bluuebunny/crossref_metadata_2025 huggingface dataset:
High-power, long-pulse CO2 laser transversely excited by a damped oscillating discharge through dielectric electrodes
Authors: Hokazono Hirokazu , Midorikawa Katsumi , Obara Minoru , Fujioka Tomoo
Published: March 2003

Applying a damped oscillating discharge to a dielectric-electrode TE (transversely excited) CO2 laser, we obtain a high-power and long-pulse CO2 laser output. With a decreasing value of the inductance inserted in parallel with the discharge load so as to make the discharge condition damped oscillating, laser output energy increased remarkably. When the inductance was 500 nH, a uniform glow discharge was obtained up to gas pressures of 500–600 Torr without any preionization. At a total pressure of 700 Torr (CO2/N2/He=1/2/8), a maximum CO2 laser output energy of 270 mJ/pulse (7.3 J/l atm) was obtained with an electrical efficiency of 4.3% and with a pulse duration of 7 μs.
Filter correlation photometer
Authors: Olsowski W. , Nestler V.
Published: March 2003

A nondispersive photometer has been developed featuring a novel harmonic signal analysis for application oriented choice of functional components. These consist of rotating gas filters and interference filters as well as solid-state and optoacoustic detectors. Applications include direct measurement of concentration ratios. Simple models explaining the features of functional components as well as calibration procedures are given. Experimental data are presented, in comparison.
Integrated transducer for color distinction
Authors: Kato Hisao , Kojima Masahiko , Yoshida Akira
Published: March 2003

A method for fabricating the improved version of an integrated transducer for color distinction is proposed. It consists of three SnO2(n)–Si(n) photodiodes on a Si wafer and a trichromatic filter prepared by arranging filters of the three primary colors (Eastman Kodak gelatin filters; Nos. 47B, 58, and 25) on an infrared glass filter (Hoya Glass; B-460). Its photoelectric characteristics and dependence of error of color distinction on the dimension of the transducer are reported. The photodiodes employed in this conversion assembly are produced by the simple spray method and are most suitable for detecting the low illumination. Since this transducer adapts the trichromatic color resolution method, highly accurate color distinction is possible. With this type of transducer, three photodiodes sensitive to the primary colors, red, green, and blue, respectively, are arranged on a plane. An error in color distinction can occur due to the differences in the strength of the light incident upon the respective photodiodes. This problem is reduced by making the transducer more compact. Finally, 11 kinds of colors are discerned in this experiment as an application of the transducer.
Torsion viscosimeter for liquid crystals
Authors: Grupp J.
Published: March 2003

A new plate–plate torsion viscosimeter designed for the investigations of liquid crystals is described. This viscosimeter enables the measurement of torques at very low shear rates and the simultaneous optical observation of the sample. Short accounts of the application of the viscosimeter to viscosity measurements, to backflow investigations, and to the study of dissipative structures are given. In the case of dissipative structures, self-organization of the torsion pendulum system is observed.
uhf resonant cavity suitable for high-field NMR
Authors: McGurrin M. , Gully W. J.
Published: March 2003

We describe an easily tuned toroidal uhf cavity well suited for use as a probe for NMR.
Apparatus for volume measurement by helium expansion measured with a temperature-compensated, differential tensimeter having symmetrical design
Authors: Suzuki Isao
Published: March 2003

An apparatus is described which permits the accurate determination of the volume of solids by helium expansion. The apparatus consists of a differential micromanometer whose two arms are connected to a pair of sample and reference burets of nearly equal volume for helium expansion into sample and reference cells also of nearly equal volume. The volume of solids of 20 cm3 or smaller can be measured with an accuracy on the order of 0.0005 cm3.
Alternative methods for determining the electrical conductivity of core samples. II
Authors: Lytle R. J.
Published: March 2003

Electrode configurations are described that can be used in measuring the electrical conductivity of a core sample from a borehole in ground. The use of these configurations is warranted for laboratory measurements simulating the pressure and fluid flow conditions encountered at depth within the earth. Three particular electrode configurations are illustrated with numerical results depicting their relative merits.
Uniform magnetic field produced by three, four, and five square coils
Authors: Merritt R. , Purcell C. , Stroink G.
Published: March 2003

The optimal dimensions of thin coil systems of three and four square coils for producing uniform magnetic fields are calculated. We find that for three square coils, of side d and separation s between the outer coils, the most uniform field distribution occurs with s/d=0.821 116 and with I′/I=0.512 797. I′/I is the ratio of the currents in the center coil to that of the outer coils. With four square coils, the best uniformity is obtained when a/d=0.128 106 and b/d=0.505 492, where a is the distance from the center to the inner coils and b is the distance from the center to the outer coils. The ratio of the current in the inner pair of coils to that in the outer pair must be I′/I=0.423 514. We compare the uniformity of the field produced by these coil systems with each other and with Rubens’ five-coil system, both on and off axis. It is shown that the optimal four-coil design is superior to the three- and five-coil systems. The sensitivity of the uniformity to the precision of construction is discussed. Dimensions of regions around the center of the coil systems, uniform to 1 part in 106 to 1 part in 102, are given.
Dedicated multiprocessor system for calculating Josephson-junction noise thermometer frequency variances at high speed
Authors: Cutkosky R. D.
Published: March 2003

