Progress in MJ plasma focus research at IPPLM

The well-known feature of a Plasma-Focus (PF) system is the strong dependence between the current flowing in a pinch and the intensity of ionizing radiation emitted from the pinch. Especially, the experimental neutron scaling law based on measurements performed on devices with condenser banks of energy from few to hundreds kJ was expressed by Yn ~ I3.3–5 [5]. Later investigations, however, carried out on MJ devices showed [2, 3] that there is a certain condenser bank energy limit above which the scaling law is not valid and the neutron yield stabilizes at a level of 1011–1012 neutron/shot. Since, for the last few years, research on MJ plasma focus has been dealing with the following problems: Which physical mechanisms determine high efficien – cy of neutron production for such a configuration. What is the reason of the saturation effect of neutron – production vs. current. This effect of saturation can appear when a part of all PF current flows outside a PF pinch. Measurements of current distribution carried out in a Frascati megajoule PF experiment showed that a part of all current flowed in the rest plasma near insulator of the megajoule PF and did not participate in pinch compression [2]. The mentioned points touches the understanding of physics which dominates the plasma formation. This question is closely related to neutron production mechaProgress in MJ plasma focus research at IPPLM Marek Scholz, Leslaw Karpinski, Viacheslav I. Krauz, Pavel Kubes, Marian Paduch, Marek J. Sadowski