Description
Models and simulations of drift wave edge turbulence in magnetically confined plasmas generally make use of various simplifications. A common approximation is to employ the "delta-f" form of equations, where only small turbulent perturbations (compared to the average "background" quantities) are evolved. As in the edge and scrape-off layer of tokamaks and stellarators the fluctuation amplitudes can become large in the order of the background, over recent years several "full-f" (or "total-f") gyrokinetic, gyrofluid and fluid codes have been developed around the world.
Full-f gyrokinetic and gyrofluid models are for consistency usually considering only long-wavelength approximated polarization. Going beyond this limit, Pade-based arbitrary wavelength polarization closures for full-f models have recently been formulated by Held et al. [1].
Here, we report on our implementation and testing of solvers with second order accurate Finite-Larmor radius polarization in "full-f full-k" gyrofluid codes [2,3] for resistive drift wave turbulence.
The impact of various approximations to the polarization equation on edge turbulence and transport is evaluated and discussed by means of the 2d gyrofluid Hasegawa-Wakatani code "TIFF" [2] and the 3d electromagnetic isothermal toroidal flux-tube code "T3FF" [3].
References:
[1] M. Held, M. Wiesenberger, and A. Kendl. Nuclear Fusion 60, 066014 (2020).
[2] A. Kendl. Computer Physics Communications 294, 108953 (2024).
[3] A. Kendl, P.B. Somu, and F. Grander. Computer Physics Communications 324, 110137 (2026).