bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge-coupled detector readout method for visible emission profiling of a tokamak discharge
Authors: Zurro B. , Pacios L.
Published: July 2002

A handy method and hardware for readout and display on a digital oscilloscope the repetitive visible emission profiles, obtained in the TJ-I tokamak with a standard linear charge-coupled detector, is presented. A detailed description of the electronics, alignment procedure, and detector calibration as well as typical profiles obtained in the TJ-I tokamak are given.
Twenty-channel grating polychromator diagnostic system for electron cyclotron emission measurement in JT-60
Authors: Ishida S. , Nagashima A. , Sato M. , Isei N. , Matoba T.
Published: July 2002

A twenty-channel grating polychromator diagnostic system has been built to measure the temporal evolution of local electron temperatures in JT-60. A cross Czerny–Turner diffraction grating spectrometer is utilized for the measurement of second-harmonic electron cyclotron emission with extraordinary modes in the range 85–300 GHz, in which a grating plate grooved on both faces with different grating periods is applied effectively to yield a wide coverage for the toroidal fields. The grating angle is automatically set up by control of a stepping motor according to the relation of the grating equation. The diffracted light is detected by 20 indium-antimonide hot-electron bolometers cooled at 4.3 K in a modified Solvay cycle cryogenic refrigerator. A typical resolving power of the instrument was measured to be λ/Δλ∼130, providing a spatial resolution of 2.3 cm at the plasma center. The transmission line over ∼38 m long is composed of oversized S-band waveguides. The total transmissivity of this system is estimated to be ∼0.01.
Plasma parameter dependences of the electron density profile in TEXT
Authors: Li W. L. , Brower D. L. , Kim S. K. , Nagatsu M. , Yu C. X. , Peebles W. A. , Luhmann N. C. , McCool S. C. , Bravenec R. V. , Yang X. Z. , Zhang Z. M.
Published: July 2002

A multichannel, heterodyne, far-infrared laser interferometer with high spatial and phase resolution is employed on TEXT to characterize the equilibrium density profile for the full range of TEXT discharge parameters. Gaussian and parabolic functional fits with three free parameters are made to the measured profiles and compared. Scaling of the equilibrium density profile shape with plasma current, toroidal magnetic field, and density is clearly observed. By performing a regression analysis on each free parameter for the functional fit, one can construct a set of analytical relations describing the TEXT density profile for steady-state ohmic discharges. The database used to identify these relations contains 50 different discharge conditions.
X-ray diagnostic for measurement of hot-electron power loss
Authors: Ress D. , Rice B. W. , Horton R. D.
Published: July 2002

A significant fraction of the power lost from a confined plasma can be carried by energetic electrons. When such electrons are incident on a probe or limiting surface, they produce thick-target x rays. It is shown that a properly filtered measurement of this x-ray flux is proportional to the electron-power loss, with little dependence on the electron loss mechanism and velocity-space distribution. The diagnostic was successfully implemented to study the radial loss of hot electrons in the Tandem Mirror Experiment-Upgrade. The method provides a very fast measurement of electron loss processes, and could therefore be useful in other areas of plasma research such as magnetic confinement in tokamaks, and inertial-confinement fusion.
Soft x-ray pinhole imaging diagnostics for compact toroid plasmas
Authors: Crawford E. A. , Taggart D. P. , Bailey A. D.
Published: July 2002

Soft x-ray pinhole imaging has recently become established as a valuable diagnostic for visualization of field reversed configuration (FRC) plasmas in the TRX-2, FRX-C/LSM devices. Gated MCP image converter devices with CsI cathodes and Be filters with a peak response around 11 nm wavelength are used for exposure durations ranging from a few tenths up to several microseconds. Results of experiments with single and Chevron channel plates are discussed along with estimates of linear exposure limitations with both film and CCD cameras as recording media. Plans for multiframe devices on the FRX-C/LSM and the LSX devices are also discussed.
Time-resolved pinhole cameras for imaging multiterawatt Z pinches
Authors: Nash T. , Deeney C. , LePell P. D. , Prasad R. , Krishnan M.
Published: July 2002

X-ray pinhole images are formed on microchannel plate striplines to time-resolve Z-pinch emissions. Applications include a study of Z-pinch linearity necessary for x-ray lasers, the evolution of hot spots, and a study of Z-pinch heating mechanisms. In particular, multiple pinholes per strip with different filters allow the spatial and temporal variation of different temperature regions to be studied.
Algorithm for crystal alignment with a two-axis goniometer
Authors: Milstein Joseph B.
Published: July 2002

An algorithm for determining the necessary angular corrections to bring a selected direction in a crystal into alignment using a two-axis goniometer is presented. The procedure requires the measurement of the specimen-to-film distance, the x and y (or polar) coordinates of the reflection of interest, and the recording of the values of the rotation and oscillation axis settings used to make the back-reflection photograph. A solution in closed form may then be calculated and checked for feasibility, given the physical oscillation limits of the goniometer.
Beam-energy control during a beam pulse in a neutral beam injection system
Authors: Matsuoka M. , Akiba M. , Arimoto K. , Horiike H. , Kuriyama M. , Matsuda S. , Ohara Y.
Published: July 2002

