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Micro-instabilities, turbulence, and zonal flows are central to achievable tokamak performance. Knowledge of their poloidal structure would improve theoretical models and experimental interpretation. The poloidal structure of micro-instabilities may be altered by global effects. Global simulations can be computationally expensive, but global behaviour can be recovered from an array of local simulations via the “local-global method”. This method is, for the first time, demonstrated in the pedestal. Local gyrokinetic simulations of a JET pedestal reveal that magnetic shear causes narrowing in ballooning angle of kinetic ballooning modes via ideal ballooning physics. Narrowing in ballooning angle is shown to decrease local accuracy, but this may be mitigated by increased shear. The localglobal method is applied to a low shear pedestal-like case and compared to global gyrokinetic and MHD simulations. Good agreement suggests the local-global method is valid for toroidal mode numbers & 3 to 12. Simple models show that global and kinetic effects can affect EPED-like calculations by 0 to 110% in this case depending on the Peeling-Ballooning constraint. Experimental measurement of zonal flows is difficult due to the limited poloidal extent of relevant diagnostics. Knowledge of the poloidal structure of zonal flow drive would improve interpretation of such data. Nonlinear energy transfer functions calculated from local nonlinear gyrokinetic simulations reveal the poloidal structure of zonal flow drive for the first time. This demonstrates that zonal flows are driven by a broad spectrum of turbulence, and that zonal flows exhibit a limit cycle oscillation (predator-prey) type response with marginal turbulence but enter a quasi-steady state with strong turbulence. In both cases, zonal flow drive peaks on the outboard side, and is correlated with but not proportional to the turbulent energy.

DOI: 10/1/Biggs-Fox_2022_PhD-Thesis.pdf