Author: Debabrata Banerjee
Requested Type: Pre-Selected Invited
Submitted: 2018-03-10 02:02:04
Co-authors: P. Zhu, Charlson C. Kim, the CFETR Physics Team
University of Science and Technology of China
96 Jinzhai Road
Hefei, Anhui 300026
For China Fusion Engineering Test Reactor (CFETR), an efficient and reliable disruption mitigation system (DMS) will be essential. Massive Gas Injection (MGI) of inert gas has been found efficient for triggering the thermal quench (TQ) and current quench (CQ) phases of disruption, and radiating the no-longer confined thermal energy safely inside the machine wall in existing tokamak
experiments. In this work, a resistive single-fluid MHD model is solved in the NIMROD code, and impurity related ionization, recombination and radiation rates are calculated using a 0-D coronal equilibrium model adapted from the KPRAD code. With the inward motion of ionized impurity species, radiation level gradually increases with the edge plasma cooling, and then the excitation of global MHD kink/tearing modes can induce the onset of a rapid TQ phase. The MHD instabilities centered around the q=3 resonant surface are found to trigger the TQ phase in CFETR, whereas in experiments and related simulations on current tokamaks worldwide, the MHD instabilities on the q=2 resonant surface usually lead to the TQ onset. The results of MGI on CFETR will be reported in terms of the time scales of pre-TQ, TQ, impurity mixing and MHD mode activity, efficiency of energy conversion into radiation, and heat loads on the first wall.
This was Supported by the National Magnetic Confinement Fusion Program of China under grant Nos. 2014GB124002 and 2015GB101004, the 100 Talent Program and the President International Fellowship Initiative of the Chinese Academy of Sciences.