The kinetic excitation of ideal magnetohydrodynamic （MHD） Alfvén instabilities is investigated for operations at the EAST tokamak. The instabilities include α-induced toroidal Alfvén eigenmodes （αTAE; here, α =-q2 Rdβ/dr, with q being the safety factor, β the ratio between the plasma and magnetic pressures, R the major radius, and r the minor radius）, toroidicity-induced Alfvén eigenmodes （TAE）, and the energetic particle continuum mode （EPM）. The αTAE, trapped by α-induced potential wells along the magnetic field line, can be readily destabilized by energetic particles due to negligible continuum damping via wave energy tunneling. It is shown for the geometry and the parameters similar to those of the EAST equilibrium that αTAE is different not only from the EPM by the potential-well determined frequency, but also from the TAE by the broad frequency spectrum outside the toroidal frequency gap.
A predictive study on the plasma current and position control was carried out by applying TSC to the EAST experiments with a plasma control system （PCS）. Good agreement was achieved between predicted and experimental results in the plasma current, major radius, minor radius, elongation and plasma electron density, etc., which indicates that TSC has high predictability and reliability.
The heating and current drive using NBI （neutral beam injection） with a variable injection angle （the angle between the axis of the NBI system with the center axis of the injection window） on EAST is simulated by using NBEAMS code. The influence of the injection angle on the neutral beam current drive, heating efficiency and beam shinethrough power is discussed to explore the optimum injection angle for the EAST NBI system. According to the simulation, an injection angle of 19.5° is the optimum for EAST with its typical experimental parameters. With this injection angle, the increase in both the beam energy and power can improve the current drive and heating efficiency. The problem that the beam shinethrough power increases with the higher injection energy and power could be controlled through an increase of the plasma density.
