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Dec 1994

Volume 65, Issue 12, pp. 3611-3874

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Crossatron‐based modulator for high repetition rate operation with arbitrary pulse widths

J. Mathew

Rev. Sci. Instrum. 65, 3756 (1994); http://dx.doi.org/10.1063/1.1144502 (5 pages) | Cited 3 times

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This article describes a Crossatron‐based modulator for driving 10–1000 μs duration plasma discharges. The modulator has demonstrated burst mode operation at pulse repetition rates of 50 kHz. Insulated gate bipolar transistors (IGBTs) are used to trigger the Crossatron. The pulse width of each individual pulse in a burst can be varied over a large range. A Jorway 221 timing and sequencing module command triggers the modulator, and a Labview‐based program is used to control the timing module via a GPIB bus. The modulator can output 25 kV pulses at 100 A. It can also operate at 10% duty cycle with peak currents of 10–20 A. © 1994 American Institute of Physics.
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52.80.-s Electric discharges
52.50.Dg Plasma sources
52.25.Os Emission, absorption, and scattering of electromagnetic radiation

Imaging Bragg spectrometer for pinched plasma experiments

K. Hirano, N. Hisatome, T. Yamamoto, and K. Shimoda

Rev. Sci. Instrum. 65, 3761 (1994); http://dx.doi.org/10.1063/1.1144503 (5 pages) | Cited 9 times

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A compact Bragg spectrometer for monochromatic imaging in the soft x‐ray region was designed and examined. With this spectrometer, a pinhole image is simultaneously recorded with a monochromatic image. This makes it possible to easily identify the wavelength when the location of the soft x‐ray source fluctuates from shot to shot, such as in the plasma focus and Z‐pinch plasma. An rubidium acid phtalate (RAP) flat crystal was examined and monochromatic images of the argon K lines around 4 Å were successfully obtained and displayed. The resolution power and dispersion obtained in situ were compared with the calculated values. © 1994 American Institute of Physics.
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52.70.La X-ray and γ-ray measurements
52.55.Ez Theta pinch

Surface‐enhanced Raman optical data storage: A new optical memory with three‐dimensional data storage

T. Vo‐Dinh and D. L. Stokes

Rev. Sci. Instrum. 65, 3766 (1994); http://dx.doi.org/10.1063/1.1144504 (5 pages) | Cited 1 time

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A new optical data storage technology based on the surface‐enhanced Raman scattering (SERS) effect has been developed for high‐density optical memory and three‐dimensional data storage. With the surface‐enhanced Raman optical data storage (SERODS) technology, the molecular interactions between the optical layer molecules and the substrate are modified by the writing laser, changing their SERS properties, so that they are encoded to store information as bits. Since the SERS properties are extremely sensitive to molecular microenvironments, very small ‘‘spectrochemical holes’’ approaching the diffraction limit can be produced for the writing process. The SERODS device uses a reading laser to induce the SERS emission of molecules on the disk and a photometric detector tuned to the frequency of the Raman spectrum to retrieve the stored information. The results illustrate that SERODS is capable of three‐dimensional data storage. © 1994 American Institute of Physics.
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42.79.Vb Optical storage systems, optical disks

Isolation of test masses in the advanced laser interferometric gravitational‐wave antennae

V. B. Braginsky, V. P. Mitrofanov, and S. P. Vyatchanin

Rev. Sci. Instrum. 65, 3771 (1994); http://dx.doi.org/10.1063/1.1144505 (4 pages) | Cited 21 times

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We analyze the experimental conditions required for the action of thermal, seismic, and excess noises on the test mass in the advanced LIGO experiment to be smaller than the uncertainty of the coordinate corresponding to the standard quantum limit. It is shown that the contribution of thermal noise can be made small enough if existing low‐dissipation materials are used for the suspension. On the other hand, the contribution of excess noise can be large and has to be examined thoroughly. © 1994 American Institute of Physics.
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04.80.Nn Gravitational wave detectors and experiments

Ultralow frequency oscillator using a pendulum with crossed suspension wires

Mark A. Barton and Kazuaki Kuroda

Rev. Sci. Instrum. 65, 3775 (1994); http://dx.doi.org/10.1063/1.1144506 (5 pages) | Cited 12 times

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A pendulum using four suspension wires in an X formation is described which can provide an arbitrarily long period in one dimension. Design equations are derived, and tested experimentally. A number of applications are outlined, including a low‐frequency vibration isolation system for a laser‐interferometric gravity wave observatory. © 1994 American Institute of Physics.
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07.10.-h Mechanical instruments and equipment
95.55.Ym Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques

