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  • American Institute of Physics (AIP)  (46,193)
  • Annual Reviews  (4,726)
  • 1990-1994  (48,688)
  • 1970-1974  (1,509)
  • 1955-1959  (722)
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  • 1
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A lateral sample modulation technique is presented to measure simultaneously lateral friction forces and topological features with an atomic force microscope (AFM). The employed technique allows one to use an AFM without any additional displacement sensor. This dynamic detection scheme is well suited for AFMs equipped with a fiber-optic displacement sensor. The technique and the mechanism of the contrast formation are discussed. The performance of the microscope is demonstrated by imaging flat surfaces and large corrugated films as well as low friction samples.
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  • 2
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A computer-controlled rotating polarizer ellipsometer, operating in the infrared spectral region between 3.00 and 3.75 μm, has been developed for in situ characterization of amorphous hydrocarbon (a-C:H) thin films, deposited from methane in a rf plasma-enhanced chemical vapor deposition reactor. Spectroscopic IR ellipsometry permits insight into the chemical bonding structure of a-C:H coatings by the nondestructive detection of infrared stimulated C:H stretch vibrations. It is shown that the sp2CHx/sp3 CHx ratio, the content of bonded hydrogen, the infrared linewidth, and the real refractive index of the films depend on the negative self-bias voltage, which is formed at the samples during the deposition process. A transition from a-C:H films with polymerlike properties to hard a-C:H films was attained at a self-bias voltage of approximately −75 V.
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  • 3
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a new method for measuring time-resolved photoluminescence on a time scale of microseconds and milliseconds using correlational analysis, and we demonstrate it to work on porous silicon and GaP:Fe. We modulate the pumping laser with a pseudorandom binary sequence which yields correlational properties similar to white noise. The photoluminescence decay is computed via cross correlation of the detector signal with the pumping sequence. The presented method is highly sensitive, simple in application, and inexpensive.
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2896-2900 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We present a methodology to retrieve the thermal diffusivity of bulk homogeneous samples based on a set of simple linear relations that exist between two measurable magnitudes in modulated photothermal experiments. The influence of the photothermal parameters involved (exciting beam radius and height and radius of the probe beam) is evaluated to assert the validity of the linear relations. Specifically, we discuss the thermoreflectance and mirage techniques and their more convenient use and method, depending on the kind of sample to analyze (solid, liquid, gas), to obtain the thermal diffusivity.
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A commercially available flat flame burner with a sintered porous bronze disk was used to stabilize premixed H2/air flames at atmospheric pressure. Temperatures for various stoichiometries, flow rates, and heights above the burner disk have been measured by coherent anti-Stokes Raman scattering with an accuracy of ≈2.5%. The corresponding exhaust gas compositions have been derived from equilibrium calculations. This burner together with the data presented in this article can be used for the verification or calibration of a variety of measuring techniques in combustion research.
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed a high-resolution ac susceptometer that uses a rf superconducting quantum interference device to directly measure the flux coupled into a superconducting detection coil from a sample's changing magnetic moment in an applied ac field. The system operates in a frequency range from 0.01 to 1500 Hz and an applied ac field range of 0.1–400 μT with a sensitivity of about 5×10−12 A m2 for magnetic moment measurement, and at a reduced sensitivity down to 0.001 Hz. The instrument is based on an existing dc magnetometer system and uses that system's temperature control and dc superconducting magnet to allow operation over a temperature range from 2 to 400 K and in applied dc fields of ±5.0 T. During a measurement all operations are controlled automatically by computer from a menu-driven software system, with user input required only on initiation of a measurement sequence. Both real and imaginary components of the ac susceptibility can be determined.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2653-2657 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microwave impedance bridge covering from 8.2 to 12.4 GHz used for measuring complex dielectric constants over a wide temperature range is described. This apparatus is suited for materials formed into solid posts having different cross sections. The effective diameters for use in the analysis of circular, elliptical, or rectangular cross-section posts are presented. The effective diameters are applied to determine the complex dielectric constant of rectangular-shaped conducting polymer film. The frequency and temperature dependence of the dielectric constant and conductivity are presented, and compared with those obtained using a microwave cavity perturbation technique at 6.5 GHz. The bridge results are well suited for independent determination of the depolarization factor of a rectangular post for use in analysis of results of the cavity perturbation method.
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  • 8
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2667-2671 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Problems concerning the response of microwave radiometers to the polarization of incident radiation are examined. Particular attention is given to their consequences in experiments measuring the intensity anisotropy of the cosmic background radiation. Considered in detail are instrumental configurations in which metal reflectors are used to redirect the antenna beam. Some effects introduced by such reflectors are calculated and modelled for different values of some relevant parameters, in order to evaluate their contribution to instrumental errors. The analysis of a real experiment is then considered. It is shown that such mechanisms, if ignored, can seriously affect the measurements.
