Studies of plasma dynamics in a small plasma focus operating in hydrogen-argon mixtures

We report on experimental observations in PFP-I, a small 3.8 kJ plasma focu s, which is operated in Hydrogen-Argon mixtures to investigate the effect o f parameter modifications on the overall performance of the device. An exte nsive array of diagnostics is been used, which includes voltage and current probes in the external circuit, a novel small magnetic probes array locate d along the cathode rods, filtered PIN diodes located side and end on, and filtered multi-pinhole and slit-wire X-ray camera. Extended operating range from below 0.2 Torr upwards has been achieved. Hot spot formation has been investigated as a function of H-2-Ar mixing ratio. Hot spot sizes around 1 50 mu m in the soft X-ray region, have been inferred from the slit-wire mea surements. Pin-hole time integrated X-ray pictures and time resolved PIN di ode measurements have been used to determine characteristic hot-spot temper atures in the 350 to 450 eV range.