Microwave Radiation from Plasmas

In the present experiments observations were carried out in a micro-wave region, where the wavelength was comparable to or shorter than a dimension of the discharge tube. Incoherent radiation, namely, noise radiation from plasmas which were semi-opaque or opaque was observed. Comparison between the electron temperature determined from microwave measurement and that from electrostatic probe measurement gives a satisfactory agreement. It is experimentally investigated that the plasma oscillation in a hot cathode discharge tube gives rise to radiation. Obtainable power of this radiation is estimated about 0.1 µW.