bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic multipole line-cusp plasma generator for neutral beam injectors
Authors: Stirling W. L. , Ryan P. M. , Tsai C. C. , Leung K. N.
Published: March 2003

The magnetic multipole line-cusp device developed by MacKenzie and associates has been adapted for use as a neutral beam ion source. It has produced high-density, large volume, quiescent, uniform hydrogen plasmas, which makes it a potential candidate for use as a plasma generator for neutral beam injectors. The device is a water-cooled cylindrical copper discharge chamber (25 cm in diameter by 36 cm long) with one end enclosed by a set of extraction grids with a 15-cm-diam multi-aperture pattern. The chamber wall serves as an anode and is surrounded by an external system of rare-earth cobalt magnets arranged in a line-cusp geometry of 12 cusps; plasma is produced by electron emission from a hot cathode assembly. This source has achieved extracted beam currents of 12 A at 18.5 kV, radial plasma density uniformities of ±5% over a 15-cm diameter, noise levels of less than ±0.5%, and arc efficiencies (beam current/arc power) of 0.6 A/kW.
Pulsed differential reactors and their use for kinetic studies of gas–solid reactions—application to mechanistic studies of the reactions of hydrogen sulfide and the alkaline minerals in coal
Authors: Attar A.
Published: March 2003

An experimental system has been constructed and used to measure the rate of gas–solid reactions. The main advantages of the experimental technique are that it can be used to measure the individual rates of reactions when complex reactions occur simultaneously, and that it permits one to measure very accurately the isothermal rate of reaction of very exothermic or endothermic reactions. The components of the system are a microdifferential reactor, a gas chromatograph, and a pulse injector, all of which are available commercially. Pulses of reactive gas were injected periodically into the differential reactor and the pulses of gaseous reaction products were separated and analyzed by chromatographic techniques. The signal from the chromatograpgh was recorded and integrated. The injector and the integrator were synchronized so that completely automatic operation was possible. The system was used to measure the rate of reaction of hydrogen sulfide with the alkaline minerals which are present in coal, calcit, dolomite, and sidrite. Data are presented and the mathematical analysis of the data is described in detail.
Video fluorometer
Authors: Johnson David W. , Gladden James A. , Callis James B. , Christian Gary D.
Published: March 2003

Details of a unique computer controlled multichannel fluorometer are given. Features include: a novel optical system enabling simultaneous acquistion of excitation and emission data over broad spectral ranges, a highly sensitive silicon intensified target (SIT) vidicon detector, and a video interface to a minicomputer allowing data acquisition at the standard television rate.
Device for quenching studies on rare gas and metal halide excited complexes
Authors: Mandl A. , Parks J. H.
Published: March 2003

A device is described in which HgCl* is photolytically produced by optically exciting HgCl2. The same apparatus can be used to excite other metal and rare gas complexes. The device is small, allowing rapid screening using repetitive pulsing and signal averaging techniques.
Two-frequency method for measuring impurity profiles
Authors: Sukegawa T. , Ogita M.
Published: March 2003

A new method of plotting the impurity profile is described. It makes efficient use of the advantage of an operational amplifier and the nonlinearity of the junction capacitance in a semiconductor. When two small ac signals are applied to the inverting input terminal of the operational amplifier, intermodulation arises due to the nonlinearity of the junction capacitance inserted in the feedback loop, at the time the reverse bias voltage to the junction can be supplied from the noninverting input terminal; then the signals concerning both the depletion layer width x and the impurity concentration N (x) arise at the output terminal of the operational amplifier. By detecting each of the amplified input signals and the difference-frequency ones corresponding to x and N (x), respectively, the relation of x−N (x) can be plotted easily, at the same time, in a short time, and at a low cost.
Synchronous modulation in scanning Auger electron microscopy
Authors: Goto K. , Ichimura S. , Shimizu R.
Published: March 2003

The modulation frequency on the cylindrical mirror analyzer of a scanning Auger microscope has been synchronized to the digital scanning system. This technique allows one to obtain an Auger image free from moiré patterns which arise from the beat between scanning and modulation frequencies, and permits operation at frequency settings which optimize use of the electronics in the detection system.
Highly sensitive microwave temperature-jump apparatus
Authors: Aubard J. , Nozeran J. M. , Levoir P. , Meyer J. J. , Dubois J. E.
Published: March 2003

A temperature-jump apparatus with repetitive microwave heating and spectrophotometric detection is described. Temperature jumps of 1.5°C are achieved in a flow microcell within 1.5 μs (two shorter heating times of 0.5 and 0.25 μs are also available) at a repetition rate up to 50 Hz. On-line accumulation of the relaxation signals is performed with a PDP 11 processor, leading to very short recording times (more than 1000 signals accumulated in less than 50 s) and to a sensitivity better than 10−4 optical density (OD) units. Nonlinear identification treatment permits processing the summed signal even when it is strongly blurred by noise. To demonstrate the capabilities of our apparatus, highly shifted fast prototropic equilibria in aqueous solutions of pyrimidine base have been studied.
Ultraminiature high-power gas discharge lasers
Authors: Hasson V. , von Bergmann H. M.
Published: March 2003

The authors describe the development of millimeter-size photopreionization stabilized atmospheric pressure uv nitrogen lasers. Sealed-off versions of these lasers can provide peak powers of 30–150 kW and average power of 1–5 mW. The discharge and pulsing concepts are very general and are being adapted to a variety of other high-pressure TE-type laser systems.
Optimization of data-acquistion rates in time-correlated single-photon fluorimetry
Authors: Haugen G. R. , Wallin B. W. , Lytle F. E.
Published: March 2003

Four different operating configurations of a time-to-amplitude converter were examined for performance in the time-correlated single-photon fluorimetric experiment. Parameters considered were the intensity/count linearity, maximum data rate, and decay distortion. The inverted configuration with an interactive source was optimum. This arrangement combined total linearity with a 37-kHz conversion rate and did not distort the fluorescence decay. In addition, the pulse-height analyzer could severely limit the overall system data rate and could destroy the TAC intensity/count linearity.
New digital filter for the analysis of experimental data
Authors: Marmet P.
Published: March 2003

The extremely simple mathematical technique called ’’straightening through smoothing,’’ which is a numerical frequency filter, is generalized in order to provide a transmission function having any shape. This frequency filter requires such a small memory that it can be performed using a minicomputer or even a programmable hand held calculator and the number of channels used is not limited to a power of 2, as in the case of the fast Fourier transform. For some filtering functions the number of operations required is smaller than with the fast Fourier transform.
Simple humidity control system
Authors: Nakamura Osamu , Ogino Isao , Kodama Teruo
Published: March 2003

This note describes a control system for maintaining constant humidity by passing a gas through a saturated aqueous solution.
Direct grounding tool for examination of uncoated specimens in the scanning electron microscope
Authors: Cowan George S. M. , Horner Jack A.
Published: March 2003

By combining a micromanipulator, a medical cystoscope, and a forked specimen probe, a direct grounding tool for examination of uncoated specimens in the SEM has been developed, tested, and successfully demonstrated. It provides a valuable alternative technique when it is undesirable to coat SEM specimens. The apparatus is nondestructive, simple, and does not require major modification of the instrument. It provides the additional benefits of direct optical specimen orientation and viewing, allows better electron and x-ray resolution than conventional coating techniques, and is practical with a wide range of SEM objects.
A simple and compact constant-volume valve for use in gas thermometry
Authors: Kemp R. C. , Smart P. W.
Published: March 2003

A design for a simple constant-volume valve is described. The valve is recommended for use in gas thermometry or similar applications.
Design and properties of a multianode, cylindrical proportional counter for position sensing at high count rates
Authors: Hanson J. A. , Kopp M. K.
Published: March 2003

A cylindrical proportional counter with six anode wires was designed and tested. The electron drift velocity was greater than that of similar single-anode, coaxial proportional counter, thus, allowing counting and position sensing of low-energy photons (<60 keV) at high count rates (≳105 counts/s).
Automated instrumentation for research on the lingual tactile sensory system
Authors: Telage Kal M.
Published: March 2003

Modifications in lingual vibrotactile instrumentation including programmable stimulus control, signal delivery, and data acquisition are presented. A discussion emphasizes advantages of the system for evaluating children and previews recent experimental procedures.
Multichannel neutral-particle analyzer system
Authors: Nexsen W. E. , Turner W. C. , Cummins W. F.
Published: March 2003

A multichannel neutral-analyzer system developed for the analysis of charge-exchange flux from magnetically confined plasma is described. The system uses tandem magnetic–electrostatic deflection of ions produced from neutrals stripped in a gas cell to obtain the energy spectra of specific charge-to-mass-ratio species. The analyzer is collimated with a spatial resolution of 2 cm FWHM at the plasma and is movable so that radial scans of charge-exchange flux can be made. Data are recorded digitally, allowing frequency response of fluctuations in charge-exchange flux up to 50 kHz. The calibration procedure employs an auxiliary single-channel analyzer calibrated over the full energy range of the multichannel instrument with an atomic-beam setup. Typical data obtained from the 2XIIB neutral-beam-injected mirror machine are briefly presented.
A system for a multiframing interferometry and its application to a plasma focus experiment
Authors: Hirano Katsumi , Shimoda Katsuji , Emori Susumu
Published: March 2003

A four-framing Mach–Zehnder interferometer system which has variable intervals from frame to frame is developed. TEA N2 lasers that are operated with atmospheric-pressure N2 gas are employed as light sources. Applicability of the system is demonstrated for a rapidly changing plasma in the plasma focus discharge.
Automatic and simultaneous measurements of ultrasonic velocity and attenuation changes
Authors: Matsuda Takashi , Hatta Ichiro
Published: March 2003

A method is described for measuring ultrasonic velocity and attenuation simultaneously by sampling echo pulses along with the repetition rate of velocity measurements. This is achieved by extending the pulse superposition method. This system enables us to measure the attenuation coefficient with a precision of 0.001 dB/cm, and the ultrasonic velocity with better precision than 1 part in 106. Velocity measurements can be made automatically up to five times the initial round trip time and can also track fast changes of 50 ms. Since the operation under the p=1 condition can be applied, the system can be used for the measurements of high-loss materials.
Transformer–rectifier flux pump using inductive current transfer and thermally controlled Nb3Sn cryotrons
Authors: Atherton David L. , Davies R.
Published: March 2003

