X-ray radiation from cathode spot fragments in low voltage vacuum arcs

Temporal evolution of X-ray emission of laser-induced discharges was investigated by means of a picosecond X-ray streak camera. Point-like structures and thin hot layers of intensive X-ray radiation with life time from 30 ps to 1.5 ns in a spectral range 100 eV-10 keV and hence temperature T⩾100 eV have been found at first in a comparatively low voltage vacuum discharge (U≈150 V-2.7 kV) initiated by picosecond laser beam. The radiation of laser-induced breakdown was investigated just after ignition as well as with a long delay time (up to 20 ns) relative to the ignition point by the laser beam in order to eliminate the X-ray radiation coming from the laser-produced plasma