Asymmetric wall force reduction in ITER and JET including Runaway Electrons

It has been shown that a fast current quench (CQ) in JET [1] and ITER [2] AVDE disruptions greatly reduces the asymmetric wall force. This was shown in simulations with the M3D 3D MHD code [3] and in JET experiments [4] in which the current was quenched with massive gas injection (MGI). If the current quench (CQ) time is less than the resistive wall penetration time the asymmetric wall force is reduced. A fast CQ may cause production of runaway electrons (REs), which tend to have a long quench time. JET data shows that they produce a small asymmetric wall force. Simulations using a modified version of M3D with a fluid RE model [5] show a small asymmetric wall force, even when the runaways are in a regime with CQ time much longer than the wall time. Evidently the REs cause stabilization of MHD activity. Details of the simulations of REs in ITER and JET will be reported.

[1] H. Strauss, E. Joffrin, V. Riccardo, teal, Phys. Plasmas 24, 102512 (2017).

[2] H. Strauss, Physics of Plasmas 25, 020702 (2018).

[3] W. Park, E. Belova, G. Y. Fu, etal, Phys. Plasmas 6, 1796 (1999).

[4] S. Jachmich, P. Drewelow, etal, 43rd EPS Conf. Plasma Physics (2016)

[5] Huishan Cai and Guoyong Fu, Nucl. Fusion 55, 022001 (2015).