Transformer–rectifier flux pumps using thermally switched Nb3Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz.
Vidicon-camera parallel-detection system for angle-resolved electron spectroscopy
Authors: Weeks S. P. , Rowe J. E. , Christman S. B. , Chaban E. E.
Published: March 2003

A multiple-angle, parallel detection scheme for ultraviolet photoemission spectroscopy and LEED has been developed based on a minicomputer-controlled vidicon camera and a LEED-grid energy analyzer. This system allows rapid data acquisition and display so that one can obtain energy spectra over a 70°×70° collection geometry with ±1.5° resolution in 30–40 min, or collect the intensities of all visible LEED beams in a few seconds. This is nearly two orders of magnitude faster than a conventional movable single-detector system. Operating principles and design limitations will be discussed.
Generation of quasistatic magnetic fields
Authors: Praddaude H. C. , Foner S.
Published: March 2003

A prototype switching system has been developed which can switch 20 kA at 230 V furnished by low-voltage dc generators at the National Magnet Laboratory. The energy is used to generate quasistatic magnetic fields in liquid-nitrogen-cooled copper coils for times approaching 1 s. The present arrangement is limited to fields up to 40 T. The silicon-controlled rectifier switching system, protective devices, circuit operation, and magnet structures are discussed.
System for continuous monitoring of point defect concentrations during irradiations and anneals
Authors: Jackson J. J. , Ryan E. A.
Published: March 2003

An integrated system, cryostat, electronics, and computer used for detailed resistivity measurements during low-temperature irradiations and anneals of metals is described. The thermal response time and rate of heat removal from the specimens are optimized. The system has excellent stability for extended isothermal anneals; measurements of deviations from Mathiessen’s rule are discussed to illustrate this feature. Examples are given of the use of the system to determine dense sets of thermal activation energies during anneals through state I. These determinations are made by linear heating at different rates during recombinations of close Frenkel pairs, and by abruptly and repeatedly changing the annealing temperature during the recovery of more widely separated pairs.
High-speed digital image processor with special-purpose hardware for two-dimensional convolution
Authors: Okuyama H. , Fukui K. , Ichioka Y.
Published: March 2003

A high-speed digital image processor combined with a flying spot scanner and special purpose hardware for two-dimensional convolution has been developed. This processor is applicable to image enhancement, image restoration, and feature extraction. The parallel and/or serial architectures of the processor enable digital image processing for a high-resolution image at a fast process rate. Realization of the high-speed operation of two-dimensional convolution is greatly due to the special scanning method of a flying spot scanner. This processor is well suited to process the image recorded on the photographic film by means of the two-dimensional digital filtering technique. Some experimental results are given to verify the capability of the developed processor.
Ultrafast Pockels cells for the infrared
Authors: McLellan Edward J. , Figueira Joseph F.
Published: March 2003

The design and performance of a 2.25-cm2-aperture Pockels cell system for 10-μm radiation is described. Pulses as short as 90 ps can be reliably generated with this device.
Semiautomatic measurements of thin-film breakdown voltages
Authors: Gaebler W. , Conrad R. , Braeunig D. , Fahrner W. R. , Ferretti R. , Wulf F.
Published: March 2003

A semiautomatic setup is described which provides the destruction-free measurement of breakdown voltages of thin-film structures for applications like process control and quality prediction. The method of measuring the breakdown voltage consists in feeding a constant current to the thin-film device and analyzing the voltage buildup across the device. This method has been described in a recent paper. The setup provides the successive analysis of breakdown behavior of a given matrix of wafer dots by means of a positioning table, an electropneumatic prober, and a microprocessor-controlled measurement unit via handshake commands. The results are given in a histogram form.
Photon flux measurements using calorimetry
Authors: Olmsted John
Published: March 2003

A simple photometric calorimeter has been constructed, consisting of a vacuum-jacketed cell equipped with flat quartz windows to admit incident light, a thermistor probe to monitor temperature change, and a resistance heater for calibration. An optically dense, photochemically inert solution inside the cell absorbs incident radiation, converting it quantitatively into heat. The calorimeter gives photon flux measurements in agreement with ferrioxalate actinometry at 366 and 436 nm. It has a sensitivity of 2×1015 photons/s and is useful throughout the optical spectral range.
Radio-frequency probe for bubble size and velocity measurements
Authors: Abuaf N. , Feierabend T. P. , Zimmer G. A. , Jones O. C.
Published: March 2003

A radio frequency (rf) probe that can provide local void fraction and interface velocity measurements in a gas–liquid two-phase flow was developed. The probe response to bubble passage was investigated with single-bubble controlled experiments. For a fixed geometry, the probe response was dependent on the dielectric constant of the medium surrounding the probe tip (air or water) and on the frequency of the carrier signal supplied to the probe. Bubble lengths (< 1 cm) and average bubble approach velocities (< 160 cm/s) were independently measured by two light sources and detectors placed at a known distance from each other and sensing the passage of each bubble. By choosing a sensitive probe tip length of 2.75–3 mm, the rf probe output provided enough information to determine the bubble length and velocity. The results obtained by the two independent methods show reasonable agreement (±10%).
Mass filter and focusing ion detector for use with time-of-flight velocity distribution measurements
Authors: Burrows M. D. , Ryan S. R. , Lamb W. E. , McIntyre L. C.
Published: March 2003

