arXiv:1002.3109v1 [physics.plasm-ph] 16 Feb 2010 1 Nonlinear gyrofluid computation of edge localised ideal ballooning modes Alexander Kendl Bruce D. Scott Institut f¨ ur Ionenphysik und Angewandte Physik, Association Euratom- ¨ OAW, Universit¨ at Innsbruck, A-6020 Innsbruck, Austria Tiago Ribeiro Euratom Association, D-85748 Garching, Germany Max-Planck-Institut f¨ ur Plasmaphysik, 1) Max-Planck-Institut f¨ ur Plasmaphysik, Euratom Association, D-85748 Garching, Germany 2) Instituto de Plasmas e Fus˜ ao Nuclear, EURATOM/IST Association, 1049-001 Lisboa, Portugal (Dated: October 25, 2018) Three dimensional electromagnetic gyrofluid simulations of the ideal ballooning mode blowout scenario for tokamak edge localized modes (ELMs) are presented. Special emphasis is placed on energetic diagnosis, examining changes in the growth rate in the linear, overshoot, and decay phases. The saturation process is energy transfer to self generated edge turbulence which exhibits an ion temperature gradient (ITG) mode structure. Convergence in the decay phase is found only if the spectrum reaches the ion gyroradius. The equilibrium is a self consistent background whose evolution is taken into account. Approximately two thirds of the total energy in the edge layer is liberated in the blowout. Parameter dependence with respect to plasma pressure and the ion gyroradius is studied. Despite the violent nature of the short-lived process, the transition to nonlinearity is very similar to that found in generic tokamak edge turbulence. PACS numbers: Abstract