Global electromagnetic effects of ion temperature gradient and magnetic shear on intrinsic rotation generation

We investigate the influence of the ion temperature gradient (ITG) and magnetic shear on the global electromagnetic (EM) ITG mode and the resulting intrinsic rotation generation. Using global linear simulations based on a five-field fluid model in toroidal geometry, we evaluate the EM parallel residual stress within the quasi-linear framework for a wide range of plasma beta (βe), normalized ITG (R/LT), and normalized magnetic shear length (Ls/R). We find that both R/LT and Ls/R accelerate the parity mixing of the global EM-ITG mode, which is the key symmetry-breaking mechanism responsible for residual stress generation. The EM residual stress increases with βe at a rate governed by R/LT and Ls/R and generally increases with these parameters as well, although it can be transiently suppressed in certain parameter regimes as the per-mode stress profiles transition from dipolar to unipolar with strengthening parity mixing. The combined dependence collapses onto a single scaling curve as a function of βeLs/LT.