Speaker
Description
In this work we report on the implementation and verification of a phase-space resolved energetic particle (EP) transport model [1, 2]. It is based on the Phase Space Zonal Structure transport theory [3, 4, 5] , which extends the conventional transport equations into Phase Space and consistently evolves a (nonlinear) equilibrium referred to as the Zonal State. Its focus is primarily directed toward understanding the meso-scopic character of EPs and its consequences [6] . Compared to the conventional description of thermal radial transport via a one-dimensional radial diffusion equation, the newly developed model is three-dimensional using canonical constants-of-motion (CoM) variables. The model does not assume diffusive processes to be dominant a priori,
instead the EP fluxes are self-consistently calculated and directly evolved in CoM space. A Fokker-Planck collision operator with orbit-averaged numerical coefficients evaluated on the same CoM coordinate grid allows us to treat EP sources and wave-induced transport consis- tently on background transport and EP slowing-down time scales. The code named ATEP-3D is fully embedded in ITER IMAS framework and closely connected to the EP-Stability work- flow [7] and the HAGIS code. As first application, phase space fluxes are determined either in the limit of constant mode amplitudes (kick-limit), or an energy-conserving quasi-linear model. The latter model relies on time-evolving phase space fluxes that are related to the evolution of the fluctuation amplitudes δ B/B (see fig 1). Single and multi-mode cases addressing the transition from isolated to overlapping resonances are discussed. The consequences of finite parallel electric fields due to non-ideal kinetic effects on the diffusion tensor and on the overall EP transport are investigated. Finally, non-linearly evolving beat-driven zonal fields are included using an analytical model [8] for radial mode structure and saturation, leading to non-linear modifications of the phase-space zonal structures and the resulting EP transport.
References
[1] Lauber P, Falessi M.-V., Meng G, Hayward-Schneider T, Popa V A, Zonca F and Schneider M 2024 Nuclear Fusion 64 096010 URL https://dx.doi.org/10.1088/1741-4326/ad6336
[2] Meng G, Lauber P, Lu Z, Bergmann A and Schneider M 2024 Nuclear Fusion http://iopscience.iop.org/article/10.1088/1741-4326/ad5190
[3] Falessi M.-V., and Zonca F 2019 Physics of Plasmas 26022305 https://doi.org/10.1063/1.5063874
[4] Zonca F, Chen L, Falessi M V and Qiu Z 2021 Journal of Physics: Conference Series 1785 012005 https://dx.doi.org/10.1088/1742-6596/1785/1/012005
[5] Falessi M V, Chen L, Qiu Z and Zonca F 2023 New Journal of Physics 25 123035 URL https://dx.doi.org/10.1088/1367-2630/ad127d
[6] Chen L and Zonca F 2016 Rev. Mod. Phys. 88(1) 015008 URL https://link.aps.org/doi/10.1103/RevModPhys.88.015008
[7] Popa V A, Lauber P, Hayward-Schneider T, Schneider M, Hoenen O and Pinches S 2023 Nuclear Fusion 63 126008 URL https://dx.doi.org/10.1088/1741-4326/acf056
[8] Qiu Z,Chen L, and Zonca F 2017 NuclearFusion 57056017 URL https://dx.doi.org/10.1088/1741-4326/aa6413
| Presentation type | Oral |
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