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  • 9
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2953-2956 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method of preparing ion beams of known mass and charge for time-of-flight scattering and recoiling spectrometry (TOF-SARS) using sequential deflection pulses (SDP) has been developed. A double-pulsing sequence is described in which the first pulse is used to create ion pulses and the second pulse, triggered after a suitable delay, allows only the species of interest to be transmitted to the target. A mass resolution of m/Δm=3–5 was achieved with the present system, eliminating the need for conventional mass resolution devices when high mass resolution is not required. Examples of the direct separation of Ar+ and Ar2+ ions from an ion beam and separation of Ar+ and Ar2+ scattering and recoiling spectra from an indium phosphide (InP) surface are provided.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2947-2952 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The mean plasma potential was measured on the LBL advanced electron cyclotron resonance (AECR) ion source for a variety of conditions. The mean potentials for plasmas of oxygen, argon, and argon mixed with oxygen in the AECR were determined. These plasma potentials are positive with respect to the plasma chamber wall and are on the order of tens of volts. Electrons injected into the plasma by an electron gun or from an aluminum oxide wall coating with a very high secondary electron emission reduce the plasma potential as does gas mixing. A lower plasma potential in the AECR source coincides with enhanced production of high charged state ions indicating longer ion confinement times. The effect of the extra electrons from external injection or wall coatings is to lower the average plasma potential and to increase the neτi of the ECR plasma. With sufficient extra electrons, the need for gas mixing can be eliminated or reduced to a lower level, so the source can operate at lower neutral pressures. A reduction of the neutral pressure decreases charge exchange between ions and neutrals and enhances the production of high charge state ions. An aluminum oxide coating results in the lowest plasma potential among the three methods discussed and the best source performance.
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  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2019-2022 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A fast and low cost pressure monitor is presented that can easily be mounted on pulsed molecular beam sources and allows one to measure the pressure pulse in the source during operation. The pressure monitor has a time resolution of 10 μs and is especially suited for the control of gas dynamics and nucleation in pulsed laser vaporization cluster sources.
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  • 12
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Holifield Radioactive Ion Beam Facility now under construction at the Oak Ridge National Laboratory will use the 25 MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility. The choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. Although direct-extraction negative ion sources are clearly desirable, the ion formation efficiencies are often too low for practical consideration; for this situation, positive ion sources, in combination with charge exchange, are the logical choice. The high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the facility because of its low emittance, relatively high ionization efficiencies, and species versatility, and because it has been engineered for remote installation, removal, and servicing as required for safe handling in a high-radiation-level ISOL facility. The source will be primarily used to generate ion beams from elements with intermediate to low electron affinities. Prototype plasma-sputter negative ion sources and negative surface-ionization sources are under design consideration for generating radioactive ion beams from high-electron-affinity elements. The design features of these sources and expected efficiencies and beam qualities (emittances) will be described in this report.
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  • 13
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2023-2027 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe the design, construction, and implementation of a low-pass energy filter for use with a liquid metal ion source (LMIS) cluster deposition system. When combined with deceleration of cluster ions to a surface for landing, this filter provides bandpass energy selectivity for high resolution mass separation of clusters produced by the LMIS. We also present results of our initial testing, which shows the filter has an experimental relative energy resolution of less than 0.3%.
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  • 14
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2028-2033 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have measured atomic hydrogen velocity distributions in an effusive beam coming out of a rf discharge dissociator by using a magnetic deflection technique. Dissociator pressures varied between 0.028 and 0.340 Torr. At low dissociator pressures the measured atomic velocity distributions were narrower than the expected beam Maxwellians; at higher pressures they were indistinguishable from beam Maxwellians at the dissociator wall temperature, indicating full thermalization of the atoms prior to exiting the dissociator. Monte Carlo simulations of the thermalization process within the dissociator reproduce these results, and point out the important role of vibrational excitation of the background hydrogen molecules as an energy loss mechanism. Our results are significant when designing magnetic state selectors for spin- or hyperfine-polarized atomic hydrogen beams.
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  • 15
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A novel type of source for excited species of cesium is described. It employs an effusive flux to the back of a metal foil, with the excited-state emission from the other side of the covered foil. The foil is kept at a temperature of 1000–1900 K by direct heating with an electric current. From the foil, various excited species of ions and atoms, some of which are rather short lived, are emitted at large densities. Only the species observed at a distance of at least 40 mm from the source emitter are of interest here. Excited species are observed by both steady-state and pulsed field ionization, at current densities up to 10−4 A cm−2, which is several percent of the total beam flux. Positive and negative excited ions can also be observed in the flux from the source, by their ability to emit electrons with energy-independent efficiency at impact on surfaces. The corresponding flux densities are up to 10−5 and 10−4 A cm−2, respectively. Doubly excited atoms can be observed as Cs2+ after field ionization in a mass spectrometer. They also produce ions after energy transfer to small molecules.
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  • 16
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Measurements of electron temperature using electron cyclotron emission (ECE) may be contaminated by density effects in plasmas with low optical depth. ECE intensity fluctuations in these plasmas will include a component dependent on density fluctuations as well. Correlation measurements, which will extract the temperature fluctuations from the dominant radiometer thermal noise, will include correlated density fluctuations in the result. In tokamak core plasmas, where normalized density fluctuations have been measured to be about 1%, this effect can be considerable (∼100%) at low levels of temperature fluctuations. However, at "relevant'' levels, defined by the amount of anomalous heat transport, these effects are reduced, at least in TEXT-U. While exact interpretation of temperature fluctuation amplitudes is compromised, statements regarding the relevance of the inferred temperature fluctuation amplitudes can be made relatively unambiguously.
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  • 17
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2049-2055 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Stigmatic spectroscopic observations of laser produced plasma have been performed in the 50–200 A(ring) spectral interval. The purpose was to demonstrate the good instrumental performances of an intensified bidimensional detector installed on a stigmatic soft x-ray spectrometer. The latter is the combination of a grating spectrograph in Rowland circle mount and a toroidal mirror, both working at grazing incidence. The detector is composed of a scintillator on the spectrograph focal circle, an image intensifier, and a charge coupled device. The resulting spatial and spectral resolution are of 60 μm and 1000, respectively. The observations show a marked improvement in term of dynamic range, sensitivity, ease of operation, and real-time data presentation in comparison to both traditional photographic film and photodiode array detection technique.
