Measurements of neutral gas fluxes under different plasma and divertor regimes in ASDEX Upgrade

Induced tungsten melting events in the divertor of ASDEX Upgrade and their influence on plasma performance

Tungsten rods of 1×1×3mm were exposed at the outer divertor plate of ASDEX Upgrade using a manipulator system. Controlled melting of the W rod in H-mode discharges was induced by moving the outer strike point towards the W-rod position. Visible light emission of ejected W droplets was recorded by fast camera systems. The resulting increase of tungsten concentration in the confined plasma was co...

Fast-ion D-alpha measurements at ASDEX Upgrade

Pedestal Studies at ASDEX Upgrade

The ASDEX Upgrade suite of edge pedestal diagnostics has been significantly improved. A new edge ion temperature and toroidal velocity diagnostic as well as a novel diagnostic for radial electric fields (Er) have been added. The application of integrated data analysis in a probabilistic framework contributes substantially to the quality of Er and electron density profiles. The equilibrium recon...

Fast Ion Loss Diagnostic in ASDEX Upgrade

The confinement of fast particles is of crucial importance for next step fusion devices like ITER. Since fast ion losses might reduce the core heating and, in addition, cause untolerable first wall load, it is important to understand and possibly avoid them. Here, an integrated approach is presented for the analysis of neutral beam injection related fast ion losses in ASDEX Upgrade. It consists...

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 ν∗i ≈ 1 as expected from analytic theory. The transition in ASDEX Upgrade, however, o...