Scenario Design Of The China Fusion Engineering Test Reactor(CFETR) Baseline Operation

TIhe baseline scenario of China Fusion Engineering Test Reactor(CFETR)is designed to achieve CFETR phase I mission.To study this physical feasibility,the time-dependent modeling of CFETR baseline scenario is performed.A workflow of scenario design with auxiliary heating and current drive,which includes Tokamak Simulation Code(TSC)and ONETWO,is developed on CFETR integrated Design Platform.To validate the workflow and the related modules,some DIII-D and EAST experiments are simulated.Based on the simulation results of DIII-D and EAST,the CFETR baseline scenario design is studied,which satisfies the design target of rampup,flattop and rampdown phase at once.The heating and current drive characteristics of auxiliary heating systems are indicated by scanning studies.The main achievements and highlights are listed as follows:1.The workflow of TSC coupling ONETWO is developed on CFETR integrated Design Platform.The plasma evolution coupling with auxiliary heating and current drive provides an effective tool for CFETR scenario design.The interface between TSC and some instability analysis codes is compiled to analyze ideal MHD during plasma evolution.And the interface between TSC and ANSYS is compiled to analyze electromagnetic loads on structures.Three DIII-D ITER-like shoots and one EAST shoot are simulated to validate the physical modules in the workflow.2.In the simulation of three DIII-D ITER-like shoots and one EAST shoot,five transport models(the Coppi-Tang,BGB,GLF23,MMM95 and CDBM model)are validated by comparing the simulated plasma internal inductance,beta,temperature and volt-seconds consumption.Since Coppi-Tang model trends to describable a lower transport coefficient in the early phase of rampup,the model is revised by adopting a scale factor on the overall tranport.The revised model agrees best with experiments in the simulation of plasma parameters.For DIII-D H-mode sustained by NBI,CDBM agrees best with experimental plasma internal inductance and beta.It's concluded that the Coppi-Tang model and CDBM model seem to be the favorable choices for the CFETR ramp up design in L-and H-mode,respectively.3.Time-dependent modeling of CFETR baseline scenario is performed.During plasma current ramp-up,the ramp rate,Zeff and shape evolution is optimized.10 MW of EC or LH heating is used to effectively save volt-second consumption to a reasonable level within magnet coil capability.Three reference scenarios with different external heating and current drive,which are NB+EC,NB+LH,and LH+EC,respectively,are designed to target full non-inductive operation with qmin>2.Two scenarios with neutral beams reach the required fusion power of CFETR phase I target.Ideal MHD analysis shows that both large toroidal mode number n ballooning mode and low n kink mode are stable in the three reference cases independent of whether the current is totally relaxed or not.Scanning study of N maps out the ideal MHD stable operation space for CFETR.The L mode and H-L back transition ramp-down are designed to successfully reduce the plasma current to 2 MA and keep li below 2 with ramp-down rate of 80 kA/s.The H-L back transition ramp-down yields improvements in the power transfer and coil current evolution as well as the li evolution.4.The heating and current drive characteristics of three auxiliary heating sources are indicated by scanning studies.A 2D scan of NB energy and tangency radius indicate that the possible NB parameters should be inside the region of 410<Rrt<660 cm and 300<E<1000 keV through considerations of power deposition,current drive,torque and shine through power.The 2D scan of EC launch angle shows that EC waves launched from LFS above the midplane yield a higher on axis driven current,while waves launched from top yield a higher near edge driven current at p>0.5.Scanning of n(?) in LH spectrum shows that nll should be set around 1.7 to get enough penetration for current drive and avoid strong accessibility problem.It is found that LH waves launched from HFS drives more current than that launched from LFS when n(?) is small.