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  • 18
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3028-3029 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The beam-bending method is very useful for the viscosity determination of glasses, but the time spent to run the measurement is usually very long. The present note describes the performance of an improved beam-bending viscosimeter at the support stand and loading rod to get the faster measurements of high viscosity glasses with better reliability and precision. The testing time was reduced from 8 to less than 4 hours to run one measurement at three different temperatures (1100, 1200, and 1300 °C), with the precision of almost one order of magnitude better (±0.01 for 1g η in poise).
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  • 19
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3030-3031 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two simple three-electrode spark gaps have been constructed to operate at high voltages up to 30 kV for use in a gas laser triggering system. The performance of each spark gap has been tested in a nitrogen laser system designed for this purpose, and the results are described in this report. The pressure-controlled spark gap has shown better results in terms of stability and lifetime, and it is highly reliable for high repetition rate switching.
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  • 20
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3032-3033 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An analog instrumentation for estimating dimensions of chaotic dynamical systems has been developed. The technique employs time series of the Poincaré points successively displayed on the screen of an oscilloscope. It provides a rapid way to estimate the pointwise dimension from a single variable directly in an experiment. The instrumentation is easy to build and is convenient to employ. We have tested it by applying to periodic and quasiperiodic oscillators, and have verified by means of the fractal two-dimensional Poincaré map, simulated from the Duffing–Holmes differential equation. The measured values well agree with the computer calculated ones.
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  • 21
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3034-3035 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In time resolved measurements of neutron emission, the most common practice is to use a plastic scintillator coupled to a fast photomultiplier. There are different ways of coupling the light emitted by the scintillator to the photomultiplier (PM), according to the size and the shape of the scintillator. Some of the more usual coupling geometries are light pipes, Plexiglas cones with silvered walls or mirror "huts'' facing the PM window.
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  • 22
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3038-3039 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a simple portable mechanical structure to support a medium size cryostat. The structure can provide adequate support for an helium-3 cryostat with an 8 T magnet while the Dewar can be stored between experiment in a pit hole area below the temporary structure.
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  • 23
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3036-3037 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A simple technique is demonstrated for preventing microchannel plate (MCP) response to scattered laser light in a multiphoton ionization experiment. The MCP is gated on after the laser pulse, with a turn-on time of less than 1 μs, by switching its cathode from 0 to −1900 V. The high-voltage pulse circuit uses power MOSFETs and was designed according to the procedure of Baker and Johnson [Electron. Lett. 29, 56 (1993)].
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  • 24
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1017-1018 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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  • 25
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1019-1020 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Described is the design for a new electrochemical cell for in situ studies with the atomic force microscope. Improvements over presently used cells include an axially symmetric electrode geometry, large counter electrode, and the ability to incorporate a standard reference electrode close to the working electrode.
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  • 26
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 3044-3045 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The frequency dependence of the complex ac susceptibility of a magnetic conducting sphere is derived. The resultant formulas can be used to determine electrical conductivity from ac susceptibility measurements, to calculate ac susceptibilities of standard samples for the calibration of ac susceptometers, and to analyze ac losses in materials research.
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  • 27
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2433-2459 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe here several types of mass spectrometry in which the mass selectivity is combined with a highly selective laser ionization method to achieve both high sensitivity and very high selectivity. These methods combine the most sensitive and highly selective laser ionization methods with mass selectivity in order to improve on both the sensitivity and the Z and A selectivity previously achievable in detecting atomic species. Applications of these methods include the dating of geophysical specimens, the on line analysis of rare short-lived isotopes produced in high-energy collisions, the detection of low levels of heavy metals or radioactive isotopes in biological samples, the detection of impurities in ultrapure materials, and a host of other applications. Because some versions of this method offer sensitivity to a hundred atoms of a particular isotope of an element in a macroscopic sample, there are new possibilities for fundamental studies of rare events. Several types of facilities for elemental and isotopic analysis will be described.
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  • 28
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2460-2463 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Using the stimulated Brillouin scattering phase conjugation and pulse compression technique, a conventional long pulse ruby laser was successfully converted to give 300 ps pulses at 1 J energy level. The technique allows the use of smaller amplifiers than required in a conventional short pulse laser which in turn leads to operation at increased repetition rate. The completed laser when operated at 1.5 Hz produces stable output parameters. Each laser pulse is characterized by a sharp rise and a measured pre-pulse level of less than 10−6 of the main pulse, making it suitable for LIDAR Thomson scattering measurements.
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  • 29
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Excimer lasers are excellent sources of coherent light in the ultraviolet range of the spectrum. However, they have the drawback of requiring significant maintenance due to the corrosive gases, generation of dust, and contamination of the laser chamber optics which occur during normal operation. Improvements which are generally applicable to any excimer laser system are specifically described in terms of the two Questek (Lambda Physik, Acton, MA) model 2860 lasers in our lab. The same basic procedures are currently being implemented in two Lambda lasers in other research groups at our university. A novel gas triple filtration system, a simple cold trap with a counter-flow heat exchanger, and a careful selection of valves have been added to minimize dust contamination of the optics, to decrease contamination and leakage of the gas fill, to provide safe and easy dust removal, and to reduce maintenance downtime.
