Studies of Runaway Electron Damage on Plasma Facing Components

Four detection probes were designed with the PTA code package and fabricated to study energy deposition, temperature rise, and damage to plasma facing components from runaway electrons in the Advanced Toroidal Facility, Oak Ridge National Laboratory. The PTA code package is a unique application of PATRAN, the Integrated TIGER Series, and ABAQUS for modeling high energy electron impact on magnetic fusion components and materials. Two of the probes were made of stainless steel, one of graphite, and one of molybdenum. They were inserted one at a time on the magnetic axis of ATF during field ramps. Each probe had two thermocouples to measure temperature increases. One of the stainless steel probes had activation foils to detect photonuclear reactions. Analysis of the experiment concluded that runaways on the order of 10 MeV exist in ATF. Damage to the materials was in the form of melting and ablation. The graphite probe survived with less damage than the other probes.