Ion orbit loss current in ASDEX upgrade

The orbit loss current is calculated for the ASDEX Upgrade geometry using the 5D (3D in configuration space and 2D in velocity space) Monte Carlo code ASCOT. The balance between the obtained current and the analytical estimate of the return current shows an L-H transition for the normalized collision frequency as expected from analytic theory. The transition in ASDEX Upgrade, however, occurs at larger values of .