Conversion of Magnetic Energy of Runaway Electrons During Disruption Termination

A substantial portion of poloidal magnetic energy stored in the RE beam could dissipate in the first wall (FW) armor due to ohmic dissipation of inductive current. Relatively small part of magnetic energy can also be converted into heat during a direct impact of the RE beam on the FW due to the ohmic dissipation of a return current, induced by penetration of the RE beam into a metal in the skin time scale. The observed increase of temperature at a spot on the JET dump plate upon increasing the RE current can be explained by assuming that 50 % of the RE energy, predominantly magnetic energy, is converted into heat. Calculations of the RE stopping power (SP) onto the ITER FW Be bulk armor predict strong erosion. While the threshold energy for beryllium melting is about 5 MJ/m(2), the RE heat deposition is expected to be almost twice as large. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim