Local Gyrokinetic Vlasov Simulations with Realistic Tokamak MHD Equilibria

Abstract

A local gyrokinetic Vlasov simulation code GKV is extended to incorporate realistic tokamak equilibria including up-down asymmetry, which are produced by a free-boundary 2D Grad-Shafranov equation solver MEUDAS. By using a newly developed interface code IGS, two dimensional rectangular equilibrium data from MEUDAS is converted to straight-field-line flux coordinates such as Hamada, Boozer, and axisymmetric coordinates, which are useful for gyrokinetic micro-instability and turbulent transport analyses. The developed codes have been verified by a cross-code benchmark test using Cyclone-base-case like MHD equilibrium, where good agreement in the dispersion relation of ion temperature gradient (ITG) driven mode has been confirmed. The extended GKV is applied to two types of shaped plasmas expected in JT-60SA tokamak devices, i.e., ITER-like and highly-shaped plasmas, and ITG-mode stability and residual zonal-flow level are investigated. Through the detailed comparisons, more favorable stability properties against the ITG mode are revealed for the highly-shaped case, where the lower ITG-mode growth rate and higher residual zonal-flow levels compared to the ITER-like case are identified.

Impact of Geodesic Curvature on Zonal Flow Generation in Magnetically Conned Plasmas

“…More detailed expressions are available in e.g., Refs. [11] and [12]. The local fluxtube gyrokinetic simulations of the linear zonal-flow response and the ITG-driven turbulence have been carried out for the several magnetic configurations, i.e., Large Helical Device (LHD), NCSX-like [13], and the axisymmetric cases, where the adiabatic electron response is assumed.…”

Flux tube train model for local turbulence simulation of toroidal plasmas

“…5 The new model is also implemented with the GKV code extended for a generalized toroidal geometry. 6,7 Gyrokinetic simulations of the toroidal ion temperature gradient (ITG) turbulence 8 are carried out for different poloidal periodicity (N h ) or number of flux tubes (N t ). A large-aspect-ratio tokamak with concentric circular flux surfaces (with c h ¼ 1) is employed for solving the gyrokinetic equations for perturbed ion distribution function with the adiabatic electron response model.…”

“…The periodic boundary condition for the poloidal angle h with q and f fixed is A½xðqÞ; yðh; fÞ; zðhÞ ¼ A½xðqÞ; yðh þ 2p; fÞ; zðh þ 2pÞ; (7) which leads to the boundary condition for the Fourier coefficients represented in the (x, y, z) coordinateŝ…”

Benchmark of Electromagnetic Gyrokinetic Codes in High Performance Fusion Plasma

“…To construct flux coordinates from the MHD equilibrium data (EQDSK format), GKV uses the interface code IGS [9], which provides Hamada, Boozer, or Axisymmetric type flux coordinates. In this benchmark the axisymmetric coordinates are employed, since it coincides with the coordinates employed in GENE (via the TRACER interface [14]).…”