Numerical Simulation and Experimental study of fast Ion confinement with neutral beam injection on EAST *

The confinement of fast ions is one of the key problems. For the fast ion loss, a great deal of work has been done^[1-2]. This research applies numerical and experimental measurement to investigate the fast ion confinement. By using the multi-step fitting numerical method, we present analytical quantitative expressions of beam heating percentage and beam torque.

 In our simulation, firstly, we analyzed the prompt loss and beam heating in different beam injection ways. The results displayed the prompt loss increased with the beam energy and plasma density. Moreover, it is obviously reduced when the injection direction is changed from counter- to co-current. Secondly, the experimental and simulation data show beam heating improved about 40% for the high plasma density. By comparing the neutron production, the heating ratio is verified within the experimental error. By using the multi-step fitting numerical method, we present analytical quantitative expressions of beam heating and torque. In the end, the fast ion beta has been investigated by the numerical methods. The results show that the fast ion beta is positively correlated with Enbi and negatively with ne due to the extension of slowing down time.