A Josephson-junction noise thermometer produces a sequence of frequency readings from whose variations the temperature of the thermometer may be calculated. A preprocessor system has been constructed to collect the frequency readings delivered to an IEEE 488 bus by an ordinary counter operating at up to 1000 readings per second, perform the required calculations, and send summary information to a desk calculator or minicomputer on another 488 bus at a more convenient rate.
New method to measure plasma potential with emissive probes
Authors: Makowski M. A. , Emmert G. A.
Published: March 2003

A new method of measuring the plasma potential using emissive probes is presented; the ‘‘droop’’ method. This method may be used in a steady-state experiment in which Te≫Tw, where Te and Tw are the electron and filament temperatures, respectively. The method is based on the observation that the floating potential of an emissive probe depends on Tw. A filament temperature which changes in time causes the floating potential also to vary. The proportionality constant between the two is extremely sensitive to whether the probe is above or below the plasma potential. Thus, a floating emissive probe which is allowed to cool can be used to discriminate between voltages above and below the space potential.
Fluorescence lifetime resolution with phase fluorometry
Authors: Ide Geert , Engelborghs Yves , Persoons Andre
Published: March 2003

A phase fluorometer for the measurement of fluorescence lifetimes was constructed from commercially available components. The instrument was tested by using optical delays of 4 and 2 cm, showing an accuracy of 10 ps. Lifetimes, as short as 0.3 ns, obtained by the quenching of fluorescein by KI, were analyzed with a standard deviation of 3 ps. The lifetime resolving power was checked using mixtures of acridine and quinine–sulphate and least-squares fitting procedures. Accurate amplitude ratios were obtained with the technique of phase-sensitive detection [J. R. Lakowicz and H. Cherek, J. Biochem. Biophys. Methods 5, 19 (1981)].
Conversion of liquid-nitrogen traps to mechanical refrigeration
Authors: Coggiola M. J. , Leon R. L. , Scally R. L.
Published: March 2003

A simple technique is described which allows a reservoir-type liquid-nitrogen trap to be converted to continuous operation with a closed-cycle mechanical refrigeration system. The conversion requires no internal modification to the trap and uses only standard commercial refrigeration components. Using 502 refrigerant as the working fluid, temperatures of −52 °C are readily achieved in a trap operating above a 6-in. water-cooled baffle and oil diffusion pump.
Simplified real-time television image analyzer based on an Apple II microcomputer
Authors: Bordes Michel , Bernengo Jean-Claude , Renaud Jean-François
Published: March 2003

A simple system for black-and-white image acquisition and treatment, based on a consumer TV camera and an Apple II microcomputer, is described. This system provides a real-time analysis up to 20 images per second with a resolution of 40×48 pixels. The acquired images are displayed on the Apple monitor, at the same rate, with a color scale. The operation of the specially designed hardware interface is extensively explained, together with the associated software, and some applications are proposed.
Simple direction of rotation indicator for ac motors
Authors: Zachariah E. J. , Vasudevan K. , Nair K. G.
Published: March 2003

A very simple circuit for driving two indicators showing the direction of rotation of reversible ac motors is described.
Geometrical efficiency of the prototype neutral beam injector unit for JT-60
Authors: Ohara Yoshihiro , Akiba Masato , Araki Masanori , Horiike Hiroshi , Kuriyama Masaaki , Matsuda Shinzabro , Matsuoka Mamoru , Okumura Yoshikazu , Tanaka Shigeru
Published: March 2003

The geometrical efficiency of the prototype neutral beam injector unit for the JT-60 was measured experimentally and was compared with numerical estimates. The measurements agreed well with the calculations in the wide range of perveance by taking into account the distortion of the beamlet intensity distribution function from a Gaussian distribution. Overdense operation of the ion source was preferable in that the high geometrical efficiency could be obtained at high perveance values.
Plasma measurements from neutral-beam attenuation
Authors: Foote J. H. , Molvik A. W. , Turner W. C.
Published: March 2003

Extensive and informative plasma measurements have been made with the intense and energetic neutral-particle beams that are used for fueling and heating magnetically confined, controlled-fusion experimental plasmas. This diagnostic technique does not perturb the plasma because only the unused transmitted fraction of a neutral beam is detected. Orthogonal arrays of highly collimated detectors of the simple secondary-electron-emission type are used in magnetic-mirror experiments to measure neutral-beam attenuation (directly related to the plasma line density) along chords through the plasma volume at different radial and axial positions. Data from these arrays yield radial and axial plasma-density profiles, ion angular distributions at the plasma midplane, estimates of the neutral-beam input power to the plasma, and information on macroscopic plasma motion. Representative results obtained by applying this useful diagnostic technique to the recently completed tandem-mirror experiment TMX are included here. This diagnostic method can also be advantageously applied to other controlled-fusion experiments that use neutral-beam injection.
Electron temperature measurements using a 12-channel array probe
Authors: Wild N. , Stenzel R. L. , Gekelman W.
Published: March 2003

The electron temperature in a pulsed high-β ( β≡2μnkT/B2≊1) plasma is studied as a function of time using a miniature array of 12 planar Langmuir probes. Instead of sweeping the bias voltage on the collectors, each is set at a different voltage corresponding to points along the characteristic I–V curve. A fast-analog multiplexer, together with a computerized data-acquisition system, allows determination of Te to within a few percent accuracy, with a time resolution of 1 μs. The probe is used to study temperature fluctuations and heat transport in a plasma current sheet.
Radial isolated Blumlein electron beam generator
Authors: Adler R. J. , Miller R. B. , Prestwich K. R. , Smith D. L.
Published: March 2003

