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  • 1985-1989  (8)
Source
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Spectroscopic determination of the electrostatic potential profile in a plasma-prefilled ion diode (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1627-1629 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrostatic potential profile in the accelerating gap in a plasma-prefilled magnetically insulated intense pulsed ion beam diode has been determined using laser-induced fluorescence spectroscopy. Results for a 300–400 kV planar diode are presented, both with and without an electron emitting vane protruding from the cathode. In both cases, a 5–6 mm accelerating gap forms in the 1012–1013/cm3 plasma in a few nanoseconds. The experimental potential profiles are not consistent with electrons confined to a sheath near the cathode. Rather, electrons are required throughout the gap to explain the observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102219
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Magnetosonic wave generation by super-Alfvénic ion ring propagation in plasma (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2727-2729 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A weakly diamagnetic rotating proton beam propagating at about four times the Alfvén speed along a magnetized hydrogen plasma column generated magnetosonic waves when the beam rise time was less than about three radial Alfvén transit times. The waves were collisionally damped and the damping increased as the induced cross-field plasma current became stronger. Our beam and plasma conditions suggest that the damping is due to an enhanced collision frequency resulting from a modified two-stream instability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101936
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Magnetically insulated ion diode with a gas-breakdown plasma anode (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 1872-1876 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An active anode plasma source has been developed for use in a magnetically insulated ion diode operated on a 1010-W pulsed power generator. This source uses an inductive voltage from a single turn coil to beak down an annular gas puff produced by a supersonic nozzle. The resulting plasma is magnetically driven toward the radial insulating magnetic field in the diode accelerating gap and stagnates at a well-defined surface after about 300 ns to form a plasma anode layer defined by magnetic flux surfaces. An ion beam is then extracted from this plasma layer by applying a 150-kV, 1-μs pulse to the accelerating gap. Optimization of the timing of the gas puff, the plasma production discharge, and the high voltage pulse has resulted in 1-μs duration 75–150-keV ion beam pulses with 〉100-A/cm2 peak ion current density over an area of about 400 cm2. Up to 5 J/cm2 has been collected by a 4-cm2 calorimeter. The diode impedance history can be varied so that rising, flat, and falling voltage pulse waveforms can be produced. Streak photographs of beamlets impinging on a scintillator and time integrated targets both show beam divergence angles ≤3°. However, under certain operating conditions, large excursions (∼25°) in mean aiming angle on time scales of 20–200 ns are observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339884
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    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Propagation of intense ion beams across a plasma-filled magnetic cusp (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 4095-4101 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Preionized plasma has been compared with vacuum and with neutral gas as a medium for the propagation of intense ion beams across magnetic fields. Two cusp-injection ion ring experiments have been used to study the effectiveness of these three cusp-fill media for space-charge neutralization, as shown by the subsequent spreading of the injected rings. In the ion ring experiment a (approximately-less-than)100-ns ion beam was injected into ∼20-eV plasma fills of (approximately-less-than)1012/cm3, giving much better propagation than vacuum, but not as good as 100-mTorr H2 gas. In the long-pulse ion ring experiment with (approximately-greater-than)200-ns beam rise time, plasma fill and vacuum gave similar propagation. The results suggest that for complete neutralization of space charge in ion beams propagating across magnetic fields, background media must be provided to meet certain minimum requirements of conductivity and collisionality which depend upon the beam current and rise time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337794
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Measurements of ion transverse-velocity distribution in the gap of an ion-beam diode (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 4781-4785 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the distributions of ion transverse velocities in the acceleration gap of a magnetically insulated ion diode. The measurement is based on observing the spectral profile of the Doppler-broadened spontaneous line emission from accelerating ions. The velocity distributions of C++ and Al++ ions were peaked at zero transverse velocity and symmetric with respect to the directions parallel and antiparallel to the magnetic-field lines. The mean transverse velocities for both of the ion species corresponded to energies of about 200 eV in experiments with a gap potential difference of 260–330 kV. The divergence angles observed for both of the ion species are significantly smaller than previously observed for protons outside the diode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338816
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Microwave and ion beam studies of an Applied Bθ diode (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1655-1670 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A parametric study of microwave radiation emitted from an "applied Bθ'' magnetically insulated ion diode, covering frequencies between 0.3 and 85 GHz, indicates that collective mechanisms are responsible for the 1–10-MW peak output. These collective mechanisms may also be related to the degradation in ion beam quality seen by a scintillator/streak camera diagnostic. This degradation is most apparent when the microwave flux is at its maximum. A deformation of the plasma appears to be the most likely cause of the disturbances seen in the ion beam.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.339589
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Proton ring formation and trapping in a gated magnetic mirror (1989)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 1 (1989), S. 1059-1072 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed study of the trapping of proton rings in a magnetic mirror both in uniform gas fillings and in localized puffed-gas fillings is presented. The trapping of about 3×1014, 400 keV protons in a 1.5 m long, 0.8 T magnetic mirror was accomplished with a static 1.23:1 downstream mirror and a fast "gate'' upstream mirror with mirror ratio 〈1.3:1. Protons were trapped for 4 μs (〉50 cyclotron periods) or longer. The proton ring mean radius, length, and annular thickness in the trap were 10 cm, 1.5 m, and 5–8 cm, respectively. Detailed study of the dynamics of the injected and trapped protons with a variety of diagnostic techniques showed that the bulk of the protons followed trajectories that could be fully explained using the ion diode voltage and the details of the applied magnetic field configuration. However, a small fraction of the injected protons had axial energy much higher than was possible from single-particle trajectories; incomplete electrostatic neutralization of the proton ring by the beam-generated plasma in the injection region is postulated to explain this observation. Ring proton lifetime in the mirror trap appeared to be determined by mirror losses upon initially encountering the downstream and then the upstream mirrors, followed by a gradual radial loss due to charge-exchange collisions with the neutral gas contained in the experiment chamber.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859028
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Efficient proton ring trapping in an ion ring experiment (1986)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 29 (1986), S. 908-911 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In an 8 kG magnetic mirror, 400 keV proton rings, containing up to 3×1015 protons and 0.2 kJ energy, have been trapped. The trapping is accomplished by injecting a rotating proton ring through a 1 μsec rise-time, 1.4:1 pulsed mirror coil. Negligible loss occurs through the 1.45:1 static downstream mirror after the first bounce, when (approximately-greater-than)90% of the injected beam is reflected. The pulsed upstream mirror traps (approximately-greater-than)70% of the returning protons, after which there is very little particle loss for the first four ring bounces in the mirror well. Ring decay then increases as a result of slowing down and charge exchange in the 〉50 mTorr H2 background, and the ring is observable for 〉10 bounces, or (approximately-greater-than)5 μsec.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.865685
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    Paper (German National Licenses)
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