Generation of electromagnetic radiation by an electron beam with a bump on the tail distribution function

This paper considers, in a linear approximation, the instability of a low-density electron beam propagating along the magnetic field of the solar corona, with respect to the excitation of electromagnetic (transverse) waves at cyclotron harmonics. It is shown that the extraordinary mode is excited at harmonics, beginning with the second and higher. Results of calculations check well with observed spectra of groups of solar 'spike' radio bursts in the decimetric wavelength range.[PUBLICATION ABSTRACT]