Synchrotron maser emission in the saturated regime

Using the method of Einstein coefficients, we derive a quasi-linear kinetic equation for relativistic electrons, in which synchrotron emission of the particles is taken into account. We discuss the evolution of the electron distribution taking into account the effect of weak radiative diffusion of the particles over pitch angles. We analyze a solution of the quasi-linear kinetic equation for electrons and the radiation transfer equation in a stationary thick plasma layer in which maser amplification of the synchrotron radiation takes place. In this case, we assume that population inversion in the electron distribution and, thus, stationary synchrotron emission occur due to an external (nonsynchrotron) acceleration mechanism. The efficiency of this acceleration mechanism is assumed to have a power-law dependence of the electron energy. Under these conditions, we find the spectra of synchrotron maser emission, which are entirely determined by the external acceleration. Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 43, No. 7, pp. 575–594, July, 2000.