Accession Number : AD0622876

Title :   AN EXPERIMENTAL STUDY OF NONLINEAR PLASMA-WAVE INTERACTION.

Descriptive Note : Scientific rept.,

Corporate Author : STANFORD RESEARCH INST MENLO PARK CALIF

Personal Author(s) : Taylor,William C.

Report Date : AUG 1965

Pagination or Media Count : 44

Abstract : A study was made of the effect of pulsed L-band radiation from a slot antenna upon a layer of hot ionized air passing over the slot, and of the resulting time-resolved radiated power received by a monitoring antenna well beyond the plasma layer. The plasma layers were produced by an RF plasma jet and were nonuniform in electron density and collision frequency, similar to those expected in hypersonic flight through densities ranging between 0.0001 and 0.001 atmospheres. The plasma frequency at the maximum was varied between about one-tenth and twice critical. Measurements were made of the RF power thresholds required for producing (1) perceptible electron heating and (2) perceptible additional attenuation produced by RF-induced changes in the plasma conductivity. At low pressures, the electron heating thresholds were found to be considerably lower than required to produce new electrons in the hot gas, and about two orders of magnitude lower than required for breakdown in cold air at the same pressure. The thresholds for additional attenuation over the pressure range were about 8 db below the usual breakdown levels in cold air. The variation with pressure of power transmitted through the resulting plasma corroborates earlier experiments with discharges in cold air in a waveguide, showing a monotonic decrease as pressure decreases when the input power is much higher than the threshold required for nonlinear interaction. (Author)

Descriptors :   (*ANTENNA RADIATION PATTERNS, PLASMA JETS), (*PLASMA JETS, ANTENNA RADIATION PATTERNS), (*SLOT ANTENNAS, ANTENNA RADIATION PATTERNS), RADIOFREQUENCY POWER, L BAND, ELECTRON DENSITY, ELECTRIC DISCHARGES, ELECTROMAGNETIC RADIATION, PROPAGATION, NONLINEAR SYSTEMS, EXPERIMENTAL DATA

Distribution Statement : APPROVED FOR PUBLIC RELEASE