bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-energy high-intensity extraction system for CHORDIS
Authors: Tinschert K. , Zhao W.
Published: July 2002

The high current ion source CHORDIS is operated at the GSI 300 kV accelerator with a typical extraction voltage of 40 kV. The ion beam is injected into the 300 kV accelerating gap without mass or charge analysis. To obtain a beam of well-separated ion species that is desirable for ion implantation applications it is intended to use a compact 90° dipole magnet (magnetic rigidity 0.2 Tm) for ion separation on the HV platform. To analyze heavy ions (mass/charge≤132) the ion energy must be decreased to 15 keV while keeping sufficient beam current at low emittance for beam matching to the accelerating gap. A single aperture accel-decel extraction system was developed that combines a high accelerating voltage with a high decelerating voltage to obtain the low ion energy. Shaping and distances of the electrodes have been optimized by computer simulation with the axcel-gsi code. Measurements of ion currents and beam emittances have been performed with Ar- and Xe-ion beams and compared to the results of the computer simulation.
A multipassage spectrometer for the study of electron–ion interactions in the EBIS
Authors: Kleinod M. , Dietrich J. , Lakatos A. , Langbein I. , Becker R.
Published: July 2002

A multipassage magnetic spectrometer has been constructed which allows selection of a specific high charge state from the extracted ion pulse of our electron beam ion source (EBIS) and to reinject it in the emptied source, now using the electron beam of meanwhile changed energy as a target of free electrons for the study of ionization, dielectronic recombination (DR), or radiative electron capture (REC). The spectrometer consists of a H-magnet with round pole pieces and 4 identical arrangements of achromatic lenses and mirrors under 90° forming a versatile ion switchyard with the possibility of recirculation. The chromaticity of the recirculating transport system and the dispersion of this spectrometer are adjustable by electric potentials on suitably placed electrostatic deflectors inside of the magnetic field. For the injection of ions from an external ion source into the EBIS and to the beam lines, the mirror potentials are pulsed accordingly.
The ion cooling in EBIS
Authors: Shirkov G. , Donets E. , Becker R. , Kleinod M.
Published: July 2002

The article is devoted to the problems of heating and cooling of highly charged ions in EBIS. The loss rates for ions with the Boltzmann distribution function of energies for different ionic species are determined. The results suggest the use of the lightest possible ions for ion cooling. Continuous flow of light ions is proposed for cooling. The necessary parameters of light ion flow are defined in the article.
Investigation of the electron fluid equations in a hydrodynamic model of the negative ion source
Authors: Haas F. A. , Surrey E. , Holmes A. J. T.
Published: July 2002

The ‘‘hydrodynamic model’’ developed by Haas, Holmes, and Lea has been extended to include all elastic collision processes between the species. The properties of the electron momentum equations are investigated in detail; the solution of these equations revealing a critical point along the source axis at which the electron drift velocity reverses direction.
Versatile cold cathode ion source for use with materials in any thermodynamic phase
Authors: Lama F. L. , Garzino-Demo G.
Published: July 2002

A new type of cold cathode ion source has been designed that is suitable for beams of variable cross sections and can also employ source elements in any thermodynamic phase: it has been given the name universal cold cathode ion source (UCCIS). There are two versions of this ion source: the first (LE-UCCIS), suited to low energy operations such as ion beam assisted deposition (IBAD) and etching, the second (HE-UCCIS) suited to high energy processes such as ion implantation and ion mixing. A prototype of the LE-UCCIS has been built and is undergoing testing. The main feature of the LE-UCCIS when used for IBAD processes is to combine in a single unit both the source of neutrals that grow the film and the source of ions that assist the deposition
The computer simulation of an intense Cs0 beam source for a colliding-beam polarized negative ion source
Authors: Rao Yusheng , Xi Youhao , Xi Boling
Published: July 2002

The computer simulation of the intense Cs0 source attached to the Wisconsin colliding polarized negative ion source has been performed. The beam phase diagram and phase density distribution function are applied to the study. The principle of the simulation is described. In consideration of the scattering effect of the particles in the neutralization region the characteristics of the phase space is modified and finally the Cs0 beam intensity after passing through the drift region can be obtained by means of beam-transport theory. The calculated results are in good agreement with the experimental data and the main factor limiting the resultant Cs0 beam is found out.
A compact microwave ion source with permanent magnet
Authors: Song Zhizhong , Yu Jinxiang , Li Renxing , Yuan Zhongxi
Published: July 2002

A compact microwave ion source has been developed. The magnetic field in the source is produced by a permanent magnet. The dimension of the source is 46 mm in diameter and 50 mm in height. The discharge chamber and extraction hole is 20 and 2 mm in diameter, respectively. The microwave frequency is 2.45 GHz and the power consumption is less than 50 W. It is easy to extract a total beam current of more than 1 mA from this compact source.
The study of a fundamental law in extracting metal ions from a rf ion source by applying a plasma chemical reaction
Authors: Guibin Bai , Xiuling Shi , Zhaoxing Meng
Published: July 2002

Experimental metal ions are extracted from a rf ion source by applying a plasma chemical reaction. The process has been generalized into a law; it is used in practicing and many metal ions are extracted, such as: Re+, W+, Mo+, Ta+, Pt+, Pd+, Au+, Ag+, Nb+, Ti+, V+, Cr+, Ni+, Fe+, Cu+, Zn+, Ga+, Ge+, Se+, Si+, Al+, Mg+, Be+, Li+, Bi+, In+, Sn+, Pb+, Cd+, etc., and rare-earth ions Y+, Nd+, Ce+, Sm+, Tm+, Dy+, Gd+, Er+, and so on.
Performance characteristics of a capacitively coupled 3 cm rf ion source (abstract)a)
Authors: Korzec D. , Engemann J. , Rapp J.
Published: July 2002

