NEGATIVE CYCLOTRON RESONANCE ABSORPTION.
Abstract
The kinetic theory of waves in an infinite plasma in a uniform, constant magnetic field predicts that radiation near the cyclotron frequency in a sufficiently non-thermal plasma may grow in time. One effect which can cause such growth or negative cyclotron resonance absorption of radiation which propagates perpendicular to the magnetic field direction is the relativistic energy dependence of the electron's mass. Another is the energy dependence of the electron-atom collision cross section for low energy electrons in a neutral gas background. The cyclotron resonance absorption of microwave energy by monoenergetic electrons which drift through a cavity resonator has been measured in order to verify these predictions. In each case the observed absorption spectra are similar to those calculated in a perturbation theoretical solution of the Boltzmann equation treating the cyclotron resonance interaction between the electron beam and the bounded standing wave fields of the cavity resonator. An experiment which exhibits the radiative response in time of a weakly relativistic, monoenergetic electron ensemble to a short pulse of cyclotron resonance radiation is also described. The radiation calculated in an exact solution of the Boltzmann equation is found to occur in repetitive bursts of diminishing amplitude following the stimulating pulse. Experiment and theory are observed to be in qualitative agreement. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 25, 1967
- Accession Number
- AD0665886
Entities
People
- Jonathan M. Wachtel
Organizations
- Yale University