Transfer function of a crossed wire pendulum isolation system

Nobuyuki Kanda, Mark A. Barton, and Kazuaki Kuroda

Rev. Sci. Instrum. 65, 3780 (1994); http://dx.doi.org/10.1063/1.1145202 (4 pages) | Cited 14 times

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We measured the vibrational transfer function of a newly proposed crossed wire pendulum in the frequency range 0.03–3 Hz. We confirmed that it behaves as a much longer simple pendulum of the same period as far as one dimensional movement of its center of mass is concerned. We conclude that the pendulum shows promise as a component in an ultra‐low frequency anti‐vibration system. © 1994 American Institute of Physics.
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07.10.-h Mechanical instruments and equipment
43.40.Tm Vibration isolators, attenuators, and dampers

Thin film position sensitive detector based on amorphous silicon p–i–n diode

Elvira Fortunato, Guilherme Lavareda, Manuela Vieira, and Rodrigo Martins

Rev. Sci. Instrum. 65, 3784 (1994); http://dx.doi.org/10.1063/1.1144507 (3 pages) | Cited 4 times

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The application of hydrogenated amorphous silicon (a–Si:H) to optoelectronic devices are now well established as a viable low cost technology and is presently receiving much interest. Taking advantage of the properties of a–Si:H based devices, single and dual axis large area (up to 80×80 mm2) thin film position sensitive detectors (TFPSD) based on a–Si:H p–i–n diodes have been developed, produced by plasma enhanced chemical vapor deposition. In this study, the main optoelectronic properties presented by the TFPSD as well as their behavior under operation conditions, concerning its linearity and signal to noise ratio, are reported. © 1994 American Institute of Physics.  
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85.60.Gz Photodetectors (including infrared and CCD detectors)
85.30.Kk Junction diodes

57Fe Mössbauer spectroscopy in a diamond‐anvil cell at variable high pressures and cryogenic temperatures

G. R. Hearne, M. P. Pasternak, and R. D. Taylor

Rev. Sci. Instrum. 65, 3787 (1994); http://dx.doi.org/10.1063/1.1144508 (6 pages) | Cited 16 times

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A detailed description is given of a new facility for transmission 57Fe Mössbauer spectroscopy (MS) studies on absorbers in a miniature diamond‐anvil cell in the temperature range 10–300 K and pressure range 0–45 GPa. Spectra with an adequate signal‐to‐noise ratio for a reliable analysis to be made have each been measured in 20–30 h of data accumulation time. This has been accomplished in spite of the severe constraints imposed by both the minute sample area and the high attenuation of the 14.4 keV probing radiation by the diamond anvils compared with the experimental conditions of conventional MS experiments. A custom‐made Rh(57Co) ‘‘point’’ source with a high specific activity has been used in conjunction with absorbers that have an optimal enrichment (10%–20%) of 57Fe. The successful implementation of 57Fe Mössbauer spectroscopy at very high pressures and variable cryogenic temperatures has been accomplished by making relatively simple refinements to existing elements of high‐pressure MS methodology. © 1994 American Institute of Physics.
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07.57.Pt Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells

A femtojoule calorimeter using micromechanical sensors

J. R. Barnes, R. J. Stephenson, C. N. Woodburn, S. J. O’Shea, M. E. Welland, T. Rayment, J. K. Gimzewski, and Ch. Gerber

Rev. Sci. Instrum. 65, 3793 (1994); http://dx.doi.org/10.1063/1.1144509 (6 pages) | Cited 101 times

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We describe a highly sensitive new type of calorimeter based on the deflection of a ‘‘bimetallic’’ micromechanical sensor as a function of temperature. The temperature changes can be due to ambient changes, giving a temperature sensor or, more importantly, due to the heat absorbed by a coating on the sensor, giving a heat sensor. As an example we show the results of using the sensor as a photothermal spectrometer. The small dimensions and low thermal mass of the sensor make it highly sensitive and we demonstrate a sensitivity of roughly 100 pW. By applying a simple model of the system the ultimate sensitivity is expected to be of the order of 10 pW. The thermal response time of the cantilever can also be determined, giving an estimate of the minimum detectable energy of the sensor. This we find to be 150 fJ and again from our model, expect a minimum value of the order of 20 fJ.
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07.20.Fw Calorimeters

