bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of a simple low-field solenoid for the Quantum Design© SQUID magnetometer
Authors: Wang L.-Q. , Minhaj M. S. M. , Chen J. T. , Wenger L. E.
Published: July 2002

A simple copper-wire solenoid is constructed on the exterior of the experimental sample chamber tube of the Quantum Design MPMS© SQUID magnetometer. This copper solenoid can generate fields of less than 20 Oe reproducibly and a field uniformity with less than a 0.1 % variation over a 4-cm length. With the addition of a mu-metal cylinder, zero fields of less than 1 mOe can also be attained.
High-temperature pulsed slit nozzle for supersonic jet spectrometry
Authors: Lin C. H. , Imasaka T.
Published: July 2002

An interface converting a cone flow into a rectangular flow is attached to a conventional nozzle with a circular orifice. This assembly can be heated to 300 °C, due to a metal-to-metal contact between an orifice and a plunger and to a Teflon-insulated copper wire of an electromagnet. At the top of the interface, two razor blades are attached to convert the rectangular flow into a slit flow. The enhancement factor (long axis/short axis) is 6 in fluorescence measurements. The signal intensity obtained by the slit nozzle is four times larger than the best value obtained by the conventional circular nozzle.
5 kW transversely excited atmospheric CO2 laser driven by a solid state exciter employing insulated gate bipolar transistors
Authors: Hatanaka Hidekazu , Midorikawa Katsumi , Obara Minoru , Tashiro Hideo
Published: July 2002

An average laser output power as high as 5 kW has been produced from a transversely excited atmospheric CO2 laser pumped with a new solid state exciter. The exciter providing a 100 J transfer energy consisted of a high voltage pulse generator and a two stage magnetic pulse compressor. A stack of new high power semiconductor switches, called insulated gate bipolar transistors, was employed for the main switch of the pulse generator. A sophisticated discharge head with the corona preionization behind a perforated anode was designed to realize fast and uniform gas flow in cooperation with acoustic dampers. The maximum average laser power of 4.6 kW was attained at a repetition rate of 550 pps with an overall efficiency as high as 10.5%. The maximum repetition rate achieved was 1.1 kpps, at which the resulting average laser power was 3.4 kW.
Multichannel Raman spectrometry system for weakly scattering materials at simultaneous high pressures and high temperatures
Authors: Schiferl D. , Sharma S. K. , Cooney T. F. , Wang S. Y. , Mohanan K.
Published: July 2002

A Raman system is described which is suitable for rapid determination of Raman spectra of silicates and other weak Raman scatterers under simultaneous high-pressure and high- temperature conditions. Samples are pressurized with an argon pressure medium and Sm:YAG pressure standard in an Inconel 718 or rhenium Merrill–Bassett diamond–anvil cell that is externally heated in a vacuum oven equipped with quartz windows on either side. Raman spectra are excited and collected through the front window using ≊160° scattering geometry. A triple spectrometer in conjunction with a holographic notch filter, disperses the Raman scattered radiation onto a liquid-nitrogen-cooled CCD detector. Simultaneously measured Sm:YAG fluorescence spectra are collected through the rear window and routed via an optical fiber to a second multichannel spectrometer system equipped with a diode-array detector. The high sensitivity of the detectors and the simultaneous measurement technique enable detection of and compensation of pressure drifts occurring at high temperature. The performance of the system is demonstrated by measurement of the positions and linewidths of the high-frequency Raman modes of polycrystalline forsterite (α-Mg2SiO4) at temperatures up to 930 K at pressures of ∼8 GPa and up to 842 K at pressures in the range 12–14 GPa.
A simple in situ calibration technique for soft x-ray film
Authors: Lu Pei-xiang , Fan Pin-zhong , Xu Zhi-zhan , Li Ru-xin , Wang Xiao-fang , Li Yue-lin , Zhang Zheng-quan , Chen Shi-sheng
Published: July 2002

A simple valid in situ relative intensity calibration technique for soft x-ray film is described. This is based on film exposure measurements of the uniform line-shaped distributed soft x-ray monochromatic irradiation transmitted through a step-wedge absorption filter. Fitting the calibration data with Henke’s semiempirical equation for thick-emulsion film, the characteristic curves for Shanghai 5F soft x-ray film without supercoat (SIOM-5FW) have been obtained in the wavelength region from 50 to 80 Å.
Real-time spectral analysis algorithm for space plasma three-dimensional ion mass spectrometers
Authors: Sittler E. C.
Published: July 2002

We have developed a fast real-time spectral analysis algorithm for space plasma three-dimensional (3D) ion mass spectrometers that deconvolves contributions to time-of-flight ion mass spectra for various ion species abundances. The algorithm is composed of a set of coupled linear equations with constant coefficients. The algorithm is implemented so that in-flight computers need only apply a predetermined number of multiplies and adds to the spectral data. The algorithm allows run times to be short and highly predictable, can accommodate the presence of background in the ion mass spectra, and can be updated to adjust to calibration changes and unexpected instrument anomalies or failures. Space plasma 3D ion mass spectrometers have the capability of generating large volumes of data and if not compressed would produce data rates that far exceed the telemetry rate usually allocated to space plasma instruments. The real-time application of this algorithm allows one to achieve compression ratios greater than 100 for the spectral data without introducing systematic errors to the computed ion abundances. It also allows the application of other higher level data compression techniques to provide additional compression of the telemetry data. Finally, the algorithm can be thought of as a way to increase the mass resolution of the ion spectrometer.
Novel design for a compact fiber-optic scanning force microscope
Authors: Binggeli M. , Kotrotsios G. , Christoph R. , Hintermann H. E. , Berghaus Th. , Güthner P.
Published: July 2002