A new high-voltage pulse-forming line, the radial isolated Blumlein (RIB), is described. The new configuration produces an output voltage pulse into a matched load equal to the charge voltage on the line (as in a conventional Blumlein circuit); however, the prepulse level is negligible and both sides of the load remain at electrostatic ground potential. The RIB is rapidly charged to allow 24 oil dielectric spark channels to close within ∼2 ns. With this number of channels, 94% of the theoretical peak voltage is achieved even though the pulse duration is only 15 ns. Using a foilless diode load, the device has been used to generate 4-MeV, 100-kA electron beam pulses.
Simple differential thermometer for low temperatures using a thermocouple with a SQUID detector
Authors: Maeno Y. , Haucke H. , Wheatley John
Published: March 2003

Details of design and construction of a simple and rugged thermocouple differential thermometer are presented. Gold +0.03 at. % iron wire is used, with niobium leads connected to a SQUID. It is demonstrated that at 1 K the response time is about 15 ms and that the temperature sensitivity of 10−7 K with a 10-Hz filter is Johnson-noise limited. Additional qualities such as small size, little self-heating, and high reproducibility make this device ideal for differential thermometry at low temperatures.
Photometer for quasielastic and classical light scattering
Authors: Haller Hans R. , Destor Christian , Cannell David S.
Published: March 2003

An accurate light scattering photometer capable of measuring both the angular distribution of intensity and the intensity fluctuation spectrum of laser light scattered from a wide variety of samples including solutions of polymers and other macromolecules is described. The photometer employs 18 fixed scattering angles ranging from 2.6° to 163° and is sufficiently accurate to measure a molecular radius of gyration as small as 60 Å reliably. Stray elastically scattered light normally comprises less than 1% of the light scattered from pure toluene at the smallest scattering angle and is unmeasurable at other angles. The apparatus employs optical fibers to transmit the scattered light to a single photomultiplier tube and functions automatically under microprocessor control, with sample temperature controlled to ±0.1 mK.
Novel spectrometer for time-angle resolved ultraviolet photoemission
Authors: Canivez Y. , Laude L. D. , Andrew R.
Published: March 2003

We described a new electron spectrometer for time-angle resolved photoemission. The apparatus consists of 44 electron detectors (microchannel plate) 4 mm in diameter, equally spaced on half a sphere (35-mm internal radius), and acting in the so-called ‘‘spherical retarding potential’’ method configuration. Resolution in energy is measured to be of the order of 0.3 eV and typical time resolution is 0.1 s. This spectrometer is conceived essentially for time-resolved surface reaction studies. Preliminary results are presented for the Si (111) surface.
High-temperature, high-pressure optical cells
Authors: Holland Lawrence R. , Harris Ronald P. , Smith Robbie
Published: March 2003

A strong, optically flat cell of fused silica has been developed which has routinely withstood internal pressures in excess of 60 atm at 900 °C. Construction details are presented.
Characterization of grain boundaries in polycrystalline solar cells using a computerized electron beam induced current system
Authors: Donolato C. , Bell R. O.
Published: March 2003

The automatic evaluation of grain boundary activity in a polycrystalline solar cell can be carried out by interfacing a microcomputer to a scanning electron microscope operating in the electron beam induced current mode (EBIC). The grain boundary surface recombination velocity and diffusion length in the neighboring grains are obtained by digital acquisition and processing of the related EBIC profile. The technique is applied to the evaluation of hydrogen passivation of a ribbon solar cell.
X-ray diamond-anvil press for use at high temperatures
Authors: Kikegawa T. , Iwasaki H.
Published: March 2003

This paper describes the design and operation of a new diamond-anvil press that can conduct x-ray diffraction investigations of polycrystalline materials at sustained pressure and temperature up to 30 GPa and 500 °C. Several improvements have been made in heating efficiency, uniformity of temperature, alignment operation of anvil faces, and elimination of preferred orientation effect. Examples of the application to the study of a high-pressure phase of phosphorus are shown.
Numerical calculations of electron trajectories in the 127° analyzer using a position-sensitive detector under conditions of fringing fields
Authors: Oshima C. , Franchy R. , Ibach H.
Published: March 2003

The theoretical performance of the 127° electron analyzer equipped with a position-sensitive detector has been discussed on the basis of a numerical calculation of electron trajectories. Including the Herzog correction in the calculation allows one to obtain good foci of electron onto almost all regions of the position-sensitive detector; it suggests that electron energy loss spectroscopy with high-energy resolution (ΔE/E0=1.6×10−3) can be realized by the new analyzer. A nonlinear relation between the arriving point on the detector and electron energy has also been examined for some different fringing fields.
Semiconductor detector for the selective detection of atomic hydrogen
Authors: Harvey K. C. , Fehrenbach C.
Published: March 2003

A semiconductor detector is described which responds to the atomic hydrogen in an atomic beam but is insensitive to molecular hydrogen. The hydrogen flux is measured through the change in conductivity of the semiconductor material which occurs when the hydrogen is chemisorbed. The atomic flux from a rf hydrogen discharge is used to determine the sensitivity of the detector. The minimum detectable signal is ∼109 hydrogen atoms mm−2 s−1. The detector has a response time of less than 2 ms.
Ten-channel grating polychromator for electron cyclotron emission plasma diagnostics
Authors: Fischer J. , Boyd D. A. , Cavallo A. , Benson J.
Published: March 2003

