bluuebunny/crossref_metadata_2025 huggingface dataset:
A small unbalanced magnetron sputtering source with multipole magnetic field anode
Authors: Zheng Sixiao , Sun Guanqing , Wang Peilu , Liao Xiaodong
Published: July 2002

A study of a small unbalanced magnetron source with a multipole cusp magnetic field anode is described. The coaxial magnetron principle was extended to the small unbalanced planar magnetron source. In the radial arrangement of magnets, the S pole of the magnet is directed toward the center of the permanent magnet annulus, and the core of the magnetized mild steel was only 5 mm in diameter. Such a construction of the unbalanced magnet arrangment makes the magnetron sputtering target as small as 34 mm in diameter, and increases the sputtering area of the target to 60%. The multipole magnetic field put in the anode can make the unbalanced magnetron source run in a higher discharge current at a lower arc voltage condition after beginning the arc discharge at a higher beginning arc voltage.
Production of negative lithium ions from powdery LiH by ion stimulated desorption (abstract)a)
Authors: Wada Motoi , Tsuda Hiroshi , Sasao Mamiko , Kawano Hiroyuki
Published: July 2002

Production characteristics of Li− from powdery LiH immersed in argon and hydrogen discharges were investigated. The surface of the LiH powder was covered with a Mo mesh and a negative bias potential was applied to the mesh to bombard LiH powder with plasma ions. The amount of Li− current produced at the surface of the LiH powder was an increasing function of the bombarding ion energy. The decomposition of LiH by the ion bombardment accompanied the production of hydrogen gas, and the H− current was also extracted from the ion source plasma. The addition of Cs into a discharge showed little enhancement of Li− production.
Extraction of high current Cr ion beam from a multicusp metal ion source
Authors: Yamashita Takatoshi , Inouchi Yutaka , Fujiwara Shuichi , Matsuda Yasuhiro , Inami Hiroshi , Matsunaga Kouzi , Matsuda Koji
Published: July 2002

Improvements have been made in a metal ion source, which made it possible to produce high density metal vapor plasma for extracting high current metal ion beams. Experiments of chromium ion beam extraction were performed. The ion beam current reached 250 mA at the extraction voltage of 36 kV. Furthermore, stable operation was achieved at the extracted current of 117 mA. The temporal drift of ion beam current was within ±1% for 1 h.
The preliminary experiments on laser ion source at IMP
Authors: Ping Yuan , Sixing Zhou , Baowen Wei
Published: July 2002

The experimental results of a study on a laser ion source are presented in this report. A gain of about five in the total peak current and an enhanced relative amount of higher charge states were observed when the laser-generated plasma was transported through magnetic bottle fields. Radio-frequency discharge was added to the laser ion source, further ionizing the primary laser plasma. In this case, the total peak current increased from 0.46 to 1.4 mA. It is suggested that the laser plasma can be used in an electron cyclotron resonance source to produce ions of solid elements.
Increased ion intensity and reliability of the Stockholm electron beam ion source (abstract)a)
Authors: Beebe E. , Liljeby L. , Pikin A. , Björkhage M. , Engström Å. , Paal A.
Published: July 2002

The electron beam ion source, CRYSIS, produces highly charged ions for injection into the heavy ion storage ring—CRYRING at MSL, as well as low energy atomic physics experiments and the Stockholm–Mainz Penning trap recently installed at MSL. CRYSIS has produced ions up to Ar18+ and 136Xe52+. Pulsed beams of Ar13+ ions 60 μs in duration have been injected into CRYRING via an RFQ and ions of charge up to 136Xe44+ have been used in atomic physics experiments with pulse duration 10–250 ms. A vacuum separation of the cryostat and ionization volumes has been made. Temperature control and measurement of internal electrodes have increased the gas injection efficiency and reduced the memory effect associated with a cryogenic EBIS. External ion injection has been added as an alternative to neutral gas injection for introducing the species to be ionized to high charge states. Monitoring of the radio frequency noise signal with a spectrum analyzer has aided in the propagation of quiet, high current (450 mA) dc electron beams. These quiet electron beams have been used to produce extracted ion pulses of higher intensities than in previous operation.
Selective deposition of radio-frequency power in volume sources to optimize the tandem configuration for negative ion production
Authors: Hershcovitch Ady
Published: July 2002

This article is a suggestion for the development of a microwave driven volume source. A high electron temperature plasma is to be generated by coupling microwaves at the electron cyclotron resonance into a closed field line magnetic field configuration to form the discharge chamber of a volume source. As an example, a toroidal magnetic field configuration is examined. Numerous advantages of this scheme are cited, most important of which is the possibility of having a tandem volume source with a very steep plasma temperature gradient.
Study of pulsed discharge operation of volume H− ion source
Authors: Michaut C. , Bacal M. , Belchenko Yu. I. , Auvray J. , Konieczny C. , Stephan J. P.
Published: July 2002

The pulsed operation of a negative ion volume source has been investigated, both with and without a magnetic filter present, under conditions of full-scale acceleration of the extracted negative hydrogen ion beam. This investigation is relevant to the temporal filter concept, which was recently proposed. The observation of three afterglow negative ion peaks is reported. As the negative ion current during the discharge pulse, each of the afterglow peaks can be optimized by varying the pressure, the plasma electrode bias, and the extraction voltage. Under optimum conditions, the negative ion current during the discharge pulse exceeds the afterglow peaks.
An EBIS for use with synchrotron radiation
Authors: Kravis Scott , Oura Masaki , Awaya Yohko , Okuno Kazuhiko , Kimura Masahiro
Published: July 2002

