Verification of a hybrid gyrokinetic model using the advanced semi-Lagrange code ssV

TL;DR

This paper presents the verification of a hybrid gyrokinetic model implemented in the ssV code, which combines fully kinetic ions with gyrokinetic electrons, using advanced semi-Lagrangian schemes and benchmark problems to ensure accuracy and stability.

Contribution

The paper introduces a hybrid gyrokinetic model with semi-Lagrangian schemes in ssV, addressing limitations of standard gyrokinetics and validating it through comprehensive benchmarks.

Findings

SLMP5 scheme offers superior accuracy and stability.

The hybrid model effectively captures high-frequency and steep gradient regimes.

The code resolves electromagnetic simulation issues like the Ampere cancellation problem.

Abstract

The super simple Vlasov (ssV) code was developed to study instabilities, turbulence, and reconnection in weakly magnetized plasmas, such as the solar wind in the dissipation range and the edge of fusion plasmas. The ssV code overcomes the limitations of standard gyrokinetic theory by using a hybrid model that incorporates fully kinetic ions and gyrokinetic electrons. This hybrid gyrokinetic model enables accurate modeling in regimes characterized by steep gradients and high-frequency dynamics. To achieve this, ssV implements a set of semi-Lagrangian numerical schemes, including Positive Flux Conservative (PFC), Flux Conservative fifth-order (FCV), FCV with Umeda limiters, and a Semi-Lagrangian Monotonicity-Preserving fifth-order scheme (SLMP5). Benchmark problems such as Landau damping, ion-acoustic waves, ion Bernstein waves, and kinetic Alfven waves were employed to evaluate the schemes. The SLMP5 scheme consistently delivered the best overall accuracy and numerical stability performance. The code also addresses well-known electromagnetic gyrokinetic simulation issues, such as the Ampere cancellation problem, using carefully chosen velocity-space resolutions and accurate integral evaluation.