Numerical studies of plasma pinch properties in PF1000 using Lee model code

Plasma emission (radiative recombination, bremsstrahlung, and line radiation) from a mega-joule plasma focus (PF1000) device is studied using the Lee code for nitrogen (N₂), oxygen (O₂), and argon (Ar) gases with pressure variation in the range of (0.05 - 2.5) Torr. Ion density, plasma velocity, pinch temperature, Joule heating, peak current, and minimum pinch radius are also obtained with pressure change for each of the gases. It is found that the line radiation is predominant compared to bremsstrahlung radiation and radiative recombination for each gas. At optimum pressure, the maximum line radiations are found as 3872 J (91% of total emission) at 0.945 Torr N₂, 6202 J (85 % of total emission) at 0.6 Torr O₂ and 29576 J (97 % of total emission) at 0.23 Torr Ar, respectively. The minimum pinch radii (r_min) and consequent ion densities (N_i) of these gases are computed at their corresponding optimum pressures. It is found that the r_min (0.13 cm) of Ar is 10-fold smaller than N₂(1.25 cm) whilst it is 6-fold smaller than O₂(0.82 cm). This smallest minimum pinch radius of Ar, produces the dominating ion density (71 ×10²³ m^-3) compared to N₂(3.34 ×10²³ m^-3) and O₂(4.89 ×10²³ m^-3) gases resulting in the highest line radiation is found for Ar. The sharp dropping of pinch radius of Ar plasma followed by the greatest plasma emission (most line) shows strong evidence of radiative cooling/collapse.

• Supervision