Comparative studies of ion emission characteristics in a low energy Plasma Focus operating with different gas fillings

The results of an investigation of ion emission from a low energy Plasma Focus (PF), operating at 20 kV, with 1.8 kJ stored energy, using several different gas fillings, including hydrogen, nitrogen, argon and methane, are presented. Graphite collectors, operating in the bias ion collector mode, are used to estimate the energy spectrum and ion flux along the PF axis, using the time of flight technique. The ion beam signals are time correlated with the emission of soft X-ray pulses from the focus plasma. Characteristic duration of the ion beam pulses is found to be in the 10s to 100 s of nanoseconds. Characteristic ion energy is found to be in the 50 to 500 keV range, depending on the operating gas. Ion beam energy correlations for operation in methane indicate that the dominant charge states in carbon ions are C⁺⁴ and C⁺⁵.