bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR probe for dynamic-angle spinning
Authors: Mueller K. T. , Chingas G. C. , Pines A.
Published: July 2002

We describe the design of a probe for dynamic-angle spinning (DAS) NMR experiments, comprised of a spinning cylindrical sample holder whose axis may be reoriented rapidly between discrete directions within the bore of a superconducting magnet. This allows the refocusing of nuclear spin magnetization that evolves under anisotropic interactions such as chemical shift anisotropy and quadrupolar coupling, providing high resolution NMR spectra for quadrupolar nuclei in solid materials. The probe includes an axial air delivery system to bearing and drive jets which support and spin a rotor containing the sample. Axis reorientation is accomplished with a pulley attached to the probehead and coupled to a stepping motor outside of the magnet. The choice of motor and gear ratio is based on an analysis of the moments of inertia of the motor and load, the desired angular resolution, and simplicity of design. Control of angular accuracy and precision are discussed, as well as the efficiency of radiofrequency irradiation and detection. High resolution DAS spectra of oxygen-17 and aluminum-27 nuclei in polycrystalline minerals illustrate the experimental capabilities.
Microwave-enhanced magnetron sputtering
Authors: Yoshida Yoshikazu
Published: July 2002

A sputtering source utilizing both microwave and dc planar magnetron plasmas is described. Microwave power is introduced into the plasma by a coaxial-type cavity. The magnetron target is placed on the open end of the inner conductor. The microwave propagation from the surface of the plasma column produces additional gas ionization, resulting in a denser plasma at constant voltage. The operating pressure of this source is one-tenth as low as that of a conventional magnetron source. Measured deposition uniformity for Cu is ±4.5% within a 10-cm diameter at dc 100 W and microwave 800-W discharge powers for a 15-cm-diam magnetron at 6×10−4 Torr. The plasma impedance decreases with an increase in the inner conductor diameter and target diameter. The target-plasma sheath potential can be controlled by microwave power.
A new device for transport measurements on point contacts
Authors: Weber L. , Gmelin E.
Published: July 2002

We describe an experimental device, which enables the investigation of mechanical point contacts with variable contact size. Electrical resistance, thermal resistance, and thermoelectric power can be measured simultaneously at temperatures between 1.5 and 300 K. By investigation of the phononic part of the thermal resistance we introduce a new, reliable method for determination of the contact size.
High-flux x-ray undulator radiation from proposed B factory storage rings at Cornell University
Authors: Bilderback D. H. , Batterman B. W. , Bedzyk M. J. , Brock J. , Finkelstein K. , Headrick R. , Shen Q.
Published: July 2002

Two intersecting storage rings (8 GeV, 1 A and 3.5 GeV, 2 A) have been proposed to be built at Cornell University to enhance both the production of B mesons and synchrotron radiation. Exceedingly high x-ray flux from 3-m long undulators will be the new feature of a B factory for the CHESS laboratory. The flux produced integrated over the central cone of radiation can be as much as an order of magnitude higher than from the third-generation storage rings (now under construction) operating at 0.1 A.
DAPS−A new facility proposed for synchrotron radiation research in the UK
Authors: Padmore H. A. , Poole M. W. , Munro I. H.
Published: July 2002

The design parameters for a unique third generation synchrotron radiation source (DAPS) optimized to provide peak brillance in the range 5–100 eV for high flux, high spectroscopic resolution, imaging and polarization studies in the VUV–SXR regions.
Present status of the SORTEC SR Facility
Authors: Atoda N. , Awaji N. , Kodaira M. , Kishimoto T. , Nishino J. , Koga K. , Maejima Y. , Higashigawa I. , Yanagida K.
Published: July 2002

The status and performance of the SORTEC SR facility is described. Emphasis is placed on the reliable operation and the high performance of the SR source and the status of major systems for x-ray lithography.
The ELETTRA Synchrotron Radiation Facility
Authors: Walker R. P.
Published: July 2002

The present status of the ELETTRA Synchrotron Radiation Facility, under construction in Trieste, Italy, is described.
Synchrotron radiation instrumentation and macromolecular crystallography
Authors: Helliwell J. R.
Published: July 2002

Highlights of a workshop on synchrotron radiation intrumentation and macromolecular crystallography, a satellite meeting of the 4th International Conference on Synchrotron Radiation Instrumentation, will be presented. The theme of the meeting was to look towards the developments on the next generation of high brilliance SR sources current under construction. Macromolecular crystallography needs span a very wide range of technical requirments covering the most demanding uses of SR. It is a rapidly expanding field. (AIP)
Design of an instrument for far-infrared microspectroscopy using a synchrotron radiation source
Authors: Ugawa A. , Ishii H. , Yakushi K. , Okamoto H. , Mitani T. , Watanabe M. , Sakai K. , Suzui K. , Kato S.
Published: July 2002

A design of a microspectrophotometric system using a synchrotron radiation (SR) source is described. The system covers a wide spectral range of 50–13000 cm−1, being under construction at the UVSOR BL6B beamline in the Institute for Molecular Science. Preliminary experiments in the mid-infrared region (500–5000 cm−1) have qualitatively confirmed the theoretical calculation that the synchrotron radiation is more intense than a blackbody (T=1200 K) when a microspectrophotomeric technique is applied, which is due to natural collimation and high brilliance of SR source. The SR as an infrared source exhibits its advantage on measuring the spectra of small single crystals especially in the far-infrared region.
Resonant and nonresonant magnetic scattering (invited)
Authors: McWhan D. B. , Hastings J. B. , Kao C.-C. , Siddons D. P.
Published: July 2002

