Generation of ion beams in the Frascati plasma focus devices

We report in this paper the detailed measurements carried out on the high energy ion beam (E_d >; 350 KV) generated in the Frascati 1 MJ device operated 250 kJ 20 kV. It is shown, for two geometries of the electrodes, that the low pressure filling favours beam generation but that the efficiency is very low (~ 1%). The existence of streams of medium energy (50 - 350 keV) is inferred from the neutronic properties of the discharge; they carry a small fraction of the total energy (2%). A thorough comparative discussion is carried out involving measurements done in other laboratories.