Accession Number : ADA299120

Title :   Mode Conversion in an Oxygen-Hydrogen Plasma.

Descriptive Note : Scientific rept. no. 3,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE CENTER FOR SPACE RESEARCH

Personal Author(s) : Johnson, Jay R. ; Chang, Tom ; Crew, G. B.

PDF Url : ADA299120

Report Date : 22 MAR 1995

Pagination or Media Count : 74

Abstract : The complications of mode conversion which occur near a minority resonance are studied in the context of electromagnetic ion cyclotron heating of a minority oxygen population in the magnetosphere. This problem is investigated using several different approaches. A perturbation approach demonstrates that the coupling results from non parallel propagation. The phase integral approach involves analytic continuation of (WKB) solutions and involves a discontinuity in the Poynting flux corresponding to energy absorption. The saddle point approach emphasizes the degree to which the coupling can be analyzed in terms of two mode coupling processes. When the two low frequency propagating modes coalesce near the oxygen resonance at two different coupling points, a numerical scheme which retains the two coupling points in a realistic manner is employed, and numerical coefficients are obtained. The calculated coefficients that are presented demonstrate that substantial coupling occurs between the two propagating modes and a definite absorption occurs. Such absorption is sufficient to explain the outflow and heating of ionospheric oxygen ions.

Descriptors :   *PLASMAS(PHYSICS), *MAGNETOSPHERE, NUMERICAL ANALYSIS, OXYGEN, RADIATION ABSORPTION, COEFFICIENTS, HEATING, PERTURBATIONS, ELECTROMAGNETISM, CYCLOTRON RESONANCE, ENERGY ABSORBERS, IONOSPHERIC DISTURBANCES, PLASMA WAVES.

Subject Categories : Atmospheric Physics
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE