Development of a reduced energetic particle transport model by low-frequency MHD for time-dependent integrated tokamak simulations*

Low frequency instabilities such as kinks and fishbones are well know causes of enhanced energetic particle (EP) transport in tokamaks. However, physics-based models to account quantitatively for their effects in integrated, time-dependent integrated tokamak simulations are still missing. Development of such models is needed for more reliable projections of operating scenarios from today’s devices to future burning plasmas, e.g. ITER and FNSF. This work will report on recent developments of a reduced EP transport model by fishbones and kinks, based on the existing “kick model” infrastructure already implemented in the TRANSP code. For example, the rapid (~1-5 ms) sweep in frequency characteristic of a fishbone burst implies that different regions of energetic particle phase space are affected as time evolves. The kick model can account for such changes by representing the instability as superposition of multiple, fixed-frequency instabilities with time-dependent amplitudes. Based on the initial results from the kick model, perspectives for the development of a self-consistent model for low-frequency MHD in TRANSP will be discussed.