Status of Fusion Theory and Simulation Research in NFRI

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

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

3. 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 KSTAR ITER • Physics Design Validation • Operation Scenario Development • Experimental Data Analysis • Operation Scenario Development DEMO • Physics Design & AT Scenario Development • Advanced Fusion Material Research

4. 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$/year (not including the salary of regular staff) • • now supporting mainly the research work of the field, being not covered by WCI project • WCI (World-Class-Institute) Center Project • • government project for promoting the research capability of national institutes • • our center selected as one of the three centers(Fusion, Casncer, Brain) • - Integrated modeling study of turbulent transport in fusion plasmas • • five year project (2009.12- 2014.11), with annual budget of about 2M$/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

5. Turbulent Transport • 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

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

7. Global Gyro-kinetic Simulation • gKPSP (delta-f, PIC) code developed • - Neoclassical equilibrium & trapped electron effects included • - Intrinsic rotation, momentum transport, particle transport being studied Immediate after nonlinear saturation After nonlinear saturation V|| V|| ηi = 1.0 (TEM) ηi = 1.0 (TEM) 1st APTWG meeting, J.M. Kwon et al ηi = 3.1 (ITG) ηi = 3.1 (ITG) • 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/R0 r/R0 7

8. A Parallel PC-Cluster System • HP ProLiantLinix 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 • (2011. 6)

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

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

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

12. Pedestal & ELM Control • 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 • 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. Simulation Study of RMP Control by RMP Vacuum Chirikov is similar 3.62 resonant window 3.52 Plasma-responded Chirikov is different Time (msec) • Modeling codes: XGC0 (kinetic transport), M3D (nonlinear MHD) • Numerical q95 scan (BT scan) for low collsionality DIII-D case reveals sensitive magnetic stochasticity behavior around the experimental q95 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

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

15. Study of NTV with 3D Perturbed Magnetic Field • 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. Integrated Operation Scenario (with heating & CD) • ASTRA Simulation for Operation Scenario Modeling • - KSTAR operation scenarios in the 2nd operation phase (2013-2017) • - NTM control simulation with a self-consistent calculation of plasma evolution • ※ in collaboration with SNU theory group (Prof. Y.S. Na) (cf. talk by Prof. Y.S. Na) • NBI Heating & CD Simulation • - A more detailed study performed using NUBEAM for KSTAR NBI system model • ICRFHeating & CD Simulation • - Various ICRF heating scenarios for KSTAR, which include the minority-ion heating, mode- • conversion heating, 2nd 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

17. Modeling of NBI Heating & CD • A detailed simulation performed of NBI heating & CD using NUBEAM code • - to support the optimization study of 2nd KSTAR NBI configuration • - comparison made of three possible NBI configurations <For type B1> <For type B2> <For type A>

18. Modeling of ICRF Heating & Flow Generation • Momentum transfer from RFs, calculated using TORIC for minority ion heating case Poloidal force Toroidal force on last flux surface ne=5×1019 m-3 (cf. talk by Dr. B.H. Park)

19. DivertorTransport & PWI • 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 • 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)

20. Simulation of KSTAR Divertor Transport • Simulation results using KTRAN for KSTAR divertor model Carbon Tungsten Max :8.69e18 Max :1.5e18 [m-3] [m-3] Impurity density [W/m2] [W/m2] Power Radiation Decrease of Impurity density, Increase of radiation (cf. talk by Mr. S.B. Shim)

21. Summary of Research Activities