Capability of beam-energy control during a beam pulse has been demonstrated in the JT-60 neutral beam injection system. In addition to the acceleration voltage, the acceleration current and magnetic field separating residual ion beams were simultaneously varied. A preprogram control was adopted to cope with the relatively long time constant of the magnetic field due to the eddy current induced in the magnet core. The overall time constant is about 0.4 s. Beam-energy control was first tested in the prototype injector unit for JT-60 and then applied in JT-60 heating experiments. By advancing the idea demonstrated here, it is possible to design future neutral beam systems with real-time beam-energy control that follows target plasma evolutions.
Experimental studies on debris collection for radiochemistry in inertial confinement fusion
Authors: Nakaishi H. , Miyanaga N. , Yamanaka M. , Yamanaka T. , Takagi M. , Nakai S. , Kobayashi K. , Kimura I.
Published: July 2002

We report several experimental results on debris collection for radiochemistry in inertial confinement fusion research. The collection efficiency was measured by means of radioactive tracers 24 Na, 82 Br, 152m1 Eu and activatable tracer 151 Eu in glass or plastic shells. It is shown that the collection efficiency depends on the atomic weight of the tracer and the surface condition of the collector, and does not greatly depend on the initial areal density of the target, in our experimental conditions.
An automated Langmuir trough for systematic low surface pressure measurements
Authors: Poupinet D. , Detry D. , Vilanove R. , Rondelez F.
Published: July 2002

The design for an automated, trouble-free, Langmuir trough is proposed. Surface pressure measurements down to 10 μN m−1 with a precision of 1 μN m−1 are attainable thanks to a rigorous operation protocol. Factors such as complete thermal equilibration of the whole trough assembly, temperature control of the pressure transducers, reduction and monitoring of eventual surface-active impurities, and mechanical equilibration of the monolayer following each compression step, have thoroughly been taken into consideration. The use of this instrument has enabled us to study polymer monolayers at extremely low surface densities and to measure for the first time the molecular weight dependence of the second virial coefficient for polymer chains in two dimensions.
Temperature dependence of threshold current density Jth and differential efficiency ηd of high-power InGaAsP/GaAs (λ=0.8 μm) lasers
Authors: Yi H. J. , Diaz J. , Eliashevich I. , Stanton M. , Erdtmann M. , He X. , Wang L. J. , Razeghi M.
Published: July 2002

An experimental and theoretical study on temperature dependence of the threshold current density Jth and differential efficiency ηd for the InGaAsP/GaAs laser diodes emitting at λ=0.8 μm was performed. Threshold current density Jth increases and differential efficiency ηd decreases as temperature is increased mainly because of thermal broadening of the gain spectrum. However, the measured temperature dependence of Jth and ηd could not be explained when only this effect was considered. In this letter, the temperature dependence of momentum relaxation rate ℏ/τ of carriers was investigated by performing the photoluminescence study. At high temperature, increase of the momentum relaxation rate ℏ/τ leads to reduction of the gain and mobility and increase of the optical loss, causing higher Jth and lower ηd as experimentally observed. The resulting theoretical model provides a good explanation for the mechanism of the increase of Jth and decrease of ηd.
Sensitive and selective polarimeter for application in crystal optics
Authors: Becker H. , Brach D. , Otto A. , Weber Hans-J.
Published: July 2002

A polarimeter was constructed that modulates the polarization state of a light wave at the frequencies ν1 and ν2. Depending on the property searched for, the frequencies of recorded intensity signals can be selected between ν1, ν2, 2ν1, 2ν2, ν1 ± ν2, and 2(ν1 ± ν2). Optical transfer functions are calculated by use of Jones matrices and experiments are simulated by numerical methods in order to analyze complex problems in polarization optics including propagation of error parameters. Measuring the azimuth and the ellipticity of a light wave with a dynamical analyzer the polarimeter serves for determining the linear and circular anisotropy of a crystal. A sensitivity of 2 × 10−7 radians is demonstrated. Application of the polarimeter is illustrated by measuring the gyration coefficient g11 of α quartz in two different ways. Furthermore, the polarimeter can be used for the measurement of linear and nonlinear electro-optical and piezo-optical effects between 20 and 800 K by subjecting the sample to periodical electric fields and uniaxial mechanical stresses. As an example for this kind of application a new crystal optical effect is investigated. It describes the birefringence originating from the coupling of an electric field and a uniaxial stress.     
Double-modulation spectroscopy of molecular ions: Eliminating the background in velocity-modulation spectroscopy
Authors: Lan Guang , Tholl Hans Dieter , Farley John W.
Published: July 2002

Velocity-modulation spectroscopy is a well-established technique for performing laser absorption spectroscopy of molecular ions in a discharge. However, such experiments are often plagued by a coherent background signal arising from emission from the discharge or from electronic pickup. Fluctuations in the background can obscure the desired signal. We demonstrate a simple technique using amplitude modulation of the laser and two lock-in amplifiers in series to detect the signal. The background and background fluctuations are thereby eliminated, facilitating the detection of molecular ions.
Device for simultaneously measuring stress, strain, and resistance in ‘‘whiskerlike’’ materials in the temperature range 1.5 K<T<360 K
Authors: Skove M. J. , Tritt T. M. , Ehrlich A. C. , Davis H. S.
Published: July 2002