A novel mass filter and focusing ion detector for time-of-flight studies of dissociative ionization fragments is described. The filter–dector combination is particularly suited for measuring the kinetic energy released in the molecular dissociation process. The mass filter utilizes a computer-controlled, time-dependent retarding potential synchronized with, and located a distance L from, a pulsed electron-bombardment ion source. Ions arriving at the filter at time t have a kinetic energy of mL2/2t2. The retarding potential varies with time as mL2/2et2, thus deflecting ions with masses less than m. Operation of the filter in a mode which provides unity mass resolution at 16 amu has been demonstrated. The detector consists of a channel electron multiplier and a focusing electrode configuration approximating that of a charged sphere above a grounded conducting plane. The planar input aperture of the detector is located just behind the mass filter along the ion flight path. The detector features high efficiency, large input aperture, low background, and simple operation. Ion transit times through the detector are small and essentially independent of the initial ion kinetic energy.
Automatic torque magnetometer for vacuum-to-high-pressure hydrogen environments
Authors: Larsen J. W. , Livesay B. R.
Published: March 2003

An automatic torque magnetometer has been developed for use in high-pressure hydeogen. It will contain pressures ranging from vacuum to 200 atm of hydrogen gas at sample temperatures greater than 400 °C. This magnetometer, which uses an optical lever postion sensor and a restoring force technique has an operating range of 2.0×103 dyn cm to l.6×10−4 dyn cm. An accompanying digital data collection system extends the sensitivity to 1×10−5 dyn cm as well as increasing the data handling capacity of the system. The magnetic properties of thin films in high-temperature and high-pressure hydrogen environments can be studied using this instruments.
Production of reproducible Rayleigh–Taylor instabilities
Authors: Popil R. , Curzon F. L.
Published: March 2003

A device is described that excites individual modes of the standing wave spectrum for surface waves on water in a water tank of rectangular cross section. By synchronizing the downward acceleration of the tank with the standing wave on the water, Rayleigh–Taylor instabilities with reproducible characteristics are excited at the air–water interface. By controlling the width of the tank, the fluid motion is made to be largely two dimensional. The reproducibility of the phenomenon and the two-dimensional character of the flow make it possible, for the first time, to compare details of the wave profile with results predicted with the two-dimensional models of Emmons, Chang, and Watson.
High-accuracy differential measurement of ultrasonic velocity in liquids
Authors: Elias John G. , Eden Don
Published: March 2003

An improved technique for measuring very accurately the difference in sound velocity between two liquids is described. The technique, which can be used over a frequency range from 1 to 100 MHz, uses a differential cell that is completely submerged in a thermostatically controlled fluid and a phase-sensitive detection scheme accurate to 2×10−4 signal periods. Measurements of the velocity difference between water and dilute NaCl solutions (3×10−5 to 6.6×10−4 M), accurate to ±0.02 cm s−1 (relative accuracy 1 part in 107), are presented.
Use of continuous resistive material for fringe field elimination in a cylindrical mirror analyzer
Authors: Baudais Frederick L. , Taylor James W.
Published: March 2003

The use of a continuous carbon-impregnated epoxy resistive material is investigated for the elimination of fringe fields in a cylindrical-mirror photoelectron energy analyzer. This fringe correction approach permits close coupling between the source inlet and the analyzer slits.
Optoelectronic modulation of a laser interferometer in the infrared for accurate electron density variation measurements
Authors: Lesage A. , Richou J. , Charil P. , Combier M. , Lebrun J. L.
Published: March 2003

An improved method for high-electron-density (1017 cm−3) measurement in a shock-generated plasma is described. A laser interferometer operated at 3.39 μm is regularly modulated (1 MHz) by a LiNbO3 electro-optical crystal. Thus electron-density variations of 8×1015 cm−3 μs−1 and fluctuation of 8×1014 cm−3 can be simultaneously and accurately measured in a 4×4-cm conventional shock tube. Experimental results in reflected shock waves are presented.
Simple, repeatable method for soldering superconducting wire to cryogenic leads
Authors: Lee W. David , Broach J. Thomas
Published: March 2003

A method is described for making a solder joint between a multifilamentary superconductor and a braided copper wire conductor.
Low power laser trigger switching of a solid insulated spark gap
Authors: Guenther A. H. , Copeland R. P. , Bettis J. R.
Published: March 2003

The feasibility of reliably triggering solid dielectric insulated spark gaps by low power (∼6 MW) lasers has been demonstrated. Breakdown of 10-mil Lexan dielectric sheets stressed to 70 kV was initiated by a focused 6 MW, Nd in YAG laser emitting 40 mJ in a pulse 6 ns wide at the half-peak intensity height. Delays achieved were in the tens of ns. Slight increases in laser power or electrical stress should produce shorter delays (<10 ns) and subnanosecond jitter.
High-performance UHF SQUID magnetometer
Authors: Long A. , Clark T. D. , Prance R. J. , Richards M. G.
Published: March 2003

