Energy deposition during disruption simulation experiments in a plasma accelerator

Plasma accelerators are often proposed as test beds for disruption simulation experiments on plasma facing materials for fusion applications. The incident energy fluxes and the discharge duration are of similar order to those expected during disruptions in ITER. In this work the VIKA facility of the D.V. Efremov Institute was used for calorimetric measurements and for material tests. The calorimetric measurements showed that below the threshold for the ablation of material only a small fraction of the total power of the plasma is deposited in the target. Carbon materials which were exposed to energy depositions above the ablation threshold exhibited a nearly proportional increase of the erosion with increasing total power. From these experiments it is concluded that the shielding effect of the material surface from the incident power is mainly due to the formation of a dense cloud of recycled gas in front of the target and to a smaller extent due to the ablation of target material.