A novel 13.56 MHz radio frequency capacitively coupled ion source has been developed and characterized with special emphasis on low-energy (<1 keV) broad ion beam extraction. When operating the source with chamber pressures ranging from 1 × 10−4 to 1.7 × 10−3 mbar (O2 and Ar), rf-power levels from 5 to 120 W, axial air coil magnetic fields up to 70 mT, and maximum extraction voltages of 650 V extractable ion currents were as high as 50 mA. With a total grid area of 7 cm2 and a transparency of 46%, this amounts to a grid current density of more than 7 mA/cm2 while the ion saturation current density is calculated as 9.3 mA/cm2. The potential oscillation amplitude of the rf excitation electrode can be as high as 650 V. Due to an external axial magnetic field, a dc bias up to 70 V is induced between the grounded accelerator grid and cylindrical anode. The performance data are traced back to constructional source details such as plasma excitation geometry, axial magnetic field, and floating electrostatic end confinement. Under all operating conditions, the source shows an excellent long-time stability even with reactive gases (e.g., more than 100 h without maintenance with oxygen).
Extraction characteristics of a high current metal ion source
Authors: Inouchi Yutaka , Yamashita Takatoshi , Fujiwara Shuichi , Matsuda Yasuhiro , Inami Hiroshi , Matsunaga Kouzi , Matsuda Koji
Published: July 2002

A metal ion source has been developed for extracting high current ion beams of high melting point metals. In the discharge chamber, metal vapor was confined in high-temperature shields, and the pure metal plasma was produced by the arc discharge. In order to prevent the vapor deposits, the extraction electrodes were also required to be high temperature. Thus, multislit electrodes were improved to maintain fine beam optics even if they were heated. To investigate the metal ion extraction characteristics, Al ion beams were extracted and compared with Ar ion beams. Furthermore, high current Al, Cr, Si, and Ti ion beams were extracted, and the extracted current ≳100 mA was obtained for each metal.
A new design of a Cs sputter ion source for accelerator mass spectrometry
Authors: Niklaus Th. R. , Baur W. , Bonani G. , Synal H.-A. , Wölfli W. , Suter M.
Published: July 2002

Accelerator mass spectrometry (AMS) requires ion sources delivering intense negative ion beams of high stability. In addition, a multitarget system and a vacuum lock for sample loading are essential for efficient operation. We present a new design of a cesium (Cs) negative ion sputter source with the following features: the vacuum chamber of the ion source and the target cassette are at ground potential. Batches of targets can be loaded and unloaded without interrupting the operation of the source. All control systems for sample loading and automatic changing are also at ground potential. This ion source concept has already been successfully applied to AMS at our laboratory. The new design incorporates a spherical Cs surface ionizer to increase the negative ion currents. Difficulties in realizing this concept are the high electric fields inside the vacuum chamber in an environment with high Cs vapor pressure. Also critical are the proper and reliable operation of all mechanical components under these conditions and the large temperature gradients.
ECRIS development for an on line isotopic separator at GANIL
Authors: Bricault P. , Sortais P. , Bisch M. , Lehérissier P. , Leroy R. , Pacquet J. Y. , Rataud J. P.
Published: July 2002

We plan to use the high-energy heavy ion beams provided by the GANIL facility to produce exotic beams using the on line isotopic separator approach. We will use an electron cyclotron resonance (ECR) ion source as ionizer. ECR ion sources show very good ionization efficiency and give high-charged states independently of the ion species. For future applications of exotic nuclei, we plan to post-accelerate them, so it would be very interesting to obtain high-charge states directly from the ion source of the isotopic separator with high ionization efficiency.
Ion beam diagnostics by Doppler shifted light emissions (abstract)a)
Authors: Heinrich F. , Stoll H.-P. , Hoffmann P. , Scheer H.-C.
Published: July 2002

Broad low-energy ion beams in the energy range of 0.2 to 1.5 keV originating from a filament source with argon as feed gas have been analyzed by high-resolution emission spectroscopy. The Doppler structure of Ar+ emissions reveals the existence of different velocity classes. Besides slow ions and ions possessing the main beam energy, electronically excited Ar+ ions with twice the main beam energy are detected which are attributed to a single-electron capture process in Ar++/Ar collisions. As a preliminary result from a reactive beam extracted from a microwave CF4 source, plasma fast F atoms are detected which are attributed to charge exchange and dissociative collisions in the process chamber.
Low-stress, coolable sample mount for ultrahigh vacuum studies of fragile semiconductors
Authors: Schultz K. A. , Seebauer E. G.
Published: July 2002

A sample mount is described that is particularly useful for cooling and uniformly heating thin, fragile semiconductor samples in ultrahigh vacuum while maintaining optical flatness. The design is based on spring-loaded clips and permits rapid sample exchange. Difficulties with certain conventional methods of temperature measurement are avoided.
A high-temperature infrared absorption gas sample cell
Authors: Phillips W. J. , Welch J. H. , Brashear B. J.
Published: July 2002