At RIKEN we have constructed an electron-beam ion source (EBIS) for use with synchrotron radiation to study the photoionization process of highly charged ions. The reason for using an EBIS as an ion target is that it can produce several orders of magnitude higher density ion targets than conventional ion sources in an ultra-high-vacuum environment. Calculations have shown that ion densities between 108 and 1010 ions/cm3, under various operating conditions, are obtainable in an EBIT. The apparatus will also be used to test the photon beam ion source (PHOBIS) mode of operation to create low-energy multicharged ions by replacing the electron beam with synchrotron radiation.
The ECR ion source DECRIS
Authors: Efremov A. , Kutner V. B. , Pivarč J. , Lebedev A. N. , Chugreev V. A.
Published: July 2002

The design of the electron cyclotron resonance (ECR) multicharged ion source DECRIS (Dubna ECR ion source, 14 GHz) was started at the Flerov Laboratory of Nuclear Reactions at the beginning of 1990 and in January 1992 the first plasma was ignited. A classical magnetic configuration based on the MINIMAFIOS with some ‘‘features’’ served as the basis for the source design. The DECRIS was installed on the ECR test bench. The first study of the source was carried out in continuous mode of operation at strict control of hexapole temperature. The ion source has been tested with He, N, O, and Ar ions. The results of these initial measurements are presented.
A very compact electron cyclotron resonance ion source
Authors: Boukari F. , Wartski L. , Coste Ph. , Farchi A. , Roy V. , Aubert J.
Published: July 2002

A new electron cyclotron resonance (ECR) ion source has been developed in the laboratory. The ECR condition at 2.45 GHz is obtained in a multicusp arrangement using a set of four parallelepiped-shaped SmCo magnets regularly spaced around a cylindrical ionization chamber 50 mm in diameter and 50 mm in height. The electromagnetic cavity is made of a shielded quarter-wavelength Lecher line resonator coaxially coupled to the microwave generator through an excitation loop antenna and a SMA-type connector. The extracted argon ion beam current density has been measured for different excitation modes fixed by the loop antenna orientation. A current density of 1 mA/cm2 has been reached with an incident microwave power of 110 W and a chamber pressure of 9×10−3 mbar. The small dimensions of this ion source and its performance allow to use it not only in applications such as ion beam processing and cleaning or surface treatments in advanced microelectronics, but also as a neutralizer for ion deposition applications.
A method of measurement of gas flow rates in ECR and PIG ion sources
Authors: Dubnička Š. , Kutner V. B.
Published: July 2002

A method of measurement of an instantaneous value of the volume flow rate (in the range 0.05–5 cm3 min−1)of a gas flowing into an ion chamber of an ion source is described. It consists of the measurement of pressure differences (0–100 Pa) on a system of diaphragms with a small hole (0.2 mm) made in the center of them. The pressure differences are generated by the flowing of the gas through the latter. The sensitivity of the system depends on the number of diaphragms used. Parameters of diaphragms are estimated by the special equation describing the flow of the gas through an orifice in a pipe and the equation for laminar flow in a round tube. Calibrating measurements with He, air, Ar, and Xe demonstrated that our diaphragm can be used for the measurement of flow rates of all these gases.
The properties of a metal/oxide semiconductor junction prepared using a high-purity ozone surface treatment
Authors: Shimizu Takashi , Okushi Hideyo
Published: July 2002

Electrical properties of the junction between a metal and an oxide semiconductor whose surface has been treated with high-purity ozone were investigated. In situ treatment of ozone on the surfaces of Nb-doped SrTiO3 (NSTO) and Nb-doped TiO2 (NTO) and in situ deposition of Au have been performed to make metal/semiconductor junctions. The I–V characteristics of the junctions show high rectification properties (the rectification ratios are over a ninth order of magnitude when the junctions are biased at 1.3 V) and the capacitance–voltage (C–V) characteristics show linear C−2–V relationships in the reverse condition. These results have indicated that the surface treatment of the oxide semiconductors using high-purity ozone and in situ deposition of metal electrodes drastically improve the Schottky properties of oxide semiconductor diodes.
Buckling of a vibration-isolation stack for gravity wave detectors
Authors: Kuroda Kazuaki , Shimizu Kazuya
Published: July 2002

A semi-analytic form for the axial buckling force of a multistage vibration-isolation stack for gravitational radiation detectors is deduced. This is another version of Euler’s formula for simple pillars and gives a reference value both in design of isolation stacks and in numerical analysis for more complicated situations.
A miniature interferometry sensor for monitoring the changes of film thickness and refractive index
Authors: Wu Chi
Published: July 2002

A new miniature interferometer has recently been developed for monitoring the changes of film thickness and refractive index, wherein a semiconductor laser and a photodiode detector are integrated to form a laser/detector hybrid. The laser light is collimated by a lens. When the laser light hits a film, it is reflected twice by the two interfaces between the film and the surrounding mediums. The two reflected light beams are interfered at the detector by the same lens. Due to the interference, the detected intensity is a function of the film thickness. The swelling of thin gelatin gel film has been used to demonstrate the use of this novel sensor. The sensor is ready to be used in many applications, such as inside a vacuum chamber, on a robot arm, and in a small reaction container, wherever a conventional interferometric setup cannot be easily implemented because of its size.
Tuning a rotating wave resonator
Authors: Ceperley Peter H. , Velazco Jose E.
Published: July 2002