We present a new scanning force microscope (SFM) design with a compact fiber-optic interferometric detection system that provides very high resolution for surface force measurements. The mechanical conception of the instrument includes the implementation of piezoelectric actuators for the interferometer alignment. The result of this approach is a high performance SFM with both easy handling and high versatility.
Resonance response of scanning force microscopy cantilevers
Authors: Chen G. Y. , Warmack R. J. , Thundat T. , Allison D. P. , Huang A.
Published: July 2002

A variational method is used to calculate the deflection and the fundamental and harmonic resonance frequencies of commercial V-shaped and rectangular atomic force microscopy cantilevers. The effective mass of V-shaped cantilevers is roughly half that calculated for the equivalent rectangular cantilevers. Damping by environmental gases, including air, nitrogen, argon, and helium, affects the frequency of maximum response and to a much greater degree the quality factor Q. Helium has the lowest viscosity, resulting in the highest Q, and thus provides the best sensitivity in noncontact force microscopy. Damping in liquids is dominated by an increase in effective mass of the cantilever due to an added mass of the liquid being dragged with that cantilever.
Recent advances in polarized ion source development (invited)
Authors: Schmelzbach P. A.
Published: July 2002

Experiments involving polarized beams and/or internal polarized targets are performed or proposed at many laboratories equipped with various type of accelerators and storage rings. Currently, the most powerful sources of polarized atoms and ions base on the atomic beam and the optical pumping methods. The present status of the polarized hydrogen source is discussed, with emphasis on the most recent improvements of the basic techniques allowing for the production of highly polarized, intense, dc or pulsed, positive or negative ion beams.
Development and experiments of a MEVVA ion source
Authors: Gao Y. , Yu Y. J. , Tang D. L. , Huang Y. M. , Geng M. , Gong X. R.
Published: July 2002

The MEVVA ion source presented in the present paper adopts the arc discharge mechanism with a cathode changeable by a motor for pushing in, and an accel–decel three-grid extraction system. The voltage proof level is higher than 60 kV, the ion source generally runs at a voltage of 40 kV, the average beam current is higher than 5 mA, the beam spot is about 150 mm in diameter, and the nonuniformity of beams is within ±20%. Measurements of the beam radial profile show that there is a platform of about 40 mm in diameter in the central region. Ion beams and their optimal operation conditions for the cathode materials Al, Ti, Cr, Fe, Ni, Cu, Y, Zr, Mo, Ta, W, C, LaB6, etc., have already been obtained.
Pulsed intense ion diode for surface modification
Authors: Nakagawa Yoshiro , Isaka Katsuhiko , Kohchi Akito , Matsushita Kenji
Published: July 2002

Pulsed intense ion diodes were investigated as the device made a unique processing of material surface. For the ion implantation, the intense metal ion beams were obtained from the annular magnetically insulated ion diodes. The metal ions of Cu, Al, Pb, Mo, and Ta, of the energy of ∼100 keV, the total current of ∼1 kA, and the pulse width of ∼0.5 μs were produced. For the pulsed intense heat or momentum, a cylindrically focusing pulse intense light ion beams of the ion current density ∼1 kA/cm2 were generated from a cylindrical magnetically insulated ion diode. By an ion diode of a conical PED, the high density ion beam was focused nearby the source.
Multiplate pseudospark ion sources
Authors: Jiang X. L. , Song Z. M.
Published: July 2002

A variety of intense pulsed ion beams has been generated by the multiplate pseudospark chamber with an axially symmetric, high voltage gas discharge at low pressure of about 10 Pa. The fundamentals of this new type of ion source have been discussed in this paper. The field escalation effect has been proposed to explain the discharge mechanism. The filamentation instability of the ion beam with high current densities has been studied.
Design features of a high-intensity, cesium-sputter/plasma-sputter negative ion source (abstract)a)
Authors: Alton G. D. , Mills G. D. , Dellwo J.
Published: July 2002

A versatile, high-intensity, negative ion source has been designed and is now under construction which can be operated in either the cesium-sputter or plasma-sputter mode. The cesium-sputter mode can be effected by installation of a newly designed conical-geometry cesium-surface ionizer; for operation in the plasma-sputter mode, the surface ionizer is removed and either a hot-filament or rf antenna plasma-discharge igniter is installed. A multicusp magnetic field is specifically provided for confining the plasma in the radial direction when the plasma-sputter mode is selected. This arrangement allows comparison of the two modes of operation. Brief descriptions of the design features, ion optics, and anticipated performances of the two source geometries will be presented in this report.
Production and acceleration of pulsed kiloampere currents of H− and subkiloampere currents of C−, F−, I−, and Pb− ions
Authors: Mozgovoy A. G. , Papadichev V. A.
Published: July 2002

