Gyrokinetic and ideal MHD ballooning at high beta

High beta tokamaks are attractive concepts for magnetic confinement fusion, but their stability properties can be challenging to assess. In this poster, we present high mode number (ballooning mode) stability analyses for high beta tokamak equilibria, using GS2. To benchmark the code, we compare the gyrokinetic results with the ideal MHD energy principle, in the MHD limit. For a specific, high-beta ITER configuration, we have computed the region of the second stability for arbitrary ballooning angle theta_0, using both models. We compare the results in the appropriate small gyroradius limit.