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 of a scintillator based fast ion detector mounted on the low field side mid plane manipulator, together with a code package [1] simulating particle trajectories from their birth places in the plasma out to the detector. Classical collisions as well as the effect of core and edge MHD activity and the toroidal magnetic field ripple on the fast ions are taken into account. In addition to these ion losses from the core, containing the desired physics information, ions generated in the edge regionmay hit the detector essentially without plasma interaction and hence with full injection energy (’prompt’ or ’first orbit’ losses). In experiment, these can be used for detector calibration.