Mechanism Research Of Intrinsic Rotation Change In J-TEXT

Plasma rotation plays an important role in L-H mode transition,avoiding or stabilizing magnetohydrodynamic(MHD)instabilities and suppressing plasma turbulence.Plasma can rotate spontaneously without any external momentum sources.It is important to understand the mechanism of the plasma toroidal intrinsic rotation to provide guidance for the design and operation of future nuclear fusion reactors.Therefore,the study of plasma toroidal intrinsic rotation is one of the popular directions in the field of magnetic confinement nuclear fusion,and there are still some open questions which need to be solved.X-ray Imaging Crystal Spectrometer(XICS)has been developed which can measure the plasma core toroidal rotation velocity,and the core toroidal plasma intrinsic rotation has been studied by experiments.In order to further study the plasma core intrinsic rotation change behavior in J-TEXT,the GENE simulation code was installed for the first time on the J-TEXT server.GENE is an open source plasma microturbulence code which based on gyrokinetics and can be used to efficiently compute gyroradius-scale fluctuations and the resulting transport coefficients in magnetized fusion plasmas.The core toroidal intrinsic rotation scaling experiment of ohmic heating plasama has been performed in J-TEXT.The typical parameters during the density ramping-up phase of an ohmic heated discharge in J-TEXT was selected,and the plasma turbulent mode between 0.2a and 0.4a was analyzed in combination with linear local simulations.During the plasma density ramped up,the dominant turbulent mode at 0.2a was ITG mode,while the plasma dominant turbulent mode at 0.3a and 0.4a was TEM mode.Between 0.2a and 0.3a,the plasma dominant turbulent mode transitioned from ITG mode to TEM mode.At 0.2a,the pinch term was negative,which meant the momentum pinch was inward and enhanced the counter-current direction rotation.The residual stress changed from positive value to negative value during the plasma density ramped up,the direction changed from outward to inward,and the enhancement effect changed from co-current direction to counter-current direction.The simulation results are consistent with the experiment results that the plasma rotation increased towards counter-current direction during the plasma density ramped up,which provides an explanation for the experiment results.The typical experiment data of the core intrinsic rotation experiment of ECRH auxiliary heating plasma in J-TEXT was selected,and the plasma turbulent mode between 0.2a and 0.4a was analyzed in combination with linear local simulations.Before ECRH was turned on and after it was turned off,the dominant turbulent mode was ITG mode.During ECRH was put into use,the plasma turbulent mode at 0.2a and 0.3a is the mixed mode of ITG mode and TEM mode,while the plasma dominant turbulent mode at 0.4a was TEM mode.At 0.2a,the pinch term was negative,which meant the momentum pinch was inward and enhanced the counter-current direction rotation.The residual stress was positive before ECRH was turned on,during it was put into use and after it was turned off,which enhanced the co-current direction rotation.However,compared with the residual stress before ECRH was turned on,the residual stress increased during ECRH was put into use,which enhanced the enhancement effect of the co-current direction.Compared with the residual stress during ECRH was put into use,the residual stress decreased after the ECRH is turned off,which weakened the enhancement effect of the co-current direction.The simulation results are consistent with the experiment result that the plasma core intrinsic rotation increased towards co-current direction during ECRH was put into use and increased towards counter-current direction after ECRH is turned off.