The tunability and the polarization of synchrotron radiation open up new possibilities for the study of magnetism. Studies on magnetic materials performed at the National Synchrotron Light Source are reviewed, and they fall into four areas: structure, evolution of magnetic order, separation of L and S, and resonance effects. In the vicinity of atomic absorption edges, the Faraday effect, magnetic circular dichroism, and resonant magnetic scattering are all related resonance effects which measure the spin-polarized density of states. The production and analysis of polarized beams are discussed in the context of the study of magnetism with synchrotron radiation.
Ion bombardment of thin layers: The effect on the interface roughness and its x-ray reflectivity (invited)
Authors: Puik E. J. , van der Wiel M. J. , Zeijlemaker H. , Verhoeven J.
Published: July 2002

In this paper we report on experiments which indicate the necessity of the use of ion-beam bombardment for e-beam deposited multilayer x-ray coatings. Measurements are described in which ion bombardment (200–300 eV Ar+) is used to ion etch metal layers after initial deposition and during deposition (ion-assisted deposition). In both cases a considerable smoothing of the metal surface occurs, resulting in enhanced x-ray reflectivities of metal-carbon multilayer coatings. As examples we show reflection measurements of Ni-C and W-C with nine and ten layer pairs, respectively, and d≊2.8 nm. Finally we discuss a special case: ion etching of Mo layers in Mo-Si coatings. On the one hand, we demonstrate the occurrence of smoothing of Mo, thereby enhancing the reflectivity of the layer and, on the other hand, the occurrence of ion bombardment induced intermixing at the Mo-Si interface, responsible for a decrease of the reflectivity.
Bakable superconducting magnet for magnetic circular dichroism and magnetic-imaging photoemission-spectromicroscopy studies
Authors: Koide T. , Shidara T. , Fukutani H.
Published: July 2002

An ultrahigh-vacuum compatible 5.8-T superconducting magnet system has been designed and constructed for use in magnetic circular dichroism (MCD) and magnetic-imaging photoemission-spectromicroscopy (MIPESM) studies. The design considerations and technical details of the cryosystem which is used to enable bakeouts, along with the magnet performance, are described. The experimental setups of the established MCD measurements and the planned MIPESM measurements are presented. An example of the obtained MCD spectra is also given.
Soft x-ray spectroscopy in atmospheric pressure helium
Authors: Roper M. D. , van der Laan G. , Flaherty J. V. , Padmore H. A.
Published: July 2002

We report on an environmental chamber, which is attached to a UHV beamline, in which soft x-ray measurements can be done at atmospheric pressure in helium. X-ray measurements in air can only be performed at energies above about 3 keV because of the strong absorption of soft x rays by oxygen and nitrogen. However, a low-Z scatterer such as helium has a long absorption length for soft x rays even at atmospheric pressure. Thus, this new chamber allows soft x-ray experiments to be performed on samples with physical properties that are incompatible with UHV conditions, e.g., liquid and frozen aqueous solutions, corrosive materials, etc. A helium-tight tank has been installed behind the vacuum experimental chamber of the double crystal beamline 3.4 at the Daresbury SRS. The tank is purged with helium at atmospheric pressure and the gas in the tank is isolated from the high vacuum of the rest of the beamline by a thin mylar window which is supported on a capillary array. The tank contains a sample stage, two ionization chambers and a parallel-plate gas proportional counter for fluorescence detection of dilute samples, which has produced good results on the K edges of Cl, S, and P.
Novel fiber-optic torsional vibrometers
Authors: Liu T. Y. , Berwick M. , Jackson D. A.
Published: July 2002

Two configurations for a fiber-optic torsional vibrometer are described, which can be classified as (i) differential and (ii) reference. Common features of both techniques are noncontact measurement, immunity to nontorsional vibration, large dynamic range coupled with passive, miniature, remote sensor heads. Measurements of rotation speed and torsional jitter were made with a total illuminating laser power of 130 μW (reference mode) and 1.5 mW (differential mode). Rotation speeds in the range of 270–19 000 RPM were measured.
Variable temperature ultralow compliance torque magnetometer
Authors: Pechan Michael J. , Runge Alan P. , Bait Michael E.
Published: July 2002

The design and implementation of a variable temperature, easily automated torque magnetometer is described which utilizes a commercial capacitive-based transducer system. Absolute calibration is accomplished with a current-carrying coil and the constant is found to be temperature independent to within ±0.5% over the cryogenic to room temperature range measured. Linearity is observed in all signal levels measured, ranging over four orders of magnitude, from 0.003 to 50 dyn cm.
An instrument for measuring angular distribution of sputtered neutral atoms
Authors: Whitaker T. J. , Jones P. L. , Li Aijun , Watts R. O.
Published: July 2002

