Showing papers in "Review of Scientific Instruments in 1984"
TL;DR: In this article, a single-crystal fiber growth apparatus was designed and built using optical, mechanical, and electronic control systems that enable the growth of high optical quality singlecrystal fibers.
Abstract: We have designed and built a single‐crystal fiber growth apparatus. The apparatus employs novel optical, mechanical, and electronic control systems that enable the growth of high optical quality single‐crystal fibers. We have grown oriented single‐crystal fibers of four refractory oxide materials, Al2O3, Cr:Al2O3, Nd:YAG, and LiNbO3. These materials exhibit similar growth characteristics and yield fibers of comparable quality. Fibers as small as 20 μm in diameter and as long as 20 cm have been grown. Measured optical losses at 1.06 μm for a 10‐cm‐long, 170‐μm‐diam Cr:Al2O3 fiber were 0.074 dB/cm.
220 citations
TL;DR: In this article, an experimental setup is described to microscopically observe surfactant monolayers at the air/water interface, consisting of a film balance, incorporated into a fluorescence microscope, detecting the emission of dye probes.
Abstract: An experimental setup is described to microscopically observe surfactant monolayers at the air/water interface It basically consists of a film balance, incorporated into a fluorescence microscope, detecting the emission of dye probes The apparatus is stable enough to observe dynamical processes over more than 5 h, with a spatial resolution of less than 2 μm and is sensitive enough to use probe concentrations as low as 01 mol% Examples of surface textures appearing during lipid phase transitions demonstrate the good performance characteristics
203 citations
TL;DR: In this article, a magnetometer with a superconducting pick-up loop and dc SQUID was fabricated on a single silicon chip for geophysical applications, which has a magnetic field sensitivity of typically 5×10−15 T Hz−1/2 at frequencies above about 10 Hz.
Abstract: We have fabricated a magnetometer in which the thin‐film superconducting pick‐up loop and dc SQUID are integrated on a single silicon chip. The magnetometer, which is intended primarily for geophysical applications, has a magnetic field sensitivity of typically 5×10−15 T Hz−1/2 at frequencies above about 10 Hz, and 2×10−14/( f /1 Hz)1/2 T Hz−1/2 at lower frequencies. The dynamic range is ±2×107 Hz1/2 and the maximum slew rate is about 4×10−3 T s−1 at 6 kHz. This high slew rate enables the magnetometer to be operated in a flux‐locked loop for long periods of time without losing lock.
148 citations
TL;DR: In this article, the authors present a characterization of a commercially available position-sensitive detector of energetic ions and neutrals, which consists of two microchannel plates followed by a resistive position-encoding anode.
Abstract: This paper presents a characterization of a commercially available position‐sensitive detector of energetic ions and neutrals. The detector consists of two microchannel plates followed by a resistive position‐encoding anode. The work includes measurement of absolute efficiencies of H+, He+, and O+ ions in the energy range between 250 and 5000 eV, measurement of relative detection efficiencies as a function of particle impact angle, and a simple method for accurate measurement of the time at which a particle strikes the detector.
147 citations
TL;DR: In this article, a pulsed dye laser is used to excite seeded biacetyl molecules along a line in a nitrogen flow at room temperature, and two successive exposures of the emitted phosphorescence are recorded with an intensified 100×100 element photodiode array camera.
Abstract: Visualization of a two‐dimensional velocity field by means of laser‐induced phosphorescence is demonstrated in a nitrogen flow at room temperature. A pulsed dye laser is used to excite seeded biacetyl molecules along a line in the flow. Two successive exposures of the emitted phosphorescence are recorded with an intensified 100×100 element photodiode array camera. Velocities are determined from the distance traveled in the time interval between exposures. Important factors in connection with the phosphorescence of biacetyl are discussed.
133 citations
TL;DR: In this paper, an automated method for determining dielectric constant and loss by the measurement of the time response of the dielectrics to a step voltage is presented. But the method is limited to the frequency domain.
Abstract: 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.
115 citations
TL;DR: In this article, the construction and operation of a cross-correlation phase and modulation fluorometer using the synchrotron radiation facility at the ADONE-Frascati electron storage ring is described.
