Integrated Modeling Of Plasma Ramp-up And Steady-state Operation In Tokamak

Tokamak plasma system is a very complex process related to plasma equilibrium,magnetohydrodynamics stability,transport and so on,they couple and evolve together.Physics analysis and simulation of these problems need self-consistent integration of various processes,including plasma equilibrium,transport,instability,heating and current drive.Many simulation codes focus on one main point and do not include all the necessary physics which would lead to large uncertainties.A tendency in tokamak plasma physics research is to integrate the developed simulation codes which would enable people self-consistent analyzing the tokamak plasma physics problems comprehensively(so called integrated modeling).Integrated modeling is an important part of tokamak fusion research,it has significantly impact on the explanation of the experiments,validation of physical theory as well as the design and construction of the next generation device.Based on the OMFIT platform developed by ASIPP/GA,this paper develops new integrated models for the research on plasma current ramp-up and long-pulse H-mode discharge,and validates the models with experiments.we firstly apply the advanced turbulent transport model TGLF in plasma current ramp-up simulation.we develop tokamak plasma current ramp-up integrated modeling with transport codes ONETWO,TGYRO(TGLF + NEO)and equilibrium fitting code EFIT under OMFIT framework,and validate this new model with DIII-D ramp-up experiments.Time-dependent integrated modeling of DIII-D ITER-like and high bootstrap current plasma ramp-up discharges has been performed and we find that integrated modeling does a reasonably good job in predicting the gross structure of the electron and ion temperature profile evolution and the current density profile evolution when compared with measurements.At the same time,we also analyzed the capability of this model.This model can provide good preliminary simulation prediction for future devices such as CFETR and ITER.Long-pulse discharge with high performance is a big challenge for next generation device such as ITER,CFETR towards commercialization,and also has been the thread of the research and exploration target in the EAST experiments in recent years.The capability of integrated modeling of EAST long-pulse H-mode discharge using transport codes ONETWO and TGYRO(TGLF+NEO)and equilibrium code EFIT has been developed.Simulations of the EAST long-pulse H-mode discharge have been performed.A steady-state is achieved using integrated modeling,and the bootstrap current fraction is?28%,the RF drive current fraction is?72%and mostly from the LHW driven current(70%).we demonstrate that acombination of transport codes ONETWO and TGYRO and equilibrium code EFIT yield a reasonable prediction of plasma temperature and plasma current density evolution.Some key models are also validated in the modeling of the EAST long-pulse H-mode discharge including GENRAY-CQL3D and TGLF-SATl.Analysis shows that ECH plays an important part in improving the plasma confinement.In the prediction part of different ECH conditions,both electron and ion temperature profiles come down as the ECH depositing position moving outside which means more obvious improvement obtained when heating in the core region.It is shown that the ECH heating effect is very local and not the main cause to sustained the good confinement in the EAST long-pulse H-mode discharge,the peaked current density profile has the most important effect on plasma confinement improvement.when the ECH is on and heating in the core region,the heating source helps rising the electron temperature profile,the increased electron temperature then helps the LHW driven current rising(more peaked)and the BP(poloidal magnetic field)changes(also the bootstrap current in the core region rises),the new equilibrium(peaked current density)responses to the energy transport,the electron temperature rises,and then repeating the previous process again,till a stable state is achieved.The core heating and peaked current density is of joint implementation on the improvement of the plasma confinement.This study is of great significance to the combination of simulation and experiment on EAST and the analysis of experimental results.