We describe a lumped-component stabilized point contact SQUID magnetometer, biased at 430 MHz and utilizing a cooled (4.2 K) GaAs FET preamplifier. The system incorporateds a full-bandwidth (5–10 MHz) flux-locked loop and has an overall flux sensitivity of 1×10−5 Φ0/(Hz)1/2, corresponding to an energy sensitivity ≃4.5×10−31 J/Hz.
Instrument combining x-ray photoelectron spectroscopy and secondary ion mass spectrometry for surface studies
Authors: Hewitt R. W. , Shepard A. T. , Baitinger W. E. , Winograd N. , Delgass W. N.
Published: March 2003

X-ray Photoelectron Spectroscopy (XPS) or (ESCA) and Secondary Ion Mass Spectrometry (SIMS) have been combined in the same ultrahigh vacuum system to facilitate a new approach to studying clean and reacted surfaces. The design philosophy is to connect two satellite vacuum systems via a set of magnetically driven sample transfer devices. The advantages and capabilities of this approach are discussed with respect to its flexibility and its ability to couple to other surface techniques. XPS and static SIMS spectra of an oxidized polycrystalline indium film are presented to exemplify the type of information which can be gleaned from a multitechnique investigation of surfaces. The additional ability to prepare sample surfaces in our system by ion implantation is demonstrated by a positive-ion SIMS analysis of a gold-implanted aluminum foil.
Microprocessor-based spectroscopic picture processing system
Authors: Ostertag E.
Published: March 2003

A 16-bit microcomputer has been coupled to an optical multichannel analyser (OMA). This paper describes the hardware interface which has been developed so as to permit the transfer of spectra in both directions, from the OMA into the RAM extension memory of the microprocessing system, and back from there into either one memory of the OMA. A few elementary circuit modifications of the OMA itself are required to allow that back transfer, and are also described. A brief outline of the software is given. The adjunction of the microcomputer to the OMA makes it possible to operate this instrument in a new mode: real time with optical integration and nevertheless without any baseline.
Linear position-sensitive x-ray detector incorporating a self-scanning photodiode array
Authors: Gamble Ronald C. , Baldeschwieler John D. , Giffin Charles E.
Published: March 2003

A linear position-sensitive x-ray detector for x-ray spectroscopy and diffraction applications has been tested which can provide excellent spatial resolution, wide dynamic range and good sensitivity. The heart of the system is a self-scanning, photosensitive silicon diode array. It is interfaced via fiber optics to a thin layer of ZnS which fluoresces visible light upon absorption of x-radiation. The conversion to visible light and optical coupling provide several-fold gain in the efficiency of detection as compared to the direct detection of x-ray by the diode array. Equally important is that the array is protected from irreversible damage by high energy radiation, a limitation which previously hindered this application of silicon diode technology.
Sensor-trigger device for explosion barrier
Authors: Liebman I. , Duda F. , Conti R.
Published: March 2003

A flame sensor-trigger device was developed for use with barriers to suppress coal dust explosions in undergound mines. Principal feature of the device is a dual infrared flame sensor combined with a pressure-arming element. This combination prevents false and premature triggering of the barrier. With minor modifications, the device can also be used with barriers for protection in other facilities against gas explosions and explosions involving dusts other than coal.
Method for the determination of the specific heat of metals at low temperatures under high pressures
Authors: Eichler Andreas , Gey Wolfgang
Published: March 2003

Efforts are made to determine the absolute specific heat of metals as a function of pressure with an accuracy, which, for the first time, will permit a direct evaluation of the pressure variation of the electronic and phonon parameters γ and ϑD′, respectively. This is achieved by employing the ac method of Sullivan and Seidel, and choosing a suitable sample configuration within a piston-cylinder pressure cell. Essential is the use of diamond powder as a pressure transmitting medium, which because of its low heat capacity and high thermal resistance, couples the sample loosely to the temperature bath, represented by the pressure cylinder. Thus, the thermal requirements of the ac method are met, and corrections—if necessary—are fully tractable. High sensitivity even at the lowest temperatures is obtained by the use of thin slices, prepared from standard carbon resistors, for thermometers. Although delicate, these sensors withstand pressures of more than 20 kbars and remain sensitive. A thorough comparison of results on indium with the literature data at zero pressure is undertaken. It shows that the accuracy of the present results is comparable with that from literature data. Preliminary results at pressures up to 8 kbar are shown; they will be discussed in a separate paper.
Cooling of extraction electrode of an ion source in long-pulse operation
Authors: Horiike H. , Kondoh U. , Morita H. , Shirakata H. , Sugawara T. , Tanaka S.
Published: March 2003

Experimental studies were made on the cooling of extraction electrodes of an ion source in the case of long-pulse operation. Copper electrodes with forced water cooling pipes were tested under the condition that an ion beam of 1 to 5 A at 30 keV was extracted for up to 10 s. The average heat loading to the grid are of the electrode was as high as 130 W/cm2. This high heat flux was obtained by a set of electrodes artificially arranged to produce poor beam optics, and hence the high heat loading. Temperature of the ground electrode was measured at two points by thermocouples buried and silver brazed in it, and was kept below 230 °C due to a large boiling heat transfer coefficient of the cooling water. No evidences of deformation or deterioration of the electrodes was observed after repetitious beam extraction. This heat loading was still a half of that on the grid of the ion source for the JT-60 NBI.
Temperal and spatial measurement of rf electric field in a magnetized plasma using an emissive probe
Authors: Tang J. T. , Kim C. , Stenzel R. , Higgins L. L.
Published: March 2003

rf electric field in the ion cyclotron frequency range (10 kHz–1MHz) is measured directly in the plasma using an emissive probe operated in a novel manner.
Frequency response of cold wires used for atmospheric turbulence measurements in the marine environment
Authors: Schacher G. E. , Fairall C. W.
Published: March 2003