Abstract: The construction and operation of a cross‐correlation phase and modulation fluorometer using the synchrotron radiation facility at the ADONE–Frascati electron storage ring is described. In the frequency domain the high repetition rate pulsed source gives a large series of equally spaced harmonic frequencies. Use of cross‐correlation techniques in conjunction with such a light source permits one to isolate one harmonic frequency from the adjacent frequencies with high precision. The cross‐correlation frequency required for the analysis of the phase delay and modulation ratio is obtained using two coupled frequency synthesizers, one of which drives the radio‐frequency cavity of the storage ring and the other which modulates the response of the photomultipliers used for the signal detection. The accuracy, reproducibility, and sensitivity of the instrumentation have been determined on a number of systems and are reported.
108 citations
TL;DR: In this paper, a review of recent developments in instrumentation is presented together with trends for the future, including far-infrared laser interferometry and polarimetry, ruby laser television Thomson scattering, excimer and Ndglass laser scattering, ion temperature determination via large-α scattering with FIR and CO2 lasers, collective scattering, Schottky diode mixer technology, synchrotron radiation diagnostics and imaging, ion beam probes, x-ray diagnostics, resonance fluorescence scattering, ultraviolet diagnostic, and internal magnetic field measurement.
Abstract: Recent progress in magnetically confined plasma research has brought the goal of controlled thermonuclear fusion within reach. Simultaneously, the increased size, temperature, and density of these devices has resulted in rapid changes in diagnostic techniques. In this article, recent developments in instrumentation are reviewed together with trends for the future. The topics discussed include far‐infrared laser interferometry and polarimetry, ruby laser television Thomson scattering, excimer and Nd‐glass laser scattering, ion temperature determination via large‐α scattering with FIR and CO2 lasers, collective scattering, Schottky diode mixer technology, synchrotron radiation diagnostics and imaging, ion beam probes, x‐ray diagnostics and imaging, neutron diagnostics, resonance fluorescence scattering, ultraviolet diagnostics, and internal magnetic field measurement.
105 citations
TL;DR: In this paper, a simple method was described that permits a consistent determination of thermally induced pressure variations in a pistoncylinder, self-clamping pressure cell at temperatures less than ambient.
Abstract: A simple method is described that permits a consistent determination of thermally induced pressure variations in a piston‐cylinder, self‐clamping pressure cell at temperatures less than ambient. Significant pressure changes are found to be present even for T<75 K. It is also shown that the pressure coefficient of resistance of a manganin‐wire gauge is, to within experimental uncertainty, independent of temperature over the range 0
100 citations
TL;DR: In this paper, Possin reported the fabrication of wires as small as 400 A in diameter with a method involving electroplating into etched particle tracks in mica, and can now use it to routinely produce wires as smaller as 80 A. These refinements are described and the possibility of making even smaller wires with this method is discussed.
Abstract: Some years ago Possin reported the fabrication of wires as small as 400 A in diameter with a method involving electroplating into etched particle tracks in mica. We have refined this technique, and can now use it to routinely produce wires as small as 80 A. These refinements are described, and the possibility of making even smaller wires with this method is discussed.
88 citations
TL;DR: In this paper, a simple, compact, UHV compatible Mott polarization analyzer is described that employs electron accelerating voltages in the range 20-40 keV and 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.
Abstract: 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.
TL;DR: An instrument capable of deep borehole measurement of vector plane strain to 0.3 nstrain and tilt to 1.0 nrad has been developed for deployment in crustal deformation and earthquake prediction studies as mentioned in this paper.
Abstract: An instrument capable of deep borehole measurement of vector plane strain to 0.3 nstrain and tilt to 1.0 nrad has been developed for deployment in crustal deformation and earthquake prediction studies. The instrument has been deployed in California where shear strains dominate the deformation. The 125‐mm‐diam package is grouted in 175‐mm boreholes at depths of approximately 200 m. The wall thickness and the grout thickness are chosen to match instrument strength to expected rock parameters. The instrument is capable of flat response from dc to 10 Hz on any single channel. The electronics package is stable to three parts in 108 over the temperature range 10 to 45° C. Reliable shear strain data is available immediately on installation when simple volume strain meters show only bond curing effects or thermal recovery signals.
TL;DR: In this paper, the axial magnetic field generated by a permanent magnet was used for high-density plasma production by the electron cyclotron resonance process and for high efficient ion extraction by transporting the generated ions along the magnetic force lines.