A grating polychromator for electron cyclotron temperature diagnostic experiments is described. Two aluminum gratings are used to allow the instrument to operate for tokamak magnetic fields between 16–25 kG, i.e., for second harmonic electron cyclotron emission frequencies ranging between 90–140 GHz. The instrument utilizes an array of ten cryogenically cooled InSb hot electron bolometers to collect radiation at the focal surface of the spectrometer covering a fractional plasma radial distance of ΔR/R0∼0.3–0.4, where R0 is the major radius of the plasma. The resolving power of the spectrometer has been measured to be ℛ=ν/δν≊50. This instrument thus provides high spatial (3 cm) and temporal resolution (∼1 μs) and large spatial coverage. The detector cryostat has measured cryogen hold times of ≥24 h (liquid nitrogen) and ≊9 days (liquid helium) providing ease of operation during long plasma runs.
Streak camera for picosecond x-ray diagnostics
Authors: Jaanimagi P. A. , Richardson M. C.
Published: March 2003

We report details of an x-ray sensitive streak camera with an estimated time resolution of less than 10 ps. The streak camera is based on a modified RCA 73435 image tube and features a large photocathode area and high sensitivity. A direct comparison of the relative quantum efficiency of Au and CsI photocathodes for 1–10 keV x rays is also presented.
Multiple filament plug-in module for use on the Tara neutral beam source
Authors: Coleman J. W. , Post R. S. , Torti R. P. , Tracey J. E.
Published: March 2003

A plug-in module bearing 14–20 tungsten filament emitters has been developed for use with the field-free neutral beam sources to be employed in the Tara tandem mirror experiments. Eight such modules constitute the total distributed cathode for one source. Each module has its own plug-in power connector, and may be removed from the source assembly as a unit, independently of the outer modules. The plug-in approach to construction results in a reduction both in the cost to build the source and in the time required for routine servicing and filament replacement. Plasma profiles are the same as in conventionally engineered sources of the same geometry.
Effect of magnetic field on the characteristics of a hollow cathode ion source
Authors: Tanaka Shigeru , Akiba Masato , Horiike Hiroshi , Okumura Yoshikazu , Ohara Yoshihiro
Published: March 2003

The effect of magnetic field on the performance of a hollow cathode ion source was experimentally studied. The field strength and the field distribution around the hollow cathode were changed step by step and the source parameters were recorded for each step. The result showed that with the optimum field configuration the discharge was stabilized even at low-operating gas pressures and the arc efficiency of the source was improved. Examination of the field and the neutral gas density distributions along the hollow cathode axis made it clear that the optimum field configuration was such that electrons emitted from the hot cathode surface might easily go out of the cathode cavity through the orifice being guided by the lines of force. Beam extraction from an intensively water-cooled small bucket source with the hollow cathode was carried out and hydrogen ion beams of up to 3 A at 50 keV were successfully obtained for the pulse length of up to 10 s.
Operating characteristics of a fixed alignment CO2 waveguide laser
Authors: Kucerovsky Z. , Brannen E.
Published: March 2003

A simple CO2 waveguide laser with fixed alignment is described and the operating characteristics for various gas mixtures given. Maximum power obtained was 3 W at a working pressure of 120 Torr. Alignment was still maintained after three years of operation. With a fresh filling of gas, power at the 1-W level was routinely obtained over a day’s running time.
Dewar design for optically pumped semiconductor ring laser
Authors: Fuchs A. , Salour M. M.
Published: March 2003

A simple liquid-nitrogen Dewar has been constructed to hold semiconductor platelets for use in a ring laser assembly. Laser action in an external ring cavity is observed when the platelets are longitudinally pumped by an Ar+ laser. Microscope objectives mounted outside the Dewar are used to focus the pump beam as well as the lasing beam onto the crystal. Positioning of the platelets in horizontal and vertical directions is accomplished by attaching the Dewar to an xyz stage.
Performance characteristics of a small side-window photomultiplier in laser single-photon fluorescence decay measurements
Authors: Ware William R. , Pratinidhi Madhuri , Bauer Richard K.
Published: March 2003

The performance characteristics of the Hamamatsu R928 side-window photomultiplier tube have been evaluated in the picosecond time domain. This phototube is proposed as an attractive solution to the problem of high time resolution when a sync-pumped dye laser is combined with the single-photon time correlation method for determining fluorescence lifetimes and measuring time-resolved emission spectra and polarization anisotropy. It combines excellent timing characteristics in the single-photon mode and a small-to-negligible wavelength effect with high gain, low noise, and low cost. Twice the resolution previously reported has been obtained.
Critical field measurements in superconductors using ac inductive techniques
Authors: Campbell S. A. , Ketterson J. B. , Crabtree G. W.
Published: March 2003