We describe a device for measuring Young’s modulus Y and the piezoresistance of ‘‘whiskerlike’’ samples. The device can be used in a standard vari-temp Dewar in the temperature range 1.5 K<T<360 K. One end of the sample is attached to a movable rod suspended by leaf springs and the other end is held fixed. Force is applied to the rod by a coaxial electromagnet acting on permanent magnets attached to the rod. Displacements are measured with a capacitive technique. We have used the device to measure Young’s modulus for the charge density wave material TaS3. We also measured the Young’s modulus of some Cu whiskers for comparison.
Influence of Ohmic resistance of a cylindrical Langmuir probe on its I-V characteristic
Authors: Shun’ko E. V.
Published: July 2002

The distortion of the cylindrical Langmuir probe I-V characteristic, connected with the ohmic resistance of its operating element, is investigated. The relations given in the paper enable one to reconstruct the shape of the undistorted I-V characteristic from the experimental data.
Aeroacoustic flow sensor
Authors: Shakkottai P. , Kwack E. Y. , Back L. H.
Published: July 2002

A theoretical analysis of standing waves in a pipe with flow was conducted aimed toward the development of a flowmeter based on a measurement of phase difference between two points on the circumference of a pipe separated axially by an integral multiple of half sound wavelength. Effects of nonzero Mach number, variable ratios of upstream and downstream running waves, choice of location of the sensing pressure taps, and the incorrect spacings were examined numerically. Calculations were also made for steam flow where the maximum Mach number is much smaller than in cold air flows. For an industrial application where steam flow velocities are below 50 m/s, a very accurate sensor is shown to be possible. Experimental data were obtained by using an active aeroacoustic source over the range of 50 m/s to zero in an air flow. Experimental phase plots obtained from several coast-down tests have been compared with analytical results. The agreement with theory is excellent when the spacings are near Nλ/2 and the sensing locations are near the pressure antinodes. Otherwise, some zero shifts are introduced. Theory predicts that for steam flow much better results can be expected because the maximum Mach number is much smaller. Effects due to the (1−M2) factor would be imperceptible for steam flow.
Accurate acoustic measurements in gases under difficult conditions
Authors: Gillis K. A. , Moldover M. R. , Goodwin A. R. H.
Published: July 2002

Accurate measurements of the speed of sound in gases are often made using metal resonators with small transducers that perturb the resonance frequencies in minor and predictable ways. We extend this method to gases that may be corrosive and to high temperatures by using remote transducers coupled to a resonator by acoustic waveguides. Thin metal diaphragms separate the waveguides from the resonator. Thus, only metal parts come into contact with the test gas. In the present apparatus, any gas compatible with gold and stainless steel can be studied.
Harmonic blue light generation in bulk periodically poled LiTaO3
Authors: Mizuuchi Kiminori , Yamamoto Kazuhisa
Published: July 2002

Second-harmonic generation in a LiTaO3 periodically poled by electric field is presented. The side growth of the domain-inverted region during the poling was found to be suppressed using selective proton exchange. Utilizing this technique, a first-order periodic domain inversion having uniform periodicity was realized over interaction length of 10 mm in a 300-μm thick LiTaO3 substrate. A 3.8 mW of harmonic blue light was generated for a conversion efficiency of 1.27% in a single pass through the periodically domain-inverted structure.
CO2 gas sensor using acousto-optic Bragg diffraction in As2Se3 glass
Authors: Saito Mitsunori , Miyagi Mitsunobu
Published: July 2002

An acousto-optic (AO) element made of As2Se3 glass was used for spectroscopic gas sensing. With the AO element, desired wavelengths in the infrared can be monitored by simply switching the oscillation frequency of the ultrasonic transducer. The concentration of the CO2 gas was measured by using the absorption band at 4.3 μm wavelength. To avoid measurement error due to the fluctuation in the sensing system, a probe light of 4.3 μm and a reference light of 4.7 μm were measured alternatively by switching the acoustic frequency between 50 and 54 MHz. It has been demonstrated in a preliminary experiment that the AO element is a promising device for constructing a fast, compact, and inexpensive measurement system for monitoring pollutants.
Kilohertz-range flash x-ray generator utilizing a triode in conjunction with an extremely hot cathode
Authors: Sato E. , Shikoda A. , Kimura S. , Sagae M. , Isobe H. , Takahashi K. , Tamakawa Y. , Yanagisawa T. , Honda K. , Yokota Y.
Published: July 2002

The construction and the fundamental studies of a kilohertz-range flash x-ray generator having a triode in conjunction with an extremely hot cathode are described. This generator consisted of the following components: a constant-high voltage power supply, an energy storage condenser of 100 nF, a constant high-voltage power supply for regulating an initial grid voltage of −1.6 kV, a grid pulser, and an x-ray tube. The x-ray tube was of an enclosed-triode type and consisted of the following major parts: an anode rod made of copper, a plane anode tip (target) made of tungsten, a focusing electrode made of iron, a hot cathode (filament) made of tungsten, a grid made from tungsten wire, and a glass tube body. The energy storage condenser was charged from 50 to 70 kV, and the electric charges in the condenser were discharged repetitively to the x-ray tube by the grid electrode driven by the grid pulser. The temperature of the filament was about 2000 K, and the cathode current was primarily controlled by the grid voltage and its value was less than 1.2 A. The pulse widths were about 1 μs and the maximum repetitive frequency was about 2.0 kHz. The x-ray intensity was 19.7 nC/kg at 0.5 m per pulse with a peak grid voltage of 1.0 kV and a condenser charged voltage of 70 kV.
Rare gas moderated electrostatic positron beam
Authors: Massoumi G. R. , Hozhabri N. , Lennard W. N. , Schultz P. J. , Baert S. F. , Jorch H. H. , Weiss A. H.
Published: July 2002