An infrared absorption sample cell was designed and constructed for use in the temperature range from 300 to 1000 K. The design’s emphasis was on maintaining an inert environment to eliminate the possibility of depleting the absorbing gas due to reactions with the sample cell material. This design was successfully used for CO2 4.3-μm band absorption measurements in the temperature range extending from 300 to 1000 K.
An iron-core magnetic inductance probe to measure critical current densities in superconducting thin films
Authors: Hylton T. L. , Beasley M. R. , Taber R. C.
Published: July 2002

We describe a magnetic induction probe capable of rapid measurement of the critical current densities of superconducting thin films in a noncontacting, nondestructive fashion. The use of an iron core enables us to generate field levels at the sample surface of 4000 A/cm (0.5 T) and thereby to measure a critical current density of 8×107 A/cm2 in a film 0.5-μm thick. The technique provides the ability to measure a current-voltage relationship without contacting the film and, thereby, to establish criteria for the definition of a critical current. We discuss the design, operation, and calibration of the device. The probe has proven effective in evaluating YBa2Cu3Ox (YBCO) thin films. We observe evidence of ‘‘flux creep’’ in YBCO films and ‘‘flux jumps’’ in Nb and NbCN films.
Magnet enhanced optical falling needle/sphere rheometer
Authors: Chu Benjamin , Wang Jian
Published: July 2002

A magnet enhanced falling needle/sphere rheometer equipped with a precision optical monitor and signal feedback system has been developed. The instrument which utilized the basic features of a magnetic sphere/needle rheometer could be controlled using a PC/AT(286) computer. The important advantages of this instrument over existing falling needle/sphere viscometers are as follows: (1) An extremely large viscosity range from the usual solvent viscosity (say, ∼1.0 cP) to that of polymer melts (say, 1010 cP) is available with an experimental precision of ≲1%. (2) The measurement time could be reduced by about 4 orders of magnitude (e.g., from hours to seconds) for a high viscosity fluid. (3) One single needle/sphere could cover a few orders of the viscosity range and two needles with appropriate densities could cover the whole viscosity range (1 cP≲η≲1010 cP). (4) Only a small amount (∼4 mL with the present setup) of sample is needed. (5) The sample chamber can be sealed hermetically and is suitable for toxic fluids. (6) The instrument permits measurements of the shear rate dependence of viscosity using a single needle/sphere. (7) For nonNewtonian fluids, the viscoelastic behavior could be measured. A set of viscosity standards was used to calibrate the device. Linear calibration curves of viscosity against the reciprocal of the falling needle velocity under both natural gravity field and fixed artificial magnetic fields were obtained. A flow curve was determined for a random copolymer solution using a single needle but varying the magnetic field, showing the applicability of the device for measuring the rheological properties of polymer solutions and melts.
Study of moisture transfer in a deformable porous medium through attenuation of two different energy gamma rays
Authors: Cid J. , Alquier J. F. , Crausse P.
Published: July 2002

The hydromechanical behavior of a moist fibrous medium is tested with the help of the principle of attenuation of two collinear gamma rays (cesium and americium). The detector is made up of a single spectrometric acquisition system and of a multichannel analyzer which differentiates the two gamma rays. This differentiation allows the simultaneous discovery of the density and of the moisture at each part of the medium. The measurement is carried out by moving the sample tested in relation to the gamma ray with the help of a very accurate apparatus which functions with a stepping motor engine. A microcomputer carries out the positioning, the measurement findings, and the signal processing. Software programs have been developed which define the parameters of each experiment as well as visualizing the diffusion and deformation properties of the medium tested. Numerical simulations representative of the medium in experimental situation are presented. This technique, believed original, permitted the study of the hydrodynamical behavior of a macroporous medium (containing 98% of air) in a way unused so far.
Spectroscopic ellipsometry near the Brewster angle on transparent substrates
Authors: Zalczer Gilbert , Gurfein Véronique
Published: July 2002

We present a measurement scheme which, if applied with a commercial spectroscopic ellipsometer, allows us to collect reliable data when the parameter tan  ψ is as small as 2×10−3. By using it we could determine the average amplitude of thermally excited capillary waves at the free surface of toluene.
Contact potential measurement: Spacing-dependence errors
Authors: Rossi Frank
Published: July 2002

We examine the causes of spacing dependence of the nulling bias voltage in the vibrating capacitor contact potential measurement technique. In addition to effects already recognized in the literature, namely, nonuniform work functions, nonparallel surfaces, fringe fields, and capacitive coupling to distant surfaces, we investigate the effects of finite gain and spurious signals in feedback loop systems. We argue that much of the spacing dependence reported in the literature may be due to microphonic signals, which are very difficult to eliminate. We also discuss the means by which existing spacing dependence can be minimized.
Improved scanning tunneling microscope feedback for investigation of surfaces with micron-scale roughness
Authors: Scholl D. , Everson M. P. , Jaklevic R. C. , Shen Weidian
Published: July 2002

When scanning steeply sloped features which are near micron size or taller, scanning tunneling microscopes with conventional feedback control loops exhibit slower response on downhill slopes than on uphill slopes. This effect is caused by the exponential dependence of the tunneling current on the tip-sample distance. A gap smaller than the setpoint produces a sizable error signal, whereas a gap larger than the setpoint gives only a weak error signal. As the scan rate is increased, the tip begins ‘‘flying’’ well above the surface on steep downhill regions. We have developed a modification of the conventional integral feedback system which eliminates this problem. This circuit makes the error signal growth with increasing distance between the tip and sample similar to the usual exponential growth when the tip-sample distance decreases. This modification allows an increase in scan rates by a factor of 5–10 with no reduction in image quality. The modification can be dialed in or out of circuit as needed, such as when switching between large scale images and atomic scale images, and can easily be installed in any existing scanning tunneling microscope that uses an analog feedback circuit.
A high-efficiency focusing Cherenkov radiation detector
Authors: Lewis Katina–Pilar , Moran Michael J. , Hall James , Graser Michael
Published: July 2002

