Study of Current Sheath Velocity and Its Distribution Using Tridimensional Magnetic Probe in Sahand Plasma Focus

The current sheath velocity in 0.25 Torr gas pressure of Filippov type plasma focus is studied experimentally. By using two tridimensional magnetic probes on top of the anode surface, the current sheath velocity is measured for argon, oxygen and nitrogen. Additionally, the effect of charging voltage on the current sheath velocity is studied in both axial and radial phases. We found that, the maximum current sheath velocities at both radial and axial phases are respectively 4.33±0.28 (cm/µs) and 3.92±0.75 (cm/µs) with argon as the working gas at 17 kV. Also, the minimum values of current sheath velocity are 1.48 ± 0.15 (cm/µs) at the radial phase and 1.14 ± 0.09 (cm/µs) at the axial phase with oxygen at 12 kV. The current sheath velocity at the radial phase is higher than that at the axial phase for all gases and voltages. In this study, variation of the full width half maximum (FWHM) of magnetic probe signals with voltage is investigated for different gases at radial and axial phases.