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Dec 1982

Volume 53, Issue 12, pp. 1815-1941

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Biomagnetic instrumentation

Gian Luca Romani, Samuel J. Williamson, and Lloyd Kaufman

Rev. Sci. Instrum. 53, 1815 (1982); http://dx.doi.org/10.1063/1.1136907 (31 pages) | Cited 80 times

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We present a review of recent developments of the instrumentation for measuring magnetic fields emanating from the human body and other biological systems. The techniques for using various types of field sensors in shielded and unshielded environments are described, with special attention paid to recent advances in the application of SQUID systems. We also outline the present technical frontiers and point to avenues along which further improvements in performance are desirable.
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87.50.C- Static and low-frequency electric and magnetic fields effects

Improved instrumentation for measuring the magnetic field of cellular action currents

John P. Wikswo

Rev. Sci. Instrum. 53, 1846 (1982); http://dx.doi.org/10.1063/1.1136908 (5 pages) | Cited 8 times

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The instrumentation for measuring the magnetic field associated with the action potential in isolated nerve bundles has been improved to the extent that measurements can now be made in a typical laboratory without magnetic shielding. The superconducting magnetometer is operated in a liquid‐helium storage Dewar so that transfers of liquid helium are no longer required. A power‐line trigger circuit is used to minimize the interference of 60 Hz noise and its odd harmonics. A compensation circuit has been developed to correct, in real time, for the high‐pass characteristics of the magnetometer. As a result of these improvements, it is possible to observe action currents as small as 0.1 μA in a 1.0‐Hz to 1‐kHz bandwidth without signal averaging.
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87.80.-y Biophysical techniques (research methods)
07.55.-w Magnetic instruments and components
87.50.C- Static and low-frequency electric and magnetic fields effects

Apparatus for subjecting living cells to fluid shear stress

Steven R. Bussolari, C. Forbes Dewey, and Michael A. Gimbrone

Rev. Sci. Instrum. 53, 1851 (1982); http://dx.doi.org/10.1063/1.1136909 (4 pages) | Cited 52 times

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This apparatus subjects cultured cell specimens to controlled levels of fluid shear stress in vitro. The cone‐plate geometry permits long term (≳7 days) investigation of the effects of external fluid forces on living cells.
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87.80.-y Biophysical techniques (research methods)
87.16.-b Subcellular structure and processes
87.17.-d Cell processes

Nozzle design yielding interferometrically flat fluid jets for use in single‐mode dye lasers

Hans‐Peter Härri, Samuel Leutwyler@f@f, and Ernst Schumacher

Rev. Sci. Instrum. 53, 1855 (1982); http://dx.doi.org/10.1063/1.1136910 (4 pages) | Cited 14 times

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Fundamentals and design principles are presented for the generation of interferometrically flat jets of viscous fluids. The jet quality is optically analyzed and nozzle performance investigated in cw single‐mode dye laser operation. A nozzle providing a dye jet with an optically flat area of 9 mm2 is described. It produces a single‐mode bandwidth of ∼5 MHz without any active stabilization.
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47.15.Fe Stability of laminar flows
42.55.Mv Dye lasers

Simple arrangement for spatially scanning gain measurements in cw lasers

Juergen H. Massig

Rev. Sci. Instrum. 53, 1859 (1982); http://dx.doi.org/10.1063/1.1136911 (2 pages)

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A scheme for spatially scanning gain measurements is presented. Here, the parallel shift of the probe laser beam is effected by a rotating assembly of two plane mirrors. The arrangement is inexpensive and easy to adjust. It was applied to measure spatial gain profiles of a cw DF laser.
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42.60.Da Resonators, cavities, amplifiers, arrays, and rings

Miniature, sealed TEA‐CO2 lasers with integral semiconductive preionization

Paul Pace, Pierre Mathieu, and James Cruickshank

Rev. Sci. Instrum. 53, 1861 (1982); http://dx.doi.org/10.1063/1.1136912 (3 pages) | Cited 8 times

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A novel excitation technique is presented for TEA‐CO2 lasers. A homogeneous self‐sustained discharge is obtained with preionization provided through semiconductive plates. The laser can operate in a sealed configuration using a room‐temperature catalyst. Details of the construction and operating characteristics are given. Emphasis has been placed on simple and efficient construction in a compact device.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers

Production of 75‐keV, 70‐A, 10‐s ion beams

Masato Akiba, Masanori Araki, Hiroshi Horiike, Takao Ito, Mikito Kawai, Masaaki Kuriyama, Shigeru Kitamura, Shinzaburo Matsuda, Mamoru Matsuoka, Hidetoshi Mukaida, Yoshiaki Oguchi, Yoshihiro Ohara, Tokumichi Ohga, Hiroshi Ohtsuki, Yoshikazu Okumura, et al.

