Plasma Current Sheath Shape and Trapping Efficiency in the 2.2-kJ EAEA-PF1 Plasma Focus Device

Abstract

The plasma current sheath (PCS) shape and trapping efficiency η are investigated experimentally. The experiments are carried out at the 2.2-kJ Egyptian Atomic Energy Authority Plasma Focus device, EAEA-PF1, of Mather-type geometry. Three versions of the inner electrode (IE) lengths, z₀ = 9.5, 10.5, and 11.5 cm, are used. The investigations are performed with argon gas at a pressure ranging between P = 0.2 to 1.8 Torr. The PCS shape in term of its inclination angle of curvature θ and thickness λ are detected at an axial distance approaching the coaxial electrode muzzle and at three different radial distances through the annular space within the coaxial electrode assembly. Results on the trapping efficiency η are obtained from the magnetic force and PCS acceleration data under these discharge conditions. Diagnostic tools applied are a Rogowski coil and magnetic probes. Results on the PCS profile show that it has the best profile at an argon gas pressure of 0.8 Torr and IE length of 10.5 cm. The trapping efficiency η has the maximum value at gas pressures within the range of 0.6−1.8 Torr, where the maximum axial force is detected for most experimental data.