Study of the azimuthal magnetic fields and scaling laws at the KPF-4-Phoenix facility

Abstract

Results are presented from magnetic probe measurements in the pinching region formed during the compression of the plasma current sheath (PCS) in a discharge in deuterium at the KPF-4-Phoenix plasma focus facility. The fine structure (shock front-magnetic piston) of the PCS and its time evolution in the course of plasma compression toward the facility axis was studied by means of magnetic probes. It is shown that the fraction of the current transported into the axial region by the PCS does not exceed 65% of the total discharge current. The integral neutron yield Yn is well described by the formula Yn ≈ (1.5–3) × 1010Ip4, where Ip (in MA) is the pinch current flowing in the region r ≤ 22 mm.