Fabrication and characterization of diamond film thermistors

Koichi Miyata, Kimitsugu Saito, Kozo Nishimura, and Koji Kobashi

Rev. Sci. Instrum. 65, 3799 (1994); http://dx.doi.org/10.1063/1.1144510 (5 pages) | Cited 1 time

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Diamond film thermistors were fabricated from polycrystalline diamond films grown on sintered Si3N4 by microwave plasma chemical vapor deposition. An undoped diamond layer and a zigzag or rectangular pattern of B‐doped semiconducting diamond were successively deposited by a selected‐area deposition technique. For ohmic electrodes, a Ti/Au bilayer was used. The resistance‐temperature characteristics were measured from room temperature to 300 °C. It was found that the temperature coefficient of a diamond film thermistor with a B‐doped diamond layer grown using 0.1 ppm B2H6 as dopant gas was higher than those of platinum resistive temperature detectors and SiC film thermistors. © 1994 American Institute of Physics.
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84.32.Ff Conductors, resistors (including thermistors, varistors, and photoresistors)

Time‐dependent resistance relaxation in carbon and RuO2 based thermometers

L. Skrbek, J. Stehno, and J. Šebek

Rev. Sci. Instrum. 65, 3804 (1994); http://dx.doi.org/10.1063/1.1145168 (5 pages) | Cited 1 time

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The long‐term time‐dependent relaxation of the electrical resistance in several carbon and RuO2 based temperature sensors at helium temperatures was investigated. The relative change of the resistance at fixed low temperature, measured immediately after sufficiently rapid cooldown has been found to be always logarithmic with time. In the helium temperature range, the spurious temperature drift associated with this effect for Allen–Bradley and Matsushita carbon radio resistors and for Philips RuO2 based thick film sensors reaches about 1 mK per time decade, while for Rivac carbon film sensors it is an order of magnitude higher. The theoretical model explaining this relaxation based on the variable range hopping conductivity mechanism and the standard levels AHV theory of glasses at low temperatures was developed. © 1994 American Institute of Physics.
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07.20.Dt Thermometers
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

High‐Tc three‐axis dc SQUID magnetometer for geophysical applications

E. Dantsker, D. Koelle, A. H. Miklich, D. T. Nemeth, F. Ludwig, J. Clarke, J. T. Longo, and V. Vinetskiy

Rev. Sci. Instrum. 65, 3809 (1994); http://dx.doi.org/10.1063/1.1145169 (5 pages) | Cited 9 times

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A prototype three‐axis magnetometer has been developed, intended for geophysical applications, involving high‐transition temperature dc superconducting quantum interference devices (SQUIDs). Each SQUID was fabricated from a thin film of YBa2Cu3O7−x deposited on a SrTiO3 bicrystal to form two Josephson junctions, and was directly coupled to a single‐turn pickup loop patterned in the same film. The three orthogonally mounted sensors were immersed in liquid nitrogen in a fiberglass Dewar and operated in separate flux‐locked loops. In nominally zero ambient magnetic field, the best magnetic field resolution was 170 fT Hz−1/2 in the white noise, increasing to 225 fT Hz−1/2 at 1 Hz. The dynamic range was ±1.6×106 Hz1/2 in the white noise, and the highest slew rate achieved was 1.6 mT s−1, at 900 Hz. The 3 dB point in the frequency response was about 90 kHz. The three channels were mutually orthogonal to about 1%. The three‐axis magnetometer was also operated outside the laboratory in the presence of 60 Hz and radio‐frequency noise. © 1994 American Institute of Physics.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)
93.85.-q Instruments and techniques for geophysical research: Exploration geophysics

Design and fabrication of direct‐feedback gradiometer: Axial gradiometer made of superconductive films and SQUIDs

Koichi Yokosawa and Shinya Kuriki

Rev. Sci. Instrum. 65, 3814 (1994); http://dx.doi.org/10.1063/1.1145170 (6 pages) | Cited 5 times

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A new type of SQUID gradiometer, a direct‐feedback gradiometer, is introduced in this paper. It is an axial gradiometer made of thin superconductive films. It consists of two magnetometers: a ‘‘cancellation magnetometer’’ and a ‘‘sensing magnetometer.’’ The feedback flux of the cancellation magnetometer is applied to both pickup coils of these magnetometers by connecting their feedback coils in a series. Environmental magnetic noise applied to the sensing magnetometer is cancelled by the magnetic flux measured by the cancellation magnetometer, when the two magnetometers are connected with normal conductive wires. The gradiometer has been fabricated and operated in a moderate magnetically shielded room. The capability to reduce environmental noise and thus to measure auditory evoked fields from the human brain has been confirmed. © 1994 American Institute of Physics.
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85.25.Dq Superconducting quantum interference devices (SQUIDs)
87.50.C- Static and low-frequency electric and magnetic fields effects
87.80.-y Biophysical techniques (research methods)