Abstract: We have developed a new type of microwave ion source which has an axial magnetic field generated by a permanent magnet. By the combination of the permanent magnet and ferromagnetic materials, a closed magnetic circuit is formed through an ion extraction electrode. This axial magnetic field is utilized both for the high‐density plasma production by the electron‐ cyclotron resonance process and for the high efficient ion extraction by transporting the generated ions along the magnetic force lines. The continuous ion beams of 2–3 mA are delivered from the extraction aperture (2 mm in diameter) when various gases (Ar, N2, CO2), metal vapors (Cs, Rb), and reactive gas (O2) are used. Extremely low impurities are present in the extracted ion beam. An ion beam with low emittance of 10−8 m rad order and high brightness of 1011 A m−2 rad−2 order is obtained. The size of this ion source is 50 mm in diameter and 65 mm in height. The discharge power of the microwave with the frequency of 2.45 GHz is 7 to 30 W. Thus, a...
TL;DR: In this paper, a vibrating tube flow densimeter for measuring the density of fluids as functions of temperature and pressure is described, with a precision of 30 ppm at temperatures to 700 K and pressures to 40 MPa.
Abstract: A vibrating tube flow densimeter for measuring the density of fluids as functions of temperature and pressure is described. The apparatus allows relative density measurements to be carried out on 6 cm3 of solution in about 20 min with a precision of 30 ppm at temperatures to 700 K and pressures to 40 MPa. The accuracy of the densimeter has been verified by measurements on NaCl solutions. Good agreement with literature values was obtained.
TL;DR: In this article, the absolute magnetic susceptibility of cylindrical specimens is obtained with an ac susceptometer whose calibration is based on a calculation of mutual inductance between a solenoid and a pickup coil of arbitrary dimensions.
Abstract: The absolute magnetic susceptibility of cylindrical specimens is obtained with an ac susceptometer whose calibration is based on a calculation of mutual inductance. An axially magnetized cylinder is modeled as a solenoid of the same size. The mutual inductance between such a solenoid and a pickup coil of arbitrary dimensions is computed. The susceptibility is then a function of the mutual inductance, the cylinder length, the magnitude and frequency of the ac magnetizing field, and the voltage induced on the pickup coil. Demagnetization factor and eddy‐current effects are considered, an example is given, and pickup coil compensation is discussed. Other calibration methods are also presented.
TL;DR: In this article, a method for the laser vaporization and ionization of individual micron-size particles is presented whereby a particle is ionized by a laser pulse while in flight in the beam.
Abstract: A method for the laser vaporization and ionization of individual micron-size particles is presented whereby a particle is ionized by a laser pulse while in flight in the beam. Ionization in the beam offers a real-time analytical capability and eliminates any possible substrate-sample interferences during an analysis. An experimental arrangement using a high-energy Nd-YAG laser is described, and results are presented for ions generated from potassium biphthalate particles (1.96 micron in diameter). The method proposed here is useful for the chemical analysis of aerosol particles by mass spectrometry and for other spectroscopic and chemical kinetic studies.
TL;DR: In this paper, a high-resolution, differentially pumped, electron energy-loss spectrometer with the capability of measuring both valence and inner-shell spectra (at impact energies of 1-10 keV) has been constructed.
Abstract: A new high‐resolution, differentially pumped, electron energy‐loss spectrometer with the capability of measuring both valence and inner‐shell spectra (at impact energies of 1–10 keV) has been constructed. Advanced electron optics have been incorporated, and the design and operation of the electron optics is discussed. Spectra of N2 are presented, demonstrating the significant improvements obtained in signal to noise and collection time in the inner‐shell region compared with previous instrumentation. In addition, both valence and inner‐shell spectra of HCl are presented, demonstrating the efficiency of the differential pumping, and the ability of the instrument to study highly reactive target species.
TL;DR: In this paper, a high magnetic field, large volume magnetic multipole ion source has been designed and tested to enhance the proton fraction in hydrogen ion beams, which is made of a water-cooled rectangular copper chamber, surrounded by a set of mild steel strips and samarium-cobalt magnets arranged in a continuous line-cusp geometry.