An apparatus utilizing laser-induced fluorescence (LIF) has been developed to measure high-resolution angular distributions of sputtered neutral atoms. LIF provides sensitive detection, a feature necessary to monitor the low atomic fluxes inherent to angularly resolved sputtering measurements in the static sputtering regime. The apparatus incorporates a detector assembly which rotates about the sample in an ultrahigh vacuum (UHV) chamber, allowing a large range of angular measurements at different ion beam incidence angles. Laser light is brought to the detector in the UHV chamber via a single optical fiber and fluorescence photons exit the chamber via a fiber bundle. The optical fiber and fiber bundle are mounted in a fixed orientation on the detector, maintaining constant alignment as the assembly rotates. Angular resolution in the polar plane containing the incident ion beam and the surface normal is better than 3°. Angular resolution in the direction perpendicular to the polar plane is governed by the Doppler shift and is 0.028° for 3.2 eV atoms. Overall detection efficiency is estimated to be 5×10−9 counts per sputtered atom and 2×10−3 counts per atom entering the detection volume. Initial experiments using polycrystalline Zr to characterize the device are described.
An improved fabrication technique for porous silicon
Authors: Diaz D. C. , Osmanski M. , Guan H. , Das B.
Published: July 2002

An improved technique for fabrication of porous silicon is described. Silicon wafers of any size and shape can be anodized with this very versatile apparatus. Also, this technique is shown to be safer due to reduced HF acid handling. Overall, this equipment allows more efficient fabrication of uniform and good quality porous silicon safely on silicon wafers of variable sizes and shapes.
High sensitivity absorption spectroscopy in glow discharge plasmas
Authors: Wamsley R. C. , Mitsuhashi K. , Lawler J. E.
Published: July 2002

A highly sensitive absorption experiment for diagnosing glow discharge plasmas is described. This experiment is applicable from the VUV to the IR. A very stable Xe arc lamp is used as a source of continuum radiation. An echelle spectrometer equipped with a gated, image-intensified, charge-coupled device detector array is used to disperse and detect the continuum, with absorption features, after it has traversed the glow discharge. Digital subtraction is used to discriminate against the line emission from the glow discharge and detect only the continuum emission from the arc discharge. Estimates of the relative spectral radiances of glow and arc discharges suggests the subtraction technique is broadly applicable to glow discharge studies. A fractional absorption of 10−3 is detectable with a signal-to-noise ratio limited primarily by shot noise. A detection limit for excited Hg atoms of 7×109 cm−2 is demonstrated in a 400-mA Hg–Ar glow discharge. Further improvements in the experiment are proposed.
The rotating wing drum: An apparatus for ion beam treatment of powders
Authors: Ensinger W. , Müller H. R.
Published: July 2002

In order to study ion implantation effects in irradiated powders a rotating wing-drum apparatus has been constructed. It consists of a conical vessel with wings inside which hosts the powder. The vessel is rotated. The wings lift the powder grains which then drop down through the ion beam line and are hit by the ions. This process is repeated until statistically a homogeneous ion beam treatment is achieved. Setup and features of this technique for agitating powder in an ion beam are described in detail, including different wing drums and an implantation chamber in which the wing drum is mounted. Problems with powder loss and sputtering of the drum rearside are discussed. As an example, results of gold ion implantation and deposition on alumina powder are presented.
A broadband picovoltmeter based on the direct current superconducting quantum interference device with additional positive feedback
Authors: Polushkin V. , Drung D. , Koch H.
Published: July 2002

A picovoltmeter working at 4.2 K and based on a direct current superconducting quantum interference device (dc SQUID) with additional passive positive feedback for investigating the properties of superconducting thin films, Josephson junctions, and SQUIDs has been developed. It has a large small-signal bandwidth fm≂800 kHz, a slew rate of ≂38 mV/s, a dynamic range of 146 dB, and a voltage resolution of 5 pV/Hz1/2 for a signal source impedance Rs=0 Ω. The noise temperature is ≂0.6 K for Rs=1 Ω. In this article the dynamics and noise properties of the instrument are discussed.
Improvement of a beam-bending viscosimeter for fast measurement
Authors: Torikai Delson , Suzuki Carlos Kenichi , Shimizu Hiroshi , Ishizuka Toshio
Published: July 2002

The beam-bending method is very useful for the viscosity determination of glasses, but the time spent to run the measurement is usually very long. The present note describes the performance of an improved beam-bending viscosimeter at the support stand and loading rod to get the faster measurements of high viscosity glasses with better reliability and precision. The testing time was reduced from 8 to less than 4 hours to run one measurement at three different temperatures (1100, 1200, and 1300 °C), with the precision of almost one order of magnitude better (±0.01 for 1g η in poise).
Eliminating microchannel plate response to scattered laser light in a multiphoton ionization experiment
Authors: Gostein Michael , Sitz Greg O.
Published: July 2002

A simple technique is demonstrated for preventing microchannel plate (MCP) response to scattered laser light in a multiphoton ionization experiment. The MCP is gated on after the laser pulse, with a turn-on time of less than 1 μs, by switching its cathode from 0 to −1900 V. The high-voltage pulse circuit uses power MOSFETs and was designed according to the procedure of Baker and Johnson [Electron. Lett. 29, 56 (1993)].
Low cost open loop vibrating reed mechanical spectrometer using pulse train excitation and capacitive current detection
Authors: Devos P. , De Batist R. , Cornelis J.
Published: July 2002

