Plasma diffusion in a space‐simulation beam‐plasma‐discharge

Szuszczewicz, E. P.; Walker, D. N.; Holmes, J. C.; Leinbach, H.

doi:10.1029/gl006i003p00201

Cited by 31 publications

(6 citation statements)

References 9 publications

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“…This type of loss is consistent with our toe model, since it produces axial plugging. We should note that there is experimental evidence for I/B dependence of the diffusion coefficient[Szuszczewicz, 1979] and an independent check of the We/•'• e ratio resulting from(10)tests very well against the experimental values [Szuszczewicz et alas a function of current. The line is the frequency of the upper branch with we determined from (10), with 0 --88 ø, and results from assuming the smallest ki that satisfied the radial boundary conditions and that k• ----•'•e/ Vb.…”

supporting

confidence: 69%

Scaling of the beam‐plasma discharge

Rowland¹,

Chang

Papadopoulos

1981

J. Geophys. Res.

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It is shown that the scaling observed in a recent experiment of the beam-plasma discharge is consistent with the assumption that triggering occurs when an instability threshold condition is exceeded for electron plasma waves with •0 = •0e, the electron plasma frequency. INTRODUCTIONThe importance of the beam-plasma discharge (BPD) in the feasibility and interpretation of active experiments using electron beams injected in space is very well known [Galeev et al., 1976;Bernstein et al., 1978Bernstein et al., , 1979. This type of discharge can be described qualitatively as follows. When an electron beam propagates through a neutral gas, it collisionally produces a plasma with a density comparable to its own. As the beam interacts with the plasma, a two-stream instability sets in, and the electric fields of the excited waves either heat or accelerate some of the plasma electrons to energies comparable with the ionization energy. Subsequently, the collisions of these electrons with the neutral gas atoms lead to an onset of an avalanche breakdown; the neutral gas is ionized over a time comparable to the mean free time of plasma electrons between inelastic collisions. Although several experiments have been carried out on the BPD [Getty and Smullin, 1963; Alexeff et al., 1966; Kharchenko et al., 1962; Smullin, 1968; Cabral et al., 1969], a theoretical understanding has not yet emerged. The more recent results of Bernstein et al. [1978, 1979] under steady state conditions and long interaction lengths provide us with sufficient details to test against a theoretical model. It is the purpose of this paper to examine whether the scaling of the critical beam current required for ignition Io as well as the narrow band emissions observed for I < Io can be understood on the basis of a model of the two-stream instability with finite boundaries.The plan of the paper is as follows. In the next section we review the pertinent experimental results. Section 3 deals with the theory of the two-stream interaction in a finite geometry. Section 4 presents a model of the BPD scaling, and section 5 discusses the emissions observed for I < Ic. REVIEW OF THE EXPERIMENTAL OBSERVATIONSThe experiments were performed in the large vacuum facility at Plum Brook, Ohio, and at the Johnson Space Center. The electron gun produced a cold, moderately high perveance (k = 10 -6 AV -3/2) energetic beam. The ambient magnetic field varied between 0.8 and 1.5 G, and the neutral density varied from 3 x 10 •ø to 10 •2 cm -3. The detailed experimental results can be found in Bernstein et al. [1978, 1979]. However, the main features were the following: ' 1. The BPD appeared at a critical current Ic, which scaled •Permanent affiliation:

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supporting

confidence: 69%

Scaling of the beam‐plasma discharge

Rowland¹,

Chang

Papadopoulos

1981

J. Geophys. Res.

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“…In the laboratory the conditions are easier monitored and the reproducibility of phenomena is much higher. For instance, the study of a plasma-beam discharge near the rocket required the phenomenon to be reproduced in the laboratory (BERNSTEIN et al, 1979;SZUSZCZEWICZ et al, 1979).…”

Section: B Electron Beams In the Earth's Magnetospherementioning

confidence: 99%

Active experiments in space, laboratory experiments and numerical simulation.

Podgorny

1982

J. geomagn. geoelec

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“…Paper number 4A8163. the laboratory environment described here, earlier investigations of the BPD phenomenon [Szuszczewicz et al, 1979] yielded estimates of perpendicul.ar diffusion coefficients orders of magnitude higher than predicted for classical collisional diffusion. Those results were consistent with a Bohm-like diffusion process created by wave t•rbulefice.…”

Section: I• C Oc Vs3/2b-ø'?p -•-• (1)mentioning

confidence: 61%

“…- Huba and Ossakow, 1979;Singh and Szuszczewicz, 1984;Kelley, 1982;Gary, 1983;Szuszczewicz, et al, 1982b) are often sufficient to produce low frequency drift instabilities. In the laboratory environment described here, earlier investigations of the BPD phenomenon (Szuszczewicz, et al, 1979) yielded estimates of perpendicular diffusion coefficients orders of magnitude higher than predicted for classical collisional diffusion. Those results were consistent with a Bohm-like diffusion process created by wave turbulence.…”

Section: Introductionmentioning

confidence: 92%

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Electrostatic wave observation during a space simulation beam‐plasma discharge

Walker¹,

Szuszczewicz²

1985

J. Geophys. Res.

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We have studied ELF waves which were observed during beam‐plasma discharge in the large vacuum chamber at Johnson Space Center. Phase delays as a function of radius (obtained from cross‐correlation measurements of density fluctuations) along with measurements of frequency and plasma potential, density, and temperature have been compared to a zero‐order slab model of nonlocal azimuthal drift wave propagation. The inferred wave phase velocity in the plasma frame after Doppler correction is found to be near one half the electron diamagnetic drift velocity. Although our measurements do not uniquely define a propagation mode, a model of azimuthal drift wave propagation is found to be consistent with our observations.

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Plasma diffusion in a space‐simulation beam‐plasma‐discharge

Cited by 31 publications

References 9 publications

Scaling of the beam‐plasma discharge

Scaling of the beam‐plasma discharge

Active experiments in space, laboratory experiments and numerical simulation.

Electrostatic wave observation during a space simulation beam‐plasma discharge

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