Statistical analysis of disruptions in ASDEX
A database of disruptive discharges in ASDEX has been set up. It contains data for all 33,509 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 characterised by a typical current profile change of about -0.37. It is found that some 50 % of all disruptions have clear precursors lasting for more than 50 ms, these being locked modes or minor disruptions which, in a future machine, might be used to trigger the application of stabilisation 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.
Bibliographic Reference: Article: Nuclear Fusion, Vol. 33 (1993) No. 4, pp. 655-662
Record Number: 199311142 / Last updated on: 1994-11-29
Original language: en
Available languages: en