A plasma arc reactor for fullerene research

T. T. Anderson, P. L. Dyer, J. W. Dykes, P. Klavins, P. E. Anderson, J. Z. Liu, and R. N. Shelton

Rev. Sci. Instrum. 65, 3820 (1994); http://dx.doi.org/10.1063/1.1145171 (3 pages) | Cited 6 times

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A modified Krätschmer–Huffman reactor for the mass production of fullerenes is presented. Fullerene mass production is fundamental for the synthesis of higher and endohedral fullerenes. The reactor employs mechanisms for continuous graphite‐rod feeding and in situ slag removal. Soot collects into a Soxhlet extraction thimble which serves as a fore‐line vacuum pump filter, thereby easing fullerene separation from soot. Thermal gravimetric analysis (TGA) for yield determination is reported. This TGA method is faster and uses smaller samples than Soxhlet extraction methods which rely on aromatic solvents. Production of 10 g of soot per hour is readily achieved utilizing this reactor. Fullerene yields of 20% are attained routinely. © 1994 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
52.75.-d Plasma devices

Development of a centrifuge ball viscometer for polymer melts

Kung Linliu, Fengji Yeh, Jeffrey W. Shook, William H. Tuminello, and Benjamin Chu

Rev. Sci. Instrum. 65, 3823 (1994); http://dx.doi.org/10.1063/1.1145172 (6 pages) | Cited 2 times

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A centrifuge ball viscometer was developed for fluids with a wide viscosity range. The viscosity η could be obtained from an empirically derived relationship ac=b(ηV∞)c, where ac is the applied acceleration, b and c are empirically determined parameters, and V∞ is the terminal velocity. The key features of this viscometer are as follows. (1) A wide range of viscosities can be accommodated: about 10−1 to 105 Pa s with 1010 Pa s achievable, in principle, for about a one‐data point per day measurement. (2) A computer controlled motion controller allows rotation speed of the motor varying over a speed of 1 to 5000 (±0.01) RPM (revolutions per minute). Thus, measurements at different low shear rates can be accomplished. (3) About 0.5 ml of sample volume is needed for the present setup. (4) The temperature can be maintained from ambient to over 400 °C (±0.05 °C). (5) The samples are isolated by sealing them in glass tubes, a potential advantage when dealing with polymer solutions, polymer melts, and/or those systems subject to oxidative degradation. © 1994 American Institute of Physics.
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83.85.Jn Viscosity measurements
83.80.Rs Polymer solutions
83.80.Sg Polymer melts

High‐temperature ovens (1700 °C) for a wide range of oxygen gas pressures (10−6–2×103 bar): A new two‐chamber autoclave

J.‐Y. Genoud, T. Graf, G. Triscone, and A. Naula

Rev. Sci. Instrum. 65, 3829 (1994); http://dx.doi.org/10.1063/1.1145215 (5 pages) | Cited 2 times

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We describe the construction of four different systems used for annealing samples in oxygen. The gas pressure can be controlled over nine decades (10−6–2×103 bar). The maximum temperature, 1700 °C, is limited by the ceramic materials used for thermal insulation and for the crucibles. The low‐pressure furnaces (10−6–1 bar) have an external heating system and incorporate an active regulation of a small gas flow. The intermediate pressure furnaces (1–150 bar) are heated either by a special resistive wire or by rf heating with a Pt‐20%Rh susceptor, both in the pressurized gas chamber. Quenching is possible in the latter. For the kbar range, we designed a double‐chamber autoclave with separate heater and sample spaces, filled with Ar and O2. The gas pressures are balanced in a cold, separate vessel by means of a silicon hose. The temperature is measured with a thermocouple feeding into the hot, pressurized oxygen environment very close to the sample. The construction problems of this new autoclave have been solved with particular emphasis on the safety requirements. © 1994 American Institute of Physics.
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07.20.Hy Furnaces; heaters
07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
74.72.-h Cuprate superconductors
74.62.-c Transition temperature variations, phase diagrams

