Accession Number : AD0697773

Title :   THE RELATION OF BRIGHTNESS TEMPERATURES TO THE EFFECTIVE TEMPERATURE OF PLASMA WAVES RADIATING IN THE RADIO-WAVE RANGE,

Corporate Author : STANFORD UNIV CALIF INST FOR PLASMA RESEARCH

Personal Author(s) : Smith,D. F. ; Sturrock,P. A.

Report Date : DEC 1968

Pagination or Media Count : 23

Abstract : An effective temperature for plasma waves, Tp, is introduced and its relation to radiation temperature Tr and brightness temperatures is examined. The effects of scattering between the source and the observer on the observed brightness temperature are investigated and it is proposed that two brightness temperatures should be used. The standard observed brightness temperature Tb is the brightness temperature of the scatter image of the source unresolved into its separate components while the 'source brightness temperature' Tbs is the brightness temperature which would be observed in the absence of scattering outside the source. If the total absorption coefficient is positive at a given frequency and the plasma is not near a state of radiative instability, then Tb < or = Tbs < or = Tr < or = Tp. In the case of a zero or negative total absorption coefficient, Tb < or = Tbs < or = Tp (c/square root /3 v sub Te) cubed as long as all radiation and all negative absorption coefficients for separate processes are due to plasma waves. Here v sub Te is the electron thermal velocity. The large role that scattering outside the source may play is illustrated by the example of Type III solar radio bursts. (Author)

Descriptors :   (*PLASMA MEDIUM, RADIO WAVES), (*SOLAR RADIATION, RADIO WAVES), TEMPERATURE, BRIGHTNESS, SCATTERING, SOLAR CORONA

Subject Categories : Astrophysics
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE