peak height of the interferogram center burst. These modifications increase the ease and convenience of setting up and removing the GC–IR hardware, allow better utilization of an ’’older’’ model optical bench which requires placement of the GC–IR light pipe in the sample chamber, and provide a time savings.
Simple tunable dye laser using a dielectric multilayer filter
Authors: Nomura A. , Shimomura Y. , Saito Y. , Kano T.
Published: March 2003

We describe a nitrogen laser pumped dye laser tuned by a dielectric multilayer filter. The construction is simple and the adjustment of tuning is easy. It is found that the tuning is possible over a range of 10 nm from 445 to 455 nm in alcoholic solutions of coumarin 1, that the linewidth (0.8 nm) is independent of the filter tilt angle, and that the output intensity is remarkably flat over this tuning range.
Numerical determination of Marmet’s filter parameters
Authors: Morawski Roman Z.
Published: March 2003

An algorithm is given for the calculation of the parameters of a digital filter for the analysis of experimental data.
Method for measuring the powder charge in the electrostatic powder-coating process
Authors: Masui Noriaki , Murata Yuji
Published: March 2003

A simple method for measuring the electrostatic charge of powder particles in a powder cloud sprayed from an electrostatic powder-coating gun is described. Powder particles accompanied with ions were drawn into an insulator suction pipe and their charge was measured after they passed through the pipe by employing the suction-type Faraday Cage. Most ions are eliminated by both electrostatic repulsion force against the charged tip of the pipe and charge recombination against the pipe wall. The suction pipe had almost no effect on the measured value for powder charge.
Instrument for synchronizing plasma diagnostic measurements with tokamak internal disruptions
Authors: Gerassimenko M. , Petrasso R. , Seguin F. H. , Ting J.
Published: March 2003

We describe an instrument which detects internal disruptions in real time, providing one pulse at each disruption and another pulse at a selectable phase of the internal disruption cycle (as determined by the interval between the two preceding disruptions). By appropriate gating, this instrument allows diagnostics requiring integration times long compared to the internal disruption period to be used in the study of plasma parameter changes produced by internal disruptions. It also permits selection of the phase of the internal disruption cycle at which diagnostics with short sampling times are used. Several features of the instrument are discussed in light of its performance in firing the Thomson scattering laser on the Alcator-C tokamak.
Thomson scattering diagnostic for a low-density, high-temperature, steady-state plasma
Authors: Cobble J. A. , Bighel L.
Published: March 2003

A ruby-laser, Thomson scattering diagnostic for electron temperature (Te) and density (ne) measurements has operated on EBT-S. This is significant because the density is of order or less than 1012 cm−3, because the temperature is a few hundred electron volts, and because this rather harsh environment in which measurements are taken persists for hours at a time. The problems presented by this steady-state plasma have been successfully addressed, and radial scans of Te and ne have been obtained.
Light Ion Mass Spectrometer for space-plasma investigations
Authors: Reasoner David L. , Chappell Charles R. , Fields Stanley A. , Lewter William J.
Published: March 2003

Recent studies of the low-energy plasma population in the Earth’s space environment have revealed that this plasma population is much more complex than previously supposed and that a simple model of ionospheric evaporation cannot explain the distributions. There was a need to develop an advanced instrument to study this plasma in detail, and this paper describes the scientific background, design, development, and in-flight characteristics of such an instrument, the Light Ion Mass Spectrometer (LIMS). This instrument combines a magnetic mass spectrometer, a planar-grid retarding potential analyzer, and multidirectional sensor heads to measure the mass composition, density, temperature, and flow velocity of low-energy (E〈100 eV) plasma. The studies which were conducted leading to the final design will be discussed in detail and will illustrate certain effects which arose in the combining of energy and mass analysis into a single sensor. The instrument was flown on a high-altitude satellite in February 1979, and selected flight data will be presented to demonstrate the instrument performance.
High-power, continuous frequency tunable TE CO2 laser
Authors: Midorikawa K. , Wakabayashi K. , Obara M. , Fujioka T.
Published: March 2003

A continuously tunable TE CO2 laser is described, whose frequency tunable ranges of 16 cm−1 in the P-branch and 14 cm−1 in the R-branch of 9.6 μm band were obtained with a single line energy of about 400 mJ/pulse. This large output was realized by decreasing the intracavity laser power illuminating the optical components used due to the increase in discharge width. A grid-type, UV-preionized TE CO2 laser using a cable PFN was scalable and able to decrease optical damage of components.
High-repetition-rate, recirculating hydrogen fluoride/deuterium fluoride laser
Authors: Rudko R. I. , Drozdowicz Z. , Linhares S. , Bua D.
Published: March 2003

A compact, gas-efficient, pulsed chemical laser operated with HF, DF, or HF and DF simultaneously, is described. This laser produced over 1 mJ/pulse up to over 4000 pps repetition rates with maximum average power over 4.5 W. Maximum repetition rate was 10 000 pulse/s.
Simple period timing device for laser Doppler signals
Authors: Venkatesh Prabha , Prasad C. R.
Published: March 2003

