bluuebunny/crossref_metadata_2025 huggingface dataset:
A Laser Velocimeter for Remote Wind Sensing
Authors: Lawrence T. R. , Wilson D. J. , Craven C. E. , Jones I. P. , Huffaker R. M. , Thomson J. A. L.
Published: February 2004

A continuous wave carbon dioxide laser Doppler radar has been developed and applied to remote measurement of atmospheric wind velocity and turbulence. The carbon dioxide laser illuminates residual particulate matter in the atmosphere. Radiation scattered by these particles is homodyned with a local oscillator to provide the Doppler signal. The performance of the instrument is verified by comparison of wind velocity data recorded simultaneously by the laser Doppler system and a cup-anemometer-wind-vane system. Data were recorded, for 45 min intervals, of a single component of the horizontal wind velocity at an altitude of 10 m above the ground. The principle of the laser Doppler system and the theory of the system configuration are presented first, followed by the evaluation of the system. Sample data of a 20 min duration test run of a laser Doppler system are compared with conventional anemometer data. Further comparisons are given of the power spectral densities derived from the two time histories. All data comparisons indicate very close agreement of the two systems. Data inconsistencies are within the accuracy limitations of the conventional anemometer system. The range of the laser Doppler system during these tests was confined to approximately 30 m. Laser Doppler wind velocity data were observed at ranges exceeding 300 m; however, no conventional anemometer was set up at these ranges for data comparisons. Tests are planned for the near future, at which time comparison data at extended ranges will be recorded. These tests will also incorporate an on-line data processing system.
Modification of the Varian XL-100 NMR Spectrometer for Fourier Transform Operation
Authors: Sternlicht H. , Zuckerman D. M.
Published: February 2004

A procedure is described for converting the Varian XL-100 NMR spectrometer from continuous wave to Fourier transform operation. The modification is relatively simple, permitting the use of many different kinds of computer systems and pulse amplifiers. Selection of either the continuous wave or Fourier transform mode is straight-forward in the modified spectrometer.
Laser Reflection as a Technique for the Study of Dynamic Changes in Surface Morphology
Authors: Tester J. W. , Herrick C. C. , Reid R. C.
Published: February 2004

Changes in the surface morphology of a growing or evaporating crystal were measured by observing the intensity variation of a laser beam reflected from the crystalline surface of interest. In a specific application, the evaporation flux resulting from developing thermal etch pits on the (0001) plane of arsenic was successfully correlated to a function of the laser intensity and time.
A Versatile Apparatus for Neutralizing Stray Magnetic Fields of ac Origin
Authors: Hadley Gerald L. , Hart Roger G. , Yoshiyama James M.
Published: February 2004

Stray magnetic fields from power lines near a high-resolution electron microscope installation can be a serious problem. A convenient method of neutralizing these stray magnetic fields by generating an opposing field is presented. An oscillating stray magnetic field of more than 10 mG in the region of the microscope column can be effectively neutralized.
A Capacitance Depth Gauge for Thin Liquid Films
Authors: Marshall Billy W. , Tiederman William G.
Published: February 2004

A depth gauge useful in measuring the thickness of thin liquid films is described. The gauge operates on the principle of an end effect capacitance variation and offers the advantage that no part of the gauge protrudes into the liquid flow. Amplitude and frequency characteristics of the interface waves may also be measured with the gauge. The gauge has been utilized to measure the thickness and interface wave characteristics of a liquid film interacting with a supersonic gas flow. The data suggest that the gauge can sense wave frequencies up to 500 Hz provided the mean wavelength is an order of magnitude larger than the streamwise dimension of the gauge sensing elements.
Differential Micromanometer
Authors: Gill S. J. , Dresden Carl
Published: February 2004

A highly sensitive differential manometer is described. A unique feature of this manometer is its immunity to tilting. This feature is realized by a design which uses concentrically located regions of large fluid surface area which are connected to each other by means of a small capillary. Slight changes (1μ H2O) of pressure can be detected by bubble movement in the capillary.
Time Correlation Method for Extracting a Fast Rising Component from a Complex Pulse
Authors: Berzins G. , Lieber A. J. , Galbraith J. D. , Hoffman M. M.
Published: February 2004

A technique of shape discrimination, especially useful for certain types of input pulses, is presented. The parametric response of a system employing this technique is examined. The results of an experimental evaluation are discussed.
Note on the Falling Cylindrical Shell Viscometer
Authors: Lindgren E. Rune
Published: February 2004

A simple theory is presented according to which forces appear which tend to center the cylindrical shell in the fall tube of a falling cylindrical shell viscometer. This same result essentially should be obtained also for the falling cylinder viscometer, which necessarily must obey the same general principles but is more complicated in the analytical manipulations.
Programmed Sweep Unit for Expanding the Capabilities of a CAT
Authors: Hall Lawrence H.
Published: February 2004

The versatility of the CAT is expanded by a newly designed programmed sweep unit, which varies the dwell time during the sweep so as to optimize placement of points. System performance with the programmed sweep unit is at least an order of magnitude better than alternative methods such as oscillography.
Quasielastic Light Scattering under Optical Microscope
Authors: Maeda Tadakazu , Fujime Satoru
Published: February 2004

