Numerical Simulation of Toroidal Momentum Transport with Neutral Beam Injection on Tokamak

Abstract

In modern tokamaks, the toroidal plasma rotation has been demonstrated to play a beneficial role in the fusion plasmas. In this paper, the simulation of the toroidal momentum sources, momentum diffusivity χ _ϕ and plasma rotation with neutral beam injection (NBI) on EAST tokamak have been carried out by using MMM95 and GLF23 anomalous transport models in ONETWO and NUBEAM codes. The physical characteristics of the toroidal momentum transport for the different plasma density and temperature are analyzed. According to the simulation results, the main momentum sources for NBI are from the collision and $\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {J} \times \overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B}$ ($\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {J}$ is the plasma current and $\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\rightharpoonup}$}} {B}$ is the magnetic field). The former is most in the center and the latter is primary in the middle of the plasma. Also, for EAST, χ _ϕ is about twice of the thermal diffusivity χ _i according to the MMM95 model in the like H-mode. Moreover, because of the enhancement of collision and deposition, the density tends to improve the total beam torque. Nevertheless, to keep the neutrality of the plasma, the density reduces the plasma rotation by increasing the ion density and the momentum diffusivity according to the MMM95 and GLF23 anomalous transport models. In addition, in the L-mode plasma, although the increasing temperature displays little influence on the beam torque, it improves the momentum diffusivity because of the ion temperature gradient (ITG) mode in the anomalous transport and reduces the plasma rotation. The results will be valuable for the experimental research of the momentum transport on EAST or ITER.