Numerical validation of the electromagnetic gyrokinetic code NEMORB on global axisymmetric modes

This is a report about a comparison of collisionless simulations on global modes (i.e. low poloidal mode number) with gyrokinetic code NEMORB against analytical theory and other codes. Only axisymmetric modes, i.e. with toroidal mode number n=0, are considered, and flat equilibrium profiles. Benchmarks are performed for GAMs against local analytical theory. In the presence of energetic ions, local benchmarks of NEMORB are performed against semilagrangian gyrokinetic code GYSELA. The models of adiabatic vs trapped-kinetic- vs fully-kinetic-electrons and of electrostatic vs electromagnetic at very low beta are compared. Scalings of Alfven modes are also presented.