Plasma focus research in the PF-300 device by means of optical diagnostics

Both the forming and decay stages of dense pinch in the PF-300 device /of energy up to 360 kJ/were investigated by means of four-frame shadow photography. A streak camera and standard diagnostics /neutron and electrical measurements/ were applied as well. The characteristic times and velocities in the course of PF phenomenon, the dimensions of plasma sheath and pinch were also measured. The high neutron yield was connected with the thin and homogenous plasma sheath, minimum radius of the pinch /about 2.5mm/ and short duration of the expansion and decay of one. It was also observed a MHD instability of the plasma sheath during its collapse in form of two distortions. Theoretical investigations confirm such instability may appear. In some cases an anomalous structure of the plasma sheath was observed, when it was delaminated. One may conclude it was due to non-classical development of the MHD instability. Besides, a very low neutron yield was registered in such discharges