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  • Artikel: DFG Deutsche Nationallizenzen  (125)
  • Digitale Medien  (125)
  • 1
    Digitale Medien
    Digitale Medien
    A 1-V series-array Josephson voltage standard operated at 35 GHz (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 4700-4702 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Josephson voltage standards utilize microwave-induced constant voltage steps in the dc characteristic of Josephson tunnel junctions. This paper describes the design and operation of array circuits with 108 and 2000 junctions connected in series. In contrast with similar realizations, simple Q-band equipment is used for the microwave supply. The microwave attenuation of 1000 junctions was about 1 dB. The version with 2000 junctions generated Josephson voltages up to 1.2 V when operated at 35 GHz. The stability times of the quantized levels were, under normal laboratory conditions (unshielded room), better than 10 min.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.346149
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  • 2
    Digitale Medien
    Digitale Medien
    Lithium beam Zeeman spectroscopy diagnostic development (abstract) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1070-1070 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A local magnetic field diagnostic, based on the Zeeman splitting of lithium atoms is under development at Los Alamos. A modified duoPIGatron ion source1 is used in conjunction with an 80-kV accelerator to produce a high-density atomic lithium beam, permitting access to plasmas with a wide range of parameters. Detection of the Zeeman pattern in the plasma will be enhanced by the use of a dye laser, either using fluorescence or intracavity absorption (ICA). While the sensitivity of resonance fluorescence is well known, that of ICA is less well understood where short time scales are involved. Experiments to study the time/concentration trade-offs in ICA have been performed on lithium vapor, and show that the sensitivity of ICA is at least equal to that of fluorescence (assuming a dark background), under conditions of submillisecond detection times. ICA is also 103 times more sensitive than single-pass absorption under these conditions. Optimization of the atomic beam and integration with the dye laser systems are in progress.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1138223
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  • 3
    Digitale Medien
    Digitale Medien
    Pellet injection on the ZT-40M reversed field pinch (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 1401-1405 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The four barrel pneumatic pellet injector originally used on the Alcator C tokamak at MIT has been reconfigured for use on the ZT-40M reversed field pinch (RFP) at Los Alamos National Laboratory. The lower temperature and density in this device require operation at velocities significantly lower than on Alcator. Allowing a 2-s warmup prior to firing the injector has enabled operation with pressures as low as 40 psig and velocities ranging as low as 200 m/s with H2 pellets, without major cryostat modification. Initial injection experiments in the ZT-40M plasma have verified that pellet refueling is effective for density control, but the net particle inventory increase is less than might be expected based on simple models. Indications of nonoptimal penetration and curvature of the pellet trajectory, in addition to comparable time scales for particle confinement and pellet transit, may account for this.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1139421
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  • 4
    Digitale Medien
    Digitale Medien
    Development testing of the U.S. common long pulse source at 120 kV (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2357-2365 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The U. S. magnetic fusion energy program has developed a single design, long-pulse neutral beam source for TFTR, MFTF-B, and DIII-D. The arc is a very compact axial magnetic line cusp. The accelerator is an actively cooled tetrode with water-cooled grid tubes of shaped molybdenum forming "slot'' beamlets. DIII-D and MFTF-B configurations have an 80-kV accelerator gap, with a 12×18 cm aperture, and a 10-m "module'' focus. TFTR modules are unfocused, with a 120-kV gap and 12×43-cm mask. The first CLPS was tested in the TFTR configuration, at 120 kV, 2s. Optimum current was 73 A, or 1.76 μpervs (deuterium), with 80%–85% atomic fraction. Optimum divergence of ions plus neutrals was 0.4° parallel to the slots, and 0.7° perpendicular to the slots (1/e half-angle). The combination of an axial cusp magnetic bucket and slot accelerator apertures gives the common long pulse source about twice the beam power per unit cross section of other long pulse sources, plus lower divergence in the direction parallel to the slots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1139961
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  • 5
    Digitale Medien
    Digitale Medien
    120-kV testing of a 10×40-cm prototype of the U. S. common long pulse neutral beam source (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2714-2719 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The 10×40-cm long pulse neutral beam source developed at Lawrence Berkeley Laboratory has been selected as the prototype for the design of the U. S. common long pulse source to be used on tokamak fusion test reactor (TFTR), Doublet-III, and mirror fusion test facility (MFTF-B). The long pulse source consists of a magnetic line cusp bucket with an actively cooled backplate electron dump and a four-grid accelerator using slot apertures and water-cooled molybdenum rails. Deuterium testing of the long pulse source at 120 kV and 53 A and with a 2-s pulse length has been completed on the neutral beam engineering test facility, including an 8-h 100-shot test to demonstrate the durability and reliability of the source. Maximum 2-s beam parameters obtained (not simultaneously) are 125 kV, 58 A (deuterium), and 7.1 MW. Beam pulse length has been extended to 5 s at 120 kV. Atomic species fractions in excess of 80% have been obtained, with a beam divergence (full energy, 1/e half-angle) of approximately 0.8×0.4°. Calorimetric measurements on the accelerator grids and backplate electron dump indicate heat loads consistent with predictions and within the design limits of the source. This testing has verified the design of the source and its ability to exceed the basic performance requirements.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1139082
