The Investigation Of Issues Related To Ion Cyclotron Waves Heating And Current Drive

Heating with Radio Frequency(RF)waves in the Ion Cyclotron Range of Frequencies(ICRF)is a primary auxiliary means of heating in the tokamaks.besides,the fast wave in ICRF can penetrate into the centre of high-density plasma,providing central current drive without limits on accessibility,the mode conversion current drive(MCCD)have the potential for current profile controlling.Thus,ion cyclotron waves current drive and heating,which play an important role in the steady-state operation of tokamak plasma with high performance,are of significance in controlled nuclear fusion.Based on actual discharge data from Experimental Advanced Superconducting Tokamak(EAST),ICRF on-axis and off-axis heating,ICRF fast wave current drive(FWCD)and MCCD are investigated theoretically and numerically using full-wave methods.The main results are listed as follows:(1)Both on-axis and off-axis D(H)minority heating experiments have been carried out in EAST.Some progress has been made on the effect of ICRF heating in the off-axis heating experiment,and the central ion temperature rose above 1.3keV with an overall rise in the ion temperature.Full wave analysis was used to model and examine the physics of the ICRF heating regimes in the two discharges with the real plasma parameters.The wave power deposition profiles of different heating regimes were given in the modeling using a single toroidal mode number,and a comparison was made among the fractions of the power deposited to different plasma species due to various heating mechanisms.More than 90% of the total power is absorbed by ions via ion cyclotron resonance in both on-axis and off-axis D(H)heating,and the extremely low H ion concentration might play a key role in the effective ion absorption.In addition,the influence of the toroidal mode number on different heating mechanisms was studied by scanning a series of the toroidal mode numbers.(2)A numerical study on the ICRF FWCD and MCCD in the Experimental Advanced Superconducting Tokamak(EAST)is carried out by means of the coupled full wave and Ehst-Karney parameterization methods.The results show that FWCD efficiency is notable in two frequency regimes,i.e.,f≥85MHz and f=50-65 MHz where ion cyclotron absorption is effectively avoided,and the maximum on-axis driven current per unit power can reach 120kA/MW.The sensitivity of the CD efficiency to the minority ion concentration is confirmed,owing to fast wave mode conversion,and the peak MCCD efficiency is reached for 22% minorityion concentration.The effects of the wave-launch position and the toroidal wavenumber on the efficiency of current drive are also investigated.(3)A numerical study on current profile controlling using ICRF MCCD were performed.The results show that the mode converted waves can effectively drive on-axis or off-axis currents and modify the current profile.The optimum frequency of the launched wave and the minority ion concentration for MCCD with maximum current density at the arbitrary objective position in the normalized minor radius range(-0.60≤r/a≤0)are obtained.The off-axis efficiency of the MCCD peaks at 233 kA/MW,which is greater than the efficiency of the fast wave current drive.The mode converted ion-cyclotron waves play a key role in these scenarios.The effects of electron temperature and toroidal wave number on the MCCD are also investigated.