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Laboratory Simulation of the Injection of Energetic Electron Beams into the Ionosphere—Ignition of the Beam Plasma Discharge

  • W. Bernstein
Part of the Astrophysics and Space Science Library book series (ASSL, volume 84)

Abstract

Experiments, which somewhat simulate the injection of monoenergetic (several KeV) electron beams into the ionosphere, have been performed in the very large (17 m × 26 m) vacuum chamber at Johnson Space Center. Typical operating ranges were: Beam current, I [0–130 ma], beam energy, V [0.5–3 kV], magnetic field strength, B[0.3–2G.] neutral gas pressure, P,[l × 10- 6−1 × 10- 4torr], path length, L [10–20 m], and injection pitch angle, α[0–800]. Measurements were carried out in both steady state and pulsed modes. In steady state and for constant V,B,P,L, α,the beam plasma discharge [BPD] is abruptly ignited when the beam current increased above a critical value; at currents below critical, the beam configuration appears grossly consistent with single particle behavior. If it is assumed that each of the experiment parameters can be varied independently, the critical current required for ignition obeys the empirical relationship at P < 2 × 10-5 torr.
$$ {\text{I}}\;{\mkern 1mu} \alpha {\mkern 1mu} \frac{{{{{\text{v}}}^{{3/2}}}}}{{{{{\text{B}}}^{{0.7}}}{\text{PL}}}}$$
The BPD is characterized by 1) a large increase in the plasma production rate indicated by the increase in the 3914 A light intensity + plasma density, 2) intense wave emissions in a broad band centered at the plasma frequency and a second band extending from a few KHz up to the electron cyclotron frequency, 3) beam heating, and 4) radial expansion and pitch angle scattering of the primary beam leading to the disapppearance of single particle trajectory

Keywords

Magnetic Field Strength Ambient Plasma Beam Configuration High Density State Beam Plasma Discharge 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© D. Reidel Publishing Company 1981

Authors and Affiliations

  • W. Bernstein
    • 1
  1. 1.Center for Space Physics Department of Space Physics & AstronomyRice UniversityHoustonUSA

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