| The social development relies heavily on energy. Tokamak becomes a focus of today’s peaceful uses of nuclear energy as an important means to solve the future energy crisis. The neutral beam system of EAST tokamak, the first non-circular cross-section and fully superconducting nuclear device on the world, is being built and tested. It’s particularly important to simulate the heating and beam-driven current due to neutral beam injection. It can be used to predict the results and efficiency of heating and beam-driven current, and analyze the physical mechanism to optimize the effects as well.This article first provides an overview of the basic mechanisms and characteristics of the ohmic heating, radio frequency wave heating, and points out their advantages and disadvantages. The designed parameters and working principle of EAST neutral beam system are introduced. From the prototype test results, the quality of the EAST neutral beam is the best in China. The basic principles and characteristic parameters of the neutral beam heating and current drive are also introduced. For neutral beam heating, there exists a critical energy εc. The beam mainly heats the electrons when beam energy is above the critical energy, and on the contrary, it mainly heats ions. The beam driven current are mainly determined by the collisions between ions of beam, electrons and the ion and its correction is given too.The integration of tokamak transport code ONETWO and Monte Carlo beam simulation code NUBEAM is used to simulate heating and current drive of neutral beam injection on EAST. Two anomalous transport model, the GLF23model based on the gyro-Landau-fluid model and the Weiland model based on ITG and TEM model are introduced in ONETWO. With The introduction of anomalous transport model, the simulation results are much closer to the real experimental results. The NUBEAM code takes into account the Beamline geometry, quality parameters, the power deposition and current drive, momentum transfer, fueling, fast ion deposition and slowing down, and correction of loss. The successful integration of ONETWO and NUBEAM opens a new approach to study the interaction between the beam and plasma. In particular, it’s the first time that the two anomalous transport models are applied to ONETWO on EAST.For the need of the future neutral beam physics experiments in EAST, different target plasma density, temperature, toroidal field, beam power and energy, neutral beam injection, the discharge constraints model, different anomalous transport model and other single-variable change are included to predict the the deposition of the injected beam power, power loss, the heating efficiency, thermal transport coefficient and density evolution with co-injection and counter-injection. Through the analysis of the relationship between physical processes and the results predicted by the codes, we can deeply understand the beam heating effect on the target plasma.For more concerned about the target plasma density, temperature, beam energy and power, Zeff, injection direction in the simulation of neutral beam current drive experiments, it can qualitatively and quantitatively result in the relationship between the neutral beam driven current and the above parameters. The contribution of these variables in the analytic form of beam-driven current can not be directly pointed out, and to study them can guide the beam driven current experiments.We can optimize the beam injection effect and reduce power loss by the analyze the influence factors through the neutral beam injection simulation. |
