Global gyrokinetic simulations of magnetic geometry and radial electric field effects on turbulent transport in Wendelstein 7-X

We present a more detailed numerical analysis of the global GENE-3D simulations of Bähner et al (the W7-X Team) 2026 Nucl. Fusion 66 016007, focusing on turbulent heat and particle transport and the role of the equilibrium radial electric field across mirror ratio and rotational transform (ι) configuration scans in Wendelstein 7-X (W7-X). Ion and electron heat fluxes show only mild sensitivity to both configuration parameters. The particle flux, however, exhibits a pronounced dependence on the mirror ratio, with the low-mirror configuration driving a strong inward particle pinch and the high-mirror configuration producing a net outward flux. Density fluctuation levels at fixed plasma profiles do not reproduce the experimentally observed configuration dependence in the mirror scan, a discrepancy that can be understood in terms of the simulations not satisfying power balance. A synthetic phase contrast imaging (PCI) diagnostic applied to the simulations reproduces the experimental ordering of the wavenumber and frequency spectra in the ι scan but not in the mirror scan, consistent with the same interpretation. The equilibrium radial electric field modifies turbulent transport, with the largest effect on the electron heat flux in regions of strong $E$ x $B$ shear. A controlled parametric study, in which the $E_r$ profile is systematically varied in amplitude and radial location, confirms that transport suppression follows the classical shear decorrelation criterion, being strongest where the shear rate exceeds the linear growth rate over the widest radial extent.