Investigation of Shock Compression in Toroidal Geometry in the High Voltage Belt Pinch

摘要

Fast magnetic compression in investigated in the High Voltage Belt Pinch at two initial densities nsub(eo) = 3 x 10 exp 13 cm exp -3 and nsub(eo) = 7 x 10 exp 13 cm exp -3 . At the lower density the electrons are heated to 3 keV in the piston region, the ions trapped in the piston obtaining an energy of 0.7 keV. A third of the ions are reflected off the piston attaining an energy of 2.5 keV. At the higher initial density a central beta = 1 plasma in formed. Electrons are heated to 1 keV in the sheath, the piston ions obtaining an energy of 0.4 keV. The degree of ion reflection is 60%. Ion acoustic turbulence in both cases dominates the implosion phase and gives rise to the anomalous field diffusion and electron heating observed. Steep electron density and temperature gradients decisively enhance the effective drift velocity for wave growth. The experimental results are compared with numerical calculations using a hybrid code which includes anomalous transport. Scaling studies with the hybrid code in a wider density range show in agreement with the experiment increasing efficiency of shock heating for higher initial densities due to increasing ion reflection. (Atomindex citation 09:350944)