A period timing device suitable for processing laser Doppler anemometer signals has been described here. The important features of this instrument are: it is inexpensive, simple to operate, and easy to fabricate. When the concentration of scattering particles is low the Doppler signal is in the form of a burst and the Doppler frequency is measured by timing the zero crossings of the signal. But the presence of noise calls for the use of validation criterion, and a 5–8 cycles comparison has been used in this instrument. Validation criterion requires the differential count between the 5 and 8 cycles to be multiplied by predetermined numbers that prescribe the accuracy of measurement. By choosing these numbers to be binary numbers, much simplification in circuit design has been accomplished since this permits the use of shift registers for multiplication. Validation accuracies of 1.6%, 3.2%, 6.3%, and 12.5% are possible with this device. The design presented here is for a 16-bit processor and uses TTL components. By substituting Schottky barrier TTLs the clock frequency can be increased from about 10 to 30 MHz resulting in an extension in the range of the instrument.
High-performance, time-correlated single photon counting apparatus using a side-on type photomultiplier
Authors: Kinoshita Shuichi , Kushida Takashi
Published: March 2003

Improvements of a previously reported simple fluorescence decay-time measuring system are described. By the application of a high voltage between the photocathode and the first dynode of a side-on photomultiplier, as well as by some modification of the electronic systems, the full width at half-maximum of the response curve has been reduced to 160 ps and the wavelength dependence of the time response has become negligibly small. It is also demonstrated that the fluorescence decay time as short as several picoseconds can be analyzed by this system.
Real-time analysis system for a gravitational wave antenna
Authors: Brown B. L. , Mills A. P. , Tyson J. A.
Published: March 2003

Real-time analysis of a gravitational wave detector signal yields a condensed summary of the antenna history in the system described here. Optimal filtering is performed on the antenna signal and impulses above a preset threshold are recorded in detail using a microprocessor system. Histograms are made of the optimal filter output and of the long-term Brownian motion of the antenna. A permanent record of the large events is made on a chart recorder and a teletype, giving the details of the event pulse shape as well as numerical values of the energy and the time of the event. This provides a record of any large events in a form that can be easily correlated with data from other experiments. No events were recorded above 113 gravitational pulse units (105 erg/cm2 Hz) at 710 Hz in the 39.5 days of data presented here.
Electrical resistance measurements at high pressure and low temperature using a diamond-anvil cell
Authors: Sakai Nobuko , Kajiwara Takashi , Tsuji Kazuhiko , Minomura Shigeru
Published: March 2003

A new method of measuring electrical resistance in a diamond-anvil cell has been developed. The sample assembly consisting of copper-plate electrodes and polymer film has been used for a modified two-probe method. The resistance measurements have been carried out at pressures up to 250 kbar and temperatures down to 1.7 K using a diamond-anvil cell driven by helium gas. This method has been applied to investigate the pressure-induced phase transition in iodine and superconducting transition in hydrogenated amorphous silicon films.
Measurement of the three components of the electron-spin polarization vector
Authors: Kisker E.
Published: March 2003

The new method for measuring the three components of the electron-spin polarization as proposed recently by Beerlage and Farago is compared to an existing solution, requiring one additional pair of electron detectors in the Mott scattering setup. It is shown that the method of Beerlage and Farago requires much longer measuring times and is operationally more complex than the conventional one with additional detectors. The same arguments apply for a LEED spin polarization detector.
Apparatus designed to measure phase angles for detecting an interaction between ac superficial discharge and an insulating surface
Authors: Abulzahab E. , Ai Bui , Huraux C. , Plueksawan W.
Published: March 2003

A system consisting of two electronic circuits capable of detecting an interaction between ac superficial discharge and an insulating surface is described. The first of these circuits gives out pulses with amplitudes proportional to phase angles of discharge current and the second passes only those that correspond to the interaction. By analyzing the results with a multichannel amplitude analyzer, the occurrence of this kind of interaction can be detected.
Method of eliminating the effect of decay products in continuous measurement of 222Rn
Authors: Janka K. , Lehtimäki M.
Published: March 2003

In most types of radon monitors the effect of radon short-lived decay products makes the measurement of rapidly fluctuating radon concentrations inaccurate. A method of eliminating the effect of short-lived decay products is developed. It can be used to correct the readings of different types of radon monitors either computationally afterwards or electronically in real time. As a result, a simple ionization chamber radon monitor with a relatively fast response (τ≃5 min) is developed.
Long-pulse ion source for neutral-beam applications
Authors: Tsai C. C. , Menon M. M. , Ryan P. M. , Schechter D. E. , Stirling W. L. , Haselton H. H.
Published: March 2003

A rectangular ion source is being developed for producing 120-keV/25-A hydrogen ion beams for pulse durations up to 10 s. It consists of a plasma generator with a rectangular arc chamber (25×35 cm cross section) and an ion accelerator with rectangular grids (10×25 cm hole pattern). The plasma generator is a modified duoPIGatron type. It has been operated at 120 V, 1100 A, and 10 s arc durations to produce a dense and uniform plasma sufficient for supplying a 25-A ion beam current. The electron emitter used is either a LaB6 hollow cathode or a LM (molybdenum doped with La2O3) indirectly heated cathode. The ion accelerator having four (or three) rectangular grids with multiple circular apertures has been utilized to form high-energy ion beams above (or below) 80 keV. With substantial improvements in water cooling and mechanical stability, this ion accelerator has been operated reliably to deliver long-pulse ion beams with energies in excess of 100 keV and pulse lengths of many seconds. The results of measurements made on the power transmission efficiency (70%–80%), power density profile at the target (±0.5% HWHM near the focal plane), and grid loadings (≲1% for each grid) are elaborated. The important characteristics associated with this long-pulse ion source are also presented and discussed.