Abstract: In order to enhance the proton fraction in hydrogen ion beams, a high magnetic field, large‐volume magnetic multipole ion source has been designed and tested. The plasma source is made of a water‐cooled rectangular copper chamber, which is surrounded by a set of mild steel strips and samarium–cobalt magnets arranged in a continuous line‐cusp geometry. The magnetic field at the inner wall surface is 2.7 kG. This strong magnetic field enables us to enlarge the chamber volume without increasing the ion loss area. Large plasma volume and small ion loss area increase the ion confinement time and enhance the proton yield. The proton fraction in the beams, as measured by both a magnetic momentum mass analyzer and a optical spectrometer, is found to be more than 90% at an ion beam current of 28 A ( j=250 mA/cm2). This source is also operated with a weak magnetic field (∼0.6 kG) by replacing the samarium–cobalt magnets with AlNiCo magnet, in which case the proton fraction decreases to 80%. These experimental values are in good agreement with the values predicted by a simple scaling equation of the proton ratio on the plasma volume and the ion loss area.
TL;DR: In this paper, a powder gun with a keyed launcher (keyedpowder gun), which is capable of accelerating projectiles of 20-40 g in weight without rotation to velocities of even greater than 2 km/s, was produced for the first time.
Abstract: Experimental equipment for the precise oblique‐impact shock study of solids in several 10 s of GPa region was developed. A powder gun with a keyed launcher (keyed‐powder gun), which is capable of accelerating projectiles of 20–40 g in weight without rotation to velocities of even greater than 2 km/s, was produced for the first time. The gun has a double‐wall structure launcher with a key whose muzzle shape resembles an old moon (basic bore diameter is 27 mm). Measurement of projectile velocities in the launcher by the reflected‐light method, including a logic trigger circuit for shock‐wave measurements, is combined with this gun. It was confirmed that the parallel‐plate impact experiment (normal type or oblique type), in which the tilt angle of parallel plates is less than 0.18° could be performed, allowing precise measurements of impact velocity and shock‐wave data by electrical and optical methods. Further, the keyed‐powder gun should find other widespread applications, e.g., for hypervelocity‐aerodynamic simulation study.
TL;DR: In this article, an active vibration isolation system for an interferometric gravitational wave antenna was proposed, which was able to reduce the effective resonant frequency of the test mass to 0.04 Hz.
Abstract: We discuss an active vibration isolation system which is a prototype of an isolation system for an interferometric gravitational wave antenna. Particular attention is paid to factors which limit the isolation which can be achieved. We were able to reduce the effective resonant frequency of the test mass to 0.04 Hz. Between 3 and 8 Hz, this was sufficient to bring the motion of the test mass within a factor of 2 of its Brownian motion amplitude.
TL;DR: In this paper, the authors describe modifications of a commercial NOx detector for very high sensitivity and ease of computer assisted data acquisition, including a larger gold-coated reaction chamber, increased ozone flow, a faster vacuum pump, analog outputs to define mode and range status, and enhanced cooling for the PMT.
Abstract: We describe modifications of a commercial NOx detector for very high sensitivity and ease of computer assisted data acquisition. These changes include a larger gold‐coated reaction chamber, increased ozone flow, a faster vacuum pump, analog outputs to define mode and range status, and enhanced cooling for the PMT. The detection limit, defined as a signal‐to‐noise ratio of 1:1 at the ±2 σ level is about 10 ppt with a 1/e response time of about 20 s or about 45 ppt for 1 s. Detection of other reactive nitrogen compounds is also discussed.
TL;DR: In this paper, a singlemode fiber-optic interferometer for measuring subangstrom vibrations has been designed and constructed based on the Fizeau configuration and employs peak detection schemes in the signal processing.
Abstract: A single‐mode fiber‐optic interferometer for measuring subangstrom vibrations has been designed and constructed. The interferometer is based on the Fizeau configuration and employs peak detection schemes in the signal processing. The instrument has been used to measure the displacement of a cricket’s tympanic membrane.
TL;DR: A time-resolving grazing incidence spectrograph based on an image intensified photodiode array detector has been constructed and has demonstrated its utility as a fusion plasma diagnostic.
Abstract: A time‐resolving grazing incidence spectrograph based on an image intensified photodiode array detector has been constructed and has demonstrated its utility as a fusion plasma diagnostic. The total wavelength coverage is 15–360 A with 0.7 A resolution (line profile FWHM); portions of this range may be observed during a single plasma discharge with a bandwidth of ∼40 A when the detector is centered at 40 A and ∼80 A with it centered at 200 A. Integration times from 5.4 to 13.1 ms are available when the entire photodiode array is read out; integration times as short as 1 ms can be obtained for a few lines of interest through the readout of selected photodiodes. The spectrograph has been radiometrically calibrated over the 60‐ to 360‐A range at the NBS SURF II electron storage ring and is currently in operation on the Princeton Large Torus (PLT) tokamak.
