Optical observations of the plasma motion in a fast plasma focus operating at 50J

Plasma images with 5 ns exposure time were obtained in a very small plasma focus. The plasma focus operates at low energy (160 nF capacitor bank, 65 nH, 25 kV, 50 J). A single frame ICCD camera was used to obtain plasma images in the visible range. The umbrella-like current sheath running over the end of the coaxial electrodes and the pinch after the radial collapse can be clearly observed in the photographs. The velocity of the radial collapse is of the order of 10(5) ms(-1). The observations are similar to the results obtained with devices operating at energies several orders of magnitude higher.