Prebreakdown phase in atmospheric discharges

Pulsed X-ray radiation with quanta energy higher than 5 keV is recorded during the prebreakdown phase under discharges in atmospheric-pressure air at a maximum voltage from the 0.8–1.2 MV range. The UV and X-ray generation region has been localized using collimated and time-resolved diagnostics. In the near-UV range, the maximum radiation intensity corresponds to the instant of X-ray generation.