A system for quasielastic light scattering under an optical microscope is proposed. This system makes it possible to obtain some information about dynamic properties of macromolecules in a limited part (100×100 μ2) of a living cell.
A Compact High Speed Low Impedance Blumlein Line for High Voltage Pulse Shaping
Authors: Crouch J. H. , Risk W. S.
Published: February 2004

Design, construction, and operation of a low impedance Blumlein line are presented. Glycerol was used as a dielectric to obtain a 14.5 Ω line which in conjunction with a Marx generator driver could produce 5 nsec long 240kV pulses. The line, which is small enough to be housed in a Lucite box 30 cm wide×30 cm long×13 cm thick, was used to drive a bank of four 2.2 m long×30 cm wide×7.62 cm gap streamer chambers. Properties of the Blumlein line with water as the dielectric are also given and limitations on further shortening of the pulse are discussed.
A Data Acquisition System with Isolated Output Voltage for Acquiring Events-versus-Voltage Spectra
Authors: Auer Robert E.
Published: February 2004

A high speed, power supply programer with standoff capabilities in excess of 4 kV has been developed. By interfacing this programer with a multichannel analyzer, an automated data acquisition system for taking events-versus-voltage data has been constructed. The use of this system with a hemispherical electrostatic analyzer is discussed. Also discussed are electronic measurements of the total and relative accuracies of the system.
Diffractometer-Multichannel Analyzer Interface
Authors: Caustin Earl I.
Published: February 2004

A device is described which makes possible the storage of x-ray diffraction data in a multichannel analyzer, permitting convenient data display and manipulation.
Thermodynamic Temperature Measurement with a 161Dy Mössbauer Thermometer
Authors: Hess John
Published: February 2004

Measurements of thermodynamic temperature using a 161Dy Mössbauer absorber thermometer are described. It is suggested that the thermometer may be useful in calibrating or checking other thermometers below 0.6 K.
Comment on Density Determination of Nozzle Beams
Authors: Grace R. S. , Morrow D. P. , Aldridge J. P. , Skofronick J. G.
Published: February 2004

A method of measuring the scattering gas density in a molecular beam is described. The relative beam profile is normalized to the center line density determined by a probe connected to an absolute manometer. Reference is made to a nozzle beam system, but the technique is more general. Considerations of design parameters and probe location are given.
A High Current Density Thorium Carbide Thermionic Cathode
Authors: Glascock H. H.
Published: February 2004

Procedures for fabricating large indirectly heated thorium carbide cathodes are described. These cathodes will yield an emission current density of 10 A/cm2 at 2150 K and can be used in poor vacuum. The variation of effective work function with cathode temperature is presented.
Tubular Fast Flow Reactor for High Temperature Gas Kinetic Studies
Authors: Fontijn Arthur , Kurzius Shelby C. , Houghton James J. , Emerson John A.
Published: February 2004

A fast flow reactor suitable for gas kinetic studies at temperatures up to ≈2000 K is described. The reactor has been used in studies of the reactions of atomic Fe and Na with O2, for which performance data are given.
A Photon Counting Apparatus for Kinetic and Spectral Measurements
Authors: Bachrach R. Z.
Published: February 2004

An apparatus is described for spectral and time response measurements in luminescent materials using photon counting techniques. The system's most novel feature is its ability to switch rapidly between spectral and kinetic modes. Using the delayed coincidence method, with its excellent sensitivity, the kinetic measurements can be made easily with bandpasses as small as 0.5 meV. The system uses laser excitation pulsed by an acousto-optic modulator (3 nsec 1/e time) and for very fast measurements, mode locked pulses are used (0.25 nsec wide). Luminescent time decays from 1 nsec to 80 μsec can be obtained. The delayed coincident technique has been adapted to provide time resolved spectra with small time windows (<10 nsec) in the same range.
An Optical Thickness Monitor for Thin Film Vacuum Deposition Control
Authors: Kampwirth R. T.
Published: February 2004

An optical thickness monitoring device is described which utilizes simple mechanical construction and integrated circuit electronics to achieve a system which is easy to align, accurate, and highly reliable.
A Method for Studying Distribution Function Evolution during Wave-Particle Interactions
Authors: Murakami M. , Lidsky L. M.
Published: February 2004

A gated electrostatic trap has been developed that enables experimental observation of the time evolution of particle distribution functions for a wide range of wave-particle interactions. The technique entails trapping of an electron beam in a region where arbitrary wave fields are set up and the analysis of the perturbed distribution function after an arbitrary interaction time.
A Uniaxial Stress Apparatus
Authors: Seiler D. G. , Addington F.
Published: February 2004

A detailed description is given of the design and construction of a new type of uniaxial stress apparatus that is based on the use of a rotating cam to transmit the stress to the sample. The apparatus can be used at low temperatures and in large magnetic fields. Some preliminary data (for stress values up to ∼7.6 kilobar, the highest value yet reported for InSb) on the effect of stress on the frequency of magnetophonon oscillations in n-InSb at 77 K are presented.
Use of Fiber Optics in the Study of Chemiluminescent Reactions
Authors: Brown Robert L.
Published: February 2004

