Abstract Details
Abstracts
Author: Ge Wang
Requested Type: Poster
Submitted: 2019-02-22 14:30:57
Co-authors: C.Sovinec
Contact Info:
University of Wisconsin-Madison
1500 Engineering Drive
Madison, WI 53706
United States
Abstract Text:
Plasma disruption poses a serious threat to continuous operation of tokamaks, which cools down the plasma temperature quickly in the thermal quench phase and produces a great amount of runaway electrons in the current quench phase. The post-disruption runaway current profile is observed to be more peaked than the pre-disruption current, and thus it may drive the ideal and resistive MHD instabilities, which in turn may improve or deteriorate the confinement of runaway electrons. Applying the drift-kinetic description with the interaction of the low frequency mode [1], the runaway electrons travel at the speed of light along the magnetic field. They also execute drift orbits from the magnetic surfaces at a much slower drift velocity (but comparable to the Alfv'en speed) due to EXB drift, curvature drift and a drift term due to the changing of the direction of the magnetic field. Moreover, the whistler instability driven by the normal and anomalous cyclotron resonant interactions recently has been discovered to play a important role of scattering the runaway electrons in the quasi-linear limit [2]. Then an additional term in the kinetic equation has to be taken into account of the cyclotron interactions. We are incorporating this reduced runaway electron model in the NIMROD code. The runaway electron density is solved as a new scalar field, and the runaway current is provided to update the fluid velocity in the momentum equation and the perturbed magnetic field in Faraday's law using the NIMROD framework. The predictor and corrector scheme is used to iterate the runaway density at each time step.
1. Hazeltine, R.D. 1973, Plasma Physics, 15, 77
2.Liu, C., Hirvijoki, E., Fu, G.-Y., et al. 2018, Physical Review Letters, 120, 265001
Comments:
1. Computer Simulation of Plasmas