Creation of a rotating wave field in a high-Q resonator usually requires the resonator to be tuned to compensate for manufacturing errors. The tuning of a rotating wave resonator is more complicated than that of a common resonator. A theory of tuning rotating wave resonators and a procedure for efficiently carrying out this tuning is presented in this paper, along with the authors’ experience in tuning a rotating TM110 mode in a 1.28 GHz microwave resonator.
Charged nanocantilever as a generator of microscopic ac fields
Authors: Pogorelov Yu.
Published: July 2002

An application of an electrically charged nanosize mechanical oscillator for generating strong ac electromagnetic fields, limited to a microscopically small volume, is indicated. The study by this method, of dynamic response of the nearby microscopic objects, may considerably expand the experimental techniques in solid state physics, chemistry, and biology. Possibilities of realizing a tunable frequency spectrum and ways to discriminate between different polarizations are suggested. The proposed method can be well realized with the available nanocantilevers.
Oscillation characteristics of diode-pumped Tm:YAG and Tm,Ho:YAG microchip lasers
Authors: Yokozawa Takeshi , Nakajima Hayato , Yamamoto Takanobu , Hara Hiroshi
Published: July 2002

We have studied the output power, slope efficiency and oscillation threshold of a diode-pumped Tm:YAG microchip laser by using two different resonator configurations (half-symmetric and near-planar) for the development of an eye-safe remote sensing laser system. The half-symmetric resonator was superior in output power, slope efficiency and threshold, their values for a crystal temperature of 20 °C being 29 mW, 37%, and 28 mW, respectively. But the near-planar resonator was superior in producing single mode oscillation, giving an output power of 2 mW at a crystal temperature of −10 °C. Between Tm:YAG and Tm,Ho:YAG microchip lasers, moreover, the latter was found to fall short in slope efficiency and threshold, indicating that the effects of Ho as a dopant on the output power is negative. Possible explanations for the difference are given.
Soft-x-ray multilayer mirrors with laterally varying film thicknesses fabricated using laser-beam-scanning chemical vapor deposition
Authors: Yamada Yuka , Takeyama Shigeru , Mutoh Katsuhiko , Miyata Takeo
Published: July 2002

The authors have developed a control method of spatial film thickness distribution of multilayer mirrors for soft-x-ray focusing systems using an argon–fluoride (ArF) excimer laser-induced chemical vapor deposition (LCVD). A line-shaped laser beam is unidirectionally scanned over an area of 100×100 mm2. The scanning speed is controlled in response to a film thickness distribution which is required to be obtained. A tungsten–silicon (W/Si) multilayer with laterally varying film thickness is successfully fabricated on the design rule, and soft-x-ray (λ=12.8 nm; not polarized) reflectivities from 37% to 20% are obtained at the grazing angles from 18° to 22° in response to the film thickness distribution. Furthermore, the amount of the soft x rays reflected by the multilayer within 100 mm of the substrate is estimated at about 90% of that in the case of the designed distribution, and the feasibility of LCVD for fabricating multilayer mirrors for high performance soft-x-ray focusing systems has been demonstrated.
Sun photometry using photodiode open circuit voltage measurements
Authors: Acharya Y. B. , Jayaraman A.
Published: July 2002

A simple technique is explored in which the open circuit voltage of a photodiode is measured using a simple digital multimeter to monitor the solar irradiance and atmospheric optical depths in three spectral bands. The advantage of this technique is that the photometer only consists of an optical interference filter, photodiode, and a measuring digital multimeter, while the electronics circuitry otherwise needed in a conventional photometer is avoided. This makes the system very simple, cost effective, and versatile for even nonprofessionals to handle.
Scanning procedures for calibration of radiation detectors
Authors: Birattari C. , Manfredi G. , Silari M.
Published: July 2002

Three different scanning procedures that can be adopted to reproduce a uniform irradiation by a radiation field over a large detector, when the beam size is less than the monitor dimension, are discussed. These procedures are spot scanning, in which the scan is performed over a mesh of points; linear scanning, in which the instrument is moved continuously in front of the beam in the two transverse directions; and cross scanning, in which the scan is obtained according to a law yielding a ‘‘pseudo-Lissajous’’ figure. An instrument which has been designed and built for the calibration of a neutron rem counter is described.
Augmented railgun using a permanent magnet
Authors: Katsuki S. , Akiyama H. , Eguchi N. , Sueda T. , Soejima M. , Maeda S. , Sato K. N.
Published: July 2002

The use of a permanent magnet instead of an electromagnet has been proposed for the augmentation of the magnetic field of a railgun driven by a current of approximately 20 kA. A permanent magnet has the following advantages in comparison with conventional augmentations using additional turns: (1) simple configuration of the system, (2) temporally and spatially constant magnetic fields, and (3) high efficiency. Here, the operation of a conventional railgun and that of an augmented railgun using a permanent magnet are compared experimentally, and the usefulness of the permanent magnet is described.
Interface state measurements by the DLS-82E lock-in spectrometer
Authors: Dmowski K. , Vuillaume D. , Lepley B. , Losson E. , Bath A.
Published: July 2002

