A hybrid gyrokinetic ion and isothermal electron fluid code for astrophysical plasma

JOURNAL OF COMPUTATIONAL PHYSICS

卷:360

Article

Kawazura, Y.¹  Barnes, M.^1,2 

[1] Univ Oxford, Rudolf Peierls Ctr Theoret Phys, Oxford OX1 3NP, England

[2] Culham Sci Ctr, Culham Ctr Fus Energy, Abingdon OX14 3DB, Oxon, England

关键词: Gyrokinetics;    Isothermal electron fluid;    Kinetic-fluid hybrid;   

DOI  :  10.1016/j.jcp.2018.01.026

来源: Elsevier

【 摘 要 】

This paper describes a new code for simulating astrophysical plasmas that solves a hybrid model composed of gyrokinetic ions (GKI) and an isothermal electron fluid (ITEF) Schekochihin et al. (2009) [9]. This model captures ion kinetic effects that are important near the ion gyro-radius scale while electron kinetic effects are ordered out by an electron-ion mass ratio expansion. The code is developed by incorporating the ITEF approximation into AstroGK, an Eulerian delta f gyrokinetics code specialized to a slab geometry Numata et al. (2010) [41]. The new code treats the linear terms in the ITEF equations implicitly while the nonlinear terms are treated explicitly. We show linear and nonlinear benchmark tests to prove the validity and applicability of the simulation code. Since the fast electron timescale is eliminated by the mass ratio expansion, the Courant-Friedrichs-Lewy condition is much less restrictive than in full gyrokinetic codes; the present hybrid code runs similar to 2 root m(i)/m(e) similar to 100 times faster than AstroGK with a single ion species and kinetic electrons where m(i)/m(e) is the ion-electron mass ratio. The improvement of the computational time makes it feasible to execute ion scale gyrokinetic simulations with a high velocity space resolution and to run multiple simulations to determine the dependence of turbulent dynamics on parameters such as electron-ion temperature ratio and plasma beta. (c) 2018 Elsevier Inc. All rights reserved.

【 授权许可】

Free