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DOI码：10.1063/1.5012767

发表刊物：Physics of Plasmas

摘要：Recently, the validity of the guiding-center approach to model relativistic runaway electrons in tokamaks has been challenged by full-orbit simulations that demonstrate the breakdown of the standard magnetic moment conservation. In this paper, we derive a new expression for the magnetic moment of relativistic runaway electrons with , which is conserved significantly better than the standard one. The new result includes one of the second-order corrections in the standard guiding-center theory which, in case of runaway electrons with , can peculiarly be of the same order as the lowest-order term. The better conservation of the new magnetic moment also explains the collisionless pitch-angle-scattering effect observed in full-orbit simulations since it allows momentum transfer between the perpendicular and parallel directions when the runaway electron is accelerated by an electric field. While the derivation of the second-order correction to the magnetic moment in general case would require the full extent of the relativistic second-order guiding-center theory, we exploit the Lie-perturbation method at the limit which simplifies the computations significantly. Consequently, we present the corresponding guiding-center equations applicable to runaway electrons.

合写作者：Ruili Zhang,Yulei Wang,Yang He,Jianyuan Xiao,Jian Liu,Hong Qin,Yifa Tang

论文类型：期刊论文

学科门类：理学

卷号：25

期号：2

页面范围：022117

是否译文：否

发表时间：2018-02-16

收录刊物：SCI

发布期刊链接：https://iopscience.iop.org/article/10.1088/1741-4326/aad2a5