A calculation procedure to determine the energy distribution of interface states from the deep level transient spectroscopy spectrum measured in metal–insulator–semiconductor structures by means of the DLS-82E lock-in spectrometer is described. Interface states in metal–boron nitride–InP and metal–oxide–Si capacitors have been examined by the DLS-82E spectrometer to demonstrate the practical application of the proposed procedure.
Sol–gels with fiber-optic chemical sensor potential: Effects of preparation, aging, and long-term storage
Authors: Badini G. E. , Grattan K. T. V. , Tseung A. C. C.
Published: July 2002

The features of sol–gels, incorporating pH-sensitive dyes, designed as potential substrates for fiber-optic chemical sensors, have been investigated in terms of a variety of characteristics resulting from the preparation methods used and following the storage of samples for a period of several years. These materials, organically doped sol–gels, have been used as the heart of a number of prototype chemical sensing instruments, and a key issue in their effective use in instrumentation is their long-term durability and stability. In this work, it has been shown that such aged gel substrates can withstand immersion in water, drying, and reimmersion without fragmenting. Such impregnated gels were shown to still exhibit strong fluorescence, although some changes to the gel structure, determined from microhardness measurements, were observed and reported, reflecting their potential for use in chemically sensitive fiber optic-based instruments.
Impurity-free layer disordering in p-i-n and n-i-p AlGaAs-GaAs multiple quantum well device structures: The Fermi level effect revisited
Authors: Seshadri S. , Guido L. J. , Mitev P.
Published: July 2002

Spatially resolved values of the Al-Ga interdiffusion coefficient for p-i-n and n-i-p AlGaAs-GaAs device structures are found to be nearly identical in magnitude, but to vary with position by a factor of 2 across a 1 μm thick multiple quantum well active region. These observations are in marked contrast with theoretical predictions given that the Fermi level to valence-band energy separation changes by 0.7 eV across the intrinsic region and suggest that impurity-free layer disordering does not provide the necessary uniformity in energy shift for photonic integrated circuit fabrication in its present state of development.
An electrostatic analyzer for surface structure measurements by low-energy-ion-scattering
Authors: Hird B. , Gauthier P. , Armstrong R. A.
Published: July 2002

A cylindrical electrode electrostatic analyzer has been designed for surface structure measurements which has sufficient sensitivity that shadowing/blocking data can be obtained without significantly damaging the surface structure. A modification to the standard π/√2 design compensates for that part of the spread in the ion energies due to elastic scattering kinematics. The analyzer is small enough to fit inside a standard 25 cm diameter UHV chamber on a turntable, allowing angular distribution measurements over a wide range of scattering angles. An example of a shadowing/blocking angular scan of a clean Si(100) surface is shown.
Solenoid pinch valve
Authors: Alburger D. E.
Published: July 2002

In order to minimize dead volume an ordinary solenoid valve, designed for 115 V, 60 cycles, is modified to serve as a neoprene tubing pinch valve operating reliably at 37 V dc.
Ultrahighly sensitive laser-Doppler velocity meter with a diode-pumped Nd:YVO4 microchip laser
Authors: Okamoto S. , Takeda H. , Kannari F.
Published: July 2002

Extremely high sensitivity of a diode-pumped microchip Nd:YVO4 laser to external light injection is demonstrated in optical detection of Doppler shift from a moving object. Intensity modulation induced by reflected scattered light from a rotating object at the Doppler-shift frequency is measured for a 1-mm-long diode-pumped Nd:YVO4 laser. When adjusting the diode pump power so that the relaxation oscillation frequency is resonant to the Doppler-shift frequency, the minimum detectable intensity of scattered light injected back into the microchip laser can be <−170 dB weaker than the intracavity laser intensity.
Reflectance meter with high spatial resolution and its application for a surface emitting laser diode
Authors: Okada Takumi , Ogura Mutsuo
Published: July 2002

A reflectance meter with high spatial resolution is realized with a Ti–sapphire tunable laser as a light source. The spot size of an incident beam is 2 μm when an objective lens with the power of 20 was employed. The reflectivity of the optical cavity for a surface emitting laser diode (SELD) and its change with carrier injection was measured. The gain and refractive index variation of the active layer in the SELD was estimated by the parameter fitting based on a simple Fabry–Perot cavity model with material loss.
The macromolecular crystallography beamline at ELETTRA
Authors: Bernstorff S. , Busetto E. , Gramaccioni C. , Lausi A. , Olivi L. , Zanini F. , Savoia A. , Colapietro M. , Portalone G. , Camalli M. , Pifferi A. , Spagna R. , Barba L. , Cassetta A.
Published: July 2002

A new beamline for macromolecular crystallography has been constructed and is currently under commissioning. Its source is the high-power wiggler at the 2 GeV storage ring ELETTRA. The optics consists of a double-crystal monochromator in nondispersive configuration followed by a toroidal focusing mirror, and is designed to allow both diffraction experiments with monochromatized beam in the energy range 4–25 keV, and Laue experiments with white beam. The experimental station is based on an imaging plate area detector from MarResearch and a model 5020 Huber 4-circle diffractometer. To control the second apparatus, a plug-in board interface for a personal computer and a crystallographic package, CS, have been developed.
Broadband optical reflector—an application of light localization in one dimension
Authors: Zhang Daozhong , Li Zhaolin , Hu Wei , Cheng Bingying
Published: July 2002