An electrostatically guided positron beam which is variable in energy from 0 to 60 keV is described. A frozen inert gas (Ar, Kr, and Xe) is used as the positron moderator. The efficiency, ε, defined as the ratio of the number of slow positrons at the target to the number of positrons emitted by the source has been measured; the values obtained for Ar, Kr, and Xe were ε∼ 2.5×10−4, 1.6×10−4, and 1.1×10−4, respectively. We estimate a source/moderator efficiency of εm∼7.6×10−4, 4.7×10−4, and 3.0×10−4 for Ar, Kr, and Xe, respectively, which includes source effects, grid transmission, geometrical losses, and beam transport. These values are comparable to the best reported values for thin metal foil moderators. The measured εm is specific to the electrostatic system; significantly higher values for the same moderator should be attainable in magnetically guided beams, where higher transmission for moderators with large energy spreads is usually obtained.
CCD-based reflection high-energy electron diffraction detection and analysis system
Authors: Barlett D. , Snyder C. W. , Orr B. G. , Clarke Roy
Published: July 2002

A CCD-based, computer controlled RHEED detection and analysis system that utilizes an on-chip integration technique and on-board data manipulation is described. The system is capable of in situ time-resolved measurements of specular and integral-order intensity oscillations, their phase differences, streak linewidths, and epitaxial layer lattice constants. The digital RHEED techniques are described in the context of Co/Au bilayer, GaAs/GaAs, and InxGa1−xAs/GaAs MBE growth. The system is compared to other RHEED detection devices.
The equation of state of water to 250 °C and 200 MPa obtained from a high pressure dilatometer
Authors: He Jing , Zoller Paul
Published: July 2002

We have evaluated the performance of a commercially available, completely automated high pressure dilatometer (PVT apparatus) by determining the equation of state of water over the ranges 30 °C–250 °C and 0–200 MPa, using a sample of only 1–2 g. Although the apparatus was designed for the measurement of solid and molten polymers, we conclude that the system is quite capable of measuring PVT properties of water (and presumably other simple liquids) with a reasonable accuracy (0.001 to 0.005 cm3/g, depending on the temperature range), typically five to ten times less accurate than dedicated equipment using 40–250 times larger samples and, in general, smaller pressure and temperature ranges. Two polynomial fits (for separate pressure ranges) with twelve coefficients give 0.0004–0.0005 cm3/g absolute average deviations from the experimental data for the whole range. Comparisons with the NBS/NRC steam tables show deviations within 0.001 cm3/g below 200 °C, reaching their maximum of 0.006 cm3/g at 250 °C.
A new method for measuring low resistivity contacts between silver and YBa2Cu3O7−x superconductor
Authors: Hsi Chi-Shiung , Haertling Gene H. , Sherrill Max D.
Published: July 2002

Several methods of measuring contact resistivity between silver electrodes and YBa2Cu3O7−x superconductors were investigated; i.e., two-point, three-point, and lap-joint methods. The lap-joint method was found to yield the most consistent and reliable results and is proposed as a new technique for this measurement. Painting, embedding, and melting methods were used to apply the electrodes to the superconductor. Silver electrodes produced good ohmic contacts to YBa2Cu3O7−x superconductors with contact resistivities as low as 1.9×10−9 Ω cm2.
High-speed pitch angle sorter
Authors: Keller John W. , Torbert R. B. , Vandiver James
Published: July 2002

We have developed a high-speed method to compress the two-dimensional angular distribution of space particles gathered by space plasma instrumentation into the pitch angle distribution, where the pitch angle is polar angle with respect to the ambient magnetic field. The pitch angle sorter can handle rates of up to 2 MHz and it is designed to accommodate high angular resolution plasma analyzers that are placed on a rotating spacecraft. This compression is achieved by relying on digitally encoded lookup tables to eliminate all arithmetic operations while applying the high symmetry of this compression to reduce the amount of digital memory.
A polarimeter for localized continuous measurement of the poloidal magnetic field in a tokamak
Authors: Huang L. K. , Finkenthal M. , Moos H. W.
Published: July 2002

A polarimeter for the circular polarization of Zeeman-split spectral line emissions has been developed to measure the poloidal magnetic field in tokamak plasmas. The Li I 6708 Å line originating from a monoenergetic lithium beam provided a localized spectral source. In the polarimeter, interference filters of narrow bandpass were set at the peak wavelength of the circular polarization, enabling the measurement to be continuous and sensitive.
The laser ion source test facility at CERN
Authors: Amdidouche Y. , Haseroth H. , Kuttenberger A. , Langbein K. , Sellmair J. , Sherwood T. R. , Williams B. , Sharkov B. , Sharmaev O.
Published: July 2002

Due to the growing demand for high currents of highly charged heavy ions the potential of laser ion sources is investigated at CERN. A test facility consisting of a 50-J carbon dioxide laser, a versatile ion production chamber, and electrostatic and magnetic analyzing systems has recently been put into operation. First results of charge state analysis as well as plasma temperature measurements are presented.
ECR ion source and spectrometer for the new high charge state injector at GSI
Authors: Schulte H. , Tinschert K. , Bossler J. , Wolf B. H. , Klabunde J. , Dahl L. , Schwab Th. , Klein J.-P.
Published: July 2002