A new design uses advanced technology to produce an efficient, high-bandwidth Cherenkov detector for relativistic charged particles. The detector consists of a diamond-lathe machined ultraviolet-grade Lucite radiator, a parabolic focusing mirror, and a photodiode with an S-20 cathode. This article discusses some details of the detector design and describes preliminary measurements of its response characteristics. The data show the detector to have an overall gain of ≊76 signal electrons per incident electron and a photodiode-limited response time of ≊450 ps.
Visible-light spectroscopy of pulsed-power plasmas (invited)
Authors: Arad R. , Clark R. E. H. , Dadusc G. , Davara G. , Duvall R. E. , Fisher A. , Fisher V. , Foord M. E. , Fruchtman A. , Gregorian L. , Krasik Ya. , Litwin C. , Maron Y. , Perelmutter L. , Sarfaty M. , Sarid E. , Shkolnikova S. , Shpitalnik R. , Troyansky L. , Weingarten A.
Published: July 2002

We describe the investigations of the plasma behavior in three pulsed-power systems: a magnetically insulated ion diode, and plasma opening switch, and a gas-puffed Z pinch. Recently developed spectroscopic diagnostic techniques allow for measurements with relatively high spectral, temporal, and spatial resolutions. The particle velocity and density distributions within a few tens of microns from the dielectric-anode surface are observed using laser spectroscopy. Fluctuating electric fields in the plasma are inferred from anisotropic Stark broadening. For the plasma opening switch experiment, a novel gaseous plasma source was developed which is mounted inside the high-voltage inner conductor. The properties of this source, together with spectroscopic observations of the electron density and particle velocities of the injected plasma, are described. Emission line intensities during the switch operation are discussed. In the Z-pinch experiment, spectral emission-line profiles of various charge-state ions are studied during the implosion phase. Radial velocity distributions are observed from the line Doppler shifts and widths.
Absolute calibration of fusion gamma ray detector on TFTR
Authors: Medley S. S. , Roquemore A. L. , Cecil F. E.
Published: July 2002

An in situ measurement of the absolute detection efficiency of the fusion gamma ray detector on TFTR has been completed. The efficiency was determined by measuring the yield of the 4.44 MeV gamma ray from a plutonium-berrylium source situated within the vacuum vessel. The absolute detection efficiency at 4.44 MeV is extended to higher energies using the known energy dependence of the gamma ray attenuation coefficients in the vessel port cover, the detector neutron moderator, and the scintillator. The absolute detection efficiency (full energy peak detected gamma rays per source gamma ray) varies from 8.6E−9 at 4.44 MeV to 1.1E−8 at 17 MeV and is insensitive at the few percent level to relatively large variations in the radial profile of the gamma ray source distribution in the plasma. The absolute detection efficiency is used to determine the total d-3He reaction rate during recent deuterium neutral beam heated 3He plasmas on TFTR.
Plasma temperatures from first-hit neutron time-of-flight spectra
Authors: Lerche R. A. , Hatchett S. P. , Cable M. D. , Nelson M. B. , Murphy T. J.
Published: July 2002

We describe a new technique for determining an inertial-confinement-fusion plasma temperature from a neutron time-of-flight spectrum recorded with a multielement detector array−even when each array element becomes fully saturated. A temperature uncertainty <20% is achieved over a yield range ≳10 000 using a 960-element array. Analysis of a spectrum formed by the first detected neutron (first hit) in each array element is used to determine the full spectrum’s temporal width. Temperatures for deuterium filled capsules have been determined from spectra recorded with the 20-m, 960-element LaNSA detector. A temperature of 0.88±0.09 keV was determined for a capsule producing only 1.4×106 neutrons. Temperatures determined for capsules yielding more than 2×109 neutrons are consistent with those determined with a 20-m current-mode time-of-flight detector.
Time-resolved analysis of Mirnov oscillations
Authors: Franco H. , Ribeiro C. , da Silva R. P. , Caldas I. L. , Galvão R. M. O.
Published: July 2002

We discuss the application of time-resolved spectral analysis to interpret the magnetohydrodynamic or Mirnov oscillations in tokamaks. As an example, the technique is applied to analyze the Mirnov oscillations measured in the small tokamak TBR-1 with and without external helical perturbations.
Laser diode beam exposure instrument for rapid quenching of thin-film materials
Authors: Nishiuchi Kenichi , Yamada Noboru , Akahira Nobuo , Takenaga Mutsuo , Akutagawa Ryutaro
Published: July 2002

