On an Estimation of the Coronal Magnetic Field Strength from Spectrographic Observations in the Microwave Range

Abstract

Observations of the solar radio emission in the microwave frequency range show fine structures consisting of a number of the almost parallel narrow frequency bands. We interpret these bands as the cyclotron harmonics plasma emission. This emission is generated by the anisotropic electron beam, which excites longitudinal waves on the normal Doppler effect resonance. Then the longitudinal waves convert into the radio emission on the second harmonic of the longitudinal waves frequency and sometimes into the fundamental one. Estimations of the magnetic field strength made on the basis of such a model give the values of the magnetic field in the microwave burst sources as ~ 100-200 G. The estimations of density variations are also given.