For the new high charge state injector (HLI)at GSI a 14.5 GHz electron cyclotron resonance ion source of CAPRICE type was built at CEN-Grenoble. Test bench results were obtained prior to installation at HLI for Ar and Fe including emittance data. The HLI installation of the source and the high-resolution spectrometer is described in some detail. First systematic studies for Ar charge state spectra (including gas mixing) are presented. The spectrometer resolution was tested using Xe isotopes. The analyzed beam is very stable and proved to be well suited for injection into the RFQ accelerator.
A new pattern of ion source extractor
Authors: Bisoffi Giovanni , Cavenago Marco
Published: July 2002

An innovative design for an ion source extractor has been carefully investigated, aimed at transporting a beam that is as parallel as possible between the plasma hole and the puller. The known ideal solution in radially unbounded electrodes is used for part of the plasma electrode, while a reentrant puller is designed and proposed, in place of a sharp or a flat one, in order to best shield the beam from the close beam pipes (as confirmed by electrostatic simulations). Beam tracking shows accordingly a substantially better current density uniformity for the reentrant puller case, when no magnetic field is present. A significant B (∼7.4 kG at the plasma hole in our case) tends to smooth out the differences in performance and improve the beam uniformity.
Peak position and width of the energy distribution of ion beams extracted from a plasma source
Authors: Glatzel H. , Wittmaack K.
Published: July 2002

Energy spectra of 1 keV He+ and Ar+ ion beams have been investigated using a sector field analyzer with a resolution ΔE/E<10−3. The ions were generated in a filament type plasma ion source with axial magnetic confinement. The energy spectra exhibited a unimodal, almost symmetrical peak. Width and position of the peak were measured as a function of the operating parameters of the ion source. The smallest energy spread of the ions was measured at relatively high source pressures and low magnetic field strength, in which case the full width at half-maximum of the peak was ΔE=1.5 eV. Correcting for the resolution of the analyzer, an energy spread of less than 1 eV thus appears to be achievable with the source employed in this study. Rather large peak shifts (up to 10 eV and more) were observed upon changing the axial magnetic field strength and the discharge current, the effect being much more pronounced for He than for Ar. By contrast, the peak position was almost independent of the applied discharge voltage, provided the terminal voltage was connected to the anode of the discharge. This implies that the zero point of the ion energy is closely related to the anode potential.
Negative ion beam acceleration and transport
Authors: Michaut C. , Devynck P. , Bacal M. , Sledziewski Z. , Valckx F. P. G. , Whealton J. H. , Raridon R. J.
Published: July 2002

The optimum conditions for focusing a negative ion beam are discussed. The distribution of the current between the Faraday cup and a large ring collector, surrounding this cup, has been investigated experimentally and theoretically, at constant extraction voltage (1.9 kV), with the acceleration voltage being varied in a wide range. The effects of beam space charge, negative ion temperature, and stripping are analyzed.
Application of aperture displacement technique to producing flat beam distributions
Authors: Tanaka Shigeru , Araki Masanori , Okumura Yoshikazu
Published: July 2002

Beam steering technique using aperture displacement was applied to produce uniform beam distributions for testing high heat flux components. Only the apertures of a suppression grid of the JT-60 ion source were programmatically displaced with respect to those of the other three grids. Flat heat flux distributions with a uniformity within ±5% were experimentally obtained over an area of 10 cm ×10 cm at a position 4 m from the ion source. The peak heat flux ranges from 3 to 60 MW/m2 with the beam energies of 30–70 keV.
The PSI 870 keV high intensity Cockcroft–Walton preinjector
Authors: Olivo M. , Mariani E. , Sherman Joseph
Published: July 2002

As part of the program to increase the beam current from the Paul Scherrer Institute (formerly SIN) 590 MeV proton ring accelerator, a new injector system based on a 72 MeV isochronous cyclotron has been built. The preinjector for the 72 MeV machine consists of a 900 kV, 30 mA dc generator of the Cockcroft–Walton type, a high voltage dome housing a multicusp ion source with a 60 keV beam transport line, and a SF6 insulated acceleration tube. A general description and operational experience of the 870 keV preinjector and progress toward improving the H+ fractional output of the ion source will be given.
Multicusp ion source for production of negative lithium ions
Authors: Wada M. , Tsuda H. , Sasao M.
Published: July 2002

A beam of negative lithium ions (Li−) with a current density as high as 3×10−5 A/cm2 was extracted from a 5 cm diam, 7 cm long multicusp ion source. The extracted Li− current was correlated to the plasma temperature and density measured with Langmuir probes heated to avoid Li condensation. The neutral lithium flux from the ion source was measured with a Langmuir–Taylor detector, and it showed a linear correlation with the extracted Li− current. Further increase in efficiency to produce Li− current is expected by improving the plasma confinement of the ion source.
Diagnostic of CHORDIS ion source plasma
Authors: Rück D. M. , Jacoby J. , Emig H.
Published: July 2002

Each ion source consists of two principle parts: the plasma source and the extraction system. The characterization of the plasma source of a high current bucket ion source has been investigated. An optical plasma diagnostic method was used. In the following paper a description of the experimental method and the data analysis is given. The results and the limitation of the applied method are discussed.
Study of beam brightness in a radial extraction rf ion source with injected electrons
Authors: Abdelaziz M. E. , Abdelbaki M. M. , Zakhary S. G.
Published: July 2002