Experiments on acceleration of various negative ions in a high-power coaxial diode with magnetic insulation are described. Various methods of initiating cathode plasma for H− production were tried: surface discharge of a dielectric by the prepulse in two cathode configurations and laser illumination of a dielectric cathode. A new more universal method of cathode plasma initiation was developed, allowing us to produce various species of negative ions including metallic ones. Rather rare plasma was injected from a plasma gun at the outer surface of the anode. This plasma penetrates partially into the diode through holes, and positive ions are extracted and accelerated by the negative prepulse or/and main voltage pulse of the diode and bombard the cathode surface. The energy deposition and cathode plasma parameters can be easily varied by orders of magnitude by changing near anode plasma density (by varying charging voltage of plasma gun and time delay between plasma gun pulse and prepulse and main voltage pulse of the diode) and ion acceleration voltage. Up to 30 A/cm2 of H− ion current density was recorded, as well as about 1 A/cm2 for C−, 0.3 A/cm2 for F−, and 0.1 A/cm2 for I− and Pb−.
Status report on Russian super EBIT and MINIEBIS projects (abstract)
Authors: Ovsyannikov V. P. , Alfeev V. A. , Drobin V. M. , Kultashev O. K. , Golenitskiy I. I. , Liljeby Leif
Published: July 2002

Design and preliminary checking of the electron beam passage for EBIT with 0.2 A electron current and 100 keV energy are presented. The small EBIS with a permanent focusing system can be useful for some applications. A periodic magnet system using permanent SaCo magnets with 0.7 T of the amplitude of magnetic field has been made recently.
A compact and intense negative heavy ion source
Authors: Mori Yoshiharu
Published: July 2002

A small, compact negative heavy ion source based on plasma sputtering has been developed at KEK. This ion source was successfully used for a secondary-ion mass spectrometry (SIMS) system and a beam current density of about 3 mA/cm2 was obtained at the sample position of the SIMS system with a Au− ion beam.
Development of ion sources for fusion research at SWIP
Authors: Jiang S. F. , Wang G. J.
Published: July 2002

To meet the requirement of fusion research for neutral beam injection, Southwestern Institute of Physics began the development of high current ion sources in the late seventies. A 7 cm duoPIGatron ion source, a 7×35 cm multifilament field free ion source, and an 8.5 cm multicusp ion source have successively been designed, built, and tested. The 7 cm duoPIGatron ion source was developed to study physical and technological aspects relevant to the high current ion source. The 8.5 cm multicusp ion source was developed to provide neutral beam injection for a mirror device MM-2U. It produces a 9 A, 25 keV, 50 ms hydrogen ion beam. In addition, a lithium ion source for plasma diagnostics has been developed.
Evaluation of tortuosity in acoustic porous materials saturated by air
Authors: Allard Jean F. , Castagnede Bernard , Henry Michel , Lauriks Walter
Published: July 2002

Tortuosity is an important parameter for the prediction of the acoustical properties of porous sound absorbing materials. The evaluation of tortuosity by resistivity measurements is now used in several laboratories, although this method presents several drawbacks. In particular, the complete saturation by a conducting fluid of a porous foam having a high flow resistivity is difficult to obtain without partially damaging the structure of the cells. A simple technique based on ultrasonic wavespeed measurements in a material saturated by air is described. This method has been used previously only for water or superfluid helium saturated materials.
An instrument for the heat flux measurement from a contour of a surface with uniform temperature
Authors: Baughn J. W. , Hoffman M. A. , Lee Daehee
Published: July 2002

An instrument for the measurement of the heat flux distribution along an internal or external contour of a surface with a uniform temperature is described. The main element in this instrument is an electrically heated narrow nickel/chromium ribbon which is mounted flush with, but thermally and electrically insulated from, walls on all sides. The walls are separately heated and are made of a highly conducting material (e.g., aluminum) to ensure a uniform temperature. Differential thermocouples are used to measure the temperature difference between the walls and Ni/Cr ribbon at various positions along the ribbon. The ribbon power is adjusted until the differential temperature is nulled at a particular position on the ribbon. Since conduction along the ribbon is small, the electrical power divided by the sensor area is a direct measure of the surface heat flux at the nulled position. This makes it possible to measure the local time-average heat flux at various positions along a contour of a surface inside a circular duct. The time constant in this application was 13 s. An uncertainty analysis shows that this instrument has an uncertainty of ±3.84% for a convective heat flux on the order of 900 W/m2.
An ultrahigh vacuum scanning tunneling microscope for use at variable temperature from 10 to 400 K
Authors: Horch Sebastian , Zeppenfeld Peter , David Rudolf , Comsa George
Published: July 2002

We report on the construction of an ultrahigh vacuum (UHV) scanning tunneling microscope (STM) specially designed for operation in the entire range of sample temperatures between 10 and 400 K. The sample is cooled by means of a liquid helium continuous-flow cryostat, while the supporting manipulator and the surrounding devices remain at room temperature. This allows rapid variation of the sample temperature. The standard instruments for surface preparation and analysis and the STM are contained in a single UHV chamber. By rotation of the manipulator the sample can be positioned in front of any of these instruments without changing the sample temperature. The performance of the microscope is demonstrated by two examples of images of xenon adsorbed on platinum(111) showing: (a) the evolution of the morphology of a submonolayer of xenon from adsorption at 17K up to desorption at about 90 K and (b) atomically resolved images of the hexagonal incommensurate rotated phase for xenon at monolayer completion.
Humidity sensor using conductivity type transducer
Authors: Chakraborty S. , Hasmi S. A. , Chandra S.
Published: July 2002