A broad-band optical reflector based on the localization of light for one-dimensional disordered systems is proposed and demonstrated both theoretically and experimentally. The binary disordered multilayer reflector consists of alternating random layers of two coating materials. Its high reflection range is much wider than that of standard λ/4 stacks and can be obtained by a conventional coating method and ordinary materials. This kind of reflector will have significant applications in laser technology and optical equipment.
Comment on ‘‘Simple shutter circuit for protecting microchannel plate photomultipliers from excess light exposure’’ [Rev. Sci. Instrum. 65, 261 (1994)]
Authors: Thorsen C. , Baron M.
Published: July 2002

In order to obtain the quoted exposure limit, a resistor value must be increased by a factor of 1000.
Charged particle identification including Pions by pulse-shape discrimination with an NE213 liquid scintillator
Authors: Nakamoto Tatsushi , Ishibashi Kenji , Matsufuji Naruhiro , Shigyo Nobuhiro , Maehata Keisuke
Published: July 2002

Particles emitted from spallation reactions induced by protons having GeV energies were measured with an NE213 liquid scintillator, 12.7 cm in diameter and 12.7 cm thick. The pulse-shape discrimination (PSD) was carried out for charged particle identification by the two-gate integration method. Pions having energies up to 60 MeV were clearly discriminated from protons and electrons. On the contrary, pions with higher energies could not be identified since they escaped from the detector. The advantage of PSD for charged particle identification is that there is no requirement for a ΔE detector in the measurements.
Double integration of current transients in response to an abrupt change of applied bias: Application to dielectrics
Authors: Thurzo I. , Barančok D. , Haluška M.
Published: July 2002

The depolarization current transients are processed in two consecutive steps: initially the feedback capacitor of a charge-to-voltage converter (QVC) is charged by the transient current, which is followed by integrating the output of the QVC via a gated integrator operated in the mode of exponential averaging. Unlike charge transient spectroscopy [QTS; J. W. Farmer, C. D. Lamp, and J. M. Meese, Appl. Phys. Lett. 41, 1063 (1982)], intended originally for high-resistivity semiconductors, the gate aperture duration is set to intervals comparable to the rate window. Since a single channel of our advanced system represents an unrestored time-domain filter, output signals of the three gated integrators are properly combined in an analog mixer, to get a second-order filter [Crowell and Alipanahi, Solid-State Electron. 24, 25 (1980)]. Apart from the selectivity improvement, our multichannel scheme eliminates parasitic charges due to leaky dielectrics. The formalism of the evaluation of kinetic parameters of dipoles is applied to experimentally observed relaxation peaks from Gd-doped CaF2 crystals.
Thomson scattering with a gated intensified charge-coupled device camera using a frequency doubled periodically pulsed Nd:YAG laser
Authors: Hirsch K. , Volk G.
Published: July 2002

Using a gated intensified change-coupled device camera sectioned into 10 spatial and 33 spectral subchannels data collection up to 6 Hz repetition rate from the scattered signals of a Nd3+:YAG laser could be handled. This single detection system eases alignment and calibration via Rayleigh scattering. By accumulating up to 1000 Thomson pulse signals first spatial profiles of the electron temperature and electron density were received from a plasma jet. Results are in good agreement with spectroscopic data previously published.
Possible evidence of quantum size effects in x-ray photoemission spectra of ultrathin Si layers
Authors: Dibiase N. , Gabetta G. , Lumachi A. , Scagliotti M. , Parmigiani F.
Published: July 2002

This letter reports the experimental evidence of a 2.3 eV blue shift of the plasmon loss lines observed in the x-ray photoelectron spectra of an ultrathin Si layer equivalent to 1.5×1015  at./cm2 deposited onto a randomly oriented Al2O3 single crystal. The plasmon line shifts, which is roughly proportional to the deposited Si(mass)−2/3, are attributed to quantum confinement effects in agreement with electron energy loss measurements performed on nanosized Si particles.
Cluster interactions and stress evolution during electromigration in confined metal interconnects
Authors: Brown Dirk D. , Sanchez John E. , Korhonen M. A. , Li Che-Yu
Published: July 2002

In narrow metal interconnects used in advanced integrated circuits, electromigration flux divergences occur at the intersection between polycrystalline cluster segments (where grain boundaries offer a fast diffusion path), and bamboo segments (where there are no grain boundaries along the line length). In confined, passivated metal interconnects, these flux divergences are linked to the evolution of significant mechanical stresses in the metal. A quasisteady state stress distribution builds up quickly in the cluster segments and remains unchanged until the stress profiles between cluster segments begin to overlap, and the clusters begin to ‘‘interact.’’ A significant increase in stress above the quasisteady state can result from cluster interactions, increasing the potential for electromigration and stress-induced damage. If the cluster separation is small, this stress increase can occur on a time scale which is short compared to the stress evolution of the interconnect line as a whole.
Characterization of the electric field and gain of the 2 MeV energy analyzer (abstract)
Authors: McLaren P. E. , Manchester J. S. , Schoch P. M. , Crowley T. P. , Demers D. R. , Ouroua A.
Published: July 2002