The use of stationary light pipes and a stationary detector to measure light decay along a tube in a steady state flow system is described. This method exhibits a number of advantages over that of moving the detector. A means of calibrating the transmission of the light pipes in situ by using the properties of the yellow nitrogen afterglow is discussed. The high degree of spatial resolution achievable by this technique should make it especially suitable for studies of small flames and discharges.
Noise Suppression by Time Exposure Oscilloscope Photography
Authors: Huchital G. S. , Young M.
Published: February 2004

We describe a simple and inexpensive means of enhancing repetitive signals obscured by noise with roughly equal amplitude. The signal and noise are displayed on an oscilloscope, and we perform a time average over many traces by time exposure photography. If the oscilloscope triggering is synchronous with the signal, the result is a significant suppression of the offending noise.
The Movable-Junction Stationary-Lead Thermocouple
Authors: Murdock E. G. , McLaren E. H.
Published: February 2004

The construction and use of two special platinum/platinum-rhodium thermocouples are described. One type of movable-junction stationary-lead thermocouple allows a substantial increase in the accuracy attainable in temperature gradient measurements in both fixed point (0–1100°C) and low gradient (<1°C) zones over that possible with the conventional standard thermocouple, by circumventing the systematic error arising from the interaction of the variable thermopower of unavoidably inhomogeneous thermoelement wires with the entrance temperature gradient in the throat of a furnace. The second form of the movable-junction couple permits the accurate determination of the immersion characteristics of each thermoelement of a couple in fixed point environments and therefore provides a ready means of measuring and studying the separate effects of cold-working, quenching, heat-treating, gaseous environment, etc., on the thermal emf of both the unit couple and its constituent elements.
Correction of Single Photon or Particle Timing Measurements for Multiparticle Events
Authors: Donohue David E. , Stern Richard C.
Published: February 2004

In particle time of flight or photon timing measurements, usually only the first event can be timed. An algorithm is derived which uses the measured distribution of first arrivals and a measured or assumed distribution of events per sweep to generate the desired distribution of all arrivals. The theory is shown to work at all values of the average count rate per sweep by comparison with computer simulated experiments. It is found that the optimum recovery of information at long times occurs at an average count rate per sweep of 1.
A Simple Recording Thickness Gauge
Authors: Evans Robert E.
Published: February 2004

An account is given of the construction and operation of a device which allows an Instron universal testing machine to produce a continuous autographic record of thickness or contour of specimens and small parts. This device has proven useful in the nondestructive measurement of irregular cross sections.
A Measurement of the Fast Luminescent Decay Time of P-15 Phosphor
Authors: Sutton John F.
Published: February 2004

The fast decay time of the 3900 Å spectral component of electron-beam-excited P-15 phosphor has been measured using a delayed coincidence technique. The result, 1.04 nsec ±∼2%, is in good agreement with previous estimates.
On the Concept of Magnetic Insulation
Authors: Winterberg F.
Published: February 2004

In a reply to a recent Note by Hirsch [Rev. Sci. Instrum. 42, 1371 (1971)], the several conditions for the feasibility of magnetic field insulation are presented. These conditions are quite similar to those to be satisfied for the magnetic confinement of an electron cloud.
Pressure Effect on the Sensitivity of Quartz Bourdon Tube Gauges
Authors: Szaniszlo Andrew J.
Published: February 2004

The sensitivity change for a commercial fused quartz Bourdon tube precision pressure gauge, due to a change in absolute pressure level, has been analytically computed and experimentally confirmed. The computed differential pressure error is 2.5% of full scale at a 100 atm absolute pressure level. The experimental method compared the fused quartz Bourdon tube gauge digital output to the results obtained from a nitrogen gas pressure system which had a high pressure, well-type mercury manometer as the differential pressure reference.
Sapphire Filaments as Hang-Down Supports for Magnetic Susceptibility Balances
Authors: Zatko D. A. , Davis G. T.
Published: February 2004

Sapphire filaments are designed to replace metal wires and quartz fibers as hang-down supports for electro-balances. The filaments possess greater ruggedness and maintain greater linearity than other commonly used supports.
A Simple Ultrahigh Vacuum Rotatable Seal
Authors: Mills J. C.
Published: February 2004

A simple and robust high torque, high vacuum rotatable seal is described. The seal has been tested to a pressure of 4×10−10 Torr and can be adapted to bakable systems. A number of configurations are described.
The Use of Helium Eliminates Refraction Effects in Optical Free Surface Motion Detector
Authors: Schmidt R. M.
Published: February 2004

Helium, having an ambient refractivity an order of magnitude less than other common gases, is employed to minimize the deflection of a modulated laser beam used to measure the free surface motion of an expanding annular cylinder loaded by a concentrically located capacitance discharge exploding wire. An experimentally determined Paschen curve confirms the need to isolate the He from the dynamic voltage along the wire.
An X Ray Tube Anode Current Stabilizer
Authors: Stermer Raymond A.
Published: February 2004

An x ray tube anode current stabilizer circuit employing a triac is described. This circuit combined with a dc x ray system provides a high degree of stability suitable for continuous x ray inspection systems.
An Inexpensive Electron Gun with an Inert, Replaceable Filament
Authors: Holloway P. H. , Hudson J. B.
Published: February 2004