TL;DR: In this paper, a simple spherical analyzer combination suitable for use in high-resolution electron energy-loss spectroscopy (HREELS) is described, which is designed to be intrinsically insensitive to extraneous magnetic fields.
Abstract: A simple spherical analyzer combination suitable for use in high‐resolution electron energy‐loss spectroscopy (HREELS) is described. The system is designed to be intrinsically insensitive to extraneous magnetic fields. The problems presented by the control of the spectrometer are also discussed and the advantages of Fourier filtering demonstrated.
TL;DR: In this paper, a single sideband frequency demodulation scheme with large dynamic range is described, 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.
Abstract: 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.
TL;DR: In this paper, a new apparatus to simultaneously measure vapor-liquid equilibria and volumetric properties of coexisting phases is presented, especially designed to study hydrocarbon-carbon dioxide mixtures up to 45 MPa and 433 K.
Abstract: A new apparatus to simultaneously measure vapor–liquid equilibria and volumetric properties of coexisting phases is presented. It was especially designed to study hydrocarbon–carbon dioxide mixtures up to 45 MPa and 433 K. Tests have been performed on isopentane–carbon dioxide mixtures. Comparison of the new results to those from literature shows that the just developed apparatus gives reliable data. Reproducibility tests have displayed very small data dispersion.
TL;DR: In this article, two electron-spectrometer systems designed for electron-electron coincidence spectroscopy are described, one based on two hemispherical analyzers and x-ray excitation, and the other based on a cylindrical mirror analyzer and electron beam excitation.
Abstract: Two electron‐spectrometer systems designed for electron–electron coincidence spectroscopy are described. One, based on two hemispherical analyzers and x‐ray excitation, is especially suited for Auger‐photoelectron coincidence spectroscopy (APECS) of solids and surfaces. The other, using a cylindrical mirror analyzer, a hemispherical analyzer, and electron‐beam excitation is designed for near‐dipole (e, 2e) spectroscopy of gaseous samples. Typical results obtained with these instruments are presented.
TL;DR: In this article, the advantages of rapid spectral scanning have been combined with the inherent accuracy of the compensating ellipsometer operated in the polarizer-compensator-sample analyzer configuration.
Abstract: The advantages of rapid spectral scanning have been combined with the inherent accuracy of the compensating ellipsometer operated in the polarizer‐compensator–sample‐analyzer configuration. Wavelength is scanned over the visible–UV (370–720 nm) at a maximum rate of 114 nm/s by rotating a continuously variable interference filter. A three‐reflection Fresnel rhomb serves as the achromatic quarter‐wave compensator. A microcomputer is used to collect spectroscopic measurements, perform instrument calibrations, digital filtering, and data interpretation.
TL;DR: In this paper, an automated seawater sample processing line employing a two-stage activated charcoal trap system cooled by a closed cycle helium refrigerator is described, where all dissolved gases except neon and helium are adsorbed on the first stage operating at 55 K with neon and liquid helium quantitatively adsorbled on the second stage at 10 K.
Abstract: An automated seawater sample processing line employing a two‐stage activated charcoal trap system cooled by a closed‐cycle helium refrigerator is described. All dissolved gases except neon and helium are adsorbed on the first stage operating at 55 K with neon and helium quantitatively adsorbed on the second stage at 10 K. The second stage trap is heated to 40 K to release virtually 100% of the helium isotopes (3He, 4He) for mass spectrometer measurement followed by heating to 70 K to release the neon component. Performance data for helium isotope measurements on seawater samples and air standards [4He≊10−9 to 10−6 cm3 (STP) and 3He≊10−15 to 10−12 cm3 (STP)] are presented.
TL;DR: In this paper, the physical properties of lanthanum hexaboride filaments, when operated as cathodes in a gas discharge, are presented, and a hairpin-shaped filament is designed for further extension of lifetime.
Abstract: Some physical properties of lanthanum hexaboride filaments, when operated as cathodes in a gas discharge, are presented. These directly heated hairpin‐shaped filaments have been tested in different types of ion sources and are shown to be capable of long‐pulse or cw discharge operations. The design of a shaped lanthanum hexaboride filament for the purpose of further extension of lifetime is also described.