We have examined the frequency response of cold-wire thermometers using 2.5-μ platinum wires with laboratory-produced salt layers. The salt layers are produced by exposure to a saline aerosol to simulate the marine environment. The frequency response was determined by measuring the response of the coated wires to a white thermal noise air flow produced by a heated wire in an airstream. The wires exhibit a relaxation behavior, with the rolloff frequency varying as the square of the total wire plus salt radius. The results show that the frequency response of the salted wires is controlled by the laminar-air-film boundary layer.
Frequency-crossing phonon spectrometer techniques
Authors: Wybourne M. N. , Jefferies D. J. , Challis L. J. , Ghazi A. A.
Published: March 2003

An ac technique for measuring magnetothermal conductivities using frequency crossing has been developed and shows a 13-fold increase in signal-to-noise ratio over the conventional dc technique. The ac technique employs low-frequency field modulation coupled with phase-sensitive detection and a 45-fold improvement in signal-to-noise ratio may be obtained by modulation over the half-width of the frequency crossing signal. A further increase of ∼3 would be obtainable by increasing the modulation frequency and overcoming technical problems. The limit of detection and instrument revolution may be as low as 10 in. spins and a few megahertz, respectively.
Instrument for measuring tooth mobility
Authors: Smith J. L. , Wolfenden A. , Zwaaneveld K.
Published: March 2003

An instrument and intraoral mounting have been developed to assess the degree of tooth mobility induced by the wearing of cast-metal partial dentures. The instrument utilized linear instrument bearings and a transducer to record voltage changes when a load of 5 N was applied to the mesial surface of the tooth under investigation.
Electro-optical multichannel spectrometer for transient resonance Raman and absorption spectroscopy
Authors: Hansen K. B. , Wilbrandt R. , Pagsberg P.
Published: March 2003

An optical multichannel system is described, used for time-dependent absorption measurements in the gas phase and the liquid phase and for resonance Raman spectroscopy of short-lived transient species in the liquid phase in pulse radiolysis. It consists of either an image converter streak unit or an image intensifier coupled to a TV camera with computerized data handling. The system enables the recording of time-dependent absorption spectra or resonance Raman spectra of short-lived radicals and excited states with single electron and light pulses.
Simple and compact photopreionization-stabilized excimer lasers
Authors: Hasson V. , von Bergmann H. M.
Published: March 2003

A novel photopreionization-stabilized discharge scheme was developed to excite rare gas halogen excimer lasers with beam energies of 100–250 mJ. The scheme requires no auxiliary timing or switching circuits and provides for the construction of compact and reliable devices.
Optimization of continuous wave nuclear magnetic resonance to determine i
n s
i
t
u volume fractions and individual flow rates in two component mixtures
Authors: Abouelwafa M. S. A. , Kendall E. J. M.
Published: March 2003

In this paper, the optimization of continuous wave nuclear magnetic resonance in two component flowing mixtures to determine the in situ volume fractions and the individual component flow rates is described from both an analytical and an experimental point of view. A simple and accurate measuring system is discussed and the analytical and experimental results are compared for oil–water mixes. The use of a relatively long polarizing magnet prior to the highly homogeneous detector magnet has been shown to improve the flow-rate range considerably and makes feasible a relatively inexpensive, accurate, and genuine two-phase or two component flow meter. By measuring the optimum value of H1, or the rf level required to produce that optimum value, and by simultaneously measuring the magnitude of the signal at that time, both the in situ volume fraction and the flow rate can be determined. This is provided that there is no chemical reaction between the two components and that they travel at the same average velocity. The system may be also used for monitoring changes in constituency of a single substance since the optimum value of H1 depends upon this constituency.
Improved microwave Michelson interferometer operating at 140 GHz
Authors: Read L. Arthur A. , Dagg I. R. , Reesor G. E.
Published: March 2003

Several major improvements have been made to a Michelson-type microwave interferometer operating at a frequency of 140 GHz. An enlarged dielectric cell, an improved measuring system, and a highly stable microwave system allow a precise determination of the complex dielectric constant for low-loss liquids. The effect of a mismatch in the microwave system is discussed and the computed behavior of the instrument is compared to that found experimentally. An experimental technique is described which takes account of the effect. Some results are presented for various solutions of nitrobenzene in benzene and for the alkane series of hydrocarbons. The values obtained are compared with values reported by other workers using different methods.
Infrared thermography of a high-power neutral beam target
Authors: Romain R.
Published: March 2003

