学際大規模情報基盤共同利用・共同研究拠点 第12回シンポジウム

2020年 7月 9日

学際大規模情報基盤共同利用・共同研究拠点 公募型共同研究 令和元年度採択課題 12th Symposium

Whole-volume gyrokinetic simulation of magnetic fusion plasmas with in-situ data processing

森高　外征雄 (核融合科学研究所)jh190004-MDJ

International Thermonuclear Experimental Reactor (ITER)

T. Aoki (GSIC, Tokyo Institute of Technology) A. Scheinberg, C-S. Chang, S. Ethier (PPPL) S. Klasky, J. Choi and E. D’Azevedo (ORNL) Y. Idomura (JAEA) S. Ishiguro (NIFS)

Background (1) Magnetic fusion device

Collaborating Researchers

Background (2) Whole-volume modeling of fusion device

First wall

Core plasma

Scrape-off layer

Divertor chamber

Divertor Plasma

• X-point Gyrokinetic Code (XGC) - Field solver using finite element method on unstructured mesh - Hybrid use of Lagrange (PIC) and Euler (5D mesh) descriptions for

kinetic plasma dynamics

Results in FY 2019

Plasma currentTwisted magnetic field

Toroidal magnetic field

Max-Planck-Institut für Plasmaphysik

• Precise prediction of device heat load by whole device kinetic modeling has a critical importance in ITER operation and future reactor designs.

• Robust computational model and large computational resources are required for multi-physics simulation including core and edge regions.

Cross section of ITER XGC simulation using unstructured mesh

Extension to Stellarator-type fusion devices

• We have completed the basic development of the extended version of XGC including non-axisymmetric configurations.

• Fundamental plasma physics in the core region of LHD are successfully demonstrated and benchmarked with the other established codes

Stellarator edge region

Stellarator core region- Another candidate of

magnetic fusion device

- Stable but complicated 3D (non-axisymmetric) magnetic field created by twisted external coils

Tokamak-type fusion device

- Middleware for high performance parallel I/O - “on-the-fly” data aggregation, relocation and reduction

among parallel computational, staging and I/O nodes

https://hbps.pppl.gov/computing/xgc-1

• Nuclear fusion reactions, e.g., D-T reaction, can be a sustainable energy source to meet world-wide energy demands.

• To produce net power from the reactions, we have to confine the fuels with high temperature (> 108 ℃) in the reactor.

• Torus-type magnetic configurations with twisting field lines have been proposed to confine the fuels.

Large Helical Device (LHD)• Stellarator

1

-7

-6

-5

-4

-3

-2

-1

0

1

0 0.1 0.2 0.3 0.4 0.5

E r [V

/m]

t/τii

ρ = 0.51

GT5DF3D

XGC-S

Microscopic instability on flux surface Radial electric field & GAM oscillation

• We have developed a new mesh generation scheme and finite element field solver for stellarator edge region and compared with the conventional scheme using ITER configuration.

Mesh generation by field line tracing Mesh generation by flux function

Code-code coupling using Adaptive I/O System (ADIOS)

• ADIOS has been successfully installed on TSUBAME and other US DOE machines.

• We are now working for code-code coupling for effective whole-volume modeling.

• Expensive computation with full-f scheme for edge region occupies GPUs, and dynamically coupled with the core plasma simulation.

Edge (full-f scheme) CPU + GPU

Core (delta-f scheme) CPU only

J. Choi, et al. 2018 IEEE 14th International Conference on e-Science

T. Moritaka et al Plasma, 2, 179-200 (2019).