The ac in-phase and out-of-phase response of type II superconductors is discussed in terms of dc magnetization curves. Hysteresis in the dc magnetization is shown to lead to a dependence of the ac response on the rate at which an external field is swept. This effect allows both Hc1 and Hc2 to be measured by ac techniques. A relatively simple mutual inductance bridge for making such measurements is described in the text, and factors affecting bridge sensitivity are discussed in the Appendix. Data for the magnetic superconductor ErRh4B4 obtained using this bridge are reported.
Nitrite and nitrate ions as infrared pressure gauges for diamond anvils
Authors: Klug D. D. , Whalley E.
Published: March 2003

The infrared spectra of the antisymmetric stretching bands of dilute solutions of nitrite and nitrate ions in sodium bromide are proposed as pressure gauges for use with anvils and other apparatuses. Their frequencies, which are at 1279.0 and 1401.3 cm−1 respectively at zero pressure, were measured up to 186 kbar relative to the R1 fluorescence line of ruby. The pressure is related to the shift Δν of the frequency of the nitrite ion at 22 °C from the zero-pressure value by the equation p/kbar=2.356(Δν/cm−1)−1.334(Δν/cm−1)exp(−Δν/92 cm−1), and to the shift Δν of the frequency of the nitrate ion by the equation p/kbar=1.775(Δν/cm−1)−0.7495(Δν/cm−1) ×exp(−Δν/78 cm−1). Both equations were fitted by least squares, assuming that the error is in the pressure only, and the standard deviation of the pressure is 1.1 and 1.4 kbar, respectively.
Stability of some cryogenic carbon resistance thermometers
Authors: Besley L. M.
Published: March 2003

The stability of 12 commercial carbon resistance thermometers has been tested at three temperatures, 12.6, 20.3, and 30 K, when the sensors were exposed to cycling between 12.6 and 293 K. The resistances of the thermometers changed markedly over 20 such cycles by amounts equivalent to temperature changes of between 0.07 and 0.57 K at 20.3 K. Both abrupt and gradual changes were observed. A few measurements were made at 4.2 K to explore the correlation between changes in resistance at various temperatures. A two-point recalibration method is shown to be accurate to 1 mK over the range 12.6 to 30 K and can be used to 4.2 K.
Strain modulation measurements of stiffening effects in carbon fibers
Authors: Beetz C. P. , Budd G. W.
Published: March 2003

An experimental technique for directly measuring strain-induced stiffening effects in individual carbon fibers has been developed. The technique involves the superposition of a small amplitude oscillating strain (Δε∼10−4) on a slow linearly increasing strain (∼1.1×10−3 s−1). Synchronous detection of the resultant ac component of the measured stress yields a signal proportional to the slope of the stress versus strain curve provided the modulation amplitude is small compared to the ultimate strain at failure (∼0.005). The experimental arrangement has been designed for use in conjunction with an Instron tensile test apparatus. A novel design for a fiber gripping apparatus which permits direct measurement of the strain is also described. The technique has been applied to carbon fibers produced from two different precursor materials: polyacrylonitrile and mesophase pitch. Fibers from both precursors exhibited strain-induced stiffening. The modulus of the pitch-based fibers increased in proportion to the square root of the strain, whereas that of the PAN-based fibers showed an almost linear increase.
Apparatus for the measurement of the magnetic susceptibility of liquids in high magnetic fields
Authors: Brooks J. S. , Zimmerman G. O. , Meservey R.
Published: March 2003

We describe an apparatus capable of measuring the magnetic force on small liquid samples in high magnetic fields. The apparatus has been used to measure the magnetic susceptibility χ of liquid He at pressures up to 3 MPa in high magnetic fields and has a sensitivity in such measurements comparable to superconducting magnetometers in lower fields. The performance was tested by measuring the atomic diamagnetism of liquid 4He and liquid 3He as well as the nuclear paramagnetism of liquid 3He at 1.2 K in fields up to 15 T.
Fast, versatile, and inexpensive pulse sequence generator
Authors: Mohr G. A. , Edwards Carl M.
Published: March 2003

A fast, versatile, and inexpensive programmable digital pulse sequence generator (PSG) suitable for use in broadline pulsed NMR has been developed. Its features include 20 ns resolution of pulse duration, operation without direct computer supervision, and enough flexibility to produce essentially any pulse sequence. The architecture and construction of the PSG are discussed, and an example of its programming is presented.
Simple synchronous video image combiner
Authors: Lage A. L. V. S. , Gomes A. O. S. , Soares O. D. D.
Published: March 2003

A simple and inexpensive TV camera image combiner for several purposes in current video dual image acquisition is described.
Field data logger with EPROM storage
Authors: Robb A. W. , Nazaroff W. W.
Published: March 2003

A data logger using electrically programmable read-only memory for data storage is described. The storage capacity is sufficient to record measurements from eight instruments at 30-min intervals for almost ten days. This approach provides a moderately priced alternative to data loggers using magnetic tape or floppy disks when only modest data-storage capacity is needed.
Diamond-anvil system for the investigation of phase equilibria in mixtures at high pressures
Authors: Schouten J. A. , Trappeniers N. J. , van den Bergh L. C.
Published: March 2003

In order to investigate the phase behavior of mixtures at high pressures we have developed a system consisting of a diamond-anvil cell with a high-pressure vessel to match. The diamond cell can be filled at room temperature and pressures up to 10 kbar with a gaseous mixture of known composition. The cell is constructed such that a constant volume method can be used to measure the dew- and bubble-point curves of a mixture.
Gas/oil interface and high-sensitivity differential pressure indicator used for the comparison of gas with oil piston gauges
Authors: Tilford Charles R. , Martin Donald F.
Published: March 2003