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  • 30
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    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2470-2474 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The performance of a simple wavemeter for measuring changes in wavelength of a pulsed dye laser is described. Details of optics and electronic circuitary used, along with the algorithm for wavelength measurement, are given. Using this instrument wavelength changes of a dye laser could be measured, as well as introduced through a user interface, with an accuracy of 1 ppm.
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  • 31
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    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1057-1059 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The project for a superconducting electron cyclotron resonance (ECR) ion source has been funded by INFN in 1992 as a joint venture between INFN and CEA/DRFMC. The source is devoted to the production of high charge state heavy ions to be injected into the K-800 superconducting cyclotron. The magnetic system consists of three solenoids and of an hexapole which will allow one to attain a strong plasma confinement by means of a B-min field configuration with a very high magnetic field (1.4 T on the plasma chamber wall). At the intermediate frequency of 14.5 GHz, it will be possible to study the scaling of ECR ion sources at different magnetic fields far beyond the existing levels. The source will eventually work at a higher frequency, in the range 28–35 GHz of gyrotron tubes. The design of the superconducting magnets and of the cryostat has been carefully carried out, taking into account this goal, and the construction is now under course. The mechanical design of the plasma chamber is also outlined.
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  • 32
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This article gives a short summary of the performances of the electron cyclotron resonance ion sources (ECRIS) so far built by the Grenoble laboratory; emphasis is given to the high B field Caprice source, a compact in size source delivering high charge states and high intensities. Both the continuous regime of operation, and the pulsed regime having performances enhanced by the afterglow effect, as well as other noticeable effects, are surveyed. The next part of the article deals with the analysis of the data and our present understanding of the ECRIS behavior. At last the present trends of development of ECRIS are examined.
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  • 33
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We would like to present the initial results and description of the superconducting electron cyclotron resonance ion source (SCECR) operating in the high-B mode—a new high magnetic field, low-frequency mode of operation. First, we describe the operating characteristics of this mode, which include very high mirror confinement in all directions, yet having a minimum field low enough for electron cyclotron resonance heating of 6.4 GHz. The source performance for oxygen, neon, argon, krypton, and xenon is presented and comparisons are made with several existing high-performance ECR sources. In this high-B mode the SCECR matches or exceeds the performance of all existing ECR sources. These results perhaps invalidate the classical frequency squared source performance scaling law, and suggest the new possibility of high-performance, low-frequency (and hence low cost) sources as will be discussed.
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  • 34
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The main goal of this project was to increase the reliability of CRYSIS by separating the ionization region from the insulating volume which contains vacuum seals at the cryostat. These volumes are separated with two bellow units installed between the cryostat and both ends of the vacuum vessel. The bellow units contain drift tubes with different fixed temperatures, heat shields, feedthroughs for drift tubes, and a gas delivery tube for gas injection. Preliminary results of tests after CRYSIS vacuum separation are presented.
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  • 35
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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  • 36
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The space-charge compensation of electron beams by hot ions with a Boltzmann energy distribution has been investigated by solving Poisson's equation. A unique relation is obtained between the degree of central compensation and the ion temperature: At high temperatures (as compared to the potential depression inside the beam) the compensation is low and the ions stay inside the electron beam only to a minor part, while at low ion temperatures, the beam is almost fully compensated. The potential difference between the beam axis and the surrounding tube is reduced by compensation, but when measured in terms of the temperature of compensating ions, it increases. This shall better confine the ions to the electron beam, the more complete the compensation. Increasing with the square of their charge state, trapped ions are heated by the ionizing beam electrons through small angle Coulomb collisions. For different ions with different charge states, the almost compensated electron beam acts as an energy filter, where the hotter ions are lost radially or axially. Therefore highly charged ions, which became "hot'' by waiting for stepwise ionization, can be cooled by lower charged ones, which still are "cold.'' This phenomenon has been called "evaporative cooling'' in electron beam ion sources (EBIS) and traps (EBIT) and space-charge compensation of the electron beam is the driving physic for it.
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  • 37
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Fundamental questions of electron beam ion sources (EBIS) are studied using three different setups. Cryogenic classical EBIS: The limit of ion–ion cooling in EBIS devices operating near the space-charge neutralization limit has been studied experimentally. To investigate different degrees of compensation of the electron beam by highly charged ions, a hemispherical analyzer has been constructed including a novel deceleration optic for high resolution. Using its energy definition we tested different modes of ion transportation in our multipassage magnetic spectrometer, which can be operated chromatically as well as extremely dispersively: up to 200 passages could be obtained. EBIS without magnetic field: First results on ion production in the short trap at the very dense crossover of an electron beam (XEBIS) confined only inertially without the use of magnetic fields are presented. Normal conducting short EBIS: Using a normal conducting field of 0.8 T of 25-cm length an EBIS is under construction to study extremely short ion extraction of approximately 4 μs for single turn injection into a medical synchrotron for cancer therapy (MEDEBIS).
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  • 38
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A few methods for optimizing output of intermediate charge state ions from electron beam ion source devices are examined. The schemes are based on reducing the charge state of the highest charge state ions into the intermediate states, thus enhancing the relative abundance of these states. Only the most elementary considerations are invoked. Although a thorough analysis may not be feasible due to lack of good data, the schemes are easy to try experimentally.
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  • 39
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An electron-beam ion trap (EBIT) has just been completed in the Clarendon Laboratory, Oxford. The design is similar to the devices installed at the Lawrence Livermore National Laboratory. It is intended that the Oxford EBIT will be used for x-ray and UV spectroscopy of hydrogenic and helium-like ions, laser resonance spectroscopy of hydrogenic ions and measurements of dielectronic recombination cross sections, in order to test current understanding of simple highly charged ions.
