Experimental study of the initial phase of atmospheric discharges

Results of experiments on breakdown of long gaps in air are presented at atmospheric pressure on ERG installation (LPI). Generation of X-ray radiation in the form of single and multiple pulses of a nanosecond scale with quanta energy of 5÷150 keV during the various moments of a time interval from the beginning of a potential difference raise and before development of the main discharge is registered. Presence a current prepulses, connected with X-ray pulses is shown. Increase of generation of a near ultraviolet λ=240÷400 nm occurs for 20 nanoseconds, and the moment of occurrence of first X-ray pulse is necessary on UV maximum. Frame shooting of an initial stage of the discharge in a visible range has shown streamer growth on formed spherical area of the leader head.