A new, low cost, vibrating reed mechanical spectrometer has been developed. The setup consists of a pulse train generation system for capacitive excitation of the specimen in one of its flexural vibration modes and of a capacitive current measuring and amplification circuit for detection of the specimen oscillation. The used detection method is convenient for low damping levels (internal friction, Q−1≤0.02) and low vibration amplitudes (≤0.1 μm) only. The resonance frequency and the mechanical energy dissipation are derived by numerical analysis of the measured freely decaying vibrations. In terms of experimental performance several such analysis methods (Hilbert transformation method, zero-transition method, nonlinear fitting) are evaluated. The system’s performance is illustrated with some informative examples.
A microscanning electron microscope in ultrahigh vacuum for surface microanalysis
Authors: Fukuoka M. , Sakai Y. , Tsunoda K. , Ichinokawa T.
Published: July 2002

A microscanning electron microscope (SEM) column has been constructed as an attachment of an ultrahigh-vacuum chamber with a 70 mm diam flange to observe microstructures on a solid surface. The micro-SEM column is 26 mm diam and 140 mm long and operated in an energy range from 100 eV to 3 keV. It consists of a thermal-field-emission (TFE) gun and two magnetic lenses. The excitation of the objective lens for 3 kV electrons is 250 A T at a working distance of 10 mm. The saturated temperature of the objective lens at the excitation of 250 A T is approximately 50 °C and the vacuum of the chamber is 2×10−10 Torr. The electron probe is adjustable against a specimen position from the outside of the vacuum by movement of the SEM column with screws. The spot size of the electron probe is 100 Å at 3 kV and 3000 Å at 300 eV in conditions of a working distance of 10 mm and a probe current of 3×10−11 A.
Temperature measurements of a birefringent substrate (LiNbO3) in a radio frequency discharge by laser interferometry
Authors: Fujiwara Tamiya , Yamada Hiroshi
Published: July 2002

Temperatures of a birefringent substrate (LiNbO3) have been measured by laser interferometry in a 13.56 MHz rf discharge. The measurement method is based on monitoring the variation of natural birefringence with temperature. The transient temperature rises and equilibrium values are investigated in nitrogen plasma at rf powers of ∼86 W. Owing to the large heat capacity per unit area of the substrate, the time constant of temperature rises is about ten times as large as the previously reported value of a polymer substrate (PMMA).
Two-stage parallel-plate energy analyzer for simultaneous detection of positive, negative, and neutral particles
Authors: Calabrese D. , Yenen O. , Wiese L. M. , Jaecks D. H.
Published: July 2002

We describe a unique apparatus that simultaneously measures the laboratory energy and angles of several charged particles formed in a single beam. The ability to separate and detect particles of opposite polarity allows one to measure them in coincidence. Equations for the trajectories of the particles are derived and discussed in detail. The expressions for the corresponding resolution of the detected particles are also presented. Data produced in recent experiments illustrate some of the analyzer’s more important features.
A practical self-healing mercury target for efficient generation of soft x-ray radiation
Authors: Yamakoshi H. , Chin C. T. , Jaimungal S. , Herman P. R. , Zhao L. , Kulcsar G. , Budnik F. W. , Marjoribanks R. S.
Published: July 2002

We have developed a self-healing mercury-wetted target as a practical source of soft x-ray radiation for photoexciting extreme ultraviolet lasers. A threaded rod, rotating in a pool of mercury, demonstrates a soft x-ray conversion efficiency similar to that of expendable gold-coated targets in synchronous photopumping of a photoionization Xe2+ laser at 109 nm. Surfaces self-heal or are continuously regenerated by rewetting, while mercury debris is removed by evaporation from the target chamber walls and optics. Long target lifetime and self-cleaning performance of the new target system are attractive features in future high-repetition-rate, high-throughput applications for photopumping of extreme ultraviolet or soft x-ray lasers, and more generally as incoherent sources for soft x-ray lithography and spectroscopy.
Use of electron gun to regulate the radio-frequency plasma performance and beam optics
Authors: Abdelaziz M. E. , Awaad Z. , Zakhary S. G. , Abdel-Ghaffar A. M.
Published: July 2002

The addition of electrons in both rf plasma and ion beam extracted from a rf ion source enhanced the source’s performance and beam optics. The increase of plasma intensity increases the charge state of the extracted ions. The mixing of electrons with the ions within the ion beam decreases the space charge effect on beam expansion.
Progress of pocket PIG ion sources with permanent magnet at Peking University
Authors: Jinxiang Yu , Zhizhong Song , Xiaotang Ren , Renxing Li
Published: July 2002

In this article, we describe four kinds of pocket PIG ion sources with a permanent magnet. They are a side extraction PIG source and three end extraction PIG sources. The beam intensity of the sources is about 1–2 mA for gas ions, and the power consumption is less than 100 W, and the power consumption of a PIG ion source with a ring permanent magnet made of CeCoCu magnetic material for gas ions is less than 4 W for an extracted 0.5 mA ion beam sometimes at the high voltage and small arc current discharge mode. The sources also can be used for metal ions; for this purpose one can get tens μA of Be, Al, Fe, Ti, Zr, Hf, Ta, and W in the sputtering discharge mode. Now the sources have been used for research in semiconductor and material science.
H− ion source activities at DESY
Authors: Peters J.
Published: July 2002

The H− source for HERA is based on the design of that at FNAL. It was modified according to the Deutsches Elektronen-Synchrotron requirements. There is only one H− source connected to the H− LINAC. It must run for long uninterrupted periods with a low duty factor and a high reliability. The measured cesium distribution showed that it is necessary to keep the cold box as a barrier. The operation of the cold box was improved with a new type of high voltage insulator and a special protection against condensation at the feedthrough for high voltage and −30 °C freon. The bending magnet of the cold box will be further improved by using a permanent magnet instead of the electromagnet. A unit was designed that includes all the essential elements which are under vacuum. It can be replaced in minutes and contains a newly designed H2 piezovalve and a remodeled magnetron. The cathode of the magnetron can be heated. It is now possible to run at a low repetition rate of 1/4 Hz and thus reduce Cs and H2 consumption.
The investigation of a negative hydrogen ion source
Authors: Jiang Weisheng , Cui Baoqun , Li Hanjun
Published: July 2002