A free surface gas/oil interface has been constructed to aid in the comparison of gas piston gauges with oil piston gauges. A coaxial three-terminal capacitor partially immersed in the oil and partially in the gas permits the determination of hydrostatic heads and differential pressures between the piston gauges. The interface has been used in the comparison of primary standard gas and oil piston gauges with an average standard deviation about mean pressures of 4.5 Pa (6.5×10−4 psi) over the range of 0.4 to 4 MPa (60 to 600 psi).
Diamond-anvil high-pressure cell for improved single-crystal x-ray diffraction measurements
Authors: Ahsbahs H.
Published: March 2003

A diamond-anvil high-pressure cell for single-crystal x-ray diffraction studies is described. The cell is suited especially to four-circle diffractometers. The important feature of this device is that, compared to previously reported cells for single-crystal x-ray studies, a greater portion of the reciprocal space can be observed. All structure factors up to a θ limit, depending on the design of the cell, can be measured. Thus, the probability of solving complicated unknown structures is increased. The major disadvantage of the cell is the limitation of the highest achievable pressure of 35 kbar, caused by failure of the beryllium gasket.
Diffuse reflectance of GeO2–ZnO–K2O glass for CO2-laser-light absorber
Authors: Hidaka T. , Kumata K. , Endo E. , Honda T.
Published: March 2003

The diffuse reflectance of a 60GeO2–2OZnO–2OK2O glass plate was measured to be 0.13% at 10.6 μm, which is ideally small for use in power meters to compare with other absorbers such as gold black. The specular reflectance was also measured to be less than 0.01%.
High-pressure polycrystalline sodium chloride window and mounting arrangement for CO2 laser transmission
Authors: Bransford James W.
Published: March 2003

A design for an unclamped high-pressure window made from polycrystalline sodium chloride is presented. The window was used to pass an 80-W cw CO2 laser beam into a pressure chamber operating at pressures from 0.1 to 14 MPa.
Nanosecond current probe for high-voltage experiments
Authors: Krompholz H. , Doggett J. , Schoenbach K. H. , Gahl J. , Harjes C. , Schaefer G. , Kristiansen M.
Published: March 2003

A matched, slow wave transmission line is used as a current probe. It provides a linear response, fast rise time (τr <2 ns) and high-voltage gain (≂1 V/A) for current pulses up to microsecond duration.
Improved device for direct transfer of filtered liquids to volumetric flasks
Authors: Schein Daniel B. , Lee Tracy L. , Zeitlin Harry
Published: March 2003

A device for direct transfer of filtered liquids to volumetric flasks has been modified to improve time savings and simplify operational procedures.
Dense and quiescent magnetized plasma with a low-pressure hollow-cathode discharge
Authors: Subaşi M. , Tarcan G.
Published: March 2003

Diffusion of a low-pressure (10−2 Torr) hollow-cathode discharge through an anode screen produces a linear, homogeneous, and quiescent plasma column (14 mm in diameter, 80 cm in length) in a strong magnetic field (max 3 kG). Electron temperatures and densities in this plasma, as measured by Langmuir probe and microwave cavity perturbation techniques are, respectively, in the ranges of 0.3–1.2 eV and 109–1011 cm−3. Plasma noise fluctuations (e≂fl/kBTe) at the center of the plasma are about 3%.
Truly constant diameter high-pressure quartz optical cell
Authors: le Noble W. J. , Schlott R.
Published: March 2003

A small design change in a previously published model of an all-quartz high-pressure optical cell is described that allows its use without any need for corrections in the abosorbance.
Flash x-ray source for plasma shutter diagnostics
Authors: Bradley L. P. , Mitchell A. C. , Johnson Q. , Smith Ian D.
Published: March 2003

A flash x-ray source has been fabricated to examine the plasma-driven shutter for the Nova Fusion Laser System at the Lawrence Livermore National Laboratory. This source has a 20-ns pulse width and 1.5- and 4.5-keV x rays. It has been used to characterize plasma moving at 1–5 cm/μs with areal densities down to 0.1 mg/cm2 and a spatial resolution of 2.5 μm. By using this x-ray source to diagnose the Nova plasma shutter, the authors were able to discover and cure sources of plasma nonuniformity and empirically select the foil dimensions and the current required for Nova.
Simple device for measuring the two-way shape memory effect
Authors: Talmi Z. , Ganor M. , Baram J. , Pelleg J.
Published: March 2003

A simple device has been designed to measure continuously and reproducibly the amount of the shape recovery related to the two-way shape memory effect in specimens undergoing thermal cycling. Using this device, it is possible to follow the dimensional changes of the specimens, to record the exact temperatures where shape changes occur, and to evaluate the amount of hysteresis involved with the shape recovery phenomenon.
Microprocessor-based pressure controller
Authors: Redd E. , Park J. T.
Published: March 2003

A device for automatic control of pressure in an ion-atom scattering experiment has been constructed. The system was modeled to achieve the minimum time for transition from one pressure to another. The pressure controller ‘‘learns’’ the system response and iterates the parameters used in ‘‘profiling’’ the valve voltage to reduce the transition time. The device has been used with two different scattering chambers and has worked well with both.
Unusual chemical composition fluorescers and filters for low-energy x-ray diagnostics. Part I. Oxygen compositions
Authors: Jorgensen B. , Liepins R. , Day R. H.
Published: March 2003