Rev. Sci. Instrum. 53, 1864 (1982); http://dx.doi.org/10.1063/1.1136913 (6 pages) | Cited 15 times

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High‐power long pulse ion sources were fabricated and tested at a prototype injector unit for JT‐60. Ion beams of 70 A at an energy of 75 keV were extracted repeatedly for up to 10 s. The heat loadings to each grid were within our design values and each grid turned out to be thermally stable during 10 s pulse. The neutral beam power deposited to the beam target was over 1.43 MW, which corresponds to the design value of the JT‐60 neutral beam injector. The e‐folding half‐width beam divergence angle was about 1.0° at optimum beam current and a proton ratio of about 80% was obtained. It was also confirmed that other beam line components, such as the ion beam dump and the cryopump, were sufficiently reliable.
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29.25.Lg Ion sources: polarized
29.25.Ni Ion sources: positive and negative
41.75.Ak Positive-ion beams
41.75.Cn Negative-ion beams

Design and operation of a self‐calibrated thermistor plasma calorimeter

J. D. Simpson

Rev. Sci. Instrum. 53, 1870 (1982); http://dx.doi.org/10.1063/1.1136896 (8 pages) | Cited 3 times

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This report describes the design and operation of a new diagnostic instrument for measuring the conversion of laser energy into plasma ions and soft x rays during ICF laser‐target interaction experiments. The instrument is operated as a differential calorimeter, and uses low mass thermistor flakes as both energy transducers and calibration sources. The calorimeter provides its own running energy calibration, in situ, by inducing electrical self‐heating of the thermistor elements. The instrument can be calibrated over a range of energies, either automatically or by manual selection. Calibration and operating principles are discussed, as well as physical and electronic design considerations, measurement and calibration data, and error sources.
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52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.70.-m Plasma diagnostic techniques and instrumentation
07.20.Fw Calorimeters

Ballistic pendula for measuring the momentum of a laser‐produced plasma

J. Grun and B. H. Ripin

Rev. Sci. Instrum. 53, 1878 (1982); http://dx.doi.org/10.1063/1.1136897 (4 pages) | Cited 7 times

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See Also: Erratum

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We describe the use of a ballistic pendulum array to measure the momentum of a laser‐produced plasma. An in situ calibration method is described and the pendulum results are compared to measurements made with other diagnostics.
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52.70.Nc Particle measurements
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)

Digital data‐acquisition system and mode analysis of magnetohydrodynamic instabilities in a noncircular tokamak

Shunji Tsuji and Hiroshi Toyama

Rev. Sci. Instrum. 53, 1882 (1982); http://dx.doi.org/10.1063/1.1136898 (6 pages) | Cited 1 time

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A microcomputer‐based data‐acquisition system has been developed to investigate large scale magnetohydrodynamic (MHD) instabilities in a noncircular tokamak, TNT‐A. Two pairs of multiplexers, sample and hold amplifiers, and fast AD converters, together with DMA data transfer, allow the system to support fast multichannel data acquisition (sampling time≂1.3 μs). Spectral analysis of poloidal magnetic field fluctuations gives mode numbers and the relative level of instabilities. A least‐squares method has been devised to identify poloidal mode numbers, while taking into account the effects of noncircularity and displacement of the plasma column. This method proved to be effective for a noncircular tokamak and it enables us to check mode mixing between different frequencies.
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52.55.Fa Tokamaks, spherical tokamaks
52.55.Hc Stellarators, torsatrons, heliacs, bumpy tori, and other toroidal confinement devices

Improved instrumentation to carry out surface analysis and to monitor chemical surface reactions in situ on small area catalysts over a wide pressure range (10−8–105 Torr)

A. L. Cabrera@f@f, N. D. Spencer@f@f, E. Kozak, P. W. Davies@f@f, and G. A. Somorjai

Rev. Sci. Instrum. 53, 1888 (1982); http://dx.doi.org/10.1063/1.1136899 (6 pages) | Cited 21 times

