On the effect of a magnetic field on the spectrum of incoherent scattering

Abstract

The effect of an applied magnetic field is analyzed at scales of scattering smaller than the Debye length. If the scattering wave vector is directed everywhere perpendicular to the magnetic field vector, and each electron is assumed to gyrate unperturbed about a magnetic line of force, the spectrum of scattering will, in the first approximation, consist of lines. The separation of the lines is equal to the electron gyromagnetic frequency. If the average radius of gyration of the electrons is large compared to the scale of scattering, the envelope of the line spectrum is given simply by the thermal Doppler-spectrum curve that would exist in the absence of any magnetic field. As the average radius of gyration is decreased, however, an increasing fraction of power appears in the central line. Curves given in the paper reveal that the line spectrum gets smeared rapidly as the angle between the scattering wave vector and the magnetic lines of force is decreased from 90 degrees.