An extremely rapid heating and quenching instrument for thin-film materials was prepared, which established a quenching speed of 1011 K/s for a 20-nm GeSbTe film. It contains a thin-film device part and a laser diode/electro-optical section; the former is composed of the thin film which absorbs 830-nm laser light sandwiched between a transparent and highly heat-conductive ZnS-SiO2 mixture layer. It is designed to produce a high-temperature gradient between the two layers at the moment of laser exposure. In the latter, the laser beam is designed to be automatically focused with a half-value width of 1 μm at the thin-film surface to be heated. The beam exposure condition is variable: the pulse width 10 ns–10 μs, and the beam power amplitude, 0.5–30 mW. The reflectivity of the beam exposure part can be monitored in situ during the exposure as well as before and after the exposure using the same laser diode.
High-resolution monochromator for soft and hard x rays
Authors: Tolentino Hélio , Rodrigues A. Ricardo D.
Published: July 2002

An x-ray monochromator for the range from 800 eV to 10 keV has been designed, constructed, and tested at LNLS. The high resolution is achieved by a four-crystal scheme where two nondispersive double crystals (or channel-cut crystals) are arranged in the dispersive configuration. Each double crystal is installed on the axis of a precision-machined cylindrical plate. Synchronized counterrotation of both plates is achieved by a single high precision translation stage connected to them by thin metallic tapes or wires. This mechanical design makes it very stable and easy to implement as a compact ultrahigh-vacuum unit, since only one translation has to be transmitted into the monochromator vessel. To characterize the prototype we used the Cu K lines of a conventional x-ray tube and two Si(422) channel-cut crystals, yielding an angular acceptance of 2.6 arcsec and an energy resolution of 10−5. The stability of the whole system turned out to be better than 0.6 arcsec for several hours. We swept several times the angle from Cu Kα1,2 to Cu Kβ (about 5.6°) and the position was reproduced within the same accuracy of 0.6 arcsec.
Variable coupling rotational wand for on-line laser beam sampling
Authors: Sellathamby C. V. , Seguin H. J. J. , Akitt D. R. , Reshef H.
Published: July 2002

As power levels of industrial lasers increase, effective determination of beam profiles over extended operational regimes becomes problematic, due to dynamic range limitations of available detectors. To address this deficiency, a variable coupling rotating wand was developed for on-line monitoring of output radiation from high average power CO2 lasers. The concept features real-time beam sampling adjustment, activated by wand rotational speed change. An associated controller provides appropriate speed regulation of the wand motor drive, via a computer generated setpoint. Design parameters thereby ensure optimal sensor operation at all power levels. A safety override prevents sensor damage by terminating laser operation, if wand speed decreases below a safe value.
Truncated cone as a pseudoconjugator in a high-power carbon dioxide laser
Authors: Nikumb Suwas K. , Seguin H. J. J.
Published: July 2002

The incorporation of a retroreflecting, pseudoconjugating cone as a folding element in a double-pass unstable resonator of a high-power carbon dioxide oscillator–amplifier is presented. The concept, when implemented with a truncated cone, has yielded significant improvements in optical energy extraction efficiency, beam quality, and alignment stability. The performance of such a modified clear aperture cone resonator, in comparison with a standard roof prism cavity geometry, is discussed.
CO2 laser scattering technique for studying Langmuir turbulence spectra
Authors: Vyacheslavov L. N. , Kruglyakov Eh. P. , Losev M. V. , Sanin A. L.
Published: July 2002

A 12-channel system for resolving either the ω or k spectra of plasma Langmuir turbulence is developed. The direct detection system is operated with a scattering linewidth of order 100 GHz at scattering angles ranging from 10−1 to 10−3 rad. Stray light rejection of up to 13 orders of magnitude is provided by an ammonia-filled gas cell. It is possible to vary the absorption frequency width from 20 MHz to 5 GHz keeping absorption in the ammonia line center constant. The ω and k spectra of Langmuir turbulence excited in the plasma by a high-current relativistic electron beam are measured via the technique described.
Method and device for dispersiometric analysis of three-component liquid mixtures
Authors: Sainov S.
Published: July 2002

Analysis of liquid three-component mixtures by two-wavelength refractometric measurement is described. The method is applicable to systems with small additivity rule deviation. The results are presented in the form of differences between the refractive indices of the mixture and the individual components. A device for simultaneous measurement of all parameters is described. This four-channel differential refractometer helps determine the refractive index differences with an accuracy better than 3×10−6, eliminating the necessity of rigorous temperature control.
Time-encoded nuclear magnetic resonance spectrometer control
Authors: van Os J. W. M. , Janssen J. W. G. , Kentgens A. P. M.
Published: July 2002

A device is described that enables time control of many external devices on any nuclear magnetic resonance spectrometer even if it has only one control output available for switching external appliances. Furthermore, it allows activation of extra devices during so-called ‘‘wait states’’ which cannot be served by most standard spectrometer setups. The basic idea is to decode the pulse length applied to one ‘‘standard’’ control output in order to create a whole new set of ‘‘nonstandard’’ controls.
Microwave signal processing for a cryogenic gravitational radiation antenna with a noncontacting readout
Authors: Ivanov E. N. , Turner P. J. , Blair D. G.
Published: July 2002

A modified version of the microwave signal processing system for the 1.5 tonne niobium bar gravitational radiation antenna at the University of Western Australia has been developed and tested during preparations for long-term observation. Among the new features of the system are a noncontacting microwave coupling to the motion transducer, cryogenic low-noise amplification, and automatic carrier suppression with improved long-term stability.
Method for studying the electro-optic effect of isotropic crystals: Stokes–Mueller analysis of the method—experimental results
Authors: Georgieva Elena M. , Georgiev Georgi T.
Published: July 2002

