CORONAL PLASMA BEHAVIOR OF THE Z-PINCH PRODUCED FROM CARBON AND CRYOGENIC DEUTERIUM FIBERS

A series of fiber pinch experiments has been carried out on the MAGPIE (mega-ampere generator for plasma implosion experiments) generator (1 .8 MA, 150 ns) [Mithell et al, Rev. Sci. Instrum. 67, 1533 (1996)] to study the temporal evolution of the coronal plasma. Analysis of schlie ren photographs, axial streak images and gated x-ray photographs gives the radial and axial motion of the coronal plasma. The influence of a current pulse (prepulse) of 30 kA applied 200 ns before the main disc harge was also studied. Radial expansion velocities of 5.5 x 10(6) cm/ s for carbon fiber shots without prepulse and 3.6 X 10(6) cm/s for car bon fibers with prepulse were measured. Axial wavelengths (lambda(z)) of dominant instabilities in the corona were between 0.05 and 0.2 cm c orresponding to ka similar to 10-20. Comparison of the results obtaine d with carbon fibers with and without current prepulse and cryogenic d euterium fibers are presented. (C) 1998 American Institute of Physics. [S1070-664X(95)00409-1]