A multicusp volume-produced H− ion source is described. The source chamber is 10 cm in diameter. The dependence of extracted H− current on arc current, arc voltage, gas pressure, and a filter’s magnetic field has been investigated. It is found that a filter’s magnetic field has a significant effect on the extracted electron current. A 4.4 mA H− beam has been obtained at 3.2 kW arc power; the density of the corresponding current is 6.9 mA/cm2.
Studies on microwave coupling into the electron cyclotron resonance ion source Alice
Authors: Cavenago M. , Iatrou C. T.
Published: July 2002

The particular microwave off-axis injection into the electron cyclotron resonance (ECR) ion source Alice, the reflected power and the occasionally observed waveguide arcs, required a careful study both of the waveguide termination and the microwave transmission line. The high-voltage microwave window was redesigned, improving the choke flange and showing the opportunity of treating the teflon insulator to obtain a surface resistivity in the range of 107 Ω. A simple plasma model, unidimensional and based on the Krook model for electron motion, is here considered for the ECR plasma; effects of rapid spatial variation of the external magnetic field are naturally included. Profiles of the waves in the ECR cavity are given, as well as an expression for the impedance of the plasma; no substantial reflections are evidenced for a typical plasma case (ωpl/ω=0.7).
More information on the calibration of scanning stylus microscopes by two-dimensional fast Fourier-transform analysis
Authors: Carrara Sandro , Facci Paolo , Nicolini Claudio
Published: July 2002

An analysis of two-dimensional fast Fourier transform from images of periodical lattices (like highly oriented pyrolytic graphite) has been performed to understand and decouple the various parameters which account for distorted images in stylus microscopy. The effects of the various sources of image distortion have been described by means of linear maps and a mathematical approach has been developed to find the various correction coefficients resulting from the Fourier space analysis which restore the correct geometry of the images. Furthermore, the trend analysis of the distortion angle upon the scanning frequency shows the possibility of decoupling the role of ‘‘static’’ and ‘‘time dependent’’ distortion parameters. This possibility may be used for an a priori prediction of possible distortions in stylus microscopy and thus for a real-time correction of the images during scanning.
High-precision magnetic levitation device with electro-optical feedback
Authors: Echeverría Isabel , Rubio Miguel A.
Published: July 2002

We report on a magnetic levitation device with electro-optical feedback which allows for precise stabilization of the vertical position of the levitated piece (LP) within 1 μm. The vertical position of the LP is monitored through the reflection of a laser beam on a mirror placed in the upper part of the LP. The reflected beam goes to a position sensitive photodiode and suitable electronics transforms the fluctuations in the vertical position of the LP to an electrical signal. This signal is fed into a PID controller that drives an electromagnet. The output of the detection stage yields high-precision measurements of the fluctuations in the vertical position of the device and the current fed to the electromagnet provides a precise reading of the vertical force felt by the levitating part. We have also developed a model that explains most of the dynamical behavior observed. We have formulated the dynamical equations of the system and, by means of a linear perturbation technique, we have obtained the stability characteristics which compare well with the experimental response.
Inexpensive ultrahigh vacuum heatable/coolable xyz-rotary motion sample manipulator
Authors: Peterson Susan L. , Schulz Kirk H. , Schulz Carl A. , Vohs John M.
Published: July 2002

A simple design for a heatable, coolable, rotatable sample manipulator, suitable for ultrahigh vacuum (UHV) applications, is described. Highlights of the design include using a combination power/thermocouple feedthrough for heating, cooling, and temperature measurement; and the use of primarily ‘‘off-the-shelf’’ components available from most UHV components vendors. The described manipulator is capable of sample cooling to ∼100 K, sample heating to above 900 K, while maintaining 360° of rotary motion, ∼1 in. of x and y motion, and 2 in. of z motion. The apparatus can be assembled for approximately $5500 (all new parts) and uses about 3 3ℓ of liquid N2 per day.
A drop-weight apparatus for observing the behavior of thin liquid layers, dynamically loaded in tension and compression
Authors: Me-Bar Y.
Published: July 2002

An apparatus was designed which enables the loading in tension and in compression of thin liquid layers while observing the events occurring in the liquid during loading. The apparatus is part of a transparent anvils drop-weight machine, which enables loading at strain rates ∼104 s−1 and high-speed photography at up to 2×105 frames per second. The events observed include cavity formation and growth followed by cavity collapse, jetting, and secondary cavitation.
Electric field mapping system with nanosecond temporal resolution
Authors: Peterkin F. E. , Block R. , Schoenbach K. H.
Published: July 2002

