Status of Fusion Theory and Simulation Research in NFRI 6 th J-K Workshop/NIFS/2011 J.Y. Kim

Introduction 2 Major Research Activities and Plan - Turbulent Transport - MHD Equilibrium & Instability - Pedestal & ELM - Integrated Operation Scenario - Divertor & PWI Summary

Major Goal of Theory & Simulation Research To develop advanced theoretical models and simulation skills for understanding fusion plasma & material To support KSTAR, ITER, and DEMO research programs To develop advanced theoretical models and simulation skills for understanding fusion plasma & material To support KSTAR, ITER, and DEMO research programs Physics Design Validation Operation Scenario Development ITER Experimental Data Analysis Operation Scenario Development KSTAR DEMO Physics Design & AT Scenario Development Advanced Fusion Material Research 3

Projects supporting Theory & Simulation Research Projects supporting Theory & Simulation Research  Fusion Simulation Project started from 2007 for promoting the simulation research of fusion plasma in NFRI annual budget of about 700k$/year (not including the salary of regular staff) now supporting mainly the research work of the field, being not covered by WCI project 4  WCI (World-Class-Institute) Center Project government project for promoting the research capability of national institutes our center selected as one of the three centers (Fusion, Casncer, Brain) - Integrated modeling study of turbulent transport in fusion plasmas five year project ( ), with annual budget of about 2M$/year now, about 11 people with 6 foreign and 5 domestic members (Director : Prof. P. Diamond)  KSTAR Project mostly for supporting the experimental research and device upgrade of KSTAR partial support for the theoretical modeling and data analysis work

Turbulent Transport 5 Intensive study being performed through WCI project - Intrinsic rotation and momentum transport - Transport barrier formation and evolution (ITB, ETB) - Non-local transport & self-organization - Particle and impurity transport - MHD & turbulence interaction etc. Strong emphases on the global transport simulation study - Global gyro-fluid simulation using TRB code (circular, ES, basis-function) ※ plan to develop a more general global gyrofluid code (D-shape, EM, finite-difference) - Global gyrokinetic simulation using gKPSP code (delta-f, PIC) ※ a full-f gyrokinetic code being developed using semi-Lagrangian method (cf. GYSELA) - Recently, a parallel PC-cluster system started its operation (from June 29, 2011) A close collaboration study with KSTAR experimental group

Global Gyro-fluid Simulation Global Gyro-fluid Simulation 6 TRB code imported and upgraded - global transport simulation study with a reasonable computation time - extensive study being done of ITB formation, flow generation & transport etc. Global non-local transport study planned of various modes (Ohmic, H, Hybrid etc.) Upgrade also planned : circular, Electrostatic => Shaped, Electromagnetic Power ramp simulation Forward transitionBack transition [Kim et.al. NF’11] 1 st APTWG meeting, S.S. Kim et al

7 Global Gyro-kinetic Simulation Global Gyro-kinetic Simulation 7 gKPSP (delta-f, PIC) code developed - Neoclassical equilibrium & trapped electron effects included - Intrinsic rotation, momentum transport, particle transport being studied A new code (full-f, semi-Lagrangian) under development for the study of - Global non-local transport modeling from core to edge - Barrier formation of ITB and ETB, with turbulence & neoclassical effects etc. r/R 0 η i = 1.0 (TEM) η i = 3.1 (ITG) η i = 1.0 (TEM) η i = 3.1 (ITG) V || Immediate after nonlinear saturation After nonlinear saturation 1 st APTWG meeting, J.M. Kwon et al

8 A Parallel PC-Cluster System A Parallel PC-Cluster System HP ProLiant Linix Cluster (AMD 64bit 12-core 2.2GHz) Total 576 CPUs (x 12 = 6912 cores) with infiniband QDR interconnection 60TF theoretical peak performance, 40 TF HPL 2GBytes/core memory (14 TBytes total) 160 TBytes disk storage Ranked 423-th in the top 500 ( )

9 MHD Equilibrium and Instabilities Calculation of 3D error field and perturbed magnetic field for KSTAR - A detailed calculation of error field performed using OPERA/MAFLO codes - 3D perturbed field from KSTAR FEC/ELM/RWM coil under calculation using IPEC etc. Simulation study of Sawtooth, LM, NTM etc. - Reduced MHD simulation using the 4-field code (in collaboration with Dr. Aydmir in IFS) - Extended MHD simulation using NIMROD (in collaboration with NIMROD group) - The codes installed and simulation study just started Disruption Simulation for KSTAR - Initial study performed for KSTAR design using TSC code - Re-calculation being performed with the modified KSTAR passive plate model Stability Study of Energetic Particle Mode - NOVA-K imported and a preliminary study started

Calculation of Field error & 3D Perturbed Field for KSTAR Calculation of Field error & 3D Perturbed Field for KSTAR 10 q=2/1 ※ for vacuum (under calculation with response)

Disruption Simulation for a new KSTAR Model Disruption Simulation for a new KSTAR Model 11 pre-disrup. TQ CQ KSTAR coil geometry & plasma boundary Eddy current (toroidal) J T X B p force

12 Modeling of ELM Mitigation by RMP Method - in collaboration with SciDAC team (CPES) - Iterative 3D perturbed field calculation with plasma response using M3D, XGC0 - Plasma transport calculation using XGC0 Modeling of ELM Mitigation by Pellet Pace-making Method - Initial study performed using ASTRA code with an approximate PPM model - A more self-consistent modeling started using M3D code Pedestal & ELM Control Nonlinear simulation of ELM using BOUT++ code - Recently started in collaboration with Dr. X. Xu in LLNL - for a more detailed study of ELM itself and benchmark with M3D results Modeling of NTV phenomena with 3D perturbed field - in collaboration with Dr. K. Shaing in Taiwan - both of analytic calculation and simulation study using XGC0 code

