Particle transport due to energetic-particle-driven geodesic acoustic modes

David Zarzoso (1) , D Del-Castillo-Negrete (2) , D F Escande (1) , Y. Sarazin (3) , X. Garbet (3) , V. Grandgirard (3) , C. Passeron (3) , G. Latu (3) , S. Benkadda (1)

1 PIIM - Physique des interactions ioniques et moléculaires
2 ORNL - Oak Ridge National Laboratory [Oak Ridge]
3 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique

The transport of particles in the presence of energetic geodesic acoustic modes (EGAMs) is analysed by means of full-f global gyro-kinetic simulations using the multi-species version of the Gysela code and a test-particle tracking post-treatment that solves the equations of motion of passive gyro-centres embedded in the self-consistent EGAM potential obtained from Gysela simulations. It is found that EGAMs induce transport of particles that eventually results in counter-passing particle losses modulated at the EGAM frequency. A detailed analysis of the trajectories of test gyro-centres is performed and evidences of the interaction between the EGAM island and the region of magnetically trapped particles (trapping cone) is observed. In particular, we report for the first time on the complex interaction between the stochastic separatrix of the EGAM island and the X-point of the trapping cone, creating a channel for the transport of particles from v < 0 to v > 0 regions. Therefore, for the cases analysed in this work, co-injection of energetic particles might lead to a significant reduction of EGAM-induced losses. This result opens up new perspectives for further studies of the selection of energetic particle injection in order to minimize the losses due to EGAMs. Particle transport due to energetic-particle-driven geodesic acoustic modes 2

Domaines: Physique des plasmas [physics.plasm-ph]

David Zarzoso, D Del-Castillo-Negrete, D F Escande, Y. Sarazin, X. Garbet, et al.. Particle transport due to energetic-particle-driven geodesic acoustic modes. Nuclear Fusion, 2018, 58 (10), ⟨10.1088/1741-4326/aad785⟩. ⟨hal-01899139⟩