Microwave Radiation from a Plasma in a Magnetic Field (I)

Abstract

The microwave radiations from a dc discharge plasma in a magnetic field were studied. The experimental results showed that the resonant radiations of the extraordinary wave, propagating perpendicular to a magnetic field, were observed not only at ω=(ω_p²+ω_b²)^1⁄2, but also near the cyclotron harmonics. On the other hand, it was shown that the dispersion relation for the plasma type oscillations derived by Bernstein had a harmonic structure: In our experimental condition this dispersion curve was divided into many branches, each of which approached asymptotically to the curves given by ω²=ω_p²+ω_b² and by ω=nω_b(n being an integer). The resonant radiation detected was interpreted as the plasma type radiation, above mentioned. The gaps in the radiation spectrum at the cyclotron harmonics were not measured in our discharge plasmas. Further, the number of the successive harmonics in a radiation increased with decreasing a gas pressure, independently of a kind of gas used.