Effects of Magnetic Surface Shaping Parameters on Ion Temperature Gradient Turbulence in Tokamaks

Transport driven by ion temperature gradient (ITG) turbulence is believed to be responsible for most observed energy and particle losses in tokamaks. The impact of magnetic surface shaping in tokamaks on ITGs and ITG-driven turbulence are studied using local, axisymmetric equilibria. This is accomplished by computing equilibria with varying magnetic shear, pressure gradient, triangularity, and elongation. Linear ITG stability analysis is performed using the gyrokinetic code GENE. The effects of shaping on nonlinear turbulent transport physics is performed using a recently developed theory for turbulent saturation that relies on nonlinear energy transfer from unstable to damped eigenmodes [C.C. Hegna, P.W. Terry, and B.J. Faber, Phys. Plasmas 25, 022511 (2018)].