Runaway electrons preionized diffuse discharges in SF<sub>6</sub>, nitrogen and air
The present paper summarizes research results on runaway electron preionized diffuse discharges (REP diffuse discharge or shortly REP DD) in single pulsed mode. The REP DDs are initiated high voltage pulses due to the generation of runaway electrons and X-ray in an inhomogeneous electric field. It is shown that this type of discharge is formed both at negative and positive polarity of electrodes of small curvature radius. Either a cathode or an anode, or both can have a small curvature radius. During the formation of a REP DD, SAEB and X-rays are detected. The role of characteristic radiation in the formation of a REP DD is discussed. It is shown that the SAEBs are generated in the first breakdown phase when the gap is bridged by an ionization wave.