Implementation of field-aligned coordinates in a semi-Lagrangian gyrokinetic code for tokamak turbulence simulation  

作　　者：Lei YE Xiaotao XIAO Yingfeng XU Zongliang DAI Shaojie WANG 叶磊;肖小涛;徐颖峰;戴宗良;王少杰(Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031, People's Republic of China;Department of Modern Physics, University of Science and Technology of China, Hefei 230026, People's Republic of China)

机构地区：[1]Institute of Plasma Physics,Chinese Academy of Science,Hefei 230031,People＇s Republic of China [2]Department of Moderm Physics,University of Science and Technology of China,Hefei 230026,People＇s Republic of China

出　　处：《Plasma Science and Technology》2018年第7期50-63,共14页等离子体科学和技术（英文版）

基　　金：supported by National Natural Science Foundation of China under Grant Nos.11505240,11375196 and 11405174;the National ITER program of China under Contract No.2014GB113000

摘　　要：Field-aligned coordinates have been implemented in the gyrokinetic semi-Lagrangian code NLT, Ye et al （2016 J. Comput. Phys. 316 180）, to improve the computational efficiency for the numerical simulations of tokamak turbulence and transport. 4D B-spline interpolation in field- aligned coordinates is applied to solve the gyrokinetic Vlasov equation. A fast iterative algorithm is proposed for efficiently solving the quasi-neutrality equation. A pseudo transform method is used for the numerical integration of the gyro-average operator for perturbations with a high toroidal mode number. The new method is shown to result in an improved code performance for reaching a given accuracy. Some numerical tests are presented to illustrate the new methods.Field-aligned coordinates have been implemented in the gyrokinetic semi-Lagrangian code NLT, Ye et al （2016 J. Comput. Phys. 316 180）, to improve the computational efficiency for the numerical simulations of tokamak turbulence and transport. 4D B-spline interpolation in field- aligned coordinates is applied to solve the gyrokinetic Vlasov equation. A fast iterative algorithm is proposed for efficiently solving the quasi-neutrality equation. A pseudo transform method is used for the numerical integration of the gyro-average operator for perturbations with a high toroidal mode number. The new method is shown to result in an improved code performance for reaching a given accuracy. Some numerical tests are presented to illustrate the new methods.

关 键 词：gyrokinetic simulation field-aligned coordinates quasi-neutrality equation iterativealgorithm gyro-average operator 

分 类 号：O357.5[理学—流体力学] TL631.24[理学—力学]