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  • 40
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 14 GHz Caprice ECR ion source is now in operation at the high charge state injector of the Unilac accelerator. Ions with charge to mass ratio ≥0.117 can be accelerated. Performance of the source with Uranium 28+ will be presented. A rebuilt ECR ion source similar to the Caprice operates at a test bench in order to investigate metal ion production and the afterglow operation mode.
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  • 41
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Vacuum arc ion sources have been developed and used in a growing number of laboratories around the world. Primary applications of this high current metal ion source have evolved for metallurgical ion implantation and for accelerator injection. Novel source versions and features have been developed, including an electronically switchable "partitioned cathode'' whereby the metal species generated can be switched from pulse to pulse, a combined metal/gaseous source with a long lasting trigger, a low energy (∼1 keV) miniature source version, and a broad beam (50 cm diam extractor) multicathode version. Progress has been made also in characterization and manipulation of the plasma prior to extraction, e.g., in the understanding of the ion charge states produced and the development of macroparticle-removing magnetic filters. Advances in vacuum arc ion source design and operation have been accompanied by a deeper understanding of plasma production in vacuum arc cathode spots, and several features of vacuum arc ion sources can be explained by the specifics of ion formation within the spots. Here we present a short overview of some fundamental vacuum arc processes and examine some of the recent developments in vacuum arc ion source design and application.
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  • 42
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: After 30 years of research, development, and qualification work of radio-frequency ion thrusters (RIT), the RIT 10 engine has now been tested successfully in space onboard the European Retrievable Carrier (EURECA). RIT 10 produces a thrust of 10 mN and is designed for north–south stationkeeping of geosynchronous satellites. Besides, the European Space Agency (ESA/ESTEC) plans to implement ion propulsion in their technological satellite ARTEMIS, where ion thrusters shall be used operationally for north–south stationkeeping. In parallel, development and tests of a scaled-up 50 mN engine RIT 15 have been continued successfully with xenon and krypton as propellants. A large ion engine with a 35 cm ionizer diameter, the RIT 35, has been developed for primary propulsion of interplanetary probes aiming at a thrust level in the 250 mN range. A laboratory prototype has been subjected to extensive testing and performance mapping. Recently, this work has been continued in European cooperation due to a redirection of contracts. The ion source diameter has been reduced to 26 cm but the performance should be kept using a British high perveance grid at the German rf-ion source.
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  • 43
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1741-1744 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: After 30 years of research, development, and qualification work of radio-frequency ion thrusters (RIT), the RIT 10 engine has now been tested successfully in space onboard the European Retrievable Carrier (EURECA). RIT 10 produces a thrust of 10 mN and is designed for north–south stationkeeping of geosynchronous satellites. Besides, the European Space Agency (ESA/ESTEC) plans to implement ion propulsion in their technological satellite ARTEMIS, where ion thrusters shall be used operationally for north–south stationkeeping. In parallel, development and tests of a scaled-up 50 mN engine RIT 15 have been continued successfully with xenon and krypton as propellants. A large ion engine with a 35 cm ionizer diameter, the RIT 35, has been developed for primary propulsion of interplanetary probes aiming at a thrust level in the 250 mN range. A laboratory prototype has been subjected to extensive testing and performance mapping. Recently, this work has been continued in European cooperation due to a redirection of contracts. The ion source diameter has been reduced to 26 cm but the performance should be kept using a British high perveance grid at the German rf-ion source.
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  • 44
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1753-1756 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Recently, electron cyclotron resonance (ECR) discharges have been successfully applied to numerous ion source applications. These range from accelerator to etching and thin film deposition applications, and have strong potential for application in several commercial/industrial processes. Thus, new design requirements related to process automation and control are now imposed on plasma source design. Internal cavity tuning methods for excitation and impedance matching and ECR discharge control are presented. These impedance matching methods utilize a variable cavity end plate and an adjustable coupling probe to provide the two independent adjustments required to match the discharge loaded cavity applicator. Both end feed and side feed coupling create a well matched plasma source but the end feed excitation produces the most efficient (∼220–230 eV/ion) and most uniform (1σ=2.5%) discharge. Control of internal tuning can serve not only to match discharge impedance, but with the proper control can also avoid hysteresis and multiple steady states and jumps in plasma source outputs. Adjusting the internal cavity tuning to always produce a slight mismatch helps insure a stable and repeatable discharge operation.
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  • 45
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1165-1169 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: During the last decade, different types of multicusp ion sources, such as high current, high concentration H+, H+2, or N+ ion sources, negative ion sources, radio-frequency-driven sources, and high charge state ion sources have been developed at the Lawrence Berkeley Laboratory. This article reviews the history of the research and development of these ion sources and their applications.
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  • 46
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 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.
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  • 47
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The Superconducting Super Collider (SSC) ion source is required to provide a 30 mA H− beam at 35 keV with a normalized rms emittance (εn-rms) of less than 0.18 π mm mrad. An rf-driven volume source was chosen for the commissioning of the SSC linear accelerator (Linac). The divergent ion source output beam is matched into the radio frequency quadrupole accelerator (RFQ) by an electrostatic low-energy beam transport (LEBT). The SSC Linac injector (consisting of ion source, LEBT, and RFQ) is required to provide 25 mA of H− beam (pulse width of 9.6–35 μs at 10 Hz repetition rate) at 2.5 MeV with transverse normalized rms emittance (εt-n-rms) of less than 0.2 π mm mrad and longitudinal normalized rms emittance (εl) of less than 0.82×10−6 eV s. The performance of our rf volume source and initial experimental results from the SSC injector are discussed.
