A Plasma Focus device as ultra-high dose rate pulsed radiation source. Part I: Primary electron beam characterization

A Plasma Focus is a device able to generate in the pinch phase several kinds of radiation fields. One of them are the backward emitted electron's beams that can be used as source for X-ray pulses generation through the interaction with a suitable target. The worth of this source stands on two elements: first, being connected to the lifetime of the pinch phase, the electron current lasts a few tens of nanoseconds, we can say 50 ns as reference; second, the electron bunches carry a charge of the order of 0.1 mC. These two aspects grant the generation of X-ray pulses of extremely short duration, while the quite strong charge bunches allow a potential dose transfer by the X-rays in the order of 1 Gy per pulse. These characteristics have made this source of interest with respect to possible medical applications, in particular for radiotherapy of superficial tumors, given also that the extremely high dose rate could be of help in winning radio-resistance of specific cancer cells as in the case of melanoma. In this first part of the work, after a brief outline of the PF working principles, the experimental techniques used for the detection and the analysis of the characteristics of the primary electron source have been described. The results showing their correlation with the capacitor's bank energy and the possible scaling laws that could drive the setup of specific X-ray generation devices for radiotherapy treatments have been thoroughly discussed.