13 Modeling codes: XGC0 (kinetic transport), M3D (nonlinear MHD ) Numerical q 95 scan (B T scan) for low collsionality DIII-D case reveals sensitive magnetic stochasticity behavior around the experimental q 95 ELM suppression window  “Vacuum Chirikov is only a necessary condition” Current research focus Clarify effects of collisionality & density on ELM suppression mechanism Experimental validation in various tokamak RMP experiments including KSTAR Vacuum Chirikov is similar Plasma-responded Chirikov is different resonant window Time (msec) Simulation Study of RMP Control by RMP

14 Simulation result for density distribution using M3D code Initial condition of a simulation for pellet injection edge pressure and current diagram for peeling- ballooning instability using ELITE code The linear stability analysis using an ideal MHD stability code (ELITE) Simulation Study of ELM & its Control by PPM Nonlinear simulation study of ELM & its control by pellet pace-making method (cf. talk by Dr. H.S. Hahn)

Study of NTV with 3D Perturbed Magnetic Field 15 Substantial Analytic and Numerical Studies performed - As is well-known, symmetry breaking components in the magnetic field configuration increase the viscosity in the toroidal direction (so called “Neoclassical Toroidal Viscosity”). - In the last few years, significant studies on NTV performed and in each collisional regime the theory has been established solidly. - Recently, the general solution of NTV has been obtained by solving drift kinetic equation (DKE) numerically and the results are in good agreement with the analytic calculations. A Particle Simulation Study planned - for a more exact study in a more general magnetic field configuration and comparison with the analytic and DKE-based numerical results - with EFIT EQDSK files and the actual 3D field component of KSTAR - will use the codes XGC0 and (gKPSP1) - in collaboration with G. Y. Park, K. Shaing (Taiwan) (cf. talk by Dr. J. C. Seol)

16 ASTRA Simulation for Operation Scenario Modeling - KSTAR operation scenarios in the 2 nd operation phase ( ) - NTM control simulation with a self-consistent calculation of plasma evolution ※ in collaboration with SNU theory group (Prof. Y.S. Na) NBI Heating & CD Simulation - A more detailed study performed using NUBEAM for KSTAR NBI system model Integrated Operation Scenario (with heating & CD) ICRF Heating & CD Simulation - Various ICRF heating scenarios for KSTAR, which include the minority-ion heating, mode- conversion heating, 2 nd harmonic heating etc. - Flow generation from ICRF heating also being studied Plan for Integrated Scenario Modeling - trying to utilize the global gyrofluid code for a more self-consistent modeling of integrated operation scenario, particularly considering turbulence evolution & pedestal formation (cf. talk by Prof. Y.S. Na)

Modeling of NBI Heating & CD 17 A detailed simulation performed of NBI heating & CD using NUBEAM code - to support the optimization study of 2 nd KSTAR NBI configuration - comparison made of three possible NBI configurations

Modeling of ICRF Heating & Flow Generation 18 Toroidal force Poloidal force on last flux surface Momentum transfer from RFs, calculated using TORIC for minority ion heating case n e =5×10 19 m -3 (cf. talk by Dr. B.H. Park)

19 Simulation Study of KSTAR Divertor/SOL Transport - Initial study performed using UEDGE-DEGAS for KSTAR divertor design - Also, a benchmark study performed using KTRAN(SNU-developed0 code in collaboration with SNU group - Recently, a more detailed study started using B2-EIRENE or SOLPS Simulation Study of PWI - Recently, ERO code imported from Julich group in Germany - Simulation study to be started soon for the modeling of erosion, retention phenomena Divertor Transport & PWI Modeling of Charging and Transport of Dust Particle - in collaboration with Prof. N.S. Yoon (Cung-Buk National Univ.) (cf. talk by Prof. N.S. Yoon)

Simulation of KSTAR Divertor Transport 20 Simulation results using KTRAN for KSTAR divertor model Decrease of Impurity density, Increase of radiation Max :1.5e18Max :8.69e18 [m -3 ] [W/m 2 ] Impurity density Power Radiation Tungsten Carbon (cf. talk by Mr. S.B. Shim)

21 Summary of Research Activities Research area Major research subjectsSimulation codesMan power Turbulent transport (WCI-project) -Intrinsic rotation and momentum transport -Transport barrier formation (ITB, ETB) -Non-local transport -Particle & impurity transport -Turbulence & MHD interaction etc. - Global gyrofluid (TRB, BOUT++) - Global gyrokinetic (gKPSP, a new full-f) 5(+2+6) *2: domestic collaborator *6 : foreigner MHD instability -Equilibrium & 3D perturbed field -Sawtooth, LM, NTM -Disruption -Energetic particle mode -EFIT, MAFLO -NIMROD, 4-field -TSC -NOVA-K 2(+2) Pedestal & ELM -Pedestal stability (linear, non-linear) -ELM control by RMP -ELM control by PPM -NTV & neoclassical transport -BOUT++ -XGC0+M3D -M3D -XGC0 3(+1) Integrated Scenario -KSTAR operation scenarios -Heating & CD modeling (NBI, ICRF, LHCD, ECH/ECCD) -ASTRA -NUBEAM, TORIC, LSC, TORAY 2(+1) Divertor & PWI -KSTAR divertor transport -PWI (erosion, retention) -Dust* -B2- EIRENE(SOLPS) -ERO -(Prof. N.S. Yoon) 1(+1)