The effects of electrode configurations towards plasma current sheath in mather type plasma focus by using mathematical modeling

Abstract

The study of plasma current sheath (PCS) in Mather-type configuration of Dense Plasma Focus (PF) in terms of electrode configurations is crucial to determine conditions for the plasma outflow from the pinch, thereby affecting the plasma compression ratio. PCS propagation from the coaxial discharge from a typical Mather type dense PF is successfully simulated using mathematical modeling in Visual Basic. A clear uplift of the PCS from near insulator till it reaches the radial inward phase at the open end of the center anode. The dynamics of PCS in the UNU-ICTP PF device is determined based on Lorentz force while considering the retarding force from the ambient gas. Results have shown significant consistency with experimentally measured discharge current signal after accounting for the numbers of filamentary current forms that connect to each outer electrode. It is found that anode radius causes the maximum current discharged to be varied while smaller anode radius yields in larger inductance due to an increase in inductive reactance in the device. As the anode radius increases, the velocity of PCS decreases. Electrode distances have a significant impact in affecting inductance due to the density of the filled gas in the chamber as higher distances cause a higher density of filled gas and thus increasing PCS inductance.