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Resonant interaction between runaway electrons and the toroidal magnetic field ripple in TCV

Author
Abstract

This work explains the anomalously high runaway electron (RE) pitch angles inferred in the flat-top of dedicated Tokamak à Configuration Variable (TCV) experiments. Kinetic modelling shows that the resonant interaction between the gyromotion of the electrons and the toroidal magnetic field ripple will give rise to strong pitch angle scattering in TCV. The resulting increase in synchrotron radiation power losses acts as a RE energy barrier. These observations are tested experimentally by a magnetic field ramp-down, which gradually reduces the resonant parallel momentum at which the REs interact with the ripple. Resulting changes in synchrotron emission geometry and intensity are observed using three multi-spectral camera imaging systems, viewing the RE beam at distinct spatial angles in multiple wavelength ranges. Experimental reconstructions of the RE distribution in momentum- and real-space are consistent with kinetic model predictions.

Year of Publication
2024
Journal
Nuclear Fusion
Volume
64
Issue
1
Number of Pages
016021
DOI
10.1088/1741-4326/ad0dd7
PId
2c0ca3979ed7610a179c2b8542124937
Alternate Journal
Nucl. Fusion
Label
OA
Journal Article
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