The use of electron injection into rf plasma of the radial extraction rf ion source improves the beam brightness due to the decrease of electron temperature of the plasma. Also, an emphasis was given to other factors that affect beam brightness such as aberration in the extraction cathode lens and effect of perveance.
Beam measurements on a CHORDIS ion source
Authors: Sarstedt M. , Thomae R. , Klein H. , Kuhpour M. , Maaser A. , Weber M. , Wojke R.
Published: July 2002

We present beam measurements which have been carried out using a CHORDIS ion source supplied with a modified extraction system. This system is designed to handle extraction voltages up to 60 kV. For beam diagnostics, a Faraday cup and a sector magnet have been used. Presented are measurements on beam current, mass, and energy spectra in dependence on various source parameters as gas pressure, arc voltage, and extraction voltage.
A direct current polarized H− ion source based on optically pumped rubidium
Authors: Levy C. D. P. , Buchmann L. , Jayamanna K. , McDonald M. , Ruegg R. , Schmor P. W. , Zelenskii A. N.
Published: July 2002

The TRIUMF optically pumped polarized H− ion source has been modified to operate with rubidium as the optically pumped medium. The intrinsic characteristics of rubidium as well as an increase in laser power, compared with the previous system based on sodium, have led to a large increase in beam polarization to over 75%. A proton current of 2.5 μA extracted from the TRIUMF cyclotron at 230 MeV was easily attained during initial operations.
Development of polarized ion sources at KfK
Authors: Friedrich L. , Huttel E.
Published: July 2002

At the KfK cyclotron a polarized D+ source with a 77 K atomic beam has been in operation since 1985. A 30 K atomic beam source has been designed and optimized for a commercial manufacturer (NTG). In cooperation with the PSI, an electron cyclotron resonance ionizer for an atomic beam source has been developed.
Beam diagnostics (invited)
Authors: Strehl P.
Published: July 2002

Although the types of ion sources in many applications are of great diversity the quality of a source can be assessed mostly by the measurement of the same beam parameters. In this paper the characteristics of various devices for measurement of beam currents, beam profiles, and transverse emittances are discussed. Special reference is given to the limitations arising from thermal heating in case of very intense beams. On the other hand, the detection limits given by electrical noise in case of very low currents are considered.
Plasma sputter negative ion source with ECR discharge (invited)
Authors: Takagi A. , Ikegami K. , Mori Y.
Published: July 2002

A plasma sputter type of negative ion source with an electron cyclotron resonance (ECR) discharge has been developed at KEK. The ECR discharge was produced by a 2.45-GHz microwave. In this ion source, negative heavy ions are produced at the surface of the metal which is placed in a Xe plasma confined by a cusp magnetic field. In preliminary experiments, the beam current of 7 mA for Cu− was obtained in pulsed mode operation.
Development of a compact 2.45 GHz ECR ion source
Authors: Fiedler S. , Winter H. P.
Published: July 2002

ECR-heated plasmas as produced by microwave discharges in magnetic fields are now routinely utilized for production of intense singly and multiply charged ion beams. Such ECR ion sources (‘‘ECRIS’’) can be operated during extended lifetimes even with reactive working gases. Our requirement for a simple, long-lived, high current Li+ ion source for Li-CXS tokamak plasma diagnostics led to a study on plasma production with a coaxial 2.45 GHz microwave discharge (23 mm outer diameter) embedded in a variable magnetic field configuration. The chosen geometry is compatible with Li vapor production from heat pipe ovens or externally heated LiAl alloy liners, and also permits incorporation of a permanent magnet quadrupole structure for enhancing the ion confinement in the discharge region. As a first step, with a simple magnetic mirror field generated by two axially adjustable solenoids the microwave discharge properties and extractable ion beam currents have been investigated with H2, He, and Ar as feeding gases.
Advanced high-current ECR ion sources for implanters
Authors: Torii Yasuhiro , Shimada Masaru , Watanabe Iwao
Published: July 2002

We have already introduced a high-current ECR ion source producing a 200-mA beam of oxygen ions with an 80% O+ fraction. Two more advanced ECR sources with a high-current density of more than 100 mA/cm2 have been newly developed. One source provides high-current density without the accompanying damage to the microwave transmitting window found with the earlier source. This damage, which occurs when high-speed backstream electrons attack the window, limits source lifetime. By adopting a multiple microwave inlet configuration for the introduction of microwaves into the plasma chamber, the ECR condition can be satisfied and high-density plasma can be generated without an attack by backstream electrons. The other is a very compact source producing a high-current beam at a very low-power consumption. This is achieved by reducing the inner diameter of the plasma chamber to 5 cm φ, which is smaller than the cutoff dimensions for propagation of the 2.45 GHz microwave. A high-plasma density of 1 × 1013 cm−3 has been obtained at the low microwave power of 250 W.
Impedance measurements at rf plasmas in noble gases by use of the four-terminal network formalism
Authors: Wüst K. , Groh K. H. , Löb H. W.
Published: July 2002

At medium pressure (density of neutral atoms from 1021 to 1023 m−3) plasma was generated by an rf electric field of 27.12 MHz. The plasma impedance has been measured in He, Ne, Ar, and Kr. In order to avoid errors by stray reactances, the power input line was treated as a four-terminal network. The corresponding coefficients were determined by measurements with known load impedances instead of the plasma.
Intensification of an impregnated-electrode-type liquid-metal ion source by multiplying the number of tip-and-reservoirs
Authors: Gotoh Yasuhito , Fukayama Norihisa , Tsuji Hiroshi , Ishikawa Junzo
Published: July 2002