Modifications are described which were made to the cathode assembly of a conventional CRT electron gun in order to reduce outgassing, gas reactions, and to improve reliability. Modifications involved replacement of the original cathode assembly with a thoria coated iridium wire filament. This filament permits maintainance of gun currents of more than 5×10−5 A, even in the presence of reactive environments. Preliminary modification using a lanthanum hexaboride coated rhenium ribbon filament indicated poisoning in reactive environments.
Solid State Stepping Motor Controller Providing Constant Angular Motor Shaft Velocity
Authors: Dalton Larry J.
Published: February 2004

A stepping motor drive system employing a new concept has been developed which provides constant angular velocity of the motor shaft for applications in which normal stepping action cannot be tolerated. The system furnishes variable speed and preserves the desirable characteristics inherent in stepping motor performance.
A Sealed Metal Freezing Point Cell for Thermometer Calibration
Authors: Sostman Henry E.
Published: February 2004

Metal freezing point cells for realizing defining points of the International Practical Temperature Scale in thermometer calibration must be kept free from contamination. Design and construction are described for a sealed cell in which the danger of contamination is virtually eliminated.
A Multiconductor Feedthrough for Very Low Temperature Applications
Authors: Abraham B. M. , Tague J.
Published: February 2004

Details and materials of construction of a multiconductor electrical feedthrough for very low temperature applications are presented.
A Simple and Inexpensive Stereotaxic Apparatus
Authors: McClure William O. , Anderson Larry E.
Published: February 2004

A stereotaxic apparatus is described which is built from commercially available machine tool parts with a minimum of machining and expense. Placement of either electrodes or needles for injections can be carried out in the brain or spinal cord of cats, or other animals of similar size, with a precision of ±0.05 mm.
The Moving Coil Ballistic Galvanometer Revisited
Authors: Rodeback G. W.
Published: February 2004

A concise formulation is given for the calibration of a moving coil ballistic galvanometer used to measure the electric charge of a transient current. Basic calibration methods for underdamped and overdamped operation are briefly described. A method is given for a complete calibration in terms of the total Ohmic resistance of the moving coil circuit. A useful approximation of the complete calibration has a particularly concise form.
An All-Glass Liquid Helium Dewar Employing No Auxiliary Cryogens
Authors: Wheatley John C. , Strait Stephen F.
Published: February 2004

A new type of all-glass silvered Dewar for liquid helium is described in which no auxiliary shielding cryogens are required. Radiation shielding is effected by means of an auxiliary annular space around the helium vessel which is kept cold both by its own heat capacity and by the process of natural convection utilizing the refrigeration in the rising helium vapors. A test Dewar with maximum helium volume of 860 cm3 held helium at atmospheric pressure for over 40 h and at pressures below 2 mm Hg for over 28 h.
High Speed Inexpensive Photodiode Assembly
Authors: McCall Gene H.
Published: February 2004

A photodiode assembly is described which incorporates a Hewlett-Packard 5082–4220 diode in an impedance matched holder to produce a unit with a rise time of approximately 100 psec and a fall time of approximately 300 psec. The assembly was designed for detecting fast laser pulses, but it can be used for monitoring any high speed optical signal.
A Motorized Drive for the Double-Tilting Specimen Holder of an Electron Microscope
Authors: Kritzinger S. , Marais D. J. , Monaci T.
Published: February 2004

A detailed description is given of a very compact motorized drive for the double-tilting specimen stage of an electron microscope. Tilting is effected by foot controls at a speed which is continuously variable between wide limits. A warning system indicates when it is safe to lift the specimen cartridge from the stage table and a friction clutch protects the delicate tilting stage against possible hazards. Manual tilting is possible by simply turning a lever to disconnect the motorized drive. No alterations to the microscope column are necessary to receive the motorized unit.
Hall Voltage and Magnetoresistance of Bi Measured by a Sum Frequency Method in a Belt Apparatus
Authors: Lundberg B. , Bäckström G.
Published: February 2004

An alternating magnetic field, 1.4 kG in amplitude at 5 Hz, was obtained in a belt type of high pressure apparatus by the use of conical pistons made of hardened high speed tool steel, permitting operation up to 50 kilobar. A frequency of 12 Hz was used for the current through the sample, and the Hall voltage was synchronously detected at 17 Hz. A signal yielding the coefficient of magnetoresistance was extracted at 22 Hz, using another lock-in amplifier. The Ohmic resistance may also be measured in the same experiment, and, by making certain assumptions, the variation of the carrier density and the hole and electron mobilities of a semimetal may be determined. Data for polycrystalline Bi at room temperature are given.
Pattern Velocity Computers: Two Types Developed for Wind Velocity Measurement by Optical Means
Authors: Ochs Gerard R. , Miller Glen F.
Published: February 2004

We describe two types of pattern velocity computers that have been developed specifically to measure average wind across an optical beam by observing the light scintillation in two spaced receivers. The technique is applicable to a wide variety of problems of this nature.
Internal Dynamic Stress Measurement with an Embedded Quartz Crystal Transducer
Authors: Calder C. A. , Dragnich R. G.
Published: February 2004

A technique for the measurement of internal dynamic stresses is described and experimental results are presented. The method utilized an embedded piezoelectric crystal to obtain dynamic stress information interior to the body. A Hopkinson pressure bar arrangement was used to compare outputs of the embedded transducer with surface mounted strain gauges. The pulse shapes were found to be identical to those obtained from the strain gauges with stress amplitude accurately evaluated using a modified piezoelectric constant.
A Sealed Titanium Window Proportional Counter for the Detection of ½ keV X Rays
Authors: McClintock J. E. , Levine A. , Rappaport S.
Published: February 2004