In conjunction with an experiment on high-power neutral beam injection for a fusion device, infrared thermography has been used to observe the beam-target interaction in a prototype injector vessel. The infrared radiation from the beam itself was studied, which allowed the evaluation of the signal to noise ratio in the injection experiment.
Magnetization measurements using the field gradient of a high-field solenoid
Authors: Flanders P. J. , Graham C. D.
Published: March 2003

By using a high-field solenoid, the force on a magnetic sample resulting from a field gradient becomes large and measurements using the Faraday (or Curie) method are greatly simplified. By using an electronic analog dividing circuit, curves of magnetic moment or susceptibility versus field or temperature can be quickly and easily recorded. Various examples are given.
Thermal expansion of solids at high temperatures by the gamma attenuation technique
Authors: Drotning William D.
Published: March 2003

A new technique is described for the measurement of the thermal expansion of isotropic solid materials at high temperatures. The method utilizes gamma attenuation to measure thermal expansion with a noncontacting probe. The experimental apparatus and analytical method are described, and results are presented for aluminum to 900 K and type 303 stainless steel to 1660 K to illustrate the use and precision of the technique. These results agree with published values measured by other techniques, and in the case of the stainless steel alloy, some new results are presented in the temperature range 1400–1660 K.
Deep level transient spectroscopy for diodes with large leakage currents
Authors: Day D. S. , Helix M. J. , Hess K. , Streetman B. G.
Published: March 2003

A Deep Level Transient Spectroscopy (DLTS) system is described for measuring deep levels in diodes exhibiting large leakage currents. A capacitance bridge employing the diode to be tested along with a dummy diode of similar characteristics is used. The DLTS spectrum of a leaky GaAs planar diode is measured and compared to experimental results obtained with two standard DLTS systems. It is shown that measurements with the standard systems are impossible in certain temperature ranges because of overloading problems. The approach described here, however, gives the DLTS spectrum between 77° and 300° K.
Polarized light interferometer for laser fusion studies
Authors: Benattar R. , Popovics C. , Sigel R.
Published: March 2003

A polarized light interferometer, suitable for the high-speed photography of microscopic objects in laser fusion experiments, is described. Based on a Wollaston prism as beam splitter, its main advantages are its relative simplicity, the absence of alignment and stability problems, and the extended spectral range down to 0.18 μm wavelength. The interferometer has been successfully applied in CO2 and neodymium laser plasma interaction studies with laser illumination at 0.694 μm (ruby laser) and 0.265 μm (4th harmonic of the Nd3+ laser) wavelength.
Adjustable phase device for low-frequency NMR experiments
Authors: Weyand Kurt , Simon Ernst , Leuchter Yoram
Published: March 2003

In order to detect low-level NMR signals by bridge methods, a phase displacing device based on principle of voltage addition has been developed allowing the precise bridge balancing over a one decade frequency range. Using analogous multiplier devices for control and adjust circuit the phase adjustment of the output voltage is within ±3° over a frequency range from 10 to 100 kHz. For input peak-to-peak voltage levels from 0.1 to 1 V the output level is amplitude-stabilized to within 2% for all phase displacements.
Novel CO2/N2O waveguide laser
Authors: Gerlach Robert , Amer Nabil M.
Published: March 2003

We present a new design for a waveguide laser which is easily constructed from readily available materials. We have demonstrated its operation for CO2 (8.5-W output) and N2O (1.5-W output).
Coaxial lower hybrid plasma source
Authors: Motley R. W. , Bernabei S. , Hooke W. M.
Published: March 2003

We report the development of a coaxial radio frequency plasma source capable of producing pulsed plasmas of moderately high density (1013–1014 cm−3). This device may be useful either as a general purpose laboratory plasma source or as an auxilliary source for a variety of fusion applications, such as providing target plasmas for mirror machines or producing cold plasma blankets to help isolate the hot plasma core of a toroidal plasma from the walls.
In situ preparation of thin sodium films as an expendable filter in the vacuum ultraviolet
Authors: Ederer D. L. , Callcott T. A. , Arakawa E. T.
Published: March 2003

The use of a sodium film as a filter for wavelengths between 40 and 80 nm is discussed, and a technique to prepare these films is described. Sodium films of 230 nm thickness were demonstrated to have a transmission of 55% at 100° K at a wavelength 41 nm. The transmission decreased to 40% after 18 h in a vacuum of 5×10−8 Torr. Films of this thickness were shown to attenuate 20.5-nm radiation appearing in second order at 41 nm by at least a factor of 50.
Versatile four-probe ac conductivity measurement system
Authors: Phillips Terry E. , Anderson James R. , Schramm Charles J. , Hoffman Brian M.
Published: March 2003

The design of a four-probe ac conductivity measurement system is described. The system is capable of making precision conductance measurements from 10−8 to 10−5 S at 20 to 200 Hz. Driven coaxial shields and a controlled current source are utilized to eliminate phase shift/attenuation errors, and make the measurement of conductances on a variety of materials a routine procedure requiring a minimum of operator intervention.
Compact low-temperature fixed point device
Authors: Steinback M. , Matsumoto D. , Anderson A. C.
Published: March 2003

A small fixed point device is designed to be permanently mounted on a dilution refrigerator. The device contains Be and In samples with transitions at about 25 mK and 3.4 K.
Experimental study of ion beam optics in a two-stage accelerator
Authors: Kim Jinchoon , Gardner W. L. , Menon M. M.
Published: March 2003

