Spectral signature of the beam plasma discharge

Journal Article · Fri Jul 01 00:00:00 EDT 1988 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA093iA07p07586· OSTI ID:5153062

Hallinan, T J; Deehr, C S; Hoch, E; Viereck, R ^[1]; Bernstein, W ^[2]; Konradi, A ^[3]

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1. Univ. of Alaska, Fairbanks (USA)
2. Rice Univ., Houston, TX (USA)
3. NASA Johnson Space Center, Houston, TX (USA)

Spectral measurements of the light emitted from a beam plasma discharge (BPD) in nitrogen show an abrupt increase in the ratio of N{sub 2} first positive emissions to the N{sub 2}{sup +} first negative emissions (red/blue ratio) at the onset of BPD. However, at beam currents substantially above BPD threshold, the red/blue ratio reverts to that produced by the beam itself (pre-BPD). This is interpreted as the appearance, at BPD onset, of a large suprathermal electron population, followed by a hardening of the suprathermal energy spectrum at higher beam currents. The new results are used to interpret previous white-light video images of BPD experiments. It is concluded that even larger red/blue ratios may occur at lower pressures and that a pre-BPD glow associated with radio-frequency emissions at the upper hybrid frequency is produced by a softer electron population than that occurring in BPD. In addition to the red/blue ratio, it was found that the ratio of the intensities of the 4-1 band and the 6-3 band of the first positive emissions varies systematically with beam current. The overall behavior is similar to that of the red/blue ratio--an abrupt increase followed by a steady decrease to the pre-BPD level. But the detailed dependence of the two ratios on current is different.

• OSTI ID: 5153062
• Journal Information: Journal of Geophysical Research; (United States), Vol. 93:A7; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
VISIBLE SPECTRA
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ELECTROMAGNETIC RADIATION
BEAM CURRENTS
ENERGY TRANSFER
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KINETIC ENERGY
LABORATORIES
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RADIOWAVE RADIATION
VACUUM SYSTEMS
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NONMETALS
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