Excitation of ion Bernstein wave (IBW) turbulence in nonlinear ITG simulations

This work presents a first of a kind simulation of IBW turbulence in the presence of temperature and density gradients, where the Larmor-frequency-scale waves are destabilized and have a significant contribution to the turbulent transport (comparable to ITG modes). Together with the analytical derivation of stability criteria for the IBW instability,  the simulations demonstrate that the focus on gyrokinetic simulations for the edge of a fusion device is not sufficient for developing a comprehensive understanding and that simulations with more complete models are necessary.

In regimes with high gradients and large turbulence fluctuations, such as the plasma edge of a fusion device, the limitations of gyrokinetic models become apparent. While gyrokinetic transport simulations are effective in the tokamak core regime, their applicability in high-gradient regimes is questionable. More comprehensive simulations are necessary to develop a deeper understanding of the dynamics in these regions.

The newly developed semi-Lagrangian solver for the 6D kinetic Vlasov system is based on a highly efficient scheme to treat the vxB-acceleration from the strong background magnetic field. The Lagrangian treatment of the Lorentz force advection allows the simulation of excitation and the resulting turbulence of waves far beyond the gyrokinetic regime.