Role of Shafranov shift, zonal structures on the behavior of TAEs, AAEs and microinstabilities in the presence of energetic particles

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Main Authors: Rofman, B., Di Giannatale, G., Mishchenko, A., Lanti, E., Bottino, A., Hayward-Schneider, T., Sama, J. N., Biancalani, A., McMillan, B. F., Brunner, S., Villard, L.
Format: Preprint
Published: 2026
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author Rofman, B.
Di Giannatale, G.
Mishchenko, A.
Lanti, E.
Bottino, A.
Hayward-Schneider, T.
Sama, J. N.
Biancalani, A.
McMillan, B. F.
Brunner, S.
Villard, L.
author_facet Rofman, B.
Di Giannatale, G.
Mishchenko, A.
Lanti, E.
Bottino, A.
Hayward-Schneider, T.
Sama, J. N.
Biancalani, A.
McMillan, B. F.
Brunner, S.
Villard, L.
contents In future nuclear fusion reactors, even a small fraction of fusion-born energetic particles (EP) about 100 times hotter than the thermal bulk species, contributes substantially to the kinetic pressure and therefore affect the MHD equilibrium, mainly via the Shafranov shift. In this work, we perform first-principles numerical simulations using the gyrokinetic, electromagnetic, global code ORB5 to study the effect of a self-consistent finite $β$ equilibrium on the arising Alfvén Eigenmodes (destabilized by EPs), Ion Temperature Gradient (ITG), and Kinetic Ballooning Modes (KBM) microturbulence (destabilized by thermal species). Linearly, we explore the complex interplay between EP fraction, bulk gradients and a self-consistent Shafranov shift on the plasma stability. We choose single toroidal mode numbers to represent the system's instabilities and study the characteristic nonlinear evolutions of TAEs, KBMs and ITGs separately and including the axisymmetric field response to each mode separately. This study focuses on the impact of Shafranov shift equilibrium consistency, as well as the self-generated zonal ${E \times B}$ flows, the saturation levels and resulting heat and particle fluxes. In the ITG cases including the $n=0$ perturbations reduces turbulent fluxes, as expected, however, for the TAE cases including the $n=0$ perturbations is shown to enhance the fluxes. We show for the first time that Axisymmetric Alfvén Eigenmodes (AAEs) play a role in this mechanism.
format Preprint
id arxiv_https___arxiv_org_abs_2601_07652
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Role of Shafranov shift, zonal structures on the behavior of TAEs, AAEs and microinstabilities in the presence of energetic particles
Rofman, B.
Di Giannatale, G.
Mishchenko, A.
Lanti, E.
Bottino, A.
Hayward-Schneider, T.
Sama, J. N.
Biancalani, A.
McMillan, B. F.
Brunner, S.
Villard, L.
Plasma Physics
In future nuclear fusion reactors, even a small fraction of fusion-born energetic particles (EP) about 100 times hotter than the thermal bulk species, contributes substantially to the kinetic pressure and therefore affect the MHD equilibrium, mainly via the Shafranov shift. In this work, we perform first-principles numerical simulations using the gyrokinetic, electromagnetic, global code ORB5 to study the effect of a self-consistent finite $β$ equilibrium on the arising Alfvén Eigenmodes (destabilized by EPs), Ion Temperature Gradient (ITG), and Kinetic Ballooning Modes (KBM) microturbulence (destabilized by thermal species). Linearly, we explore the complex interplay between EP fraction, bulk gradients and a self-consistent Shafranov shift on the plasma stability. We choose single toroidal mode numbers to represent the system's instabilities and study the characteristic nonlinear evolutions of TAEs, KBMs and ITGs separately and including the axisymmetric field response to each mode separately. This study focuses on the impact of Shafranov shift equilibrium consistency, as well as the self-generated zonal ${E \times B}$ flows, the saturation levels and resulting heat and particle fluxes. In the ITG cases including the $n=0$ perturbations reduces turbulent fluxes, as expected, however, for the TAE cases including the $n=0$ perturbations is shown to enhance the fluxes. We show for the first time that Axisymmetric Alfvén Eigenmodes (AAEs) play a role in this mechanism.
title Role of Shafranov shift, zonal structures on the behavior of TAEs, AAEs and microinstabilities in the presence of energetic particles
topic Plasma Physics
url https://arxiv.org/abs/2601.07652