One of the key challenges facing the field of fusion plasma modeling is the nonlinear nature of the plasma response. This means that factors such as temperature and density gradients, flows, and velocity gradients all have an impact on the transport of heat, particles, and momentum in complex ways. Modeling such a system requires a range of approaches, from the highly detailed flux-driven gyrokinetics method to simpler quasilinear models within an integrated framework. These have proven effective in interpreting experimental data and predicting plasma behaviour. However, there are two significant challenges to this approach. Firstly, modeling the peripheral region of the plasma edge, at the transition between open and closed field lines, is challenging due to the confluence of significantly different underlying physics. Recent research indicates that current quasilinear transport models may have significant shortcomings in this region. Secondly, modeling the 'near marginality' regime is challenging due to the fact that it involves a state of dynamic equilibrium where the system's behaviour is self-regulated by slow, large-scale modes. Computing this state is challenging and requires a flux-driven gyrokinetic approach to move away from the typical assumption of time scale separation between turbulence and transport. Recent work from within our team indicates that current quasilinear transport models may also be facing significant shortcomings in this regime. It is crucial to understand this regime in depth as it is relevant for future machine operation. We are now in a position to address these two issues, as we have access to cutting-edge in-house tools relevant to both ends of the spectrum.
We plan to compare transport predictions in the edge and near marginality regimes from the advanced flux-driven gyrokinetic code GYSELA with those from the integrated framework using the reduced quasilinear QuaLiKiz model. The research will contribute to the development of robust reduced models for transport, crucial for the interpretation of current experimental data and for future burning plasma operation.