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  • 6
    Digitale Medien
    Digitale Medien
    Application of optical phase conjugation to plasma diagnostics (invited) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 953-957 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Several possibilities for plasma diagnostics provided by optical phase conjugation and, in particular, self-pumped phase conjugation in barium titanate (BaTiO3) are discussed. These include placing a plasma within a dye laser cavity equipped with a phase conjugate mirror for intracavity absorption measurements, time differential refractometry with high spatial resolution, and simplified real-time holographic interferometry. The principles of phase conjugation with particular reference to photorefractive media and the special advantages of self-pumped phase conjugation are reviewed prior to the discussion of the applications. Distinctions are made in the applications between those for which photorefractive conjugators are essential and those for which they only offer experimental simplification relative to other types of phase conjugators.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1138058
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  • 7
    Digitale Medien
    Digitale Medien
    High-intensity lithium beam for Zeeman spectroscopy (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 2032-2034 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The Zeeman splitting of neutral lithium introduced to a hot plasma as a beam may be used to determine both the magnitude and direction of the local magnetic field. Dye lasers can improve the sensitivity of the method, either by resonance fluorescence or by intracavity absorption. A limit on the applicability of this diagnostic is set by the lithium density in the plasma. A high density, 80-kV lithium beam has been developed to access plasmas of larger dimension and/or higher densities, or to permit measurements with better time resolution than with previous beams. The beam utilizes a high density lithium ion source. Diagnostics include 2-D ion beam profiling, Faraday cup, magnetic analyzer, and a "pepperpot'' probe for measurements of beam intensity, composition, and divergence. Beam currents can exceed 10 mA in a ≤2-cm-diameter beam with a divergence of several milliradians.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1138781
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  • 8
    Digitale Medien
    Digitale Medien
    Interface between an oscilloscope and a multichannel analyzer (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 3132-3132 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: We describe a simple device for interfacing an oscilloscope with a sawtooth output to a multichannel analyzer. The apparatus works for low scan rates only (ms range), a limitation given by the timing requirement of the MCA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1138954
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  • 9
    Digitale Medien
    Digitale Medien
    A comparison of edge turbulence in tokamaks, stellarators, and reversed-field pinches* (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 2491-2497 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Edge equilibrium, turbulence and transport related plasma parameters from the Advanced Toroidal Facility (ATF) [Fusion Technol. 10, 179 (1986)] torsatron, the ZT-40M [Fusion Technol. 8, 1571 (1985)] reversed-field pinch, the Phaedrus-T [Nucl. Fusion 32, 2040 (1992)] tokamak, the Texas Experimental Tokamak (TEXT) [Nucl. Technol. Fusion 1, 479 (1981)], and the Tokamak Fusion Test Reactor (TFTR) [in Plasma Physics and Controlled Nuclear Fusion Research, 1990 (International Atomic Energy Agency, Vienna, 1991), Vol. 1, p. 9] have been obtained using a standardized Langmuir probe array and a consistent set of data analysis packages. Additional data from some other devices have also been furnished via private communications and incorporated from published results. Experimental results over a wide range of parameters are compared and the turbulence contribution to edge transport are assessed. Certain physical properties that are relevant to the modeling of edge turbulence are identified: namely, shear decorrelation of turbulence, the role of resistive dissipation and electron parallel thermal conduction, radial mode structure in sheared magnetic field, and electromagnetic contribution to the parallel Ohm's law.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.860734
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  • 10
    Digitale Medien
    Digitale Medien
    Energetic electron measurements in the edge of a reversed-field pinch (1990)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 143-159 
    Details
    ISSN: 1089-7666
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The edge plasma of the ZT-40M [Fusion Technol. 8, 1571 (1985)] reversed-field pinch has been studied using a combination of three different plasma probes: a double-swept Langmuir probe, an electrostatic energy analyzer, and a calorimeter–Langmuir probe. The edge plasma has been measured both with and without a movable graphite tile limiter present nearby in the plasma. Without a limiter a fast nonthermal tail of electrons (T(approximately-equal-to)350 eV) is detected in the edge plasma with nearly unidirectional flow along B and having a density between 2% and 10% of the cold edge plasma (T(approximately-equal-to)20 eV). The toroidal sense of this fast electron flow is against the force of the applied electric field. A large power flux along B is measured flowing in the same direction as the fast electrons and is apparently carried by the fast electrons. With the limiter present the fast electrons are still detected in the plasma, but are strongly attenuated in the shadow of the limiter. The measured scrape-off lengths for both the fast electrons and the cold plasma indicate cross-field transport at the rate of, or less than, Bohm diffusion. Estimates indicate that the fast electrons could carry the reversed-field pinch current density at the edge and, from the measured transverse diffusion rates, could also account for the electron energy loss channel in ZT-40 M. The long mean-free-path kinetic nature of these fast electrons suggests that a kinetic process, rather than a magnetohydrodynamic process that is based upon a local Ohm's law formulation, is responsible for their generation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.859526
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