A sealed Ti window proportional counter sensitive to x radiation in the energy range 0.35–0.45 keV and >1.5 keV is described. Measurements of the Ti mass absorption coefficients and a graphical summary of the literature values are presented. For a proportional counter with a 930 μg/cm2 (2.1 μ) Ti window, the peak efficiency at 0.45 keV is found to lie between 4.6% and 7.1%. An application in x-ray astronomy involving a rocket observation of Sco X-1 is discussed.
A Portable Calorimeter for X-Ray Measurements of Fluence and Front Surface Dose Simultaneously
Authors: Wood D. S.
Published: February 2004

A small, easily portable and highly sensitive x-ray calorimeter has been constructed to measure fluence and front surface dose in tantalum from pulsed electron accelerations. Exceptional temperature stability and hence sensitivity is achieved by mounting the absorbers in an isothermal cavity cooled by an ice reservoir. Calibration of the x-ray fluence absorber was made by direct exposure to a 400 Ci 137Cs γ-ray source.
High Resolution Replicas for Electron Microscope Observation and Application to Ion Damage in Silicon
Authors: Vitali G.
Published: February 2004

A high resolution replica technique for observation with the electron microscope has been developed by applying suitable forces during the replica process. The method used allowed the resolution of surface damage structures having dimensions of the order of 40–50 Å, as produced in In-implanted Si samples.
Gateable Delay Gate Generator
Authors: Tatarczuk J. R.
Published: February 2004

An inexpensive delay gate generator is described. The unit can produce delays and pulse widths between 30 nsec and 10 msec, is externally triggered, and may be gated by a second external input. Four outputs are provided, two of which are complements of the other two and are capable of driving terminated 50 Ω cable. The unit is constructed of standard IC's and a few discrete components.
Simultaneous High Resolution Velocity and Attenuation Measurements in the Megahertz Region
Authors: Read D. , Holder J.
Published: February 2004

A pulse echo system operating in the low megahertz range for the simultaneous, continuous, and automatic measurement of ultrasonic velocity and attenuation is described and tested. The system uses a previously described pulse superposition method for the velocity measurement, but the superposition is interrupted periodically so that a conventional pulse echo attenuation measurement can be made. In an actual measurement the sensitivity of the system to changes in velocity was found to be about one part in 107, its sensitivity to attenuation changes was found to be about 0.001 dB/μsec, and no interaction between the attenuation and velocity change measurements was found.
A Technique for the Raman Spectroscopy of High Pressure Phases Recovered at Low Temperatures. The Low Frequency Raman Spectrum of Ammonium Fluoride II
Authors: Wong P. T. T. , Whalley E.
Published: February 2004

A technique is described for recording the Raman spectra of polycrystalline high pressure phases. The phase is made under pressure with a short piece of copper channel embedded in it and cooled to liquid nitrogen temperature under pressure. The sample is removed from the pressure vessel and the faces of the sample in the channel scraped flat and perhaps polished. The channel is mounted on the cold finger of a low temperature cell and the spectrum recorded at ∼100 K. Any powdered sample of a reasonably ductile material can of course be pressed into the channel and a clear block obtained. The Raman spectra of ammonium fluoride I and II obtained in this way are reported and briefly discussed.
A Versatile Soft X-Ray Appearance Potential Spectrometer
Authors: Long Robert L. , Beavis Leonard C.
Published: February 2004

The construction of a simple and versatile soft x-ray appearance potential spectrometer is described. The soft x rays are detected by measuring the positive current produced by photoemission from a stainless steel photocathode, which enables the detector circuit to be near ground potential and permits operation under pressures greater than 10−7 Torr. Typical operating conditions are described.
A Simple Method to Rapidly Advance Microelectrodes into Biological Cells
Authors: Jay A. W. L. , Duncan R. I.
Published: February 2004

A simple, inexpensive method to rapidly advance microelectrodes into biological cells has been developed. The system makes use of the pneumatic control feature of the de Fonbrune micromanipulator, which works on air bellows connected to the control joy stick by rubber air lines. A relay switch has been used to apply a small, reproducible, and accurately controlled amount of pressure on the rubber tubing concerned with the forward movement of the micromanipulator. The movements of the microelectrode are adjustable down to about 1 μ and are sufficiently fast to cause penetration of the cell membranes without excessive deformation of the membrane or damage to the cell. The system has been used successfully to measure membrane potentials from human red blood cells as well as from nerve cells in culture.
Multisample Cold Finger for a Dilution Refrigerator
Authors: Gubser D. U. , Jones L. D.
Published: February 2004

A sample holder that allows several samples to be simultaneously placed within the 3He/4He fluid of a dilution refrigerator is described. Samples are located inside a long narrow cold finger through which the cryogenic fluid is continuously circulating. Entry for installing samples is made with a removable soft solder seal. Magnetic effects of this soft solder seal are reduced by locating the seal near the top of the cold finger while samples are located near the bottom. The degree of isothermal conditions maintained along the length of the cold finger is examined, and operational characteristics of a sample holder presently being used are discussed.
An Astronomical Interface for a Small Computer
Authors: Nather R. Edward
Published: February 2004