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  • 48
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: After developing a pulsed 8X source for H− beams, we are now testing a cooled, dc version. The design dc power density on the cathode surface is 900 W/cm2, much higher than achieved in any previously reported Penning surface-plasma source. The source is designed to accommodate dc arc power levels up to 30 kW by cooling the electrode surfaces with pressurized, hot water. After striking the arc using a 600-V pulser, a 350-V dc power supply is switched in to sustain the 100-V discharge. Now our tests are concentrating on arc pulse lengths ≤1 s. Ultimately, the discharge will be operated dc. The source is described and the initial arc test results are presented.
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  • 49
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two types of the surface-plasma sources of negative hydrogen ions developed at Budker Institute of Nuclear Physics are discussed. The source characteristics and the mechanism of negative ion production are presented. It is shown that several channels of plasma particle surface conversion and desorption are responsible for an intense negative ion production in these sources. The results of a detailed study of the quasistationary honeycomb and its comparison with the data for hollow-cathode Penning sources are presented.
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  • 50
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The MEVVA ion source presented in the present paper adopts the arc discharge mechanism with a cathode changeable by a motor for pushing in, and an accel–decel three-grid extraction system. The voltage proof level is higher than 60 kV, the ion source generally runs at a voltage of 40 kV, the average beam current is higher than 5 mA, the beam spot is about 150 mm in diameter, and the nonuniformity of beams is within ±20%. Measurements of the beam radial profile show that there is a platform of about 40 mm in diameter in the central region. Ion beams and their optimal operation conditions for the cathode materials Al, Ti, Cr, Fe, Ni, Cu, Y, Zr, Mo, Ta, W, C, LaB6, etc., have already been obtained.
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  • 51
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Industrial applications of ion beams began in the 1970s with their application in fabrication of semiconductor devices. Since electronic characteristics of semiconductors are very sensitive to the amount of doped elements and to the species, the ion beams should be precisely mass separated. Nowadays, ion implantation is expected to be used for surface modification of materials. For this the needed beam purity is lower, but the needed dose is higher, since mechanical and/or chemical characteristics of materials, which are less sensitive to the dose, should be improved rather than electronic ones. Mass resolution by a separator may be lowered to allow mixing of some neighboring elements and in some cases mass separation may be completely eliminated. Many ion sources have been developed for such applications; however, most were used for research work. In this paper, some of the typical ion sources are reviewed from the viewpoint of future industrial use.
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  • 52
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An rf-plasma-sputter type heavy negative-ion source can deliver a few mA to 12 mA of dc negative-ion currents such as boron, carbon, silicon, and copper negative-ion beams. These negative-ion currents are comparable with the positive-ion currents for conventional high current positive-ion implantation, and thus could be newly used in place of positive ions. Surface interaction of negative-ion beams is extremely distinctive when negative ions are implanted into insulated materials or insulators. The surface charge-up voltage of insulated materials by negative-ion implantation saturates at only several volts, so that no breakdown of insulators takes place. As a whole system, a negative-ion implanter without charge neutralizer would be simpler and more economical than a positive-ion implanter.
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  • 53
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Several versions of Mevva ion sources have been developed in our institute since 1988. It operates in a pulsed mode with a pulse length of 1.2 ms and a repetition rate of up to 50 pps. A time-averaged beam current of 10 or 50 mA has been extracted at 30–80 kV from Mevva IIA-H and Mevva IIB, respectively. In order to develop surface modification of materials by ion implantation we have constructed three kinds of Mevva ion source implantation systems. High dose (3–5×1017 cm−2) implantation with Ti, Ce, Y, and Ti+C, etc. has been carried out for improving the lifetime of metal cutting tools, relay contacts, dies, and some sophisticated components.
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  • 54
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1298-1303 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Several microfabrication processes benefit from the application of ion sources including the physical, reactive, and chemically assisted sputtering/etching of surfaces, the deposition/growth of materials, and the modification/cleaning/preparation of surfaces. This paper reviews the types, properties, and requirements of ion sources applied to microfabrication processes including etching, epitaxial growth, ion implantation, and nanostructure formation. Particular emphasis is given to the requirements of ion streams for low-damage semiconductor processing. The types of sources covered include broad-beam ion sources; ECR, helicon, helical resonator, and inductively coupled plasma/ion sources; ion implanters; compact MBE-ECR ion/free radical sources; and focused ion beam sources.
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  • 55
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: High-energy and intense beam current broad beam ion sources have been developed for ion implantation and dynamic recoil mixing at CSSAR. The sources can be operated over beam energy and current ranges of 3–120 keV and 5–70 mA, respectively. For sputter coating of thin films, a series of focusing beam ion sources with different structures has also been developed. The energy and current range from 1–10 keV and 100–350 mA for different applications. For some applications, low-energy (below 100 eV) ion beams are required. CSSAR has developed a 6-cm-diam broad beam ion source. The source can be operated at beam energy 10–70 eV, and the beam current 15–80 mA has been extracted. Typical structures and operational data are given for the sources mentioned above. Recently a new type of broad beam metal ion source (Electron Beam Evaporation Metal Ion Source EBE) is being studied. Ion beams of several kinds of materials such as C, W, Ta, Mo, Cr, Ti, B, Cu, etc. have been extracted from the source. Typical operation conditions and ion yields are given in this paper.
