Effect Of Magnetic Islands On Plasma Rotation In Edge Region Of J-TEXT Tokamak

Plasma rotation can stabilize macro-MHD instabilities and suppress turbulent transport in micro level which is the key to stable operation of tokamak under high parameters.For future fusion reactors such as International Thermonuclear Experimental Reactor(ITER)and Chinese Fusion Engineering Test Reactor(CFETR),external momentum injection may not provide sufficient momentum.These facts highlight the importance of intrinsic rotation which exists even without external momentum injection.At present,it is most believed that the source of intrinsic rotation mainly comes from the edge of plasma.Many tokamaks develop the magnetic profile in edge region by the application of resonant magnetic perturbation(RMP).The study on the effect of magnetic islands which excited by RMP on plasma rotation helps to get further understanding on response of plasma to RMP and the mechanism which drive the plasma rotation.The effect of magnetic islands on plasma rotation has been investigated by the application of edge rotation diagnostic system(ERD)in Joint Texas Experimental Tokamak(J-TEXT).The plasma rotation in edge region has been both studied with the locked2/1 and 3/1 magnetic island excited by the static RMP penetration respectively.In the case of 2/1 magnetic island,it is observed that the toroidal rotation of carbon V changes significantly during the mode penetration,shifting from the counter-current to co-current direction.The change of toroidal rotation increased with the growing of the current of RMP coils.When the current intensity of RMP stayed constant,the change of toroidal rotation was varied under different phases.The abrupt alteration of toroidal rotation of carbon V impurities during the locked-mode penetration was discussed in terms of radial force balance and the equation of motion in fluid theory.The poloidal rotation did not change with the radial electric field E_r during the penetration because of the poloidal flow damping.The velocity of toroidal rotation should be large enough to bala+ce the components perpendicular to the line of magnetic force.In the case of 3/1 magnetic island,the locked-mode penetration has a relatively small impact on the rotation of carbon V,but a significant impact on the rotation of carbon III,which locates closer to the magnetic island.By scanning the RMP phase,it is found that the closer to the O-point of magnetic island,the larger the toroidal rotation of carbon impurities change which may due to the asymmetry of plasma flow in the magnetic island.