Interface logic has been assembled which permits a small computer to record variable star data at high speed, display the accumulating light curve in real time, and exercise control over the data acquisition process. The interface design is quite general and has been used successfully to implement several other instrumental systems.
An Inexpensive, Digital Ramp, Programmable Temperature Controller
Authors: Buckley D. J. , Timbers G. E.
Published: February 2004

An inexpensive programmable temperature controller, which uses a digitally generated voltage ramp for controlling the temperature-time relationship, is described. The instrument, in conjunction with a thermoelectrically cooled microscope freezing stage, provides selectable cooling or heating rates from 0.25 to 8°C/min, over a temperature span from −40 to +20°C.
The Geometric Factor of a Cylindrical Plate Electrostatic Analyzer
Authors: Johnstone A. D.
Published: February 2004

A method for calculating the geometric factor of cylindrical plate electrostatic energy analyzers with various detector geometries is described. The effects of the fringe field are estimated. For a special simple case an exact geometric factor is calculated, enabling an estimate to be made of the inaccuracies of the approximations used in other cases. The results of some calculations are presented, and a simple approximate expression for the geometric factor is deduced.
Design of an Inexpensive, 30 cm Diameter, Long Path Difference Interferometer
Authors: Brown D. R. , Tarasuk J. D.
Published: February 2004

A long path difference interferometer for heat transfer, mass transfer, and aerodynamic studies has been designed and built. It was developed from an interferometer developed by Goldstein [Rev. Sci. Instrum. 36, 1408 (1965)] with the additional feature that the full field of the major optics (30 cm paraboloidal mirrors) is used. All of the optical components are stock items, making the interferometer relatively inexpensive.
Spectroscopy of Pulsed HF Chemical Lasers Using an Infrared Vidicon Camera Tube
Authors: Kwok M. A. , Cross E. F. , Jacobs T. A.
Published: February 2004

The spectroscopy of pulsed HF laser outputs has been performed using a Czerny-Turner spectrograph and an infrared camera tube on the focal plane. The system and typical results are discussed.
A Low Power Heater for the LaB6 Rod Cathode
Authors: Ahmed H. , Blair W. , Lane R.
Published: February 2004

A low power LaB6 rod cathode assembly has been designed and tested. Initial results have shown that a reduction of input power from 60 to 11 W can be achieved. The low power assembly has been operated in a sealed-off device without any adverse effects in the operation of the cathode.
Doubly Insulated, Guarded Ultrahigh Resistance Vacuum Feedthroughs
Authors: Madjid A. H. , Martinez J. M. , Vaala A. R.
Published: February 2004

The design modifications to turn a commercial ultrahigh vacuum feedthrough into a sapphire insulated guarded and shielded unit are described. Feedthroughs thus modified performed well in transport and emission measurements and the impedance of the units approached 1016 Ω when the sapphire insulation was properly cleaned. Cleaning procedures and the coupling of these units to low capacitance rigid lines made from standard copper plumbing fittings are also described.
A Simple Thermogravimetric Apparatus for Pressures up to 70 Atmospheres
Authors: Bae Jae Ho
Published: February 2004

A thermogravimetric apparatus has been developed which can be operated at pressures up to 70 atm and 600°C. A microforce transducer is used as the weighing device and the heater is placed inside the pressure vessel. Thermograms for the oxidation and evaporation of a crude oil at 70 atm are given to show typical performances of the apparatus.
Flow Conditioning in Electric Discharge Convection Lasers
Authors: Eckbreth Alan C. , Owen Frank S.
Published: February 2004

Electrical power deposition in both open and closed cycle CO2 electric discharge convection lasers (EDCL) can be enhanced by controlling the velocity profile in and introducing turbulence into the discharge zone. For the multiple pin electrode geometries typically employed in rectangular cross section laser channels, this can be accomplished by an array of adjustable baffles which span the flow upstream of the discharge region. Typically four baffles, whose chord is one-quarter of the channel height, are employed. Each baffle is individually adjustable to compensate for the nonuniform flow impedance of the electrode array. Measurements of electrical power deposition in both open and closed cycle operation and results of hot wire anemometer studies are presented.
Indium Sealing Techniques
Authors: Hochuli U. , Haldemann P.
Published: February 2004

Gold films are used as an alloying flux to form 5 μ thick indium film seals at temperatures below 300°C. Pyrex was sealed to quartz, ULE, CER-VIT, Irtran 2, Ge, GaAs, Invar, Kovar, Al, and Cu. The seals can also be used as current feedthroughs and graded seals.
The Astron On-Line Beam Energy Analyzer
Authors: Fessenden Thomas J.
Published: February 2004

This paper describes an analyzing system that was developed to measure the energy of a high-current, short-pulse electron beam of a few MeV energy produced by a linear accelerator. The system is able to determine the absolute energy of the beam with an accuracy of approximately 2%. It may also be used to determine variation of the beam energy of less than 0.1% occurring in times less than 10 nsec. Measurements of the beam current averaged over a pulse as a function of energy may also be made. Since the system uses a very small fraction of the primary beam current, it causes no interference with the normal operation of the accelerator.
A Compact Faraday Cup Array for Measurement of Current Distribution from Pulsed Electron Beams
Authors: Schuch Robert L. , Kelly John G.
Published: February 2004