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  • 56
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Due to concerns about energy purity and reduced beam current, the use of multiply charged ions to achieve higher effective ion energies with a fixed acceleration potential has not been common for implantation users in the semiconductor industry. Energy purity is compromised primarily by charge exchange in the implanter beamline, caused by neutral gas originating from the ion source extraction aperture. Beam current has been an issue, since traditional implanter ion sources, such as the Freeman source, produce very limited currents of multiply charged species. At low beam currents, the implanter is not economical to use, hence the lack of commercial use of multiply charged ion implantation. Ion sources that address these issues must also meet requirements for adequate source lifetime, simplicity of operation (for computer control) and maintenance, and low cost of ownership. This paper details beam energy purity and usable beam currents for a new medium current Bernas ion source as compared to a standard Freeman ion source. The results show significant performance improvements, while also increasing the ion source lifetime.
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  • 57
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The current trends of research and development work in ion-beam microlithography are examined with particular emphasis on the choice of ion sources and the beam parameters. The common approach with duoplasmatron-type ion sources for projection ion-beam lithography is revisited, and the suitability of H− beams is examined. The beam brightness and energy spread, which constitute the figure of merit of a beam, appear to be better in the case of H− beams. From a surface plasma source type discharge operating under stable condition, H− beams with an emission current density of ∼1–5 A/cm2 and a normalized brightness of ∼7×1012 A/(m rad)2 can be extracted. Several key issues of an ion-projection lithography device, such as the ion source parameters, beam optics, and thermal load are discussed.
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  • 58
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A compact 5-cm-diam multipolar electron cyclotron resonance (ECR) ion source is characterized. The source is experimentally studied with no grids using argon gas with 50–250 W of 2.45-GHz microwave input power. Using a microcoaxial probe it was confirmed that the exciting electromagnetic fields within the resonant cavity were indeed TE111, as expected from the critical cavity dimensions. Double Langmuir probe measurements indicate high densities of about (4–5)×1011/cm3 near the source, and 5 cm downstream from the source output the densities become very uniform with a value of about 5×1010/cm3 over a 10-cm diameter. Electron energy distribution functions (EEDFs) were measured using a single Langmuir probe. Average electron energies were seen to be about 8–10 eV with an energy distribution function falling between a Maxwellian and a Druyvesteyn distribution. Ion energy distribution functions (IEDF) were measured with a multigrid energy analyzer. It was seen that the distribution functions were narrow and peaked [with a full width half maximum (FWHM) of about 5 eV] except under certain conditions. Above 200-W input power, and also below about 0.5 mTorr there is significant broadening of the ion distribution function. It is speculated that the former may be caused by gas heating, and the latter may be caused by the presence of Ar+2 ions. With its high current densities ((approximately-greater-than)10 mA/cm2) and low average ion energies (〈40 eV), it is expected that this ion/plasma source will be very useful in many etching and deposition applications.
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  • 59
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Recently, electron cyclotron resonance (ECR) discharges have been successfully applied to numerous ion source applications. These range from accelerator to etching and thin film deposition applications, and have strong potential for application in several commercial/industrial processes. Thus, new design requirements related to process automation and control are now imposed on plasma source design. Internal cavity tuning methods for excitation and impedance matching and ECR discharge control are presented. These impedance matching methods utilize a variable cavity end plate and an adjustable coupling probe to provide the two independent adjustments required to match the discharge loaded cavity applicator. Both end feed and side feed coupling create a well matched plasma source but the end feed excitation produces the most efficient (∼220–230 eV/ion) and most uniform (1σ=2.5%) discharge. Control of internal tuning can serve not only to match discharge impedance, but with the proper control can also avoid hysteresis and multiple steady states and jumps in plasma source outputs. Adjusting the internal cavity tuning to always produce a slight mismatch helps insure a stable and repeatable discharge operation.
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  • 60
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microwave ion source equipped with two linear antennae set parallel to the wall of the source chamber has been designed and built. A homogeneous plasma of Ar was produced in an aluminum chamber of 22 cm long, 9 cm wide, and 6 cm deep. Beam forming grids produced a rectangular beam of 17 cm by 3 cm. The current density of the extracted Ar+ beam was 0.16 mA/cm2 at the center of the extraction area when the input power to the magnetrons was 360 W. The energy distribution function of the extracted ions was measured with an electrostatic analyzer. The measured energy distribution showed a presence of high energy ions in the extracted beam.
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  • 61
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The electromagnetic excitation of a discharge inside a microwave plasma source has been numerically modeled in the time domain. The source is a cylindrical, single-mode microwave-excited cavity. The time-varying electromagnetic fields inside the resonant cavity, both inside and outside the discharge region, are obtained by applying a finite-difference time-domain method to solve Maxwell's equations. The electromagnetic properties of the discharge load are described using a conductivity model. The spatial electric field patterns, natural frequencies, stored energy, and quality factor of a plasma-loaded, microwave-resonant cavity are simulated. Additionally, the simulated results for a simplified plasma source structure are compared to a known analytical solution to verify the simulation technique.
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  • 62
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An ECR ion source was excited by microwaves (2.45 GHz). The discharge chamber diameter of the ECR ion source into which microwaves were introduced by a waveguide and a vacuum window, is smaller than the cut off for TE or TM modes. The magnetic structure is built with an NdFeB permanent magnet where the magnetization M is perpendicular to the source axis. This cusp structure enables us to produce an N+ ion current of 1.1 mA (ion current density of 16 mA/cm2) at an extraction voltage of 8 kV with an aperture of 3 mm diameter by a two grid system; ion beam diameter is 0.2 mm by focusing. This ion source is used for bio-organic mutation.
