Alpha particle-driven toroidal rotation in burning plasmas

Honda, Mitsuru; Takizuka, Tomonori; Tobita, Kenji; Matsunaga, Go; Fukuyama, Atsushi*

The mechanism of a torque intrinsically produced by alpha particles and the subsequent possibility to create significant toroidal rotation and shear are investigated. In DEMO, an orbit-following Monte Carlo code OFMC predicts that the magnitude of both collisional and a torques increases in a reversed shear configuration compared to that in a normal shear case. The gradient of the source profile of alpha particles produces the co-directed collisional torque and a counter-directed torque, and both torques virtually cancel each other out over the entire domain. Eventually, the toroidal rotation velocity solely driven by alpha particles is not sufficient to stabilize resistive wall modes (RWMs), but neutral beam injection will be capable of exceeding the threshold of RWM stabilization, if it is used.