An impregnated-electrode-type liquid-metal ion source has been developed which utilizes a linear array of emitters. This ion source is constructed by placing two emitters that consist of porous ion-emission tips and reservoirs for liquid metal. The emitter is equipped with multiple ion-emission points in a line. Two tip-and-reservoirs (TAR’s) are fixed by respective knife-edged electrodes. Utilization of multiple TAR’s has an advantage of reducing heater current by connecting them electrically in series. The performance characteristics of the ion source have been investigated using germanium as a source material. Ion emission from 17 points has been achieved with this arrangement; a current of 4.6 mA have been obtained immediately following the ion source. These results indicate that it is possible to extract a current approximately proportional to the number of emission points. The result also implies that a further increase in intensity can be expected by adding more TAR’s to the array.
A multiple-sample, cesium-sputter, negative ion source
Authors: Alton G. D.
Published: July 2002

A multiple-sample, cesium-sputter, negative-ion source which permits sample changes without disruption of on-line tandem electrostatic accelerator operations is described. The source is equipped with provisions for remotely selecting and moving into the beam position any one of 60 samples by means of stepping motors equipped with absolute shaft encoders. A spherical-sector cesium ionizer is used to produce the cesium beam for sputtering the sample material. The source is equipped with a three-element electrode system which has been designed to increase the perveance for cesium ion beam generation and to improve negative ion beam extraction from the source.
A pulsed-mode, high intensity, heavy negative ion source
Authors: Alton G. D.
Published: July 2002

A high intensity, plasma-sputter, negative ion source, which utilizes multicusp, magnetic-field, plasma confinement techniques is described. The source is an axial-geometry version of a radial-geometry source which has demonstrated a pulsed-mode peak intensity level of several mA for a wide spectrum of heavy negative ion species. The mechanical design features include provisions for fast interchange of sputter samples, ease of maintenance, direct cooling of the discharge chamber, and the use of easily replaced coaxial LaB6 cathodes.
Transition and rare-earth metal ion sources
Authors: Evtukhov R. N. , Belykh S. F. , Redina I. V.
Published: July 2002

The design and operation of an original transition and rare-earth metal ion source are described. Ions were produced during collisions of evaporated metal atoms with fast electrons. The source delivered the following parameters: (1) an ion energy of (1–20) keV; (2) a total ion current of (1–25)× 10−6 A; (3) an ion current stability of 0.1%; (4) a beam cross-section diameter of (1–12) mm; and (5) a period of 30–60 h of uninterrupted operation on a charge of 1 g of metal under UHV conditions. The peculiarity of the source is the creation of multiple-charged ions Mq+(q=1–6), and some part of these ions are metastable-excited. The testing results and practical applications of a proposed source are demonstrated.
A double hot cathode lateral extraction Penning ion source
Authors: Ma M. , Stephens K. G. , Sealy B. J. , Mynard J. E.
Published: July 2002

An improved Penning ion source has been developed. This ion source has two helical filaments at the two ends of the discharge chamber. The design of the filaments is such that the resultant magnetic field distribution, which is a combination of the external field and those due to the two filaments, focuses the electrons from the filaments to the plasma region near to the lateral extraction slit, thus creating a hollow cathode effect. This produces an efficient discharge and a good positive ion output. This ion source can produce various species of ions including the ions of reactive gases with a longer lifetime of filaments than for comparable sources.
Measurement of negative-ion-production efficiencies and development of a dc operation sputter-type negative ion source
Authors: Tsuji Hiroshi , Ishikawa Junzo
Published: July 2002

For the development of a high current heavy negative ion source, the production efficiency of the negative ions by Xe+ sputtering with cesium and electron detachment cross sections in xenon gas were measured. The maximum efficiency for Cu− was 12.1% and the single-electron detachment cross section was found to be of the order of 0.6–1.4 × 10−15 cm2 in the energy range of 5–50 keV. Based on the results of these fundamental experiments, a plasma-sputter-type heavy negative ion source has been constructed, in which the plasma was generated at a rf-frequency of 13.56 MHz. A total negative ion current of 2.5 mA was obtained without electrons from the source in dc operation, and the Cu− current was detected to be 91% of the total beam. The operation characteristics are described.
Ion sources for dry etching: Aspects of reactive ion beam etching for Si technology (invited) (abstract)a)
Authors: Scheer H.-C.
Published: July 2002

Aspects of ion beam sources are treated which emerge from their use for reactive ion beam etching (RIBE) in silicon VLSI technology. As a basis for this treatment, the requirements for dry etching for VLSI are elaborated, as well as the consequences of these requirements for ion beam sources to be used for such technology. Practical experience with two types of ion beam sources for this application are highlighted, a classical Kaufman source and a first-generation ECR source. Aspects relevant for microfabrication related to grid optics, and the use of reactive gases, are discussed. Most important in this context are the internal microdivergence of an ion beam and the fragmentation of molecular gases taking place in the source and the ion beam as well. The consequence for potential application of RIBE for micropatterning must be to characterize sources by measuring their energy- and angle-resolved particle fluxes to the wafer.
Bakeable duoplasmatron ion gun for SIMS microanalysis
Authors: Konarski P. , Kalczuk M. , Kościński J.
Published: July 2002

