Influence Of Gas Conditions On Parameters Of Plasma Jets Generated In The Pf-1000u Plasma-Focus Facility

Several series of high-current discharges were carried out within the PF-1000U facility at various gas conditions. The initial filling pressures were p(0) = 1.2 hPa D-2, 1.06 hPa D-2 +/- 10% He, or 0.53 hPa D-2 + 25% Ne. The discharges were performed with or without an additional gas puffing. In shots with the puffing, 1 cm 3 of gas (or mixture), compressed to the pressure of (0.13-0.20) MPa, was injected 1.5 ms before the discharge initiation. Pure D-2, He, Ne, or a mixture of 50% He + 50% Ne was used for puffing. The optical spectroscopic measurements were performed at a distance of 16 or 27 cm from the electrode outlets. Almost all discharges produced a dense plasmafocus (of about 10 cm in length) and a long plasma jet, which was observed for several mu s. The ambient plasma density at the investigated gas-conditions was about 10(16) cm(-3), but an admixture of 10% He or 25% Ne (added to the D-2-filling) induced an increase in this density by factor 1.8-2.5. In all the cases, the plasma jet density was above 10-times higher than that of ambient plasma. At the He- or Ne-puffing, this density reached (3.5-6) x 10(17) cm(-3). Electron temperatures in the plasma jet changed from about 5.0 to about 3 eV in 5-7 mu s. Published by AIP Publishing.