학술논문
TRANSP modelling of experimentally measured fast particle redistribution and losses on MAST
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English
Abstract
MAST is a mid-size spherical tokamak with BT = 0.3-0.6 T and two NBI systems delivering up to 3.5 MW of super-Alfvénic deuterons and therefore suitable for understanding the dynamics of fast particles in ITER-relevant scenarios. It is well known that MHD instabilities can cause redistribution and/or losses of fast ions as observed in many tokamaks (such as NSTX, TFTR, DIII-D, JET, ASDEX, NSTX and MAST). In particular, on MAST, the effect of fast particle driven instabilities, such as fishbones and long-lived modes upon the total neutron yield measured by fission chamber (FC) and the neutron count rates measured by Neutron Camera (NC) has been observed [1]. Fishbones are characterized by burst-like behaviour observed in magnetic and SXR diagnostics and by the sweeping of the mode frequency during a burst. The resonant interaction between the toroidal and poloidal motion of the fast ions in the plasma with the n = 1, m = 1 internal kink mode is the mechanism responsible for driving the fishbone instability [2].