Cascade acceleration of an explosive-emission subnanosecond electron beam

Cascade acceleration of a magnetized high-current subnanosecond electron beam (≈15 kA/cm2) has been demonstrated in two gaps separated by a drift tube. Synchronized negative-polarity voltage pulses of approximately the same amplitude (≈200 kV) were supplied to the gaps from autonomous high-voltage pulse generators. The pulse durations (1 and 0.5 ns) were determined by the accuracy of their synchronization (±200 ps). After passing through foil filters of different thickness (i.e., cutoff energy), the beam electrons were detected by a picosecond resolution collector sensor. It was found that the kinetic energy of the subnanosecond fraction of a tubular beam with a current of ≈1.2 kA, accelerated to 250 keV in the first gap with an explosive-emission cathode, increased to ≈500 keV at the output of the second gap.