A new method for studying the linear electro-optic effect of isotropic crystals is described. Alternating voltage of low frequency is applied to the crystal, placed between a polarizer and analyzer. The direct and the alternating signals are measured at different positions of the analyzer. A Stokes–Mueller analysis of the method is given.
A degenerate-four-wave-mixing apparatus for the study of materials in solution
Authors: Gale D. C. , Burgess G. E. , Zhai T. , Lewis M. L.
Published: July 2002

A degenerate-four-wave-mixing apparatus is described, with novel data acquisition, and sample handling techniques. Particular attention is paid to methods of noise reduction and elimination. Four-wave mixing is performed with Nd:YAG laser light, at both 532 and 1064 nm, and with a pulse length of 20 ns.
Simple optical distance meter using an intermode-beat modulation of a He-Ne laser and an electrical-heterodyne technique
Authors: Araki Tsutomu , Yokoyama Shuko , Suzuki Norihito
Published: July 2002

A phase measurement distance meter has been devised using a frequency-stabilized intermode optical beat generated from a two-mode He-Ne laser (14-cm-long cavity) and a conventional phase meter. The beat frequency (1096 MHz) is stabilized to within 1 kHz fluctuation by a feedback control system. This frequency was converted to an electrical signal and reduced to 6 MHz by a rf-heterodyne technique in order to match the best frequency response range of the phase meter. Experimental results show that the total distance error of the optical distance meter due to the frequency fluctuation of the laser and the performance of the phase meter is 1 and 19 μm, respectively, for a mirror target located 1 m away from the laser source. Further improvement in the resolution is possible if a better phase meter is used.
Development of an electron-stimulated desorption type negative ion source using a powdery sample
Authors: Kawano Hiroyuki , Ashida Yasunari , Nagayasu Hiroshi , Wada Motoi , Sasao Mamiko , Miyake Kiyoshi
Published: July 2002

A simple and small ion source (∼1 cm3) was developed to produce negative ions of even those elements having electron affinity less than ∼1 eV. A powdery sample (∼10 mg) deposited on a gauze (G, ∼0.1 cm2) was bombarded with electrons (up to ∼3 mA and ∼300 eV) emitted from a filament (F). The ions desorbed from G were easily extracted because F was mounted beneath G. Those ions of H−, D−, Li−, Cl−, Na−, F−, and Ag− were readily produced from various samples such as alkali hydrides and halides. The total ion current, its density and the ion yield (ion to electron current ratio) of H− from NaH, for example, were as large as ∼0.1 mA, ∼1 mA cm−2 and ∼1%, respectively, although the electric power to heat F was only ∼5 W. Similarly, H+ was readily produced. Introduction of H2 had little effect upon the yield of H±.
High current metal ion production (invited)
Authors: Wolf B. H.
Published: July 2002

Methods of metal ion production will be presented in relation to high current ion sources. The choice of the method of metal ion production will be influenced by the operational conditions of the ion source, in particular by the duty cycle. Various ion sources are discussed in relation to metal ion production. Problems related to formation and transport of metal ion beams will be discussed.
Laser plasma as a source of highly ionized ions
Authors: Mróz W. , Wol/owski J. , Woryna E. , Králiková B. , Krása J. , Láska L. , Mašek K. , Skála J. , Rohlena K. , Shamaev O. B. , Sharkov B. Yu. , Haseroth H. , Langbein K. L. , Sherwood T. R.
Published: July 2002

The article presents results of experimental investigation of iodine laser interaction with Al, Cu, and Ta targets, obtained on the laser system PERUN (λ=1.315 μm, E<50 J, γ∼350 ps) by means of corpuscular diagnostics. Ion energy distributions, average charge, and percent composition of the expanding plasma were determined. The plasma electron temperature was estimated to be Te∼550±100 eV. The maximum velocity (energy) of Al ions was estimated to be V∼9×107 cm/s (∼110 keV), Cu ions V∼6×107 cm/s (∼107 keV), and Ta ions V∼3×107 cm/s (∼110 keV); the maximum measured charge state was z=13 for Al ions (time-of-flight base L=196 cm), z=22 for Cu ions (L=116 cm), and z=9 for Ta ions (L=116 cm).
Small radio frequency driven multicusp ion source for positive hydrogen ion beam production
Authors: Perkins L. T. , Herz P. R. , Leung K. N. , Pickard D. S.
Published: July 2002

A compact, 2.5 cm diam rf-driven multicusp ion source has been developed and tested for H+ ion production in pulse mode operation. The source is optimized for atomic hydrogen ion species and extractable current. It is found that hydrogen ion beam current densities in excess of 650 mA/cm2 can be achieved with H+ species above 80%. The geometry and position of the porcelain-coated copper antenna were found to be of great significance in relation to the efficiency of the ion source.
The role of the ion sources in the EXCYT facility
Authors: Ciavola G. , Gammino S. , Zhou Q.
Published: July 2002

A superconducting electron cyclotron resonance (ECR) ion source is going to be installed at the Laboratorio Nazionale del Sud (LNS) as an injector for the K-800 superconducting cyclotron in order to give high intensity light ion beams to be used for the exotics at the cyclotron Tandem (EXCYT) facility. The goal will be the production of some pμA beams of O7+, O8+, C5+, C6+, Ne9+, Ne10+, and 48Ca14+ at 70–80 MeV/n to be sent onto a thick target to produce recoils. The recoils will diffuse to a source located on the Tandem injector. Such a source will be a surface ionization source or a microwave discharge source followed by a charge exchange canal. The outcoming beams are then accelerated by the Tandem and transported to the experimental areas. The role of the negative sources for the secondary beams is fundamental, because efficiencies as high as possible are needed, and the beam emittance has to be matched with the mass separator, in order to get high mass resolution. The primary source and the axial injection beam line designed for intense beams as well as the secondary beam source are being described.
Dose loss in phosphorus implants due to transient diffusion and interface segregation
Authors: Griffin P. B. , Crowder S. W. , Knight J. M.
Published: July 2002

