Both neutral beam injection （NBI） and electron cyclotron resonance heating （ECRH） have been applied on the Experimental Advanced Superconducting Tokamak （EAST） in the 2015 campaign. In order to achieve more effective heating and current drive, the effects of NBI on the heating and current drive with electron cyclotron wave （ECW） are analyzed utilizing the code TORAY and experimental data in the shot #54411 and #54417. According to the experimental and simulated results, for the heating with ECW, NBI can improve the heating efficiency-and move the power deposition place towards the inside of the plasma. On the other hand, for the electron cyclotron current drive （ECCD）, NBI can also improve the efficiency of ECCD and move the place of ECCD inward. These results will be valuable for the center heating, the achievement of fully non-inductive current drive operation and the suppression of magnetohydrodynamic （MHD） instabilities with ECW on EAST or ITER with many auxiliary heating methods.
Predictions on the ripple loss of neutral beam fast ions on EAST are investigated with a guiding center code, including both ripple and collisional effects. A 6% to 16% loss of neutral beam ions is predicted for typical EAST experiments, and a synergistic enhancement of fast ion loss is found for toroidal field （TF） ripples with collisions. The lost ions are strongly localized and will cause a maximum heat load of - 0.05 MW/m^2 on the first wall.
The NBI （Neutral Beam Inject） system of EAST has two deuterium beam lines, in which beam power is 4 MW and energy is 80 keV. To study the neutral beam shinethrough power loss, the physics processes of neutral beam attenuation in plasma are described and simulated by the code ONETWO/NUBEAM. The simulated input plasma parameter forms are tested through curve fitting of measured shinethrough in DIII-D. The power density distribution of shinethrough is obtained by analytical governing expression. The surface temperature rise testing for a copper target is also discussed.
Toroidal rotation has been recognized to have significant effects on the transport and magnetohydrodynarnic（MHD） stability of tokamak plasmas.Neutral beam injection（NBI） is the most effective rotation generation method on current,tokamak devices.To estimate the effective injected torque of the first neutral beam injection system on EAST,a simplified analytic method was derived.Calculated beam torque values were validated by those obtained from the NUBEAM code simulation.According to the results,for the collisional torque,the effective tangential radius for torque deposition is close to the beam tangency major radius.However,due to the dielectric property of tokamak plasma,the equivalent tangency major radius of the J×B torque is equal to the average major radius of the magnetic flux surface.The results will be useful for the research of toroidal momentum confinement and the experimental analysis of momentum transport related with NBI on EAST.
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.