The alternating current conductance of ammonium paratungstate pentahydrate (APT⋅5H2O) is found to change sensitively (response time ∼3 min) with changes in relative humidity, but to remain practically independent over a wide range of frequency (100 Hz–10 KHz) and temperature (up to 80 °C). This property of APT⋅5H2O has been utilized to design a sensitive humidity sensor. A circuit has been developed whose output is a voltage varying with relative humidity.
Study of a high-powered He–Ne laser having rectangular discharge cross section
Authors: Ling Yiming , Qian Meizhen , Lu Peng
Published: July 2002

A rectangular cross-section discharge tube has been used to design and make a high-powered He–Ne laser. The output power of this kind of He–Ne laser can be raised by increasing the transverse size of the discharge tube. A He–Ne laser tube of 20×4.5 mm2 rectangular cross section and 1.7 m discharge length can give an output power of above 200 mW at 0.6328 μm. In this article, the design principle and the preliminary experimental results of this kind of He–Ne laser are briefly described and discussed.
Calibration of magnetic probes mounted in a copper wall
Authors: Orvis D. J. , Jarboe T. R.
Published: July 2002

In the Helicity Injected Tokamak, magnetic probes are mounted in the tungsten-coated, copper walls surrounding the plasma so that they do not act as limiters. The magnetic field attenuation from the copper, tungsten, and inconel (supporting the probe) depends on frequency. With their signals analyzed by Fourier techniques, probes are calibrated in place to known magnetic fields containing the spectral range of interest. Once a frequency response for each probe is determined, probe signals from plasma discharges are deconvolved to extract the true magnetic field at the plasma surface. The frequency response falls off at the expected R/L and skin frequencies. Deconvolution of probe signals can amplify high frequency bit noise, but noncausal, lowpass filters can correct this problem for most probes. Small low frequency error, caused by spectral leakage, is corrected by splicing a decaying signal onto the raw data. The probes are useful within the frequency range, 4 Hz<f<300 kHz.
Design and operation of a high pulse rate intense ion beam diode
Authors: Noonan W. A. , Glidden S. C. , Greenly J. B. , Hammer D. A.
Published: July 2002

Virtually all practical applications for intense ion beams require that the beam pulses be generated at high repetition rates. This paper reports the development of the first high pulse rate, long-lived ion beam diode. It is a magnetically insulated diode which has produced ∼75 keV proton and carbon beam pulses of 1.0–2.5 A/cm2 and 100 ns duration at up to 90 Hz in four pulse bursts. It has also produced 125 keV, 5 A/cm2 Ar beams at a steady 1 pulse per 30 s for over 1000 pulses between failures in many runs. This diode employs a magnetically confined anode plasma ion source, and the high repetition rate pulsed power systems are based upon saturable magnetic switching.
Microdiffraction instrumentation and experiments on the microfocus beamline at the ESRF
Authors: Engström P. , Fiedler S. , Riekel C.
Published: July 2002

A microfocus beamline has been installed at an ESRF undulator. The applications of this beamline will be mainly in diffraction and diffuse scattering. An ellipsoidal mirror has been commissioned which results in a flux of 2×1011 Ph/s in a 10 μm (circular) collimated beam at 13 keV at a bandwidth of about 3 eV. Further tests on capillary optics and Bragg–Fresnel optics have been done.
Features of the Uramoto-type sheet plasma as a possible negative ion source
Authors: Jimbo Kouichi , Iima Masashi
Published: July 2002

The Uramoto-type sheet plasma, which has a unique magnetic field geometry, has been investigated with both Langmuir and JAERI probes [Rev. Sci. Instrum. 62, 772 (1991)]. In these investigations, the plasma potential was found to decrease while the extracted negative hydrogen ion currents increased in the cold region of the plasma. The extracted negative hydrogen ion current also increased as the plasma potential decreased at the same location when the chamber was biased more negative. These features are very favorable for negative ion generation since the destruction of negative hydrogen ions in the extraction region of the source can be minimized resulting in larger negative hydrogen ion currents at constant discharge power. An extracted negative hydrogen ion current density of 3 mA/cm2 was obtained in a 150 V–10 A discharge.
Hardware for measuring flow through microporous membranes
Authors: Arenas A. , Victoria L. , Molina C. , Ibáñez J. A.
Published: July 2002

This article presents two solutions to the problem of determining small flows of liquids in experiments with solid microporous membranes. This measurement is carried out either by means of an integrator system or a derivator system which, combined with the respective control circuits, automatically control the performance of a flow measuring cell. These devices permit the determination of small flows (1–10 cm3/min with 0.1 cm3/min of sensitivity). They can also be applied to small pulsating flows such as those generated by a peristaltic pump.
The transient internal probe: A novel method for measuring internal magnetic field profiles (abstract)a)
Authors: Bohnet M. A. , Galambos J. P. , Jarboe T. R. , Mattick A. T. , Spanjers G. G.
Published: July 2002

The transient internal probe (TIP) diagnostic is designed to permit internal magnetic field measurements in hot, high density plasmas. A small probe is fired through the plasma at high velocities and magnetic field measurements are accomplished using Faraday rotation within the Verdet glass probe. Magnetic field resolution of ±40 G and spatial resolution of 5 mm have been achieved. System frequency response is 10 MHz. Ablative effects are avoided by minimizing both the probe size and the time the probe spends in the plasma. A two-stage light-gas gun is used to accelerate the probe (held by a sabot) to 2.2 km/s. The sabot is removed using gas dynamic forces and a gas interface system prevents the helium muzzle gas from entering the plasma chamber. Work is underway to integrate the TIP diagnostic with laboratory plasma experiments.
Growth and characterization of an epitaxially grown ZnSSe/MnZnSSe distributed Bragg reflector
Authors: Salokatve A. , Rakennus K. , Uusimaa P. , Pessa M. , Aherne T. , Doran J. P. , O’Gorman J. , Hegarty J.
Published: July 2002

