18th Technical Meeting on Energetic Particles in Magnetic Confinement Systems

Full-orbit description of energetic particle transport in the presence of ion temperature gradient turbulence

Not scheduled

20m

Oral Multiscale Physics and Instabilities involving Energetic Particles in Burning Plasmas

Speaker

David Zarzoso (CNRS)

Description

Confinement of energetic particles (EP) is crucial to ensure the transfer of energy to the thermal plasma and to achieve self-sustained fusion reactions. Together with EP, turbulence is another major element in the description of a fusion plasma. When both EP and turbulence co-exist, their mutual interplay cannot be neglected. Whereas the impact of EP on turbulence has extensively been analyzed, the effect of turbulence on EP trajectories and transport has been explored in a relatively smaller number of publications, most of them using the gyro-kinetic approach [1-3]. In this presentation, we use a new GPU-accelerated code called TAPAS (for Toroidal Accelerated PArticle Simulator) [4,5] that was developed to study the transport in the presence of turbulence and electromagnetic perturbations. Owing to its efficient parallelization, TAPAS has the capability of solving a large number of full-orbit trajectories (~109) while being coupled to 3D perturbations from external codes. Here we use the perturbation from the gyro-kinetic GYSELA code [6] to study the transport and the losses of EP in the presence of an Ion Temperature Gradient driven turbulence. A parametric study is performed on the energy of particles, highlighting the difference between full-orbit and guiding-center simulations, with and without collisional effects. Numerical evidence is provided on the breakdown of the conservation of the magnetic moment of particles with supra-thermal energy. Contrary to the general belief, it is observed that turbulence-induced transport increases with energy and is associated with a significant increase of perpendicular energy, which is only possible if the magnetic moment changes in time. These results, based on the analysis of the trajectories of particles and their interaction with turbulence, can highlight potential limitations of the gyro-kinetic description of EP transport.

[1] T. Hauff et al Phys. Rev. Lett. 102 (7), 075004 (2009)
[2] W. Zhang et al Phys. Plasmas 17 055902 (2009)
[3] D. C. Pace et al Phys. Plasmas 20 056108 (2013)
[4] D. Zarzoso et al Plasma Phys. Control. Fusion 64 044003 (2022)
[5] H. Betar et al Nucl. Fusion 64 126014 (2024)
[6] V. Grandgirard et al Comp. Phys. Comm. 207 35–68 (2016)