NUMERICAL-SIMULATION OF VAPOR SHIELDING AND RANGE SHORTENING FOR IONS IMPINGING ON A DIVERTOR DURING PLASMA DISRUPTIONS

The behavior of divertor materials under the high heat load during a plasma disruption, a key problem in tokamak fusion technology, is studied at several laboratories under simulated plasma disruption conditions. Numerical modelling of the complex processes taking place at the divertor during a plasma disruption event was started recently at Kemforschungszentrum Karlsruhe. The aim of these activities is to determine the erosion rate of divertor material under different heat loads, to quantify the vapor shield effect and to give insight in the mechanisms of the beam target interaction. The simulation studies are performed with the Karlsruhe target code KATACO. This is a 1D plasma hydrodynamic code including beam energy deposition and multigroup radiation transport. First results for 10 and 100 keV proton beams with a power density of 5 and 50 MW/cm2 respectively at a pulse duration of 100 mus show, that an equilibrium state at a plasma temperature of a few electron volt is reached shortly after the beginning of the disruption. A substantial part of the incoming energy is radiated back into the cavity.