Global linear and nonlinear gyrokinetic modelling of Alfvén eigenmodes in ITER

Abstract Linear and nonlinear modelling of Alfvénic instabilities, most notably toroidal Alfvén eigenmodes (TAEs), obtained by using the global electromagnetic gyrokinetic model code ORB5 are presented for 15 MA scenario ITER tokamak. simulations show that elliptic odd-parity TAEs only weakly damped but not excited alpha particles, whose drive favours even-parity TAEs. Low mode number found to be global, requiring treatment. Nonlinearly, even with double nominal EP density, single lead saturation negligible transport however multi-mode predict enhanced significant redistribution will occur.