Gyro Resonance of Suprathermal Electrons in a Collisionless Plasma.
Abstract
Equations for the absorption coefficient and emissivity due to a tenuous component of suprathermal electrons gyrating in a magnetoactive plasma are given. An example is presented for the case where the plasma and gyro frequencies are equal, in order to illustrate the large magnitude (both positive and negative) and narrow bandwidth of the absorption coefficient when the complex doppler effect comes into play. Maximum growth rate is found when the wave normal makes a small angle (<10 degrees in the example) with the background magnetic field. It is pointed out that the large value of the longitudinal electric field makes uncertain, without further analysis, the intensity of the radiation which can escape from the plasma. A numerical example is given where the gyro frequency exceeds the plasma frequency, and the electrons exhibit an anisotropic momentum distribution function. The resultant negative absorption coefficient is shown to be plausible as a generation mechanism for the narrow bandwidth component of decimetric wavelength solar bursts. The relevance of amplified gyro radiation as an explanation for Type I bursts is discussed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1970
- Accession Number
- AD0721337
Entities
People
- B. L. Gotwols
Organizations
- Johns Hopkins University Applied Physics Laboratory