Soft X-ray emission from preionized He plasma in a 3.3 kJ Mather type plasma focus device

Soft X-ray emission from He plasma in a 3.3 kJ plasma focus system is investigated without and with preionization by a particles. Silicon PIN diodes and a multi-pinhole camera with absorption filters are employed for time-resolved and time-integrated X-ray analyzes, respectively. X-ray emission in 4 pi geometry is measured as a function of He gas filling pressures. The highest soft X-ray yield, of 0.25 +/- 0.01 J, is obtained at a filling pressure of 125 Pa without preionization, which increases to 0.50 +/- 0.02 J with preionization at a filling pressure of 150 Pa. The total X-ray yield without preionization, 1.50 +/- 0.07 J, is observed at a filling pressure of 125 Pa and this is enhanced to 2.44 +/- 0.11 J with preionization at a filling pressure of 150 Pa. The preionization makes the focus filament symmetric and enhances its volume.