Speaker
Ekaterina Matveeva
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1056.pdf
Statistical analysis of disruptions at COMPASS
E. Matveeva1,2, J. Havlicek1, A. Havránek1, O. Hronova1, V. Weinzettl1, R. Pánek1
1
Institute of Plasma Physics of the CAS, Prague, Czech Republic
2
Charles University, Faculty of Mathematics and Physics, Prague, Czech Republic
Understanding of disruptions plays an important role for design of the future fusion devices as
they induce large thermal and mechanical loads on a vacuum vessel. Statistical analysis of the
set of discharges during the period of August – December 2017 was performed in order to
improve our knowledge of disruptions on COMPASS. About 25 % of COMPASS discharges
are disruptive which provides a good opportunity of disruption studies. Disruption rate
dependence on the operational limits (Greenwald limit, plasma current limit), auxiliary power
and plasma current is investigated.
Asymmetrical disruptions are of particular concern because they induce additional currents and,
therefore, forces in the vacuum vessel. In addition to this they might lead to a resonant
amplification of the forces. The COMPASS tokamak is equipped with magnetic diagnostics,
which allow measurements of the plasma current at five toroidal locations. This enables detailed
investigation of asymmetrical disruptions (almost 80 % of disruptive discharges on
COMPASS). It is observed that a plasma current asymmetry is detected for upward, downward
and inward disruptions. However, rotation of asymmetry is never found during the upward
disruptions. Asymmetrical disruptions parameters such as magnitude, frequency, number of
rotations and duration of asymmetry are analysed within the contribution.
