Speaker
Description
Gyrokinetic and gyrofluid models for magnetised plasmas evolve gyrocenter densities ne and ni of electrons and ions, that are coupled via a polarisation equation which determines the consistent electric potential phi fulfilling quasi-neutrality. Full-f models, based on the full distribution functions f without smallness assumptions of a Bousinesq approximation, use polarisation equations in the form "div [ ni grad phi ] = Q" of generalised Poisson equations. For efficient computation of phi(x) from spatial functions ni and Q(ne,ni), many numerical models impose approximations. We study effects of different common linearisation approximations to the polarisation equation by simulations of fusion plasma edge turbulence with a thermal full-f gyrofluid model and code.