A Bragg reflector consisting of a 25-period MnZnSSe/ZnSSE Bragg stack is reported. The II–VI semiconductor structure was grown by molecular beam epitaxy on a GaAs (100) epilayer. Structural characterization of the Bragg reflector was performed with double crystal x-ray diffraction and transmission electron microscopy. These studies indicated that the epitaxial II–VI structure, whose total thickness is about 2150 nm, remains pseudomorphic with the GaAs substrate. The Bragg stack has a maximum reflectance of 81% at 468 nm. This result shows that fabrication of high reflectance mirrors from epitaxial ZnSe-based II–VI compounds is possible in spite of relatively small refractive index differences between constituent II–VI layers.
Operation of a cw rf driven ion source with hydrogen and deuterium gasa)
Authors: Melnychuk S. T. , Debiak T. W. , Sredniawski J. J.
Published: July 2002

We will describe the operation of a cw rf driven multicusp ion source designed for extraction of high current hydrogen and deuterium beams. The source is driven at 2 MHz by a 2.5 turn induction antenna immersed in the plasma. Bare stainless-steel and porcelain-coated Cu antennas have been used. The plasma load is matched to the rf generator by a variable tap N:1 transformer isolated to 46 kV, and an LC network on the secondary. With H2 gas the source can be operated at pressures between 5 and 60 mT with power reflection coefficients <0.01. The extracted ion current density with a porcelain-coated antenna is approximately given by 35 mA/cm2/kW with an 80 G dipole filter field for input powers from 3.5 to 6.6 kW. The current density remained constant for operation with a 6 and an 8 mm aperture. The source has been operated for 260 h at 3.6 kW with a single-porcelain-coated antenna. Mass spectrometer measurements of the extracted beam at this power show a species mix for H+:H+2:H+3:OH+ of 0.49: 0.04: 0.42: 0.04. The calculated beam divergence using the IGUN code is compared with the measured divergence from an electrostatic sweep emittance scanner designed for high-power cw beam diagnostics. Phase space measurements at 40 kV and 23 mA beam current result in a normalized rms emittance of 0.09 π mm mrad.
An apparatus for glancing incidence ion beam polishing and characterization of surfaces to angstrom-scale root-mean-square roughness
Authors: Wissing M. , Holzwarth M. , Simeonova D. S. , Snowdon K. J.
Published: July 2002

An instrument is described which combines a glancing incidence ion beam erosion system with a scanning tunneling and an atomic force microscope. This instrument allows the ion beam polishing and surface topographic characterization of conducting and insulating, crystalline, polycrystalline, and amorphous samples under ultrahigh vacuum conditions. As an illustration of the capability of the instrument and the polishing technique, we present results demonstrating a fivefold improvement in rms roughness of a polycrystalline Cr film and a fivefold reduction in rms roughness of a vicinal, initially mechanically polished CaF2 (111) sample. The final rms roughness of the latter sample of 0.12±0.04 nm measured over the bandwidth of 10–500 nm is just 75% of the Ca–F interlayer spacing for the (111) surface orientation.
Fluorescence correlation spectroscopy with traveling interference fringe excitation
Authors: Hattori Mineyuki , Shimizu Hideaki , Yokoyama Hiroshi
Published: July 2002

A new improved fluorescence correlation spectroscopy method for determining motional states of particles, fluorescence correlation spectroscopy with traveling interference fringe excitation (FCSTFE), is described. With this method the modulated fluorescence signal from particles excited by an interference fringe moving at constant velocity is detected, and cosine and sine Fourier coefficients at the frequency of the traveling fringe [Fcos(t), Fsin(t)] are recorded. Autocorrelation functions of Fcos(t), Fsin(t), and the square of amplitude [A2(t)=Fcos(t)2+Fsin(t)2] were found to express the motion of the fluorescent particles. The apparatus utilizing a photon counting system was constructed, and the performance of the system was demonstrated by the determination of diffusion coefficients of dispersed fluorescent polystyrene spheres. Features of FCSTFE in particle dynamics evaluation are discussed.
An inexpensive instrument to detect radio-frequency leakage from transmission lines at millimeter wavelengths for personnel safety
Authors: Simonetto A. , Muzzini V. , Bruschi A. , Cirant S. , Granucci G. , Sozzi C.
Published: July 2002

Arrays of thermopile detectors arranged on flat panels were used to measure stray radiation from high-power transmission lines at 140 GHz in the FTU tokamak electron cyclotron resonance heating experiment. These instruments are insensitive to polarization and to the direction of propagation within ±40° off normal incidence. They have a time constant of 120 ms, therefore amplification and synchronous detection are required for the measurement of short radiation pulses. No special measurement techniques are required with long pulses or cw radiation. The typical sensitivity is 2 mV cm2/mW in long pulse operation and 47 μV cm2/mW for 1 ms pulses. The detectors are sensitive to light and adequate filtering should be added to suppress it if necessary. These characteristics are adequate for the measurement of human exposure levels to electromagnetic radiation in the millimeter wave range.
Near-field optoelectronic detector probes based on standard scanning force cantilevers
Authors: Danzebrink H. U. , Wilkening G. , Ohlsson O.
Published: July 2002