A blow‐down combustion bomb for engine in‐cylinder kinetics research

M. A. Linne, R. K. Mackay, and W. L. Bahn

Rev. Sci. Instrum. 65, 3834 (1994); http://dx.doi.org/10.1063/1.1145173 (5 pages)

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In order to conduct chemical kinetic investigations under piston engine like conditions, a combustion bomb which emulates the pressure rise and decay within a piston engine cylinder has been designed and built. This allows one to investigate chemical kinetics in a realistic pressure‐time burst, without the complication of turbulent mixing. While phenomena like flame speed and heat release depend much more strongly upon fluid mechanics, emissions formation and removal depend strongly upon chemical kinetics. Typical problems of interest include soot oxidation during the pressure decay, coupling of emissions‐related chemical kinetic pathways for various components of reformulated fuel mixtures, investigation of toxics formation, and development of reduced kinetic mechanisms for engine codes which include chemical submodels. Here, the device and the processes by which it works, experimental data and a modified two‐zone thermodynamic model by which one can infer temperatures, volumes, and mass fractions are described. Combined results from experiments and the model indicate that the BDCB produces an excellent imitation of an internal combustion (IC) engine pressure‐time burst. Moreover, this device exhibits better cycle‐to‐cycle reproducibility than research engines, and it allows for unimpeded optical access and rapid sampling. © 1994 American Institute of Physics.
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82.33.Vx Reactions in flames, combustion, and explosions
82.20.Wt Computational modeling; simulation

A simple capillary rise apparatus to measure wettability in metal–ceramic systems

P. R. Chidambaram, B. Lanning, and G. R. Edwards

Rev. Sci. Instrum. 65, 3839 (1994); http://dx.doi.org/10.1063/1.1145174 (5 pages)

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An apparatus to measure the wettability parameter using the familiar capillary rise principle for a liquid metal/alloy in contact with a ceramic tube was constructed. The liquid levels outside and inside the capillary tube were measured using acoustic feedback and an electrical continuity technique, respectively. Measurements made by immersing silicon carbide, alumina, and silica tubes in various pure metals and alloys are presented and compared to previously published data in the literature. Reproducible measurements were obtained for nonwetting systems; however, the expected capillary rise was not observed for reaction wetting systems. © 1994 American Institute of Physics.
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68.08.Bc Wetting

A contactless method for measuring the bulk resistance of II–VI compound semiconductors

Edward D. Wheeler, Jack L. Boone, and James L. Drewniak

Rev. Sci. Instrum. 65, 3844 (1994); http://dx.doi.org/10.1063/1.1145175 (4 pages)

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A radio frequency measurement technique for measuring the bulk resistivity of II–VI compound semiconductors is described. Wafers of n‐type CdS are used to demonstrate the technique. An equivalent circuit model is introduced which predicts a frequency dependence for the CdS wafer impedance which agrees well with the experiment. The model assumes a broad distribution of relaxation times associated with the polarization. The radio frequency method gives values for the resistivity within 15% of four point probe measurements for the lower resistivity wafers, and within 5% for the higher resistivity wafers. © 1994 American Institute of Physics.  
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07.50.-e Electrical and electronic instruments and components
07.55.-w Magnetic instruments and components
72.80.Ey III-V and II-VI semiconductors

Extremely low‐noise amplifier for interfacing active devices to instruments for spectral analysis

P. F. Manfredi, V. Speziali, and F. Svelto

Rev. Sci. Instrum. 65, 3848 (1994); http://dx.doi.org/10.1063/1.1145176 (5 pages) | Cited 3 times

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An analog interface has been developed in order to perform very accurate noise spectral analysis with currently available instrumentation. It employs the device under test as a front‐end element, whose input‐referred noise voltage is amplified by a feedback loop which adds an extremely small noise contribution, followed by two cascaded low‐noise amplifiers. The interface is suitable for spectral analysis in the 100 mHz–100 kHz frequency range. Its intrinsic noise contribution is estimated around 1 nV/√Hz at 100 mHz and 50 pV/√Hz at frequencies beyond 1 kHz. © 1994 American Institute of Physics.
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84.30.Le Amplifiers

Development of a sealed‐off cw CO2 laser using a supported gold catalyst

A. K. Tripathi, N. M. Gupta, U. K. Chatterjee, and D. D. Bhawalkar

Rev. Sci. Instrum. 65, 3853 (1994); http://dx.doi.org/10.1063/1.1145177 (3 pages) | Cited 3 times