Accurate determination of plasma potentials in the TEXT-upgrade tokamak using the 2 MeV heavy ion beam probe requires a good understanding of detector characteristics. The detector utilized is a parallel plate electrostatic energy analyzer. A figure of merit for this analyzer is the gain, GA, which is defined as the ratio of the potential of the incident ions to the potential applied to the analyzer anode. Tests are in progress on the vertical test stand at Rensselaera) to characterize the dependence of gain on radial entrance angle, toroidal entrance angle, and toroidal position of the ion beam. Results will be used to assist with in situ calibration on the TEXT-upgrade facility.
Measurement of limiter heating due to alpha particle losses during high fusion power deuterium-tritium operation of the TFTR tokamak
Authors: Janos A. , Owens D. K. , Darrow D. , Redi M. H. , Zarnstorff M. C. , Zweben S. J.
Published: July 2002

Measurements and preliminary analysis have been completed on limiter heating during high fusion power deuterium-tritium (D-T) operation of the Tokamak Fusion Test Reactor (TFTR) in an attempt to identify heating from first orbit and ripple losses of fast alpha particles. Recent operation of TFTR with a 50-50 mix of D-T has resulted in fusion power output (≊6.2 MW) orders of magnitude above what was previously achieved on TFTR. A significantly larger absolute number of particles and energy from fusion products, compared to D-D operation, are expected to be lost to the limiters. Power and energy estimates of total alpha losses were as high as 0.13 MW and 64 kJ. Measurements were made in the vicinity of the outer midplane, where most of the losses are expected, with thermocouples mounted on the tiles of a limiter. With an increasingly more reactive mixture of D and T at constant beam power, there was a measurable increase in the limiter tile temperature as the fusion power and alpha yield increased. The measured temperature increases due to heating from alpha losses corresponded to heat loads of ≤5.9 kJ/m2, which are within a factor of 2 of estimates for alpha heating based on simulations assuming a loss rate of fast alphas of 12%. Estimates are made of heating from the various heating sources using simulations from a number of codes. The observed level of alpha heating indicates that there was probably neither an unexpectedly large fraction of lost alphas nor unexpected localization of the losses. Limits on the stochastic ripple loss contribution from alphas can be deduced.
Oxidation enhanced diffusion of Si in GaAs: The effect of excess As on diffusion depth and carrier concentration
Authors: Keller Robert C. , Helms C. R.
Published: July 2002

An investigation of the fast diffusion of Si in GaAs from deposited surface layers oxidized in an Ar/H2O ambient indicates excess As, formed by oxidation of Ga originating from the substrate, is responsible for the enhanced diffusion of Si into the substrate. The formation of the SiO2 on the surface during oxidation prevents loss of the excess As, which accumulates in the remaining Si film. Higher H2O partial pressures during the oxidation produce higher As/Si ratios, resulting in an increase in the Si diffusion depth and concentration. However, the n-type carrier concentration decreases with higher As/Si ratios in the remaining Si layer. A second, nonoxidizing anneal on samples with the SiO2 and Si layer removed produced different effects on the carrier concentration, depending on whether As was free to escape from the substrate. The results indicate that excess As related defects such as gallium vacancies are probably responsible for the n-type compensation in the fast diffused samples.
Far-infrared laser diagnostics on the HT-6M tokamak
Authors: Gao X. , Lu H. J. , Guo Q. L. , Wan Y. X. , Tong X. D.
Published: July 2002

A multichannel far-infrared (FIR) hydrogen cyanide (HCN) laser interferometer was developed to measure plasma electron density profile on the HT-6M tokamak. The structure of the seven-channel FIR laser interferometer is described. The laser source used in the interferometer was a continuous-wave glow discharge HCN laser with a cavity length of 3.4 m and power output of about 100 mW at 337 μm. The detection sensitivity was 1/15 fringe with a temporal resolution of 0.1 ms. Experimental results were measured by the seven-channel FIR HCN laser interferometer with edge Ohmic heating, a pumping limiter, and ion cyclotron resonant heating on the HT-6M tokamak are reported.
Thomson scattering experiments on a 100 MHz inductively coupled plasma calibrated by Raman scattering
Authors: de Regt J. M. , Engeln R. A. H. , de Groote F. P. J. , van der Mullen J. A. M. , Schram D. C.
Published: July 2002

A new calibration method to obtain the electron density from Thomson scattering on an inductively coupled plasma is discussed. Raman scattering of nitrogen is used for recovering the Rayleigh scattering signal. This has the advantage that no corrections are necessary for stray light, like with other calibration methods, using the direct measured Rayleigh scattering signal on a well-known gas. It is shown that electron densities and electron temperatures can be measured with an accuracy of about 15% in density and of about 150 K in temperature.
Initial results from a charge exchange q diagnostic on TEXT-U
Authors: Valanju P. M. , Duraiappah L. , Bengtson Roger D. , Karzhavin Y. , Nikitin A.
Published: July 2002

We present initial results from a new q diagnostic for TEXT-Upgrade. This method is based on using a toroidal array of detectors to determine the plane in which beam-injected neutrals are emitted after two charge exchange collisions. The potential advantages are low cost, full plasma accessibility, and good time resolution. Our initial series of experiments of TEXT-U establish the feasibility of this technique.
A comparison of an elliptical multipole wiggler and crystal optics for the production of circularly polarized x rays
Authors: Lang J. C. , Srajer George , Dejus Roger J.
Published: July 2002

