A coupled system of linear integral equations are derived from the electromagnetic gyrokinetic equations and solved in straight and sheared slab geometries. Simulation results of a finite-β modified ion-temperature-gradient-driven instability in a sheared geometry are presented. It is shown for typical tokamak parameters that the fundamental l=0 slab mode can be completely stabilized at β≊1% while the l=1 slab mode persists.
Previous numerical and analytic kinetic studies 1-3 have investigated the influence of velocity shear on the ion temperature gradient (ITG) mode. These studies relied on a differential approximation to study mode structures with kj.p_ << 1. A recently developed gyrokinetic integral code is here used to explore the effects of sheared flows on the ITG mode for arbitrary values of k.pi. It is found that both the mode structure and eigenfrequencies predicted by the integral code can differ from the results obtained by the differential approach, even in the k_p_ << 1 limit. Although some trends predicted by the differential approximation are recovered by the integral approach, there are some significant differences. For example, the slight destabilizing effect observed for small values of the perpendicular velocity shear at kj.pi << 1 is amplified when the integral approach is applied. In dealing with the higher radial eigenmodes, which can often exhibit the largest growth rates, it is emphasized that their finer radial structure usually dictates that the integral equation analysis is required. Results from the integral code are presented together @ with comparisons with results from the differential approach.
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