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  • 63
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A microwave plasma (MP) cathode for ion sources has advantages of a long lifetime for reactive gas, and a capability of a high-current electron emission of several amperes. This article describes a new MP cathode, in which a convergent magnetic field is formed at an electron emitting aperture in order to improve the working gas efficiency, that is the decreasing of the gas flow rate (Qeff) to obtain the electron emission current of 1 A. By applying a magnetic field (∼3 kG), the Qeff was decreased to 1/5 to 1/10 of that in the conventional MP cathode, and a high current of oxygen ion beam of 62 mA in a high vacuum (1.8×10−5 Torr) system was successfully obtained. Further improvements are expected by changing various parameters.
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  • 64
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The physical consideration, design, and characteristics of a compact microwave plasma cathode are expounded in this paper. The impedance matching is calculated to improve the microwave transmission efficiency. The influence of the magnetic field on the discharge property and the extracted electron beam current is investigated. The off-resonance discharge mode (a non-ECR discharge mode) is put forward, in which the magnetic field is bigger than 875 G in the discharge chamber. The dependence of the extracted electron beam current on the extraction voltage, the input microwave power, and the operation pressure is described. The 2.45-GHz microwave power is transmitted to the cathode via a coaxial line. The permanent magnets made from NdFeB are used to excite the magnetic field and the magnetic induction of 800–2600 G can be produced. This cathode can obtain the electron beam current of up to 500 mA at the input microwave power of 30–60 W, with N2 used as the support gas.
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  • 65
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An inherent feature of the vacuum arc discharge is that small droplets of micrometer size (macroparticles) are produced along with the plasma in the cathode spots. Droplet contamination of the substrate can occur when implanting metal ions using a vacuum arc ion source. The contamination can be significant for some cathode materials such as lead and other low melting point metals, which for some ion implantation applications such as for semiconductor doping and metallic corrosion inhibition can be a detriment. We have developed a vacuum arc ion source in which the plasma is filtered before the ions are extracted. By guiding the arc-produced plasma through a 60° bent magnetic duct, macroparticles are completely removed from the plasma. No additional power supply for the guiding magnetic field is required since the pulsed arc current itself is used to drive the magnetic solenoid. Tests have shown that macroparticle-free metal ion implantation can be done while maintaining the high ion beam current typical of vacuum arc ion sources.
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  • 66
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Unlike widely published sources MEVVA, since 1984 we have constructed vacuum arc ion sources of any hard electroconductive materials (like metal or composites type—TiC, TiSiC, NiCrAlY, MoS, TiMoSi, WAlB, TiBNi) for modification of materials. The principle of Technological Accelerator of Metal ion and Electron Kit—source TAMEK, provides realization of regimes mentioned in the title in each (or in any series) of a sequence of f=50 Hz pulses: t=300 μs, Ii〈1 A, Ei〈200 keV, dDi=1016 ion/cm2/min for implantation and t=1000 μs, Iarc〈2000 A, dh=50–200 nm/min for deposition and so realized, if you wish, ion implantation, deposition, mixing, ion-beam-assisted deposition of the same ions without switching off the source. The experimental data demonstrate the possibility of obtaining mutual mixed (10×90 at %) alloyed layers up to 3 μm for time in t=15 min at T=100 °C temperature surface, with structure improving (microhardness) inner layer up to 50 μm in depth and possibility of further coating growth on the surface. This report presents a brief review of TAMEK principle design and its application for modification of constructed materials.
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    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 1325-1326 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high current O+ ion source is desirable for applications to SIMOX and materials modification. To meet the requirements of this field, a new type of nonfilament high current O+ ion source has been developed successfully in our institute. Using O2 as discharge material, the typical extraction characteristics are as follows: The total oxygen ions current is 100 mA, of which the content of O+ is 80%, beam current density is larger than 200 mA/cm2 when the power consumption is 100 W; therefore the economic property is 1 mA/W. Feeding N2, the total extraction beam current is 100 mA of which 70% is N+ while the power consumption is 135 W.
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  • 68
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 775-787 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Magnet design codes, plasma dispersion solvers, and particle-in-cell (PIC) simulation codes have been used to arrive at the first step in the design of an advanced ion source based on electron cyclotron resonance (ECR) technology. The advanced concept design uses a minimum-B magnetic mirror geometry which consists of a multicusp magnetic field to assist in confining the plasma radially, a flat central field for tuning to the ECR resonant condition, and specially tailored mirror fields in the end zones to confine the plasma in the axial direction. The magnetic field is designed to achieve an axially symmetric plasma "volume'' with constant mod-B, which extends over the length of the central field region. This design, which strongly contrasts with "surface'' ECR zones characteristic of conventional ECR ion sources, results in dramatic increases in the absorption of rf power, thereby increasing the electron temperature and "hot'' electron population within the ionization volume of the source. The creation of a volume rather than a surface ECR zone is, therefore, commensurate with the generation of higher beam intensities, higher charge states, and a higher degree of ionization. A summary of the results of these studies is presented in this report.
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  • 69
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 799-802 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The use of a spherical mirror Fabry–Perot cavity as a mirror of variable reflectivity for near monochromatic light is demonstrated herein. The results of an experimental test of two control systems for the variable mirror are presented. It is shown that the reflectivity of our mirror can be controllably varied over a wide range. This technique has application in laser interferometric gravitational-wave detection.
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