Čerenkov radiation in a magneto-ionic medium (with application to the generation of low-frequency electromagnetic radiation in the exosphere by the passage of charged corpuscular streams

Abstract

The electromagnetic field of a uniformly moving point charge in a magneto-ionic medium is evaluated by representing the field due to the moving charge in an angular spectrum of plane waves. A brief discussion of the frequency ranges satisfying the Čerenkov coherence condition is given. It is shown that Čerenkov radiation in the exosphere produces low-frequency hiss. The spectral and polar distributions of radiation over the low-frequency band were computed numerically for plasma and gyro frequencies occurring in the exosphere and for particle speeds of the order of solar corpuscular cloud speeds. An interesting feature of the radiation is that the more slowly the particle moves the greater is the emitted radiation.