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Improved one‐tier and two‐tier designs for a high‐pressure–low‐pressure (HPLP) apparatus are described together with some of their recent applications. These instruments are used for surface analysis and in situ monitoring of catalytic reactions on small samples with a geometrical surface area of 1 cm2. Catalytic reactions are studied over a wide range of pressures (10−8–105 Torr) and temperatures (273–1273 K). The apparatus incorporates surface analysis methods such as Electron Spectroscopy for Chemical Analysis (ESCA), High Resolution Electron Energy Loss Spectrometry (HREELS), and 14C‐radiotracer labeling in addition to Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), and mass spectrometry. Facilities are also available for argon sputter‐ion cleaning, deposition of adsorbates by evaporation, and coverage calibration by means of a thickness monitor.
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81.65.-b Surface treatments

Local area time dissemination by carrier‐current waves

L. Mureddu and G. G. Pegna

Rev. Sci. Instrum. 53, 1894 (1982); http://dx.doi.org/10.1063/1.1136900 (5 pages)

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Carrier‐current waves (CCW) on ac power lines have been used to build up a new type of transmission network for timing signals. The peculiarities of the information carrier characterize its behavior as a standard frequency relay. Already existing very low‐frequency (VLF) timing receivers and constructed ad hoc transmitters have been used. Results reported here of tests carried out over extended time periods show that high precision and reliability are obtainable.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
07.50.Ek Circuits and circuit components

Modification of a commerical NOx detector for high sensitivity

A. C. Delany, R. R. Dickerson@f@f, F. L. Melchior, and A. F. Wartburg

Rev. Sci. Instrum. 53, 1899 (1982); http://dx.doi.org/10.1063/1.1136901 (4 pages) | Cited 16 times

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We describe modifications of a commercial chemiluminescent NOx detector to provide sufficiently high sensitivity to measure oxides of nitrogen in clean continental air. The changes include a larger reaction chamber, a faster vacuum pump, and a prereactor for background measurement. The detection limit, defined as a signal‐to‐noise ratio of 1:1 at the 2σ level, is about 0.10 ppb, with a response time of about 3 s. This corresponds to a ten‐fold improvement over the original detection limit.
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92.60.Sz Air quality and air pollution

Lightweight ozonizer for field and airborne use

E. J. Stone, J. R. Caldwell, C. de Waal, J. J. Horvath, R. Pearson, and D. H. Stedman

Rev. Sci. Instrum. 53, 1903 (1982); http://dx.doi.org/10.1063/1.1136902 (3 pages) | Cited 1 time

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An efficient, lightweight apparatus for the production of ozone in flowing oxygen or air has been constructed and tested. The exciter is an automotive electronic ignition running from a 28‐V dc power source. The discharge tube consists of coaxial conductive‐coated flint glass tubing fitting into Teflon end pieces. A single such unit will produce 4% ozone in oxygen flowing at 0.2 l/min, or a maximum of 0.020 l of ozone per minute in a total flow of 1.0 l/min.
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52.80.-s Electric discharges

Two methods for absolute calibration of dynamic pressure transducers

G. W. Swift, A. Migliori, S. L. Garrett@f@f, and J. C. Wheatley

Rev. Sci. Instrum. 53, 1906 (1982); http://dx.doi.org/10.1063/1.1136903 (5 pages) | Cited 2 times

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Two techniques are described for absolute calibration of a dynamic pressure transducer from 0 to 400 Hz in 1‐MPa helium gas. One technique is based on a comparison to a mercury manometer; the other is based on the principle of reciprocity. The two techniques agree within the instrumental uncertainties of 1%.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells

Automatic apparatus for nucleation investigations

Mark Baldwin@f@f and Bernard Vonnegut

Rev. Sci. Instrum. 53, 1911 (1982); http://dx.doi.org/10.1063/1.1136904 (4 pages) | Cited 4 times

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An automated apparatus serves repeatedly to detect and record the repeated formation of the crystalline phase in a single sample of a supercooled liquid. The technique is successfully applied to investigations of the nucleation of ice formation with silver iodide by repeatedly freezing and thawing a small volume of water in a U‐shaped capillary tube.
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82.60.Nh Thermodynamics of nucleation

Technique for producing uniform small droplets by capillary waves excited in a small meniscus

Haflidi Jonsson and Bernard Vonnegut

Rev. Sci. Instrum. 53, 1915 (1982); http://dx.doi.org/10.1063/1.1136905 (5 pages)

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The vibration caused by tapping a small liquid‐filled glass capillary causes small droplets to be ejected from the meniscus in its open end. This phenomenon serves as the basis for an apparatus capable of producing uniform water droplets in the size range from 3–150 μm diameter. The electric charge of the droplets can be controlled by electrostatic induction at their point of formation.
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47.80.-v Instrumentation and measurement methods in fluid dynamics

