April 15-17

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Abstracts

Author: Yuri V. Petrov
Requested Type: Poster
Submitted: 2019-02-28 19:44:45

Co-authors: R.W. Harvey

Contact Info:
CompX
Box 2672
Del Mar, CA   92014
USA

Abstract Text:
The time-dependent, bounce-average, finite-difference, full-radius Fokker-Planck code CQL3D[1] is applied for modeling of runaway electrons (RE), driven by the large toroidal electric field induced by the thermal quench. The code includes a non-linear relativistic collision operator, an inherent evolution of prompt “hot-tail” REs, a “knock-on” source produced by large-angle collisions of initial high energy electrons, and Dreicer “drizzle” RE evolution. Also it models electron radial transport due to stochastic magnetic field, and energy loss due to synchrotron radiation. The thermal quench is simulated with time-dependent temperature, density and effective charge profiles of background electrons and ions, based on KPRAD simulation of a DIII-D pellet injection experiment[2]. Different from the prior study[3], which was performed on a single flux surface with a constant-in-time total current density, now the CQL3D code evolves self-consistently the Ampere-Faraday equations for the time-dependent toroidal electric field and current[4]. The solution for the distribution function of electrons is obtained over the whole plasma radius. Importantly, diffusive radial transport of electrons is added into consideration. Due to these factors, the runaway current is reduced comparing to the prior study, but the basic mechanism of “hot-tail runaways”[3] still remains a dominant contribution at early times after the temperature drop.
[1] R.W.Harvey and M.McCoy,"The CQL3D Fokker Planck Code", www.compxco.com/cql3d
[2] D.G.Whyte, T.C.Jernigan, D.A.Humphreys, et al., J.Nucl.Mater. 313-316, 1239 (2003)
[3] R.W.Harvey, V.S.Chang, S.C.Chiu, T.E.Evans, M.N.Rosenbluth, and D.G.Whyte, Phys.Plasmas 7, 4590 (2000)
[4] R.W.Harvey, Yu.V.Petrov, C.C.Kim, C.B.Forest, L.L.Lao, P.B.Parks, 27th IAEA Fus.En.Conf.(2018,Gandhinagar,India), TH-P8-18; submitted to Nucl.Fus.
Work is supported by USDOE grant DE-FG02-ER54744.

Comments:
Computer Simulation of Plasmas