The preparation of filters and fluorescence of high oxygen content (53%) for low-energy x-ray measurements is described. The thin films of high oxygen content were fabricated from a 50:50 wt. % mixture of CelconTM and DelrinTM. Thermal analysis data on all the materials investigated are also presented.
3-ps synchronized multiframe photographic diagnostic for target experiments with the iodine laser
Authors: Maaswinkel A. G. M. , Sigel R. , Baumhacker H. , Brederlow G.
Published: March 2003

A diagnostic system is described with which we obtain a sequence of six pictures (interferograms or shadowgrams) of the plasma produced by the iodine laser on solid targets. The system consists of a synchronously pumped dye laser amplified in dye cells pumped by an excimer laser. It delivers a pulse with an energy of 500  μJ and a length of 3 ps at a wavelength of 580 nm that is highly synchronous with the iodine pulse.
UV radiation-triggered rail-gap switches
Authors: Taylor R. S. , Leopold K. E.
Published: March 2003

A few mJ of KrF excimer laser radiation have been used to initiate multichannel breakdown in a low-inductance gas-insulated rail-gap switch. The switch, which contains two uniform field electrodes, has been operated in a pulse-charged voltage range of 30–130 kV and has demonstrated jitters as low as 100 ps. A very simple trigger device which incorporates the important features of laser triggering but which uses incoherent UV radiation produced in a corona discharge has also resulted in low jitter, multichannel switch performance.
Shot-noise-limited detection scheme for two-beam laser spectroscopies
Authors: Andor László , Lörincz András , Siemion Jeanne , Smith Duane D. , Rice Stuart A.
Published: March 2003

We describe a single-sideband frequency demodulation scheme with large dynamic range which gives linear response and is capable of shot-noise-limited performance when used with time-resolved pump and probe, polarization, and three- and four-wave mixing spectroscopies.
Variable-temperature solid-state nuclear-magnetic-resonance probe for superconducting magnets operating in the range 3–350 K
Authors: Carduner Keith , Villa Marco , White David
Published: March 2003

A versatile, variable-temperature (3–350 K continuous), vacuum cold-finger, solid-state nuclear-magnetic-resonance (NMR) probe is described and its characteristics in several applications are discussed. The single-coil probe is specifically designed for use in superconducting magnets with bores as small as 2.5 in. and is suitable for both single- and double-resonance experiments. The tuning arrangement allows for multinuclear data acquisition without the necessity of breaking the vacuum. Various adaptations to the cold finger suitable for a variety of different solids, e.g., powders, amorphous materials (glasses), condensables, and single crystals are presented including a single-axis goniometer operable over the entire temperature range.
Precision time-domain dielectric spectrometer
Authors: Mopsik F. I.
Published: March 2003

A description is given for an automated method for determining dielectric constant and loss by the measurement of the time response of the dielectric to a step voltage. Attention is paid to the circuits necessary to achieve high accuracy (0.1%) and high sensitivity (tan δ=10−5) over audio and subaudio frequencies (104 to 10−4 Hz). These include a 100-V step generator accurate to 5 ppm, a charge detector with a time-independent bias current of 30 fA, and a clock that can control sampling time from 5 μs to 10 s. In addition, a numerical Laplace transform, based on a cubic spline, is described that preserves the accuracy of the time data when they are transformed into the frequency domain.
Simple, compact, medium-energy Mott polarization analyzer
Authors: Gray L. G. , Hart M. W. , Dunning F. B. , Walters G. K.
Published: March 2003

A simple, compact, UHV compatible Mott polarization analyzer is described that employs electron accelerating voltages in the range 20–40 keV.The analyzer provides excellent discrimination against inelastically scattered electrons and has the advantage that the major portion of the apparatus, and the scattered electron detectors, are operated near ground potential. The efficiency of the analyzer, ∼2×10−5, is competitive with those provided by other polarimeters. The analyzer can measure the polarization of electron beams having currents as low as ∼10−13 A and is suitable for use in a wide variety of experiments involving polarized electron beams.
Wide temperature range sample manipulator for surface studies in ultrahigh vacuum
Authors: Stroscio Joseph A. , Ho W.
Published: March 2003

A sample manipulator for ultrahigh-vacuum surface studies is described. The manipulator possesses long vertical (z) translation, decoupled rotary motion, x–y–z, and tilt stages. The design incorporates a simple and compact sample holder which allows the capabilities of liquid-N2 or He cooling, and high-temperature resistive heating with rapid temperature cycling.
Data-acquisition and control system for a Rheometrics Mechanical Spectrometer
Authors: Milkie T. H. , Croucher M. D.
Published: March 2003

