Observation of strongly localized fast particles ripple losses in Tore Supra
During long pulse experiments with LHCD in Tore-Supra, strongly localised hot spots are observed inside each vertical port on the electron drift side far below the last closed magnetic surface. This feature is particularly strong during low density operation. A thermal load of 100 W/cm2 localised on a few cm2 is deduced from the observation with a camera. An accurate description of these unexpected phenomena can be deduced from a model based on the collisionless interaction of trapped suprathermal electrons with the toroidal ripple perturbation. This strong focussing effect explains the formation of important local thermal loads, although the trapped electrons carry only a negligible fraction of the total injected power. Guiding centre trajectory computations, that take into account the exact magnetic field topology and edge geometry, confirm this model precisely. This work confirms that the orbit theory of ripple trapping is adequate to predict accurately the first wall thermal load inhomogeneities due to ripple losses in a tokamak.
Bibliographic Reference: Paper presented: 18th European Conference of the EPS-Plasma Physics Division, Berlin (DE), June 3-7, 1991
Availability: Text not available
Record Number: 199110386 / Last updated on: 1994-12-02
Original language: en
Available languages: en