Implementation of magnetic compressional effects at arbitrary wavelength in the global version of GENE

The global tokamak code GENE has been extended including the effect of magnetic compression caused by B 1 , | | turbulent fluctuations of the magnetic field parallel to the equilibrium one. This paper outlines the basic structure of the algorithm, valid at arbitrary wavelengths of the gyrokinetic fluctuations, with emphasis on the numerical construction of the so-called “gyrodisk-integral” operators necessary for the model. The numerical implementation is successfully verified against radially local simulations, recovering excellent agreement. Global tokamak simulations are presented as well. The upgrade enables studying a large variety of new physical scenarios at high plasma- β , such as kinetic ballooning modes, MHD-like modes or the interaction of B 1 , | | with fast particle modes, reducing the gap between gyrokinetic models and physically realistic systems. • The global version of the gyrokinetic tokamak code GENE has been upgraded to include finite parallel magnetic field perturbations B 1,|| at arbitrary wavelengths. • The approach presented uses a real-space representation in the radial direction and can readily be applied to other global codes. • The construction of the necessary ”gyrodisk-operators” comes at only little additional cost and the overall implementation requires only minor modifications to the already existing algorithm of GENE. • The upgrade enables a more realistic study of phenomena at high plasma- β , such as the kinetic ballooning modes, MHD-like modes and the interaction of B 1,|| with energetic particles.