Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes

Abstract

A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan based on “Cyclone base case parameter set.” We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.

Global kinetic ballooning mode simulations in BOUT++

“…In this paper, the 3+1 gyro-Landau-fluid (GLF) module under BOUT++ framework [21], which is well benchmarked in the cyclone case [22], is used to perform simulations on the linear and nonlinear evolutions of KBM instability and turbulence. The GLF model consists of 7 evolving equations:…”

Sensitivity of kinetic ballooning mode instability to tokamak equilibrium implementations

“…1998) and kinetic ballooning mode (KBM) (Tang, Connor & Hastie 1980; Belli & Candy 2010; Holod & Lin 2013; Tang et al. 2016) are invoked to predict the constraints of the H-mode pedestal (Snyder et al. 2011).…”

“…The H-mode is important for tokamaks since it can improve the plasma confinement to make fusion more economically feasible. The ideal peeling-ballooning mode (Connor et al 1998) and kinetic ballooning mode (KBM) (Tang, Connor & Hastie 1980;Belli & Candy 2010;Tang et al 2016) are invoked to predict the constraints of the H-mode pedestal (Snyder et al 2011). The linear and nonlinear physics of the peeling-ballooning mode have recently been studied intensively with fluid codes, such as the eigenvalue code ELITE (Wilson et al 2002) and initial value code BOUT++ (Dudson et al 2009).…”

Study on filament width of type-I ELM in EAST using VUV imaging system and simulation

“…The radial mode structure of the low-n mode is wider than that of the high-n mode, and this has been addressed in varied references, such as [17,31]. Here, we compare the radial mode structures with the same mode number between these two cases.…”