For implanted phosphorus in the dose range of 5×1013/cm2–4×1014/cm2, up to half the implanted dose may be lost during low thermal budget anneals due to transient diffusion and anomalous segregation at the Si–SiO2 interface. The phosphorus atoms, rendered mobile by the implant damage, stick in the oxide near the interface where they are electrically inactive and can be removed by stripping the surface oxide. Such a dose loss needs to be accounted for in a typical device fabrication process.
Liquid microdroplet generator with glass orifice
Authors: Moon Hee-Jong , Kim Guang-Hoon , Lim Yong-Sik , Go Chun-Soo , Lee Jai-Hyung , Chang Joon-Sung
Published: July 2002

A uniform size liquid microdroplet generator was fabricated with glass orifice. The orifice of the generator was made as small as 5 μm on a Pyrex tube. The size of the uniform ethanol droplets generated by the 5 μm orifice varied from 19 to 14 μm as the driving frequency changed from 150 to 400 kHz. Operation characteristics of this generator were comparable to those of the commercial devices. We also measured the interdroplet separation with the diffraction pattern of the array of droplets in order to get the velocity of droplet stream at various stream positions and driving frequencies. The deceleration of droplet stream was nearly independent of the driving frequency which determines the droplet size and interdroplet separation.
A new heterodyne-beat circuit for the determination of static permittivity
Authors: Castex Teodosia Arauz , de Vivar Pedro Díaz , Paz María B. Rebollo , Buep Adrián H.
Published: July 2002

A greatly improved heterodyne-beat oscillator was built using integrated circuits, to measure static permittivity of liquid samples. Frequency variation of the oscillator is of less than 0.7 Hz/h; that corresponds to a capacity variation of less than 0.005 pF/h. Permittivity can be measured with a precision of 0.003% and an accuracy better than 0.01%.
Two-detector coincidence routing circuit for personal computer-based multichannel analyzer
Authors: Jaeger H. , Abu-Raddad L. J.
Published: July 2002

A routing circuit for Oxford Instrument’s PCA II multichannel analyzer card is described. The circuit allows recording of events requiring coincident signals from two out of four detectors. As an example, the use of the routing circuit in a time-differential perturbed angular correlation spectrometer is outlined.
A new type of circular dichroism spectrometer, upgraded version
Authors: Shindo Yohji , Shouno Shuji , Maeda Shiro
Published: July 2002

Our new type of circular dichroism (CD) spectrometer previously reported was successfully upgraded to have the capability of measuring CD spectra up to 200 nm and the total performance equivalent to commercial CD instruments. Optical components exchanged in the upgraded version are a 150 W Xe lamp, a crystal quartz Rochon prism, concave holographic gratings blazed at 250 nm, and a Hamamatsu R-292 photomultiplier with fused quartz window. It is revealed that a depolarizer should be mounted on a rotatable stage equipped with a mechanism for precise adjustment and be rotated carefully to find its best azimuth angle that makes the CD baseline shift as small as possible over the entire range of wavelength.
Single bunch injection system of the storage ring NIJI-IV for free electron laser use
Authors: Yokoyama M. , Kawai M. , Hamada S. , Owaki K. , Yamazaki T. , Mikado T. , Yamada K. , Sei N. , Sugiyama S. , Ohgaki H. , Noguchi T. , Suzuki R. , Chiwaki M.
Published: July 2002

The system of single bunch injection (SBI) for the storage ring NIJI-IV was completed. The system was used for the injection of the short pulse beams from an electron gun into only one of the 16 rf buckets in the ring. On a compact storage ring, the multipulse beams in one pulse train can be stored into only one of many bunches by one injection. The optimum number of the grid pulse in one pulse train was determined to improve the storage efficiency and the storage current by one injection. The keeping time of the bump orbit was calculated by using the transfer matrices. The optimum pulse number obtained by the calculation is 2. In the SBI system, the number of grid pulses in one pulse train can be selected by the gate circuit. A snap off diode and a clip line are used to generate 2 ns grid pulses. The measured grid pulse was shorter than the longitudinal space 5.5 ns of the rf bucket with voltage of −80 V. The EIMAC Y-646B cathode-grid assembly is used as the electron source. It is expected that the injection system provides a higher peak current and easier free electron laser use operation in comparison with the rf-knockout system.
Pulse-to-pulse normalization of time-resolved Fourier transform emission experiments in the near infrared
Authors: Lindner Jörg , Lundberg James K. , Williams Richard M. , Leone Stephen R.
Published: July 2002

The signal-to-noise ratio in a time-resolved Fourier transform (FT) infrared emission experiment is improved by pulse-to-pulse normalization. The signal from the FT spectrometer is normalized by the total infrared fluorescence produced on each laser pulse. A factor of 20 enhancement in signal-to-noise ratio is demonstrated with normalization when the fluctuation of the laser pulse energy is the dominant noise source. Applications are discussed pertaining to cases where other noise sources such as detector and amplifier noise cannot be neglected and when information from the time evolution of the spectrum is required.
Radio frequency phase shifters for launching waves in a magnetized plasma
Authors: Ferrucci L. , Casanova M. R. , Maglione V. , Montiron G. , Riccardi C. , Barisoni D. , Fontanesi M. , Galassi A. , Sindoni E.
Published: July 2002

