Continuous atmospheric pressure discharges in terahertz and sub-terahertz focused beams

The paper presents the results of recent experimental studies. The subject of research was the discharge of atmospheric pressure in a gas stream in focused beams of microwave radiation. The radiation sources were: a gyrotron with a radiation frequency of 263 GHz and a power of up to 1 kW, a free-electron laser with a radiation frequency of 2.3 GHz and with an average power of up to 400 W. The paper presents the results of measurements and calculations of breakdown fields, the results of measuring plasma parameters in these cases. Possible applications are discussed.