A database of disruptive discharges in ASDEX has been set up. It contains data for all 33509 ASDEX shots. The statistics of disruptions on ASDEX are evaluated for all these shots; in a more detailed analysis, different operation regimes are regarded separately. It is found that after eliminating the most dangerous operation regimes, 17 of all shots end with a disruption. There is an indication that a well established discharge may be repeated several times at a lower disruption rate (less than 5 for ELMy H modes). The statistics of the flux expulsion at a disruption indicate that a major disruption is characterized by a typical current profile change ofli0.37. It is found that about 50 of all disruptions have clear precursors lasting for more than 50 ms, namely locked modes or minor disruptions which in a future machine, might be used to trigger the application of stabilization or shutdown schemes. From the statistics of the radial and vertical displacements during a disruption the average forces on the vacuum vessel are calculated which, in the case of ASDEX, are not critical, but may be of concern for future large devices
展开▼