Thirteen Faraday cups were fitted into a common housing to measure current distribution as a function of time, position, and drift tube pressures of the electron beam emitted by the 45 kA electron beam accelerator at the Sandia Laboratories. Description of the instrument design and the electronic configurations are given along with some examples of signals generated in individual cups by short duration (∼100 nsec) pulses of 3.2 MeV electrons.
A Simple Method for Determining the Acceleration Potential in Electron Probes and Scanning Electron Microscopes
Authors: Solosky L. F. , Beaman D. R.
Published: February 2004

In electron probes or scanning electron microscopes equipped with energy dispersive spectrometers the acceleration potential can be measured to better than 80 eV by observing the energy corresponding to the short x-ray wave-length cutoff λswl on a cathode ray tube. The intensity in the vicinity of λswl decreases linearly to a near zero count level at λswl; at higher energies there is also a linear decrease in counts. The intersection of these two lines provides an accurate measure of E0. The experimental conditions conducive to best results are described.
Simple Inexpensive Laboratory-Quality Rogowski TEA Laser
Authors: Seguin H. J. , Manes K. , Tulip J.
Published: February 2004

The design, construction, and operational parameters of a Rogowski-type TEA CO2 laser are given. The device, which is simple and inexpensive to build, incorporates a provision for intracavity experiments and appears suited for studies in plasma physics and nonlinear optics.
The Multipassage Magnetic Mass Spectrometer
Authors: Fortin Marc , Baril Marcel
Published: February 2004

A new kind of magnetic mass spectrometer is described. It consists of (n) magnetic prisms integrated into a single pole piece and (n−1) mirrors which return the beam from one prism to the other. It is shown that by an appropriate choice of the parameters of the apparatus the resolving power increases linearly with the number of passages in the prism. Experimental results verify the theory. Other properties of this system are also discussed.
Electronic Linearization of Temperature Using a Dual Element Sensing Technique
Authors: Massey John
Published: February 2004

All known temperature sensors today have some degree of nonlinearity. An analytic technique using a dual element sensing probe with a bridge type electrical thermometer is developed to reduce the magnitude of deviation from linearity. Specific algebraic solutions for nickel (concave upward) and platinum (concave downward) transducer materials are generated using this dual element technique, showing a significant improvement in linearity; i.e., worst case tracking errors are reduced to ±0.25 and ±0.043 °C for nickel and platinum, respectively, over the range −40–260 °C. Instrumentation of this technique for practical applications is discussed, leading to the development of a portable direct reading electronic thermometer having a worst case total error of 0.01 °C per year over the 0–100 °C range.
An Improved Cranz-Schardin High-Speed Camera for Two-Dimensional Photomechanics
Authors: Conway Joseph C.
Published: February 2004

The design of an improved Cranz-Schardin high-speed camera is presented and its application illustrated in a study of crack propagation. The camera, though simple and relatively inexpensive, is shown to provide adequate accuracy for studies in the field of dynamic photomechanics.
A Technique for Position Sensing and Improved Momentum Evaluation of Microparticle Impacts in Space
Authors: McDonnell J. A. M. , Abellanas Corenelio
Published: February 2004

The design of a three element piezoelectric microparticle impact sensing diaphragm is described which is sensitive to the detection of momentum propagated by the bending wave. The design achieves a sensitivity of 3×10−7 dyn·sec and optimizes the detection of the direct-path pulse from impact relative to secondary reflections and interference from discontinuities. Measurement of the relative arrival times and the maximum amplitudes of the outputs from the three piezoelectric sensors leads to the determination of the impact position and the normally resolved impact momentum exchange. Coincidence of the signals and a partial redundancy of data leads to a very high noise discrimination.
Excited State Mass Energy (ESME) Analyzer
Authors: Moses Kenneth G. , Steinhaus James F.
Published: February 2004

The instrument described in this paper can quantitatively monitor the excited state populations of intense atomic beams >30 mA. The maximum mass-energy accepted by the present apparatus is 40 keV H1+. The ESME analyzer provides a signal proportional to the total beam particle current for comparison with the fraction of the beam atoms in excited states; the electronic system performs the comparison and automatically obtains the ratio H1*/H10. Proposed is a possible future application of the analyzer in a feedback system for controlling the source and neutralizer components of a fusion reactor.
The Performance of Electron Multipliers in FIM Atom Probes
Authors: Brenner S. S. , McKinney J. T.
Published: February 2004

To produce reliable results, the particle detector in the time of flight spectrometer section of the FIM atom probe must detect all the particles incident on it, and must not generate extraneous pulses which might be misinterpreted as primary events. Three detectors of the continuous dynode type—the curved Channeltron multiplier, the magnetic strip multiplier, and the parallel channel plate multiplier—were tested in an FIM atom probe using 7 keV field ionized neon atoms as the detected particles. Under normal operating conditions all three detectors exhibited some afterpulsing, which increased rapidly with increasing gain. At low gains the broadened pulse height distribution makes detection of some of the events uncertain, and a compromise must be made between afterpulsing and detection efficiency. Only the curved Channeltron could be operated at high gains with a tolerable incidence of after pulsing (<3%) by changing the potential configuration at the input end of the detector. The time between the primary pulse and the afterpulses differed for the different multipliers. With the magnetic multiplier this time interval was the longest—about 350 nsec—and thus the afterpulses could be mistakenly attributed to metal compound ions when this multiplier is used.
Magnetic Hysteresis Loop Tracer Using Operational Amplifiers
Authors: Fay Homer
Published: February 2004

