Dynamic Studies of a Small Plasma Focus Device

Experimental study of the dynamics of the plasma in a plasma focus device is carried out in a 3 kJ plasma focus. Results obtained are analyzed and fitted with the computation results obtained by using the Lee Model plasma focus modelling package. The discharge current is measured by a Rogowski coil and the axial acceleration of the current sheath is investigated by using magnetic probe. The electrode length of the plasma focus devices is 22 cm and the operating gas is deuterium at 0.5 mbar. A good fit of the experimental and numerical current signal is obtained by incorporating current shedding factor of around 0.8. Although the system is operated at low pressure, higher percentage of mass is carried by the current sheath. The axial acceleration velocity are measured along the electrodes and has the velocity of around 9 cm/μs near the end of the electrode. This agrees reasonably well with the computed axial velocity with a mass factor in the region of 0.8 to 1 during the axial phase. 1