We have compared the circularly polarized x-ray flux obtained from an elliptical multipole wiggler to that obtained from a planar undulator combined with phase retarding crystal optics. This comparison is carried out for low (3.5–13 keV) and high (50–100 keV) x-ray energies. For both these energy regimes, we demonstrate that phase retarding crystal optics are not only a viable alternative to specialized insertion devices but in some cases provide a superior source of circularly polarized x rays.
Evolution of strain relaxation in compositionally graded Si1−xGex films on Si(001)
Authors: Li J. H. , Koppensteiner E. , Bauer G. , Hohnisch M. , Herzog H.-J. , Schäffler F.
Published: July 2002

High-resolution x-ray reciprocal space mapping was employed to determine the in-depth strain distribution of Si1−xGex films with linear composition gradings between 4.2% and 15% Ge per μm, and thicknesses between 0.4 and 1.7 μm. The variation of grading and thickness parameters of the samples provides a complete picture of the overall relaxation behavior of linearly graded epilayers. The x-ray data show a top layer of grading-dependent residual strain whereas the lower parts of the films are completely and/or partly relaxed with respect to the Si substrate.
Incorporation kinetics of rare-earth elements in Si during molecular beam epitaxy
Authors: Miyashita K. , Shiraki Y. , Houghton D. C. , Fukatsu S.
Published: July 2002

Incorporation kinetics of rare-earth elements (Er,Pr) in Si during solid source molecular beam epitaxy (MBE) is studied using secondary ion mass spectrometry. Pronounced surface segregation is consistently observed both for Er and Pr in normal MBE growth and their segregation tendencies are even stronger than those of typical dopants. Segregant-assisted growth (SAG) using Sb was successful in significantly reducing the surface segregation of rare-earth atoms, thereby opening the possibility of establishing layered structures in normal MBE.
Solid-state reaction in Pd/ZnSe thin film contacts
Authors: Duxstad K. J. , Haller E. E. , Yu K. M. , Bourret E. D. , Walker J. M. , Lin X. W. , Washburn J.
Published: July 2002

We report on solid-state reactions in Pd thin film contacts on ZnSe at temperatures below 500 °C. We found that a solid-state reaction was initiated at the Pd/ZnSe interface by thermal annealing at 200 °C. A tetragonal ternary phase, Pd5+xZnSe, consisting of highly oriented grains was formed as a result of this reaction. This phase is found to be stable up to an annealing temperature of 400 °C. The crystallography and morphology of this ternary Pd–ZnSe phase was studied by x-ray diffraction and transmission electron microscopy and has similarities to the analogous ternary Pd–GaAs phase formed in the Pd/GaAs contact structure. The Pd/ZnSe interface is found to be thermally more stable than the corresponding Pd/GaAs and Pd/Si structures. Comparisons are made between the systematics of Pd/semiconductor interfacial phenomena on the three semiconductors.
Relative efficiency of transient and stationary changes in excitonic optical properties of InGaAs/InP quantum wells
Authors: Campi Domenico , Coriasso Claudio , Nisoli Mauro , De Silvestri Sandro
Published: July 2002

Using an infrared tunable femtosecond source, we investigate the time evolution of exciton absorption bleaching in InGaAs/InP quantum wells at energies slightly below the exciton absorption peak at room temperature. We find that the bleaching due to photogenerated excitons can be stronger than that due to a thermal electron/hole plasma by a factor of 40. Numerical modeling, based on many-body theory, yields a qualitative explanation of this unusual behavior, along with its density and spectral dependence as well.
Fiber-optic high-temperature thermal source
Authors: Phomsakha V. , Djeu N.
Published: July 2002

A novel heating element powered by laser radiation via an optical fiber has been demonstrated. Temperatures approaching 2000 °C can be obtained with only a few watts of absorbed power. A prototype device has been used to join gold wires.
An electron multiplier capable of working at low vacuum: The microsphere plate
Authors: Naaman Ron , Vager Zeev
Published: July 2002

A new type of electron multiplier that has recently been developed, the microsphere plate (MSP), does not have the problem of ion feedback, which limits the operation of the known microchannel plates. Due to its structure, the MSP can amplify charge current even at pressures as high as 0.1 mbar.
Morphological instability of bilayers of copper germanide films and amorphous germanium
Authors: Doyle J. P. , Svensson B. G. , Johansson S.
Published: July 2002

The morphological instability of copper germanide (Cu3Ge) films in contact with amorphous germanium is reported. Through secondary ion mass spectrometry, x-ray diffraction, transmission electron microscopy, and electrical measurements, the breakdown of the continuous layer has been monitored. On the contrary, with Cu3Ge in contact with single crystal germanium, no instability is observed at the same temperature. The crystallization of the amorphous germanium appears to be the mechanism responsible for the instability.
A PC-controlled voltage pulse generator for electroanalytical applications
Authors: Heredia-López Francisco J. , Góngora-Alfaro José L. , Alvarez-Cervera Fernando J. , Bata-Garcı́a José Luis
Published: July 2002