Modified gauge for time‐resolved skin‐friction measurements

Christopher O. Ajagu, Paul A. Libby, and John C. LaRue

Rev. Sci. Instrum. 53, 1920 (1982); http://dx.doi.org/10.1063/1.1136906 (7 pages) | Cited 7 times

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A new gauge for skin‐friction measurements in turbulent flows involving a wire close to the surface and a second, flush‐mounted film which serves as a constant temperature guard heater is described and evaluated. It is shown that a laminar calibration of the gauge applies to measurements in turbulent flow and that the frequency response of the gauge is appropriate for time‐resolved data in such a flow. Initial results from a turbulent channel flow are presented.
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06.30.Gv Velocity, acceleration, and rotation

Subnanosecond high‐voltage 50‐Ω calibrated attenuator

L. Bartolini and M. Fascetti

Rev. Sci. Instrum. 53, 1927 (1982); http://dx.doi.org/10.1063/1.1136914 (4 pages) | Cited 2 times

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We describe a single stage 50‐Ω, 10× resistive attenuator with a rise time less than 100 ps used to measure 20‐kV, 2‐ns pulses, driving an electro‐optic shutter in a 50‐J, CO2 laser system. An aqueous solution of aluminum nitrate is used as a resistive element. An axially symmetric shielded structure allows cascade operation of more units. Practical design parameters for a given matched impedance and attenuation as well as calibration procedures are reported.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables

Discharge treatment technique of breaking alternate fingers of an interdigital transducer

Awatar Singh

Rev. Sci. Instrum. 53, 1931 (1982); http://dx.doi.org/10.1063/1.1136915 (2 pages)

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This note reports a new technique of breaking alternate fingers of an interdigital transducer that is made of just one metal. The technique is based on the discharge treatment of the film. Various advantages of the technique are also pointed out.
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07.07.Mp Transducers

Improved evaporation geometry for powdered materials

Awatar Singh

Rev. Sci. Instrum. 53, 1932 (1982); http://dx.doi.org/10.1063/1.1136916 (1 page) | Cited 1 time

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This note reports the design of an improved evaporation geometry for the deposition of thin films of powdered materials. The geometry makes use of the fact that if the powdered material is heated in a chamber covered with two perforated strips with perforations misaligned, the paths for particle ejection are eliminated and reproducible pin‐hole free film deposition is observed. The geometry is found to be compatible with other materials which do not react with the source boat construction material.
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81.15.Jj Ion and electron beam-assisted deposition; ion plating
81.10.Bk Growth from vapor

Versatile facility for shaping hard and brittle materials

Moshe Deutsch

Rev. Sci. Instrum. 53, 1933 (1982); http://dx.doi.org/10.1063/1.1136917 (2 pages)

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A simple‐to‐construct attachment for a conventional wafering machine is described. The attachment incorporates an ultra‐high‐speed air turbine with a diamond needle cutting tool, and turns the wafering machine into a versatile milling machine for hard and brittle materials.
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06.60.Vz Workshop procedures (welding, machining, lubrication, bearings, etc.)

Dispersion electron spin resonance with the loop‐gap resonator

James S. Hyde, W. Froncisz@f@f, and Akihiro Kusumi

Rev. Sci. Instrum. 53, 1934 (1982); http://dx.doi.org/10.1063/1.1136918 (4 pages) | Cited 16 times

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

High‐temperature, multihole SQUID sensor

Stefan Zarembiński and Jakub Kachniarz

Rev. Sci. Instrum. 53, 1937 (1982); http://dx.doi.org/10.1063/1.1136919 (1 page) | Cited 2 times

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A report is given on the preparation of a high‐temperature SQUID sensor by coating a niobium sensor with a Nb3Sn layer superconducting at approximately 18 K. It seems that a similar technique could make it possible for a SQUID sensor to work at even higher temperatures (e.g., 20 K for GaxNb1−x or 23 K for Nb3Ge layers).
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85.25.-j Superconducting devices

Note on decreasing the bandwidth of frequency‐selective feedback amplifiers

E. M. Kiess

Rev. Sci. Instrum. 53, 1938 (1982); http://dx.doi.org/10.1063/1.1136920 (2 pages)

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The Q of a tuned feedback amplifier can be increased by increasing the impedance of the input circuit. The quantity gain times input impedance divided by Q is found to be constant. An experimental value Q in excess of 3000 was obtained.
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07.50.Ek Circuits and circuit components
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