PLASMA GUN EXPERIMENTS AND MODELING OF DISRUPTIONS

Potentially high erosion due to ablation from plasma disruptions looms as a nemesis for advanced fusion devices such as ITER. Under some conditions, it is believed that the material ablated during a disruption forms a ''vapor shield'' that mitigates subsequent ablation. This paper presents new experimental data that identifies an absorption surface in the ablating plasma that is above the irradiated armor surface. We also present a summary of progress in modeling using a 1-D Lagrangian hydrodynamics code. Experimental erosion data will be reviewed from the PLADIS facility, a plasma gun at the University of New Mexico on several materials, including Be, tungsten, copper, graphites. Profile measurements of the crater topology showed the eroded Be surface to be much rougher than that of carbon and to demonstrate erosion rates that were almost factors of four greater than graphite. Plasma guns at the D.V. Efremov Scientific Research Institute and at TRINITI, both in the Russian Federation, are being utilized to confirm spectroscopic vapor shield data.