We present the design of a voltage pulse generator controlled by an IBM or compatible AT Personal Computer (PC) capable of synthesizing some of the voltage pulse wave forms commonly used in electrochemical studies. The included signals are: differential pulse voltametry, differential normal pulse voltametry, and differential pulse amperometry. Additionally, a triangular wave form and a constant-voltage signal, used in the pretreatment of carbon fiber microelectrodes for neurochemical analysis, are also available. Operating the generator imposes a minimum of restrictions on the specification of the duration, amplitude, and type of wave shapes. Low-cost PC-based design allows for compatibility, portability, and versatility. The operating ranges of the wave form parameters for the three voltametric signals are: initial voltage, −0.9–+0.9 V; step amplitude, 0.1–900 mV; period, 6 ms–60 s; measuring pulse amplitude, 0.1–900 mV; measuring pulse duration, 2 ms–20 s; prepulse duration, 2 ms–20 s. In the electrode pretreatment mode, the operating ranges are: amplitude, 0–±5 V; duration, unlimited; frequency, 15–240 Hz. The generator uses its own time base for the generation of all signals, thereby rendering it independent of processor clock speed or power-line frequency. The results of the experimental evaluation indicate that the system is accurate within ±10% of the expected values, taking into account the errors associated with the signal synthesis and the digitizing process. The maximum achievable scan rate is 500 V/s, and the highest frequency for the triangular wave form is 240 Hz. Therefore, the pulse generator could be used for fast cyclic voltametry (FCV). FCV and other wave forms could be added through software modules, without any hardware changes. We conclude that the PC-based electrochemistry pulse generator represents an economical and flexible alternative for electroanalytical applications.
Displacement sensor with a hollow optical waveguide and a mirror
Authors: Branzalov P. P. , Ivanov L. M. , Pavlov L. I.
Published: July 2002

A displacement sensor with a hollow metal optical waveguide and a flat mirror is investigated. The sensor utilizes the principle of different attenuation for low and higher order light modes propagated in a hollow metal waveguide. The sensor has high sensitivity for small displacements, a broad measurement range, a one-side optoelectronic device location, and simple and inexpensive design.
Dose distribution of synchrotron x-ray penetrating materials of low atomic numbers
Authors: Cheng Y. , Kuo N.-Y. , Su C. H.
Published: July 2002

This article describes the distribution of absorption doses and spectrum shift of synchrotron x-ray traversing materials. The analytical approximations of the universal function of the synchrotron power spectrum was found. From this analytical approach, the penetration doses and the high-pass window effect were estimated for materials of low atomic numbers. The result can be generally applied to the deep x-ray lithography.
Periodic drag force and particle size measurement in a double ring electrodynamic trap
Authors: Göbel G. , Wriedt Th. , Bauckhage K.
Published: July 2002

A simple method to determine the size of a spherical particle in an electrodynamic trap from its dynamic behavior is introduced. Contrary to common usage of electrodynamic traps, gravity is not compensated completely. The resulting oscillatory trajectory is phase shifted with respect to the driving ac field of the trap. A light barrier setup is sufficient to determine the phase lag. An analytical solution is available in closed form to yield the particle diameter from the measured phase lag. Numerical trajectory simulations support this solution. Our method is independent of the optical properties of the particle. Only the viscosity of the surrounding gas and the particle mass density have to be known for data evaluation.
He activated loading device for low temperature uniaxial and anvil cell pressure experiments
Authors: Pfleiderer C. , Bedin E. , Salce B.
Published: July 2002

We report on a compact loading cell for the continuous variation of uniaxial forces up to a few tons in low temperature investigations. The cell is based on a He activated bellow and a mechanical force amplification system. Due to its modular design, it may be used in studies of the effect of uniaxial pressure on solids or the in situ variation of hydrostatic pressure in an anvil cell. High pressure He is supplied by a fine capillary, so that bellow, force amplifier, and experiment may be cooled uniformly to mK temperatures even at high magnetic fields. The pressure in the bellow is controlled by a simple proportional-integral regulator at room temperature. Characteristic features of a piezoelectric sensor, used to measure the load at low temperature, are presented in detail. With the method described here, we observe long-term stability to better than ±0.2 N in sweeps over a wide range of temperatures and fields. The performance of the loading device is illustrated by means of measurements into the superconducting state of URu2Si2.
In situ fast ellipsometric analysis of repetitive surface phenomena
Authors: Costa J. , Campmany J. , Canillas A. , Andújar J. L. , Bertran E.
Published: July 2002

We present an ellipsometric technique and ellipsometric analysis of repetitive phenomena, based on the experimental arrangement of conventional phase modulated ellipsometers (PME) conceived to study fast surface phenomena in repetitive processes such as periodic and triggered experiments. Phase modulated ellipsometry is a highly sensitive surface characterization technique that is widely used in the real-time study of several processes such as thin film deposition and etching. However, fast transient phenomena cannot be analyzed with this technique because precision requirements limit the data acquisition rate to about 25 Hz. The presented new ellipsometric method allows the study of fast transient phenomena in repetitive processes with a time resolution that is mainly limited by the data acquisition system. As an example, we apply this new method to the study of surface changes during plasma enhanced chemical vapor deposition of amorphous silicon in a modulated radio frequency discharge of SiH4. This study has revealed the evolution of the optical parameters of the film on the millisecond scale during the plasma on and off periods. The presented ellipsometric method extends the capabilities of PME arrangements and permits the analysis of fast surface phenomena that conventional PME cannot achieve.