Theory of generation of exospheric very-low-frequency noise (hiss)

Abstract

The traveling wave tube amplification process proposed by Gallet and Helliwell is considered in greater detail. Account is taken of the spiral motion of particles traveling in the magnetic field, the interaction distance for which amplification at any one frequency can occur, and the slowing down of the stream particles by the wave amplification process. It is shown that narrow band bursts of hiss can be generated by weak electron streams of even very broad velocity and pitch distribution. The center frequency of such a band is characteristic of the terminating latitude of the line of force of generation. Stronger streams produce an overload effect giving rise to wide and very wide bands. Narrow bands can be produced at other frequencies by streams of narrow velocity and pitch distribution.