The electric field dependence of the absorption coefficient in semi-insulating GaAs at the absorption edge was measured in a high-voltage pulsed experiment. Pulse duration was kept below 50 ns in order to avoid thermal effects. A GaAs laser diode was used as a probe light source with wavelength varied from 902 to 911 nm. For fields up to 40 kV/cm the absorption coefficient increased from 3 to 17 cm−1 at 902 nm, with smaller absolute increases evident at the longer wavelengths. Calculation from theory was consistent with this behavior. The spatial variation of the electric field was also recorded with a CCD camera. This method was used as a diagnostic technique to study the field distribution during the switching cycle of a high-power photoconductive switch. The described system could be used as a simple electric field probe with temporal resolution of 100 ps, or as a field mapping system with spatial resolution approaching 1 μm.
Internal, nonperturbing, radio frequency wave monitor reflectometer system on the DIII-D tokamaka)
Authors: Lee J. H. , Doyle E. J. , Luhmann N. C. , Peebles W. A. , Petty C. C. , Pinsker R. I. , Rettig C. L. , Rhodes T. L.
Published: July 2002

A new reflectometer system designed to monitor density fluctuations associated with rf waves has been successfully demonstrated on the DIII-D tokamak. It is a direct, internal, and nonperturbing diagnostic with access into the plasma core. This new diagnostic is motivated by a desire to improve understanding of rf wave physics issues, such as wave trajectory, heating mechanisms, rf wave deposition profile, and wave number, and is highly relevant to planned tokamaks such as ITER and TPX. This work is the first application of reflectometry to rf wave studies in a tokamak. Feedforward tracking receiver techniques are employed to remove frequency instabilities due to inherent drifts in the microwave sources and frequency pulling. In order to minimize spurious pickup of the rf pulse (∼60 MHz), heterodyne detection techniques are utilized, and all components are installed inside an rf shielding box. The system operates in the extraordinary mode (X-mode) at 70 GHz. In this paper, a detailed description of the system, and data illustrating its successful operation will be presented.
Photon activation of the Alcator C-MOD limiter and rf antenna
Authors: Borrás M. C. , Fiore C. L. , Wenzel K. W. , Takase Y.
Published: July 2002

This paper summarizes the results from activation measurements of the limiter and the rf antenna in Alcator C-MOD. The measurements were taken after the run period from May to October of 1993, during which hydrogen and deuterium discharges were studied. We conclude that bremsstrahlung photons generated by runaway electrons striking these materials induced most of the high threshold activation reactions. This means that electrons with energies higher than 10 MeV must have been generated in runaway discharges.
First results in reflectometric plasma density measurements on RFX
Authors: Moresco M. , Cavazzana R. , Sardella A. , Spada E.
Published: July 2002

A five-band, high-sweep-speed reflectometer system for the RFX reverse field pinch experiment has been developed. To control the high-noise environment we improved the intermediate frequency amplifying and conditioning system. We checked the modified system using a new in situ calibration method that pointed out the improvements. This new method is a suitable one for calibrating the reflectometer, because it allows one to place a mirror in a well-defined position, thus giving a good radial (<2 mm) and angular resolution (<10−3 rad). Preliminary results on maximum density time evolution are presented.
Design of the neutron multicollimator for Frascati tokamak upgrade
Authors: Batistoni P. , Esposito B. , Martone M. , Mantovani S.
Published: July 2002

The design of a six-channel one-dimensional neutron/x-ray camera (multicollimator) for the Frascati tokamak upgrade (FTU) machine is described only with regard to the aspects concerning the neutron measurements. The multicollimator, viewing a poloidal cross section of FTU, provides the radial profile of neutron emission from D–D plasmas. The ion temperature profile can be derived in ohmic plasmas if independent data on density are available, while energetic ion tails can be located in the presence of additional rf heating. Information on the position and shape of FTU circular plasmas can also be obtained. The constraints imposed on the collimation and shielding by the compactness of FTU and the expected neutron fluxes are analyzed in detail. The detection system and the performance of the multicollimator are also discussed.
Amorphous silicon–carbon based thin films with efficient ultraviolet-excited photoluminescence and low self-absorptivity in the emission spectral range
Authors: Rüter D. , Rolf S. , Bauhofer W.
Published: July 2002

Amorphous silicon–carbon based thin films deposited in a microwave plasma reactor using organosilane vapors from liquid sources show efficient photoluminescence (several %) when excited with ultraviolet (UV) light together with a low absorptivity (down to 1 cm−1 at the long-wavelength side) in the spectral range of the luminescence emission (400–550 nm). On the basis of these films we have prepared luminescent waveguiding layer structures which we propose for an application as a fast, sensitive, and selective UV detector integrated on silicon.
Development and application of a nozzle-beam-type microwave radical source
Authors: Yoshida Yoshikazu , Ito Katsuyuki , Okazaki Yasunao , Mitsuyu Tsuneo , Mizuguchi Shin-Ichi
Published: July 2002

Characteristics and application of a nozzle-beam-type microwave radical source are described. This source generates microwave plasma in a space between a nozzle and a skimmer for exciting a processing gas. Long-lived metastable nitrogen molecules effective for film growth processes are observed clearly in this source. p-type doping of ZnSe films was achieved by employing this source with N2 plasma which was installed in a molecular-beam epitaxy system. A net acceptor concentration of 5.4×1017 cm−3 was obtained by C–V measurements with lower microwave power of 50 W and lower gas flow of 0.06 sccm compared to conventional rf plasma sources.
A prescan method improving the reproducibility of force-distance curves obtained with a piezoelectric tube scanner
Authors: Wigren Roger , Erlandsson Ragnar
Published: July 2002

