Comment on 'Numerical modeling of tokamak breakdown phase driven by pure Ohmic heating under ideal conditions'

Nuclear Fushion

article

Min-Gu Yoo¹  Yong-Su Na² 

[1] Plasma Physics Laboratory, Princeton University, PO Box 451, Princeton;Department of Nuclear Engineering, Seoul National University

关键词: tokamak;    electrical gas breakdown;    direct-implicit scheme;    particle simulation;   

DOI  :  10.1088/1741-4326/ab265a

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

In this comment, we point out possible critical numerical flaws of recent particle simulation studies (Jianget al2016Nucl. Fusion56126017; Penget al2018Nucl. Fusion58026007) on the electrical gas breakdown in a simple one-dimensional periodic slab geometry. We show that their observations on the effects of the ambipolar electric fields during the breakdown, such as the sudden reversal of the ion flow direction, could not be real physical phenomena but result from numerical artifacts violating the momentum conservation law. We show that an incomplete implementation of the direct-implicit scheme can cause the artificial electric fields and plasma transports resulting in fallacies in simulation results. We also discuss that their simple plasma model without considering poloidal magnetic fields seriously mislead the physical mechanism of the electrical gas breakdown because it cannot reflect important dominant plasma dynamics in the poloidal plane (Yooet al2018Nat. Commun .93523).

【 授权许可】

Unknown