Benchmark of multi-phase method for the computation of fast ion distributions in a tokamak plasma in the presence of low-amplitude resonant MHD activity
Benchmark of multi-phase method for the computation of fast ion distributions in a tokamak plasma in the presence of low-amplitude resonant MHD activity
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DOI：
10.1016/j.cpc.2017.07.022
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发表时间：
2017-11-01
影响因子：
6.3
通讯作者：
Todo, Y.
中科院分区：
文献类型：
--
作者：
Bierwage, A.;Todo, Y.
采用多相方法模拟了束流驱动JT-60 U托卡马克等离子体中快离子在共振磁流体动力学（MHD）模活动下的输运过程，其中经典蒙特-卡罗模拟（无MHD）间隔为4 ms，混合模拟（有MHD）间隔为1 ms。将多相模拟结果与连续混合模拟获得的结果进行比较，连续混合模拟最近针对实验数据进行了验证（Bierwage等人，2017年）。它示出的多相方法，尽管造成显着的过冲的MHD波动幅度，准确地再现的频率和位置的主导共振模式，以及快速离子的空间分布和速度分布，而消耗的计算时间的一小部分所需的连续混合模拟。本文件是有限的低振幅波动组成的几个长波长的模式，相互作用很弱。这项基准研究的成功为将多相方法应用于模拟突发大振幅事件（ALE）铺平了道路，这些事件在相同的JT-60 U实验中出现，但时间间隔更长。快速离子传输的减少模型的建设可能产生的影响进行了讨论。(C)2017 Elsevier B. V.版权所有。
The transport of fast ions in a beam-driven JT-60U tokamak plasma subject to resonant magnetohydrodynamic (MHD) mode activity is simulated using the so-called multi-phase method, where 4 ms intervals of classical Monte-Carlo simulations (without MHD) are interlaced with 1 ms intervals of hybrid simulations (with MHD). The multi-phase simulation results are compared to results obtained with continuous hybrid simulations, which were recently validated against experimental data (Bierwage et al., 2017). It is shown that the multi-phase method, in spite of causing significant overshoots in the MHD fluctuation amplitudes, accurately reproduces the frequencies and positions of the dominant resonant modes, as well as the spatial profile and velocity distribution of the fast ions, while consuming only a fraction of the computation time required by the continuous hybrid simulation. The present paper is limited to low amplitude fluctuations consisting of a few long-wavelength modes that interact only weakly with each other. The success of this benchmark study paves the way for applying the multi-phase method to the simulation of Abrupt Large-amplitude Events (ALE), which were seen in the same JT-60U experiments but at larger time intervals. Possible implications for the construction of reduced models for fast ion transport are discussed. (C) 2017 Elsevier B.V. All rights reserved.