Effect of electron collisions on Cerenkov radiation from magnetoplasma.

The theory of <Ccr>erenkov radiation from magnetoplasma has been modified to account for the effect of electron collision frequency. The results are compared with the <Ccr>erenkov theory for collisionless magnetoplasma The <Ccr>erenkov radiation in the magnetosphere is unaffected by electron collisions. In the ionosphere the radiated power is found to change by several times as compared to radiation by collisionless magnetoplasma.
The interaction of electrons moving through magnetoplasma is known to radiate electromagnetic waves by various processes. The <Ccr>erenkov process generates very low frequency (VLF) electromagnetic waves. The rigorous formulation for frequency spectra of radiated average power by the <Ccr>erenkov process was first given by Sitenko and Kolomenskii (1956). Following Sitenko and Kolomenskii's approach Mansfield (1964) generalized the formulation for <Ccr>erenkov radiation from charged particles spiraling around static magnetic field. Mansfield has studied the nature of VLF radiations from magnetoplasma and has compared the results of his formulation with the alternative approach developed by Eidman (1958 a, b) and substantially corrected by Liemohn (1965). We have also shown (Singh and Singh 1969, 1970) that the <Ccr>erenkov process is capable of producing VLF waves in the magnetosphere. In the present paper we have modified Mansfield's formulation to account for the interparticle collisions. The radiated <Ccr>erenkov power is found to decrease with increasing collision frequency. We have seen that the radiated power in the magnetosphere is unaffected, due to electron collisions. However, in the ionosphere the <Ccr>erenkov radiated power is reduced significantly, due to the presence of collisions. [ABSTRACT FROM AUTHOR]