We present a method based on pre- and postscanning a piezoelectric tube scanner used in a force probe that improves the reproducibility of the scan lengths. Instead of prescanning in the same direction as when acquiring data (the z direction), which could destroy a sensitive surface, we perform lateral (x/y direction) prescans. As lateral motions of the tube scanner involve out of phase elongations and compressions of the tube in the z direction, these kinds of prescans will have a stabilizing effect on the z motion as well. By adding an additional postscan in the ±z directions, we reduce the piezoelectric creep following the data acquisition scan. When comparing the lengths of z scans with and without the pre/postscan procedure, preceded by a z voltage step 60 s before data acquisition, the deviation between four consecutive scans improved from 12% to 1.4%.
Characteristics of low-energy intense ion beam formation and transport
Authors: Goncharov A. A. , Protsenko I. M. , Dobrovolsky A. N.
Published: July 2002

MEVVA-ion sources with a modified three-electrode ion optical system for the formation of wide aperture low-energy (100–400 V) ion beams were used to produce ion beams of different elements with a current up to 40 mA and energy up to 400 V. The peculiarities of such beam formation and transport by a wide-aperture plasma lens (PL) are investigated. Beam transport in the transport channel is shown to be improved by the PL. PL operation in the magnetic regime shows that the suppressor grid secondary electron emission beam accompanying the ion beam has a current of 30% of the total ion beam current. These electrons contribute to the charge-compensation plasma medium in the beam transport channel and in the PL. The main contribution to the compensating secondary electron production (60%–70%) is due to the ion beam but experimentally observed values of the beam floating potential appear high enough (25–50 V), and this does not exclude an influence of dynamical decompensation.
Production of polarized negative deuterium ion beam with dual optical pumping
Authors: Kinsho M. , Ikegami K. , Takagi A. , Mori Y.
Published: July 2002

To obtain a highly nuclear-spin vector polarized negative deuterium ion beam, a dual optically pumped polarized negative deuterium ion source has been developed at KEK. It is possible to select a pure nuclear-spin state with this scheme, and a negative deuterium ion beam with 100% nuclear-spin vector polarization can be produced in principle. Thus far, we have obtained about 70% of the nuclear-spin vector polarized negative deuterium ion beam. This result may open up new possibilities for the optically pumped polarized ion source.
Summary of the workshop on radioactive beam ion sources
Authors: Bricault Pierre G.
Published: July 2002

A workshop on ‘‘Ion Sources for Isotope Separation On Line’’ was held at TRIUMF on September 7–8, 1995. Twenty-five specialists from France, Russia, Belgium, Switzerland, Germany, Italy, the United States, and Canada and over 15 TRIUMF staff members participated. The workshop was held in conjunction with the sixth international conference on ion sources which took place at Whistler the following week. It is clear that there is no universal ion source for all the elements needed at a radioactive ion beams facility. Very specialized target/ion sources have to be developed for specific elements. The main issues are the release efficiency, the ionization efficiency, and the brightness of the ion source. The major difficulties are the operation in a very hostile environment, high radiation, and high temperature.
Recent progress of polarized ion sources (invited)
Authors: Mori Yoshiharu
Published: July 2002

Recent progress of polarized ion sources has been enormous. Polarized H− beams of more than 1 mA in dc/pulsed beam operation have been realized.
Microwave proton source development for a high-current linac injector (invited)a)
Authors: Sherman J. , Bolme G. , Geisik C. , Gilpatrick D. , Hansborough L. , Hodgkins D. , Lara P. , Meyer E. , Power J. , Rose C. , Sandoval D. , Schafstall P. , Schneider J. D. , Stettler M. , Stevens R. , Thuot M. , Wright R. , Zaugg T. , Spence D. , McMichael G. , Taylor T.
Published: July 2002

Powerful cw proton linear accelerators (100 mA at 0.5–1.0 GeV) are being proposed for spallation neutron-source applications. A 75-keV, 110-mA dc proton injector using a microwave ion source is being tested for these applications. It has achieved 80-keV, 110-mA hydrogen-ion-beam operation. Video and dc beam-current toroid diagnostics are operational, and an EPICS control system is also operational on the 75-keV injector. A technical base development program has also been carried out on a 50-keV injector obtained from Chalk River Laboratories, and it includes low-energy beam transport studies, ion source lifetime tests, and proton-fraction enhancement studies. Technical base results and the present status of the 75-keV injector will be presented.
Deuterium ion source
Authors: Dimov G. I. , Donin A. S. , Marin O. Yu. , Morozov I. I. , Savkin V. Ya. , Wiebe S. A.
Published: July 2002

The experience with an ion source for our atomic injector have been described. Ion beams with a current of 50 A, energy of 30 keV, and pulse duration of 0.1 s are extracted from a rectangular plasma emitter with dimensions 24×12 cm2. The beams have small angular divergence. Geometrical focusing through the extraction system provides the size of the beam to less than 24 cm at a distance 4 m from the ion source. The beam current density distribution has been measured by light emission. The power supply can be operated in multibreakdown mode with time periods of 0.4–2 ms. The control and the operating functions of the power supply are integrated into the computer. The data are transferred to the computer through both fiber optic channels and cable channels.
Measurement of grid heat load in a 400 keV, high current negative hydrogen ion accelerator (abstract)
Authors: Miyamoto K. , Inoue T. , Miyamoto N. , Nagase A. , Ohara Y. , Okumura Y. , Watanabe K.
Published: July 2002