Near-field probes have been developed, based on standard, i.e., commercially available, Si cantilever probes for scanning force microscopy (SFM), which directly convert the optical near-field signal into an electrical signal using Schottky contacts. With these optoelectronic probes it is possible to realize very compact near-field microscopes. The probes are inserted into a SFM and measure the topography and the optical near-field signal simultaneously. The qualitative analysis of the light-sensitive areas of the probes and the detection of the optical near field is described. Finally, subwavelength resolution is demonstrated when a polished glass surface is investigated.
Detection of apparent skin motion using optical flow analysis: Blood pulsation signal obtained from optical flow sequence
Authors: Nakajima Kazuki , Maekawa Tsuyoshi , Miike Hidetoshi
Published: July 2002

A skin motion imaging system with two modes of operation, diffusive and specular reflections, was developed. The system consists of image capturing and processing elements. Using optical flow analyses of skin motion at the wrist, we have detected successfully a blood pulsation signal that concurs with the electrocardiogram. The signal provides information not only about blood pulsation, but also about blood circulation and the biomechanical properties of the skin. This system may have other applications in the future, such as noncontact blood pulsation detection and evaluation of the biomechanical properties of skin, for example.
Temperature controlled multiple pass absorption cell for gas phase chemical kinetics studies
Authors: Pilgrim Jeffrey S. , Jennings Richard T. , Taatjes Craig A.
Published: July 2002

The application of a Herriott-type optical multiple pass cell for absorption detection of transient species in temperature controlled laser pump-probe kinetics experiments is described. Using reaction initiation by laser photolysis in combination with reaction monitoring by absorption of a multiple pass laser allows confinement of the probed reaction volume to the temperature controlled region of a slow flow reactor. For transient measurements, this apparatus provides enhanced sensitivity from increased path length and accurate temperature control by limiting the pump-probe interaction volume. In addition, for a polarized probe laser, a simple arrangement using a polarizing beam splitter and a λ/4 plate allows doubling of the path length.
Precise linear internal friction expression for a freely decaying vibrational system
Authors: Zhu Xianfang , Shui Jiapeng , Williams J. S.
Published: July 2002

From a linear motion equation, the precise linear internal friction expression for the free decay method has been deduced for the first time. A detailed comparison between the newly deduced expression and the currently used approximation has also been addressed.
Field-ionizing lens system for the detection of high Rydberg states in multicharged ions of keV energies
Authors: Pesnelle A. , Andrä H. J.
Published: July 2002

A new detector for state analysis of multicharged ions, excited in high Rydberg states, at kinetic energies of the order of keV is described. It is composed of a field-ionizing lens system (FILS), associated with two electrostatic spectrometers; the first one, in front of the FILS, selects the q-times charged excited ions of interest, and the second one, behind the FILS, analyzes the (q+1)-times charged ions resulting from field ionization according to their kinetic energy. The principle of the FILS is to generate a linearly increasing electric field, colinear with the excited ion beam, that the excited multicharged ions experience until they are field ionized. This detector has been successfully used to detect for the first time the distributions of very high Rydberg n states in the domain n=67–100 produced in Kr7+*(n) ions by electron capture into Kr8+ from laser-excited Rb*(nip) atoms.
UV modification of surface pretilt of alignment layers for multidomain liquid crystal displays
Authors: Lien A. , John R. A. , Angelopoulos M. , Lee K. W. , Takano H. , Tajima K. , Takenaka A.
Published: July 2002

Two types of ultraviolet (UV) light induced modification of the surface pretilt of alignment layers are reported. The UV modification allows the liquid crystal (LC) surface pretilt angle of a polyimide film to be selectively altered in a small area. Two device structures for fabricating two-domain liquid crystal displays based on this selective alteration of the LC surface pretilt angle of polyimides are proposed. Results from 3D simulation show that each pixel splits into two domains for the proposed structures. Experimentally, two-domain twisted nematic (TN) test panels and thin-film-transistor (TFT) addressed two-domain TN panels were fabricated using this method. The UV modification described in this letter does not require conventional photoresist technology as do other methods of fabricating two domain liquid crystal displays (LCDs). This process is simple as it requires only one polyimide coating and one rubbing step for each substrate.
Heating of metal arc plasma under high vacuum
Authors: Tamba Moritake
Published: July 2002

The possibility of electron collisional heating of metal ions in the cathode sheath, and the ohmic heating of a plasma which is confined in the mirror magnetic field will be discussed. The rate of increase in the densities of the multicharged metal ions will be described, when the dc are current varied from 30 to 100 A.
Modeling of broad beam ion sources
Authors: Tartz M. , Hartmann E. , Scholze F. , Neumann H.
Published: July 2002

