Scattered radiation in the diagnostics of a plasma channel

A method for the study of a thin plasma channel (dipole or plasmoid) is based on the analysis of the scattered radiation. The method is experimentally tested using channels that are formed due to the development of the microwave streamers in air in the vicinity of the breakdown threshold in the pressure interval 1 $\times$ 10$^4$–1.4 $\times$ 10$^4$ Pa. The effective scattering surface, amplitude of total charge, and the current that is averaged over the channel length are estimated using the results on the plasmoid dipole moment. The lower-bound limits of volume-averaged electron conductivity and concentration are also estimated. The experimental data are compared with the results of calculations using the approximate electrodynamic integral model of the microwave streamer.