Generation of electromagnetic radiation under double plasma resonance condition in a mirror-confined plasma produced by ECR discharge

Abstract

Study of kinetic instabilities of non-equilibrium plasma produced in an open magnetic trap by powerful microwave radiation under electron cyclotron resonance (ECR) conditions is of fundamental interest including prospects to simulate physical processes in the solar corona, in the magnetospheres of the Earth and other planets. For example, plasma instabilities in magnetic traps on the Sun are the sources of powerful broadband radio emission (the so-called type IV bursts) which is interpreted as the excitation of plasma waves by fast electrons in the upper hybrid resonance frequency followed by transformation in electromagnetic waves, for example, as a result of scattering by thermal ions. In the case of double plasma resonance condition when the frequency of the upper hybrid resonance coincides with one of the electron gyrofrequency harmonics the instability increment of plasma waves is greatly increased. This leads to the appearance of bright narrow-band radio emission near the harmonics of the electron gyrofrequency - the so-called zebra patterns. It should be noted that the possible manifestations of double plasma resonance effect are not rare in astrophysical plasmas. The phenomenon of zebra pattern is observed not only on the Sun, but in the decametric radiation of the Jupiter, kilometric radiation of the Earth and even in the radio emissions of pulsars. In connection with the above, verification of the effect of double plasma resonance in a laboratory plasma experiments is a very relevant task.