A 10-keV duoplasmatron ion gun with ion optical column is presented. The system is fully bakeable; copper gaskets and alumina isolators are used. The source can operate with hot filament or hollow cathode. The differentially pumped ion optical column consists of a set of three lenses, double octupole stigmator, deflection-scanning system, and diaphragm set.
The formation of coatings from ionized vapor
Authors: Nikitin M. M.
Published: July 2002

The structure and properties of metallic coatings from ionized vapor are investigated. A method of evaporating materials in vacuum by means of a non-self-maintained discharge was developed. The evaporator, consisting of a heated cathode, focusing elements, and anode (the material to be evaporated), generates an atom flux variable from 1016 to 5×1017 cm−2 s−1 and fractional ionization from 2% to 100%. The properties of the non-self-maintained discharge have been investigated over the voltage range from 30 to 700 V and current range from 1 to 50 A. The ionization of the vapor flux and control over the energy provide a deposit of strongly adhering coatings with small crystalline structure.
A new thermal emission cesium primary ion source for secondary ion mass spectrometer
Authors: Zinkiewicz J. M. , Sowa M. , Baranowski R. , Glusiec L. , Kiszczak K.
Published: July 2002

A thermal emission cesium primary ion source for investigation of solid-state surface layers by the SIMS method is described. The characteristics of the constructed ion source are presented. The optimal values of accelerating, focusing, and stopping potentials for the primary ions focusing system are found (Va = 4500 V, Vf = 2500 V, and Vs = 2560 V, respectively). This thermal emission cesium primary ion source is used in the secondary ion mass spectrometer constructed at the Institute of Physics of the M. Curie-Skl/odowska University in Lublin. To illustrate the application of the described ion source, the mass spectrum of GaAs secondary ions and the concentration profile of indium implanted into stainless steel at an energy of 150 keV and dose 5×1016 ions/cm2 are presented. The maximum concentration of In is at about 240-Å depth.
Kurchatov IAE dedicated SR facility SIBERIA status report and SR instrumentation problems
Authors: Nesterikhin Yu. Ye.
Published: July 2002

The SIBERIA facility in Kurchatov Institute of Atomic Energy, Moscow, U.S.S.R. is discussed. The experimental stations, beamlines and the necessary synchrotron radiation−instrumentation is created by the
The Photon Factory 2.5-GeV storage ring
Authors: Kobayakawa Hisashi , Matsushita Tadashi
Published: July 2002

The Photon Factory is a dedicated synchrotron-radiation research facility which has been in operation since 1982. It uses a 2.5-GeV linear accelerator as an injector, a 2.5-GeV positron storage ring and more than 50 experimental stations covering the vacuum ultraviolet to hard x-ray wavelength range. 500 experimental proposals are active during fiscal year 1991. The storage ring was operational for 4300 h during fiscal year 1990. 85% of the operational hours were assigned to user experiments; the remainder was used for machine studies. The number of registered users is now 2300.
A low cost correlator employing a personal computer
Authors: Lorusso G. F. , Capozzi V. , Minafra A.
Published: July 2002

The intention of this paper is to describe the design of a 16-bit correlation setup employing a personal computer (PC) used in intensity fluctuation spectroscopy. It is based on a hardware acquisition board which counts the photons detected in the selected sampling time. The calculation of the correlation coefficients is achieved with a PC by means of a suitable software program. This arrangement permits one to obtain various kinds of information from the recorded data, i.e., it is possible to evaluate other statistical estimators instead of the usual correlation function. Experimental tests of the apparatus have been obtained by measuring the light scattered by a liquid suspension of polystyrene latex spheres.
Vibration isolation stacks for gravitational wave detectors−Finite element analysis
Authors: Cantley C. A. , Hough J. , Robertson N. A. , Greenhalgh R. J. S.
Published: July 2002

Seismic isolation is a necessity for many delicate experiments such as those designed to search for gravitational radiation. One method of providing a significant amount of isolation has been the use of multiple stage stacks of alternating layers of dense material (metal) and elastic material (rubber). In this work finite element analysis is used to model stack systems in a relatively realistic way, allowing the importance of cross coupling of degrees of freedom to be evaluated. It becomes clear that care has to be taken with the geometrical construction in order to achieve the isolation predicted by simple dynamical analysis.
‘‘Helium jet’’ accommodator for the thermalization of atomic hydrogen gas
Authors: Mertig M. , Levkovitch A. V. , Luppov V. G. , Pilipenko Yu. K.
Published: July 2002

We have developed a helium-temperature accommodator for atomic hydrogen gas with a transmission efficiency higher than 50% and a small heat load due to the reflowing helium film. With this accommodator a stable flux of hydrogen atoms up to 5×1015 atoms/s into the low-temperature storage cell has been achieved. A high helium compression of hydrogen atoms into the storage cell has been observed.
A readout system for 3-GHz rf-SQUIDs
Authors: Mück Michael
Published: July 2002

The layout and construction of a readout electronics for rf superconducting quantum interference devices (SQUIDs) with bias frequencies of 3 GHz are described. The electronics uses standard electronic components and can be aligned using a spectrum analyzer. Differences between a conventional 20-MHz electronics and this microwave readout are explained. Each individual circuit block is described and circuit diagrams as well as information for pc-board layout is given. A brief description of thin-film rf-SQUIDs used for experiments with this readout electronics is also included.