A variable phase-shifting system, able to generate phase-shifted replicas of the same reference input signal, has been designed to properly feed the antenna system within a plasma device. The system is based on a phase-locked loop used as a voltage controlled phase shifter and is able to provide four phase-shifted output signals. The phase differences between adjacent outputs can be varied between 0° and 100°, and are maintained equal to each other, with a precision of less than 3° in the range 2.5–10 MHz.
Aluminum micropellets for hot plasma diagnostics
Authors: Zoletnik S. , Kocsis G. , Bürger G. , Ignácz P. N. , Kardon B. , Ḱlvin S. , Bakos J. S.
Published: July 2002

A novel technique for the injection of small (diameter ≤30 μm) impurity pellets into fusion plasmas is proposed and investigated. The method may be easily applied by using a special target plate in conventional laser blow-off injection devices. In the present experiments 10×30×30 μm size aluminum pellets (≊5×1014 atoms) are accelerated to average velocities up to 1 km/s by a 700 mJ ruby laser pulse. The scaling law obtained from a rocket model to the pellet velocity versus laser fluence fits well to experimental data and enables one to extrapolate the capabilities of the technique.
New plasma-assisted deposition technique using helicon activated reactive evaporation
Authors: Durandet Antoine , Boswell Rod , McKenzie David
Published: July 2002

The helicon assisted reactive evaporation is a new plasma assisted reactive evaporation device that combines an evaporation source (electron-beam evaporator) and a high density plasma source (helicon plasma source), in a coaxial configuration where the evaporant material is transported through the plasma source. Evaporating silicon into an oxygen plasma yields a deposition rate of silica onto a 100-mm-diam substrate of 200 nm/min, with a refractive index identical to that of thermal silicon dioxide (1.46). This configuration is expected to have advantages over both plasma enhanced chemical vapor deposition and ion assisted deposition techniques, without exhibiting the serious drawback of requiring the handling of hazardous chemical precursors. Initial results show that the electron beam can be run in conjunction with the high density helicon plasma (1012 cm−3).
Resonant techniques for studying the complex electrodynamic response of conducting solids in the millimeter and submillimeter wave spectral range
Authors: Schwartz A. , Dressel M. , Blank A. , Csiba T. , Grüner G. , Volkov A. A. , Gorshunov B. P. , Kozlov G. V.
Published: July 2002

In order to study the electrodynamic properties of highly conducting materials in the millimeter and submillimeter wave range, we have developed two resonant techniques which allow us to measure the complex conductivity of metals with unprecedented accuracy. In the frequency range from 8 to 37 cm−1, we employ a Fabry–Perot resonator consisting of a dielectric plate in optical contact with the sample; in the millimeter wave range (1–3 cm−1) the resonant structure is a copper cavity which is perturbed by replacing the endplate by the sample. The purpose of a resonant structure for measuring material parameters is to increase the interaction of the electromagnetic radiation with the material. In so doing, these two resonant structures not only improve the sensitivity of the measurement but also allow for the direct determination of both components of the complex optical parameters of the material.
Development and performance of a semiautomated 200 MHz surface acoustic wave resonator array-based sensor test apparatus
Authors: Townsend E. B. , Ledford J. S. , Hoffmann D. P.
Published: July 2002

A semiautomated pulse injection and data analysis system utilizing 200 MHz surface acoustic wave resonators has been constructed. A cell consisting of a separate sample splitting chamber, sample transfer lines, and sensor device areas has been constructed to allow individual temperature control over the regions. Experiments involving injections of hexane, trichlorobenzene, and 1% (w/v) of biphenyl in hexane show that all three temperatures play an important role in the magnitude and time dependency of the SAW response. Flow rate is also shown to be an important factor. The capabilities of the system have been demonstrated with uncoated and poly(isobutylene) coated devices.
Southern Hemisphere automated supernova search
Authors: Williams A. J. , Martin R. , Verveer A. , Blair D. G. , Koch R. , Lynch M. J. , Burman R.
Published: July 2002

The Perth Astronomy Research Group has developed an automated supernova search program, using the 61 cm Perth–Lowell reflecting telescope at Perth Observatory in Western Australia, equipped with a CCD camera. The system is currently capable of observing about 15 objects per hour, using 3 min exposures, and has a detection threshold of 18th–19th magnitude. The entire system has been constructed using low-cost IBM-compatible computers. Two original discoveries (SN 1993K, SN 1994R) have so far been made during automated search runs. This paper describes the hardware and software used for the supernova search program, and shows some preliminary results from the search system.
An interactive impulse response extraction system
Authors: Li Harry W. , Dallabetta Michael J. , Baker Jake
Published: July 2002

A cross-correlation method of measuring the impulse response of linear systems is presented. In theory, by using this method, the impulse response of any linear system can be obtained while the system is being used under normal operation with no significant distortion of the normal system output. A cross-correlation system was modeled and constructed using discrete components and simulation and experimental results are presented. Unfortunately, these results show that the extracted impulse response is severely distorted by the normal system input and the system noise. However, by averaging and interleaving methods, the impulse response of any linear system can be extracted with a high degree of accuracy.