The acceleration grid heat load was measured for the first time as a function of the bias voltage, with the source filling gas pressure using a 400 keV three-stage electrostatic accelerator with multi-aperture. The bias voltage dependence shows that leakage of electrons extracted with H− ions to an accelerator is suppressed efficiently in the extractor. The heat load is mainly due to electrons stripped from H− ions at a high source pressure. The heat load due to the stripped electrons could be suppressed effectively by reducing the source pressure. It was confirmed experimentally that reduction of the source pressure is important to suppress the electron acceleration.
Ion sources for heavy ion fusion (invited)
Authors: Yu Simon S. , Eylon S. , Chupp W. , Henestroza E. , Lidia S. , Peters C. , Reginato L. , Tauschwitz A. , Grote D. , Deadrick F.
Published: July 2002

The development of ion sources for heavy ion fusion will be reported with particular emphasis on a recently built 2 MV injector. The new injector is based on an electrostatic quadrupole configuration, and has produced pulsed K+ ions of 950 mA peak from a 6.7 in. curved alumino silicate source. The ion beam has reached 2.3 MV with an energy flatness of ±0.2% over 1 μs. The measured normalized edge emittance of less than 1 π mm mrad is close to the source temperature limit. The design, construction, performance, and comparisons with three-dimensional particle-in-cell simulations will be described.
Upgrade of a vacuum arc ion source using a strong pulsed magnetic field
Authors: Oks E. M. , Brown I. G. , Dickinson M. R. , MacGill R. A.
Published: July 2002

A pulsed magnetic field of up to 10 kG was incorporated into a vacuum arc ion source. The field was established by a small coil surrounding the arc discharge region, powered by either an additional power supply (capacitor bank) or by the arc power supply (arc current and coil current in series). This addition has led to a number of improvements in source performance: The mean charge state of the metal ions produced was enhanced by a factor of up to 2, for 30 different cathode materials from carbon to bismuth; hybrid metal/gaseous ion beams could be generated when an additional gas (nitrogen, oxygen, or argon) was admitted into the source, with gaseous ion fraction as high as 50%; triggering of the source could be done by a very long lifetime gaseous predischarge technique. We also report on the use of a wire mesh to stabilize the plasma emission surface at the extractor as a means for achieving a flat beam current characteristic as a function of extraction voltage.
Negative-ion extraction of gaseous materials from a radio frequency plasma-sputter-type heavy negative-ion source
Authors: Tsuji Hiroshi , Ishikawa Junzo , Tomita Tetsuo , Gotoh Yasuhito
Published: July 2002

The operational characteristics of a rf plasma-sputter-type heavy negative-ion source with a feeding of O2 or SF6 gas as an ionized material together with Xe gas is presented. To obtain negative ions of chemically reactive elements, we used a material gas and a stainless-steel sputtering target instead of an oxide or fluoride sputtering target to prevent charging trouble. In the source, gas particles adsorbed on the target surface were negatively ionized by sputtering. O− or F− was dominant in the extracted beam and increased with the Cs supply until the yield was optimized. Then, high-current negative ions of mA at an intensity of several, such as 4.6 mA for O− and 4.3 mA for F−, were extracted in a dc mode of operation. Even in this plasma-sputter source with a material gas feeding, the surface production of negative ions was found to be the dominant mechanism.
Uniform excitation of a cylindrical plasma column by a microwave ring resonator
Authors: Hunscher Andreas , Mentel Jürgen
Published: July 2002

To overcome the problem of insufficient absorption of microwave power by a plasma column a new concept for the microwave excitation of cylindrical gas discharges on the basis of a microwave ring resonator is presented. A theoretical description of this resonator loaded by a gas discharge is developed using the S parameters of its elements by which is determined the dependence of the two ring waves on the tuning of the resonator. It is predicted from theory and confirmed by measurements that one ring wave can be suppressed to a high degree by a proper tuning of the resonator. With the ring resonator a high power absorption at a frequency of 2.45 GHz is achieved over a wide pressure range. A uniform cylindrical plasma column with a length of more than 30 cm suitable for laser operation can be realized.
X-ray laser radiography of perturbations due to imprint of laser speckle in 0.35 μm laser irradiation of a thin Si foil
Authors: Kalantar D. H. , Barbee T. W. , DaSilva L. B. , Glendinning S. G. , Weber F. , Weber S. V. , Key M. H. , Knauer J. P.
Published: July 2002

A gain saturated yttrium x-ray laser operating at a wavelength of 15.5 nm has been used as an extreme ultraviolet probe to measure optical depth modulations in a thin Si foil by face-on radiography. The high brightness of this Ne-like x-ray laser allows probing of a sample with a high opacity. This technique is sensitive to very small modulations in the optical depth of the foil, corresponding to thickness variations of a few 10 nm of cold material. This technique is used to measure the effect of direct drive laser imprint on a thin Si foil by face-on radiography using multilayer optics to image the foil with 26× magnification. We have recorded modulations in a thin Si foil that was irradiated by a 400 ps, 0.35 μm beam at an intensity of about 3×1012 W/cm2.
Instrumentation for ion sources and low energy beam transport systems (invited) (abstract)a)
Authors: Olivo M.
Published: July 2002

In this article we describe computer-based instrumentation to control and optimize the operation of an ion source, and schemes to measure beam properties in low energy beam transport lines. Emphasis is given to the methods used at the accelerator complex of the Paul Scherrer Institute.