Cerenkov radiation from a slow, relativistic electron moving uniformly through microwave ferrite

Abstract

The electromagnetic fields generated by a superluminal electron in longitudinally magnetized, microwave ferrite have been derived for a narrow band of frequencies in the X band. For a superluminal electron, Cerenkov radiation is emitted in two circular cones for the ordinary and extraordinary wave modes. Using a Huygens' construction of wavelets, conditions for Cerenkov radiation were related to the propagation of plane waves through the ferrite. It was found that a slow relativistic electron will radiate only in the extraordinary wave mode. It is too slow to generate radiation in the ordinary wave mode. INTRODUCTIONThe generation of coherent microwave energy represents an area of continual interest for applications in space communications, microwave spectroscopy, and plasma diagnostics. Boundary value problems in Cerenkov theory [Bolotovskii, 1957[Bolotovskii, , 1962 Nag and Sayied, 1956] are important in connection with the theory of linear accelerators and waveguide systems. The emission of Cerenkov radiation was investigated for an electron moving with uniform velocity in an infinite, unbounded, anisotropic ferrite medium.The use of the Cerenkov effect as a means of generating microwave energy was first proposed by Ginsburg [1947]. He mentioned that it was unlikely to be an efficient way of producing microwave radiation and it would be difficult to obtain high powers. The source would give a continuous spectrum, whereas in most communication applications the aim is to produce oscillators that run at a single frequency. Three years after Cerenkov experimented with fluorescent light produced by gamma rays passing through uranyl salt solutions, Frank and Tarnrn [1937] explained the phenomenon using the classical electromagnetic theory of macroscopic media. Cerenkov radiation in anisotropic media has been studied, for the most part, in the optical spectrum [Ginsburg, 1940a, b;Tanaka, 1954;Muzikar and

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