Impact of electric potential and magnetic drift on microtearing modes stability

The stability of a microtearing mode (MTM) as a function of collisionality is investigated by means of a linear reduced model and numerical simulations using the gyrokinetic code GKW. This study is focused on the role of the electric potential and the magnetic drift, which are potential candidates for explaining the destabilization of MTM observed at low collisionality in some recent gyrokinetic simulations. In the simulations, the magnetic drift and electric potential are found to be destabilizing in the presence of a finite collisionality. This destabilizing role is captured in the analytical calculation, which further highlights the requirement for a finite collisionality. (authors)