Research On Response Of Plasma Rotation To Resonant Magnetic Perturbations And Argon Transport In J-TEXT Tokamak

Plasma rotation has positive effects on plasma confinement and the formation of H mode in tokamak plasma.Plasma rotation and its shear can suppress a variety of macro-instabilities and micro-instabilities,including the neoclassical tearing modes(NTMs)and resistance wall modes(RWMs).Plasma rotation plays an important role on steady state of plasma.Therefore,the understanding of the physical process of plasma rotation,and how to control the rotation and its profile,and optimization of plasma rotation and its profile have become a widely concerned question.The researches of plasma rotation in J-TEXT tokamak plasma have been carried in this paper.In order to study plasma rotation better,a set of tangential X-ray imaging crystal spectrometer(XICS)has been developed and upgraded on J-TEXT tokamak.X-ray imaging crystal spectrometer has high temporal resolution and spatial resolution for the measurement of core plasma rotation,the plasma rotation is derived from the Doppler shift.So the removal of mechanical vibration is the key to improve the measurement of plasma rotation.On the J-TEXT,the shores of XICS have been changed to the optical table,and the shores of the optical table are supported by the elastic damping courses.These steps can effectively eliminate the low frequency vibration brought during the discharging phase.The crystal chamber and detector chamber are fixed on the optical table,which can effectively eliminates the error caused by the vibration of the crystal and detector,respectively.The response of plasma toroidal rotation to the external m/n=2/1 resonant magnetic perturbations(RMPs)has been investigated in Joint Texas Experimental Tokamak(J-TEXT)ohmic heating plasmas with a movable titanium-carbide coated graphite limiter,where the m is the poloidal mode number and n is the toroidal mode number.For the J-TEXT's plasmas without the application of RMPs,the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction.Both static RMPsexperiments and rotating RMPs experiments have been applied to investigate the plasma toroidal rotation.The core toroidal rotation decreases to the lower level with static RMPs.At the same time,the edge rotation can spin to more than 20 km/s in the co-current direction.On the other hand,the core plasma rotation can be slowed down or accelerated with the rotating RMPs.When the rotating RMPs frequency is higher than mode frequency,the plasma rotation can be accelerated to the rotating RMP frequency.The plasma confinement is improved with high frequency rotating RMPs.The plasma rotation is decelerated to the rotating RMPs frequency when the rotating RMPs frequency is lower than the mode frequency.The plasma confinement also degrades with low frequency rotating RMPs.XICS not only measures the rotation of argon impurity,but also can be used to study the transport of argon impurity.The emissions of Ar XVII can be modulated by RMPs which indicates that the transport of argon is affected by RMPs significantly.During the field penetration phase,the emissions of argon decreased sharply.The phenomena show that the transport of argon in the core region has been enhanced.