Hydrogen ion beam optics in a two-stage linear acceleration system is studied by examining the beam divergence as a function of the voltage and gap distribution, the beam perveance, the background gas pressure, the aspect ratio, and the total accelerating energy (60-110 keV). The system consists of four electrodes with single, cylindrical, straight-bore apertures acting as an extraction-accel–decel column. An optimum relation between the field ratio and the extraction perveance is obtained from measurements for the minimum beam divergence condition. The HWHM divergence angle is <0.3° under optimum conditions. Qualitative agreement between the measurements and a previous theoretical study is noticed. A potential application of the results to high energy neutral beam injectors for fusion research is also discussed.
Simple sensitive capacitance manometer for corrosive gas laser systems
Authors: Shammas S. , Seguin H. J. J.
Published: March 2003

The design and performance of a capacitance manometer for use in corrosive gas laser environments is presented. This simple and inexpensive isolating device can be quickly fabricated in any machine shop, and permits the utilization of ordinary non-passivated pressure measurement apparatus or gauges in any gas system, irrespective of the corrosiveness.
Bremsstrahlung isochromat spectroscopy using a modified XPS apparatus
Authors: Lang J. K. , Baer Y.
Published: March 2003

The new components required for bremsstrahlung isochromat spectroscopy (BIS) in UHV (10−12 Torr range) have been developed and incorporated into an x-ray photoelectron spectrometer. They consist of a Pierce electron gun and a soft x-ray photon detector, both of which have to fulfill precise geometrical conditions imposed by the already existing monochromator. A description of the design and testing of this equipment is given. The resolution and the intensity appear to be correlated so that a compromise has to be found in order to achieve high resolution with acceptable intensity. It is demonstrated on the basis of suitable spectra that the density of unoccupied states above the Fermi level can be investigated with a resolution better than 0.43 eV.
Rotating sample holder without mechanical linkages
Authors: Azevedo L. J.
Published: March 2003

A sample rotator which operates in applied magnetic fields is described. The design eliminates mechanical linkages by magnetically orienting a gimbal ring. Three mutually orthogonal coils mounted on the gimbal provide a magnetic moment which is aligned along the field direction. The rotator is useful from room temperature down to the liquid helium range. Rotations about any desired axis are possible.
Analysis of a photographic–vidicon camera method of LEED intensity measurements
Authors: Tommet T. N. , Olszewski G. B. , Chadwick P. A. , Bernasek S. L.
Published: March 2003

Low-energy electron diffraction (LEED) has great need for a quick and efficient means of making intensity measurements (e.g., in studying reactive surfaces which quickly degrade, and in handling the enormous amounts of data needed for data averaging). The photographic–vidicon camera method fills this need. This paper describes a system and procedure for this method. We have pointed out advantages of this method over other methods of LEED intensity data collection and analysis, and have included comments on the advantages of our experimental system over other systems using this method. General properties of the photographic and vicdicon system are analyzed as well as specific tests done on the method. Estimates of probable error in spot intensity measurements due to numerous effects have been analyzed and I–V curves reduced from raw photographic data are compared. It is hoped that the description, comments, and analysis will facilitate the incorporation of the photographic–vidicon method of LEED analysis into research programs.
Noise reduction in EPR discharge-flow studies
Authors: Diebold G. J. , McFadden D. L.
Published: March 2003

In discharge-flow systems employing electron paramagnetic resonance detection, intense spectrometer noise is present under certain conditions. This noise is due to free electrons produced in the discharge and can be eliminated by the addition of an electron scavenger to the flow. Using SF6 to suppress the noise, EPR spectroscopy can be used to identify and study transient species within a millisecond after their formation in an electrical discharge.
Quartz optoacoustic apparatus for highly corrosive gases
Authors: Marinero E. E. , Stuke M.
Published: March 2003

In this paper we report on a new optoacoustic apparatus designed for the study of highly corrosive gases. The sound transducer is a thin quartz membrane sintered to one end of the solid quartz acoustic chamber. Measurements were performed on iodine chloride. Construction details, performance characteristics and the usage of the system in the study of the photo-induced reaction between ICP and C2H2 are described.
Stress apparatus for magneto-transport and far-infrared magneto-optical experiments
Authors: Kuchar F. , Veigl K. , Fantner E. J.
Published: March 2003

A stress apparatus is reported which allows us to apply forces up to 300 N to solids perpendicular to the field in a superconducting magnet. This configuration is necessary to study stress dependences of transverse magneto-transport effects and magneto-optical properties in Faraday geometry. The usefulness of the apparatus is demonstrated by Hall effect and transverse magnetoresistance measurements in n-InSb as well as far-infrared cyclotron resonance experiments on n-Ge.
Building an inexpensive microwave source for electrodeless discharge lamps
Authors: Chilukuri Santaram , Lichten W. L.
Published: March 2003

We demonstrate that a microwave power source to operate electrodeless discharge lamps can be built by modifying an inexpensive microwave oven at about 1/3 the cost of a commercial unit.
Simple, stable kinematic mirror mount
Authors: Pekelsky J. R.
Published: March 2003

A kinematic mirror mount that offers simple fabrication without compromising range or rigidity is described.