Our approach to ion beam modeling breaks down the complex interplay of competing elementary processes into a series of independent consecutive steps. Thus, both in methodological development and computational modeling, the main effort can be directed towards the processes which are of greatest relevance in the context given. Moreover, employment of the special software available allows for comprehensive and efficient optimization of multigrid ion sources for low ion beam divergence and long lifetime, even in a personal computer environment. Here, for our Kaufman-type two-grid ion source RR-ISQ 76 some ion beam characteristics in their dependence on geometrical two-grid configuration are calculated and discussed, first of all in terms of shape and area of the plasma sheath. These dependencies are used to optimize this particular ion source for a low beam divergence.
A new 14 GHz electron-cyclotron-resonance ion source for the heavy ion accelerator facility ATLAS
Authors: Schlapp M. , Pardo R. C. , Vondrasek R. C. , Szczech J. , Billquist P. J. , Vieregg J. , Xie Z. Q. , Lyneis C. M. , Harkewicz R.
Published: July 2002

A 14 GHz electron-cyclotron-resonance (ECR) ion source has been designed and built at Argonne National Laboratory. The source is a modification of the AECR [D. J. Clark, C. M. Lyneis, and Z. Q. Xie, 14th Particle Accelerator Conference (PAC), IEEE Conference 91 CH3038-7, 1991 (unpublished), p. 2796 and C. M. Lyneis, Z. Q. Zie, D. J. Clark, R. S. Lam, and S. A. Lundgren, 10th International Workshop on ECR Ion Sources, Oak Ridge, ORNL CONF-9011136, 1990 (unpublished), p. 47.] at Berkeley and incorporates the latest results from electron-cyclotron-resonance (ECR) developments to produce intense beams of highly charged ions, including an improved magnetic confinement of the plasma electrons with an axial mirror ratio of 3.5. The aluminum plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donate additional electrons to the plasma, making use of the large secondary electron yield from aluminum oxide. The source is capable of ECR plasma heating using two different frequencies simultaneously to increase the electron energy gain for the production of high charge states. The main design goal is to produce several eμA of at least U35+238 in order to accelerate the beam to coulomb-barrier energies without further stripping. First charge state distributions for gaseous elements have been measured and 210 eμA16O7+ has been achieved. A normalized, 90% emittance from 0.1 to 0.2 π mm mrad for krypton and oxygen beam has been found.
A two-dimensional ultrahigh vacuum positioner for scanning tunneling microscopy
Authors: Pond K. , Nosho B. Z. , Stuber H. R. , Gossard A. C. , Weinberg W. H.
Published: July 2002

A two-dimensional ultrahigh vacuum compatible positioner is presented. The positioner uses two piezoelectric inchworms which allow for motions of up to 1 cm with a precision of 4 nm mounted at right angles to each other in order to give two dimensions of motion. Images of three-dimensional In0.3Ga0.7As islands in cross section are presented to demonstrate the functionality of the positioner. It is found that motion towards the tip is smooth, while motion in the perpendicular direction is less smooth.
An improved method of generating analog waveforms from digital data
Authors: Bayard J.
Published: July 2002

As normally used, the digital-to-analog converter generates a series of constant amplitude signals that, taken together, approximate the desired analog equivalent of the initial digital signal. Hence, many samples are required to generate a reasonably smooth approximation. Even so, it is usually necessary to filter the resulting approximation to remove the sharp corners of the constant amplitude signals and blend them together. This requirement is particularly troublesome in the case of generating very low frequency analog signals, e.g., a 1 Hz sine wave. In this article we propose an inexpensive improvement in the commercial digital-to-analog converter cards. This improvement results in a waveform with much better quality than that produced by the usual methods.
A virtual instrument approach for automation of temperature programmed desorption
Authors: Wiegenstein Christopher G. , Schulz Kirk H. , Scott Joe
Published: July 2002

LabVIEW provides a method to create a user friendly automated Virtual Instrument that can be programmed to perform simultaneous display and control functions from several different laboratory instruments. This note describes how LabVIEW was used to create a temperature programmed desorption virtual instrument to facilitate easy control of sample temperature and data collection and handling. The program is easy to use, fairly versatile for different types of catalysis samples, and the data collected can be imported into most spreadsheets. The program as written controls the temperature in a linear fashion with very little deviation from the user defined ramp.
A high-speed variable-temperature ultrahigh vacuum scanning tunneling microscope
Authors: Nakakura C. Y. , Phanse V. M. , Zheng G. , Bannon G. , Altman E. I. , Lee K. P.
Published: July 2002

An ultrahigh vacuum scanning tunneling microscopy (STM) system capable of collecting constant-current STM images at rates exceeding 1 image/s at temperatures up to 900 K was designed, built, and tested. The microscope uses an inchworm to push a scanner assembly through a quartz tube towards the sample. When the scanner is within tunneling range of the surface, the inchworm is decoupled from the scanner, resulting in a small, rigid mechanical loop with a high resonant frequency. The cylindrical symmetry and the use of low thermal expansion materials reduces image distortion due to thermal drift. An analog proportional-integral controller with tilt correction is used to maintain a constant tunnel current. A personal computer running Microsoft WINDOWS ’95 is used to control all other instrument functions, as well as for data acquisition, manipulation, and storage. Problems associated with the non real time nature of the operating system were overcome by collecting the STM images within a virtual device driver. By taking advantage of the WINDOWS ’95 multimedia functions, the time required to display and save images was reduced below 5 ms using a standard personal computer with no special hardware other than data acquisition cards. Sample STM images of Pd(111) and halogens adsorbed on Cu(100) are presented.
Real time measurement of plasma position in the SINP tokamak
Authors: Saha S. K. , Bal A. , Kumar R.
Published: July 2002

