Abstract
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 code and a test particle tracking post-treatment, which solves the equations of motion of passive gyro-centres embedded in the self-consistent EGAM potential obtained from the simulations. It is found that EGAMs induce the transport of particles, which eventually results in counter-passing particle losses modulated at the EGAM frequency. A detailed analysis of the trajectories of the test gyro-centres is performed and evidence of the interaction between the EGAM island and the region of magnetically trapped particles (trapping cone) is provided. 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 the v ∥ < 0 to the regions v ∥ > 0. Therefore, for the cases analysed in this work, the 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.
| Original language | English |
|---|---|
| Article number | 106030 |
| Journal | Nuclear Fusion |
| Volume | 58 |
| Issue number | 10 |
| DOIs | |
| State | Published - Aug 29 2018 |
Funding
This work has been carried out thanks to the support of the A*MIDEX project (no. ANR-11-IDEX-0001-02) funded by the Investissements d’Avenir French Government program, managed by the French National Research Agency (ANR). This work has also been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under grant agreement no. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. D. dCN acknowledges support from the Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. This work was granted access to the HPC resources of TGCC under the allocation t2016057653 and to the HPC resources of CINES under the allocation A0020507653 made by GENCI (Grand Equipement National de Calcul Intensif). This work has been done within the frame-work of the Nonlinear energetic particle dynamics (NLED) European Enabling Research Project (EUROFUSION AWP15-ER-01/ENEA-03) and within the framework of the Verification and development of new algorithms for gyrokinetic codes European Enabling Research Project (EUROFUSION AWP15-ER-01/IPP-01).
Keywords
- energetic particles
- geodesic acoustic modes
- gyro-kinetic Simulations
- particle transport
- plasma instabilities