Korean Modeling Effort : C2 Code J.M. Park NFRC/ORNL In
collaboration with Sun Hee Kim, Ki Min Kim, Hyun-Sun Han, Sang Hee
Hong Seoul National University presented at ITPA CDBM TG Meeting
Princeton, NJ April 25, 2006 Slide 2 The KSTAR main structures are
almost completed. The significant progresses, especially on the
manufacture and test of TF and PF superconducting magnets, have
been achieved. (16 TF coils encased, 4 CS coils completed, 4 Large
PF coilds ready for assembly) Machine assembly has to be finished
by Aug. of 2007, then commisioning for integration will follow. If
the SCMS are commisioned successfully, the first plasma shot is
expected in June of 2998. KSTAR will open to the fusion research
society not only domestically, but also internationally. Current
Status of KSTAR Project Slide 3 Integrated Discharge Simulation
Code for KSTAR Slide 4 1 Plasma continuity 2 Parallel momentum
balance 3 Electron/Ion energy 4 Current continuity 5 Magnetic field
diffusion C2 : Coupled 2-Dimensional Finite volume method
pressure-correction 1 Finite volume method in unstructured
multi-block grid 2 All-speed compressible pressure-correction
algorithm Fully implicit 3 Fully implicit time advancing
physics-base preconditioner 4 BiCGStab solver with physics-base
preconditioner domain decomposition 5 Parallel computing: domain
decomposition A 2-D multi-fluid model extending the previous
formulations of 1-D core and 2-D edge/divertor transports: Valid
not only in the collisional edge/divertor regions but also in the
high temperature core region. A parallel transient 2-D numerical
method * ExB drift * Diamagnetic drift Slide 5 C2 Equations
Self-consistent ExB and diamagnetic drifts Parallel viscous force o
local form with neoclassical viscosity coefficients valid in all
collisional regimes, ij standard neoclassical expression if
flux-surface averaged 1-D magnetic field diffusion equation
(flux-surface averaged) Normalized poloidal velocity Slide 6 C2
Parallel Computation Sub-Domain Domain Decomposition Method with
MPI Slide 7 Radial profile of electron & ion temperatures
Benchmark with ASTRA* : Ohmic Discharge, I p = 2 MA * ASTRA :
Automated System for Transport Analysis in a Tokamak (1.5-D core
transport code) (C2 run with prescribed boundary conditions at
core-edge interface) C2 Validation: Core Region Temperature
evolution at magnetic axis Slide 8 Benchmark with B2SOLPS : T e = T
i = 100 eV, n i = 2 x 10 19 m -3 (C2 run with prescribed boundary
conditions at core-edge interface) C2 Validation: Edge/SOL Region
C2 B2SOLPS C2 B2SOLPS C2 B2SOLPS C2 Slide 9 C1 : Coupled
1-Dimensional Assume boundary T* Advance core transport equations
with boundary condition T* Calculate q u * Advance Edge-SOL
transport equations with boundary condition q u * Check T*=T** Next
time step Calculate T** 1.5D transport Code with 1D SOL model Slide
10 Module Code Feature Remark NBI NUBEAM Monte-Carlo NTCC* NBEAMS
Semi-Analytic NTCC SINBI Semi-Analytic SNU ICRF/FWCD TORIC Full
wave IPP CURRAY Ray-tracing NTCC LH LSC Ray-tracing NTCC MHD EQ FEQ
Free boundary/FDM SNU ROTEQ Fixed boundary/FEM SNU Transport MMM95
Multi-Mode Mode NTCC NCLASS Neoclassical Model NTCC ECCD TORAY**
Ray-tracing NTCC ESC Fixed boundary/Moment NTCC ICRAY Ray-tracing
NTCC FWCDSC Full wave SNU Neutral GTNEUT TEP NTCC NTRANS**
Monte-Carlo SNU Integrated Computational Modules * NTCC : National
Transport Code Collaboration Libraries (http://w3.pppl.gov/ntcc) **
Coupling algorithm under development Slide 11 Predictive Hybrid
Scenario Modeling Pre-heating L-H transition Ip = 1.0 MA, B = 2.0
T, P NBI = 8MW, /n GW = 0.5 Current ramp-up rates of KSTAR
superconducting coils are too slow to adopt a conventional fast
ramp-up method. o Current ramp-up rate of KSTAR : ~ 0.5 MA/sec o
Necessary NBI preheating power : ~ 4 MW at t = 0.5 sec unrealistic
scenario for KSTAR Slide 12 Predictive Hybrid Scenario Modeling
Pre-heating Off-axis current drive Ip = 1.0 MA, B = 2.0 T, P NBI =
8MW, P LH = 1.5 MW, /n GW = 0.5 The desired q-profiles can be
obtained with the baseline heating and current drive systems of
KSTAR by earlier central heating and subsequent off-axis current
drive during the current rise phase. o Lower hybrid power for
off-axis current drive : 1.5 MW o Necessary NBI preheating power :
~ 2 MW at t = 0.5 sec Slide 13 Electron temperature Te : keV Ion
temperature Ti : keV Ion density n i Neutral density Log(n n ) x10
19 Self-consistent 2-D Profiles in the Entire Region of KSTAR B =
3.5 T, I p = 2 MA, = 5.0x10 19 m -3, P nbi = 6 MW Slide 14 1 2 3 12
3 Self-consistent 2-D Profiles in the Entire Region of KSTAR Slide
15 Edge Pedestal Temperature during ELMs (B = 3.5 T, I p = 2 MA, =
5.0x10 19 m -3, P nbi = 8 MW) Edge Pedestal Temperature T ped :
Limited by ELM Temporal evolution of ion pedestal temperature
during ELM Temporal evolution of radial ion temperature profile
during ELM Simplified ELM model (Ballooning) Slide 16 Divertor Heat
load during ELMs Rapid Emissions of Plasma Energy and Particles
during ELM Large transient heat loads onto divertor plates Temporal
evolution of maximum Heat flux onto outer divertor Temporal
evolution of electron temperature Slide 17 A newly developed
integrated simulation code C2 has been applied to predict high
performance discharges of hybrid and standard H-mode scenario in
the KSTAR tokamak. The simulations have focused on o finding
optimum operation scenarios to establish and sustain a broad
current profiles with q0 1. o estimating edge pedestal parameters
and divertor heat load The desired q-profiles can be obtained with
the baseline heating and current drive systems of KSTAR by earlier
central heating and subsequent off-axis current drive during the
current rise phase, although the current ramp-up rates of KSTAR
superconducting coils are too slow to adopt a conventional fast
ramp-up method. Both the temperatures at the top of the edge
pedestal and divertor heat load are estimated self-consistently
during ELMs in the main heating phase. Summary