An electronic hardware has been developed for the real time determination of the position of the plasma column in the SINP tokamak. The method is based on the Fourier integration of the poloidal magnetic field using cos θ and sin θ coils. The spurious pickups in these coils due to time varying magnetic fields have been explained by a model as being due to eddy currents in the vacuum vessel and the conducting shell. These pickups have been compensated in the hardware by simulating the effects of the eddy currents by linear networks. This diagnostic provides outputs proportional to the horizontal and vertical displacements of the plasma column at three toroidal locations simultaneously. An output proportional to the plasma current is also available. Performance evaluation shows that for both plasma current and displacements, the hardware outputs are in good agreement with the values computed by software.
Peak-detector-hold based circuit for trigger synchronization of the electron beam and wiggler in a free-electron laser experiment
Authors: Ravi Kumar A. V. , Mohandas K. K. , Sathyanarayana K. , Jain K. K.
Published: July 2002

A simple circuit based on the principle of peak detect and hold has been designed, tested, and used for efficient and reliable synchronization of the triggering of the relativistic electron beam and the electromagnet wiggler that are used in a pulsed, millimeter wave free-electron laser experiment. This circuit is found to be reliable in operation and has a jitter of less than 2% for a fixed wiggler current.
Beam optics of the SINGAP 1 MeV 100 mA D− direct current accelerator for thermonuclear fusion
Authors: Bucalossi J. , Desgranges C. , Fumelli M. , Massmann P. , Simonin A.
Published: July 2002

Injection of intense neutral beams (e.g., ITER up to 50 MW of neutral power) based on the neutralization of negative deuterium ions up to energies of 1 MeV is an important option for plasma heating and noninductive current drive in future thermonuclear fusion machines. The objective of the SINGAP experiment is to demonstrate the acceleration of 100 mA of D− to 1 MeV in an electrostatic accelerator concept. It is composed of only two acceleration stages: a preacceleration to 60 keV in a multiaperture structure, and a postacceleration to 1 MeV. The particular feature of the SINGAP accelerator is that the postaccelerator by means of an electrostatic lens merges the 60 keV beamlets into a single beam and accelerates the merged beam to 1 MeV in a single gap. The present article is devoted to the SINGAP optics study (simulation and experiment) for two geometric configurations: cylindrical and rectangular (more ITER relevant). Despite a higher measured divergence (8 mrad) than expected (4–5 mrad calculated) which is due to the magnetic field of the electron suppression system, this study has proved that the SINGAP concept can meet the optical requirement (divergence <5 mrad) for multiamperes injectors.
An ultrahigh vacuum system for the fabrication and characterization of ultrathin metal–semiconductor films and sensors
Authors: Bergh Howard S. , Gergen Brian , Nienhaus Hermann , Majumdar Arun , Weinberg W. Henry , McFarland Eric W.
Published: July 2002

An ultrahigh vacuum system has been designed and built to study the magnetic and electrical behavior of ultrathin metal films deposited on semiconductors. The system allows variable temperature metal film deposition by electron beam evaporation onto an electrically active, low noise device structure. Significant features include, the use of microfabricated substrates to create reliable zero-force electrical contacts to ultrathin metal–semiconductor devices, a dark atomic beam source, and a compact magneto-optic Kerr effect (MOKE) magnetometer with an external electromagnet. A temperature controlled rotating sample manipulator allows the active metal surface to be deposited in one position and subsequently rotated between the poles of the electromagnet for simultaneous MOKE and electrical measurements while the surface undergoes controlled dosing from a molecular or atomic beam. Low-energy electron diffraction is available for sample characterization and a quadrupole mass spectrometer is used to monitor the beam. Results of iron on Si(111) show magnetic coercivity increasing approximately linearly with increasing film thickness to 6.4 kA/m at 100 Å. Current–voltage measurements of 50 Å iron and copper on Si(111) when fit to a thermionic emission model showed, respectively, ideality factors of approximately 4 and 1, and barrier heights of 0.45 and 0.65 eV after deposition at 160 K and annealing to room temperature. The use of the thin Cu film Schottky diode for atomic hydrogen detection is demonstrated.
Pressure transducer mounts for internal blast measurements on thin metal walls
Authors: Yiannakopoulos George , Kiernan Peter
Published: July 2002

Three mounts are described for installing pressure transducers on thin walls for internal blast measurements in which the walls undergo ductile rupture. Details of the mounts are presented and each mount is evaluated from several examples of pressure-time profiles obtained from thin steel walled cubes and ship compartment studies. Two designs proved effective, one having a flange and a sheath to protect the transducer, and another, a simpler and lighter design, consisting of a welded ring.
Apparatus for direct addition of reagents into a nuclear magnetic resonance (NMR) sample in the NMR probe
Authors: Perrin Charles L. , Rivero Ignacio A.
Published: July 2002

Nuclear magnetic resonance (NMR) is a widely used tool in chemistry and biochemistry. It is occasionally necessary to add small aliquots of solvents or reagents repeatedly into the NMR tube. Ordinarily this is accomplished only by ejecting the sample and carrying out the addition outside the probe. It would be preferable to add the aliquot directly into the sample. We have designed and implemented a delivery system to accomplish this. This apparatus is particularly applicable to a recent NMR titration method for measuring relative pK’s and to experiments where temperature must also be varied. This apparatus provides a safe, simple, and inexpensive method for repeated aliquot addition directly into the sample in the NMR probe.