A magnetic hysteresis loop tracer has been built to measure the magnetic properties of small cylindrical samples of nonconductive ferromagnets. Applied fields of 10 000 Oe peak amplitude are obtained from a water cooled solenoid driven at 60 Hz, and the change in flux is detected with a coil on the sample. Two operational amplifiers convert the input variables to analogs of the local field H and the induction B or magnetic intensity I. The sample area and demagnetizing factor are used as parameters, and a correction is made for the excess coil area. Tests indicate that correct loops are produced except when the demagnetizing factor and the excess coil area are both large. Application to the rapid determination of the magnetic properties of hard ferrites is illustrated. The apparatus may also be used to magnetize and demagnetize samples and measure the permeabilities in both states.
Optically Pumped Differential Absorption Apparatus for Study of Slow Traps in Insulators
Authors: Goodman Lawrence A. , Arntz Floyd O.
Published: February 2004

A method of measuring small changes (less than 0.01%) in optical absorption resulting from radiation induced variations in the occupancy of slow trapping levels in wide gap semiconductors has been developed. The wavelength-scanned double beam optics, signal averaging equipment, and attendant control systems that have been utilized are described. An example of the results obtained during a study of CdS is given.
A New Electrostatic Energy Analyzer for ESCA
Authors: Lee J. D.
Published: February 2004

The axially symmetric analyzer decelerates an electron beam by a nearly homogeneous electric field. Refraction and dispersion at the interface of the electric field directs electrons within a narrow energy range (∼1.0 eV) to a circumferential detector. An empirical field distortion near the detector, introduced by a needle, augments energy separation for nearly axial electron trajectories.
The Design and Performance of a High-Speed Economical Ultrahigh Vacuum Chamber Utilizing Titanium Sublimation
Authors: Shen L. Y. L.
Published: February 2004

The pumping action produced by evaporating titanium onto very large surfaces held between 78 and 300 K has been studied inside a 60 liter steel tank. The present design offers high pumping speed at pressures below 10−9 Torr. The partial pressures of different residual gases under operational conditions were measured with a mass spectrometer. The partial pressures of several gases are reported as a function of temperature.
Use of Resonant Helix and Coil to Observe Overhauser Effects of a Deuterated Benzene Solution with the Tanone Free Radical
Authors: Fourrier-Lamer A. , Grandjean D.
Published: February 2004

This paper is concerned with a practical design which allows simultaneous electron and nuclear paramagnetic resonance studies at, respectively, 9100 and 2.18 MHz. In this apparatus, the microwave cell is a resonant helix.
Automatic Balanced Bridge for ESR Spectrometer
Authors: Hidaka Takehiko
Published: February 2004

A servo control system is described that permits automatic balancing of a magic-T ESR bridge to −50 dB. Amplitude and phase of the reflection from the balance arm are weakly modulated and a servo loop provides the correction signals to maintain bridge balance. The correction signals drive the motor driven variable attenuator and variable short. A leakage cancellation, from source arm to output arm, of −50 dB is obtained.
Instrument Function of a Cylindrical Electron Energy Analyzer
Authors: Aksela Seppo
Published: February 2004

The instrument function describing the broadening of the spectral lines due to the energy analyzer is treated as the convolution product of the calculated partial energy distributions arising from the angular divergence, the widths of the slits, and the nonradial motion of the electrons. The cases of first order focusing, second order focusing, and minimum trace width are considered. The nonradial motion of electrons in the electric field caused by emission from outside the symmetry axis is calculated numerically without making approximations in the analytical expressions. The analysis leads to results different from those published earlier. The calculations show that combinations of electron optical parameters can be found for which the effect of nonradial motion is very small. When these combinations of parameters are used, the electron source can be made comparatively large in the transverse direction.
A Simple, Low Power, Multiple Pulse NMR Spectrometer
Authors: Vaughan R. W. , Elleman D. D. , Stacey L. M. , Rhim W-K. , Lee J. W.
Published: February 2004

A low power (100 W) pulse spectrometer is described for work in solids, and the use of the spectrometer for performing the Waugh ``line narrowing'' multiple pulse experiments is demonstrated and discussed in detail. The performance of these measurements with a low power spectrometer is made possible by controlling the nature of the transient responses of tuned circuits within the spectrometer, and means for nullifying the effects of such transients on the effective rotation axis of an rf pulse are presented.
A Simple Liquid Helium Vapor Cooled Field Ion Microscope for the Study of Vapor Deposition
Authors: Reed D. A. , Graham W. R.
Published: February 2004

A bakable liquid helium vapor cooled field ion microscope suitable for ultrahigh vacuum studies of vapor deposition and thin film growth is described. The features include simplicity of design and economy of operation over the full temperature range down to liquid helium temperature. Movable evaporators allow in situ studies of thin metal films formed by vapor deposition.