The Rheometrics Mechanical Spectrometer is an instrument that is capable of measuring both the dynamic and steady shear rheological properties of a material over a broad time scale and temperature range. The instrument uses a rotational geometry to apply a constant or periodic strain and then measures the response of the stress in three orthogonal directions FX, FY, and FZ as well as the torque about the x axis. The stresses detected are then recorded on a chart recorder as a function of rotational steady shear measurements or displayed numerically as ‘‘in-phase’’ and ‘‘out-of-phase’’ components of the applied oscillatory strain for dynamic measurements. To fully characterize the mechanical response of a material, several hundred points of data at various temperatures are required. Each point of ‘‘raw data’’ must first be normalized and then used in calculations to obtain discrete rheological parameters. To eliminate this labor-intensive process, a microcomputer has been successfully interfaced to the Rheometrics Mechanical Spectrometer to control the operation of the instrument during all modes of operation, acquire the intermediate raw data, perform calculations and numerical transformations, and present a hard-copy plot and table of rheological parameters. The microcomputer-based data-acquisition and control system not only removes the tedious process of manual operation, collection, and presentation of data, but forms an essential part of a closed feedback loop for substantially improving the speed and accuracy of experimental data. A detailed review of the microprocessor-based data-acquisition and control system is presented.
Electron-beam tetrode for multiple, submicrosecond pulse operation
Authors: Harjes C. H. , Schoenbach K. H. , Schaefer G. , Kristiansen M. , Krompholz H. , Skaggs D.
Published: March 2003

The design and the operation of a 250-kV, 400-A, e-beam tetrode is described. A simple trigger circuit allows the generation of a burst of e-beam pulses with variable pulse duration and pulse separation.
Integrating fluorometer for the measurement of chlorophyll fluorescence induction in intact plants
Authors: Toivonen Peter , Vidaver William
Published: March 2003

An economical device for monitoring the integrated chlorophyll fluorescence emission of plant material is described. The system, which uniquely incorporates an integrating sphere, light source, photographic shutter, optical filters, and a photodetector is applicable to intact plants, whole leaves, or other materials. It is noninvasive and a single sample may be repeatedly tested over time intervals of minutes to months. Data obtained provide information about the sample size (i.e., leaf area, total chlorophyll content), and the photosynthetic activity of the sample. Samples of from a few mm2 to several cm2 can be accommodated depending on the diameter of the integrating sphere and excitation light source intensity. The device should be of interest to workers in plant breeding, genetic engineering, tissue culture, horticulture, herbicides, pollution, pathology, and environmental stress.
Measurement and control of oxygen fugacity during annealing
Authors: Shepherd John P. , Sandberg Charles J.
Published: March 2003

We describe a simple analog electronic circuit to measure the voltages of a thermocouple and solid electrolyte sensor and calculate and diplay the temperature and log fO2. This circuit monitors conditions in a simple annealing system where the oxygen atmosphere is controlled by continuous flow of a gas buffer.
New large-scale laboratory sublimer
Authors: Sloan Gilbert J.
Published: March 2003

A new sublimer is described, in which a glass condenser is surrounded by a close-fitting, rotating helical scraper of stainless steel. Sublimation takes place from an annular chamber below the condenser; sublimate is scraped from the condenser and falls through a central standpipe into a collection flask. The new device makes it easy to collect several fractions, of decreasing volatility, while maintaining condenser efficiency by avoiding accumulation of a thick layer of sublimate. Batches as large as 1 kg can be sublimed conveniently, at rates above 0.05 kg h−1.
Test of wall coatings for controlled moist air experiments
Authors: Liebe Hans J. , Wolfe Vincent L. , Howe David A.
Published: March 2003

Various hydrophobic surface treatments were investigated to facilitate high humidity (relative and absolute) experiments with a millimeter wave spectrometer. There were 17 different cases tested for adsorption and desorption behavior of a vacuum chamber, employing various combinations of metal surfaces (stainless steel, aluminum, brass), coating materials (electropolish, gold plate, Teflon, HMDS, silicone, lacquer), and surface-to-volume ratios (0.3 to 1.7 cm−1). Test procedure and data are described together with a brief discussion of the findings. Trends are evaluated toward an effective reduction of the wall effect, which is a nemesis to all laboratory studies involved with polar gas molecules such as H2O in air.
Broadband phase shifter suitable for NMR applications
Authors: Sears R. E. J.
Published: March 2003

A broadband radio frequency phase shifter has been designed which provides a continuous 360° variation of the phase angle. This phase shifter is suitable for use with the broadband receiver amplifier and phase-sensitive detector combination frequently found in pulsed NMR spectrometers. A phase shifter operating between 3.5 to 76 MHz, which has an almost linear variation of the electrical phase angle with the manually adjusted phase control setting, is described in detail. While this particular phase shifter is useful for resistive magnet spectrometer applications it would be possible to cover higher frequency ranges if necessary.
Design and construction of a circular intensity differential scattering instrument
Authors: Katz Joseph E. , Wells Sam , Ussery David , Bustamante Carlos , Maestre Marcos F.
Published: March 2003

An instrument has been designed and built which can measure the differential scattering of circularly polarized light as a function of angle about the scattering volume. The rationale for making these measurements is to investigate the long-range structure of large chiral, optically active molecules, or chiral aggregates of molecules. The design is based on the principle of electro-optic modulation and synchronous demodulation to recover scattered intensities from incident left and right circularly polarized laser light. Preliminary reproducible results that have been obtained on cholesteric liquid crystals are presented.
Automatic laser scanner for solar cells
Authors: Khanna V. , Sastry O. S. , Mukerjee A. K. , Chopra K. L.
Published: March 2003

An instrument is described which controls a two-mirror scanning arrangement to raster a laser beam on a large-area solar cell. The short circuit current thus produced is plotted on an X–Y recorder, or recorded on a storage oscilloscope to study the spatial inhomogeneities of the cell.