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A compact low‐power long‐life sealed‐off cw CO2 laser has been developed by incorporating a catalyst‐coated outer jacket that helps to regenerate CO2 from the dissociation products formed during discharge. Maintaining the catalyst at an optimized temperature prevented CO2 adsorption in its bulk and resulted in the required level of CO oxidation activity. The laser system has been operated during the day for the past five months at a constant output level of about 4 W. The gas analysis performed at different catalyst temperatures suggests that although the presence of CO in large amounts is detrimental, an optimum concentration of carbon monoxide supports the CO2 laser operation. © 1994 American Institute of Physics.
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42.55.Lt Gas lasers including excimer and metal-vapor lasers
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
78.60.Ps Chemiluminescence
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Thermal conductivity, thermal diffusivity, and specific heat of thin samples from transient measurements with hot disk sensors

Mattias Gustavsson, Ernest Karawacki, and Silas E. Gustafsson

Rev. Sci. Instrum. 65, 3856 (1994); http://dx.doi.org/10.1063/1.1145178 (4 pages) | Cited 63 times

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Transient measurements of thermal conductivity, thermal diffusivity, and specific heat capacity have been performed with hot disk sensors in thin samples of metallic materials. With this new variation of the hot disk method the sample size can be reduced to a volume less than ten cubic centimeters for copper at room temperature. It is also shown that the specific heat capacity can be conveniently measured in transient recordings of slightly longer duration. On comparing with standard values the accuracy turns out to be better than 1% while the precision (standard deviation of the mean from six measurements) on the average is about 0.5% for all values recorded. © 1994 American Institute of Physics.  
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07.20.Fw Calorimeters
72.15.Eb Electrical and thermal conduction in crystalline metals and alloys
65.40.-b Thermal properties of crystalline solids
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
65.80.-g Thermal properties of small particles, nanocrystals, nanotubes, and other related systems

Novel implementation of laser heated pedestal growth for the rapid drawing of sapphire fibers

V. Phomsakha, R. S. F. Chang, and N. Djeu

Rev. Sci. Instrum. 65, 3860 (1994); http://dx.doi.org/10.1063/1.1145179 (2 pages) | Cited 5 times

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A new version of laser heated pedestal growth system is described which is amenable for the rapid growth of single crystal fibers. The system incorporates a Gaussian reflector to reshape the radial intensity profile of the CO2 laser beam. When He is used as the growth atmosphere, high optical quality sapphire fibers can be produced at rates as high as 2 cm/min with this apparatus. © 1994 American Institute of Physics.
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42.81.Bm Fabrication, cladding, and splicing
81.10.Fq Growth from melts; zone melting and refining

Further measurements of the temperature dependence of the voltage response of piezoelectric tube scanner PZT‐5A for use in scanning tunneling microscopes

K. G. Vandervoort, R. K. Zasadzinski, G. G. Galicia, and G. W. Crabtree

Rev. Sci. Instrum. 65, 3862 (1994); http://dx.doi.org/10.1063/1.1145180 (2 pages) | Cited 2 times

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We report further measurements of the temperature dependence of the piezotube coefficient for material PZT‐5A. These new results support our earlier findings that the temperature dependence of the piezoresponse is linear to within 10% and is reduced by a factor of 5.5 on decreasing temperature from 300 to 4.2 K. Our new data imply that the piezocoefficient temperature dependence is reproducible for tubes of various sizes, even when the room temperature coefficients differ by more than 20% from their published values. © 1994 American Institute of Physics.
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77.65.-j Piezoelectricity and electromechanical effects
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Ripple due to asymmetry in symmetrical Cockcroft–Walton cascade rectifier circuit

Haibo Zhang and Akio Takaoka

Rev. Sci. Instrum. 65, 3864 (1994); http://dx.doi.org/10.1063/1.1145181 (2 pages) | Cited 3 times

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We experimentally examine the ripple and its spectra in the dc output of a symmetrical Cockcroft–Walton (CW) cascade rectifier circuit. Results show that the ripple due to the load consists of even harmonics and the ripple due to the circuit asymmetry consists of odd harmonics. In the latter, the ripple caused by the asymmetry of circuit elements cannot be compensated for completely through the asymmetry of the input voltage because of nonlinearity of a CW circuit. Approximately, the residual ripple is inversely proportional to the load resistance. © 1994 American Institute of Physics.
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84.70.+p High-current and high-voltage technology: power systems; power transmission lines and cables
84.30.-r Electronic circuits
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