A multi-species collisional operator for full-F global gyrokinetics codes: Numerical aspects and verification with the GYSELA code

A linearized multi-species collision operator valid for arbitrary masses and charges has been developed and implemented in the gyrokinetic code GYSELA (Grandgirard et al., 2016) [1]. This operator has all the required properties: it conserves particles, total momentum and energy, fulfills the Boltzmann H theorem and recovers neoclassical results. This operator takes into account both pitch angle scattering and energy diffusion while operating in the v∥,μ phase space. Derivatives with respect to the magnetic moment are treated using a projection on a set of orthogonal polynomials. The numerical aspects of the implementation are detailed and a set of physical benchmarks allows a verification of the properties of the operator.