Speaker
Description
Future nuclear fusion reactors will have to magnetically confine burning plasmas. In such scenarios, even a small fraction of fusion-born energetic particles (EP), which are 100 times hotter than the electrons, will contribute greatly to the kinetic pressure and therefore to the shaping of the MHD equilibrium, mainly via the Shafranov Shift. Nonetheless, many numerical works still prefer to use simplified magnetic geometries (e.g. ad-hoc or concentric circular MHD) to draw operational conclusions.
In this work we perform first-principles numerical simulations using the gyrokinetic, electromagnetic, global code ORB5 to study the effect of a self consistent high $\beta$ equilibrium on the arising Alfv\'en Eigenmodes (destabilized by EPs) and (electromagnetic) Ion Temperature Gradient (ITG) microturbulence.
Exploring the parameter space of both bulk plasma profiles and EP fraction, we show the linear (mainly stabilizing) effects of accounting for the bulk plasma and EP kinetic pressure in the MHD equilibrium, on the unstable TAE and ITG modes in our system. Focusing on the early nonlinear phase of a single toroidal mode TAE and ITG (separately), we study the impact of self-generated zonal flows on the shearing rates, kinetic profiles and fluxes, in both consistent and not consistent MHD equilibrium.
Overall, we show that a burning plasma with a self-consistent MHD equilibrium behaves significantly differently than if the bulk or EP pressure is not considered.
