Fig. (2) Block diagram of the experimental setup: R - emitter, HVG - high voltage generator with pulse periodic form, M - monochromator, PD - photodetector, A - amplifier, DR - recorder, V - voltmeter, O - oscilloscope, RC-Rogovsky coil, GPS-vacuum pumping and gas filling system, PM-power meter, L, D₁, D₂, F-lens, diaphragm and filter, respectively.