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Parallel Unstructured Mesh Infrastructure for PIC (PUMIPic) and its integration �into Tokamak Edge Plasma (XGCm) and Impurity Transport (GITRm) Codes

Scientific Achievement

PUMIPic supports scalable and performant �PIC simulations over general 3D geometries

Significance and Impact

Allows PIC codes to advantage of unstructured meshes �to concentrate calculations into the critical areas

Research Details

• Distributed mesh approach for PIC that can scale with particles and mesh
• Supports all PIC operations on GPU and includes dynamic load balancing

Application by SciDAC Partnerships

• GITRm being used in detailed physics studies of DIII-D by General Atomics
• XGCm is showing performance improvements over XGC while having the advantage of supporting a distributed mesh
• PUMIPic will be used to support implementation of material point method in sea ice SicDAC partnership

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GITRm mesh images for DIII-D geometry with bumps and ports included. Mesh refined at impurity producing surfaces, where SOLPS mesh for background fields was fine, and at 3D geometric details.

G. Diamond, et.al., PUMIPic: A mesh-based approach to unstructured mesh Particle-In-Cell on GPUs, Journal of Parallel and Distributed Computing, Vol 157, pp 1-12 (2021).

Plasma Surface �Interactions 2

XGCm simulation of ITG on DIII-D geometry: turbulent potential

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t = 200

t = 0

t = 500

t = 990

D.D. Nath, et.al., An Unstructured Mesh 3D PIC Code for Impurity Transport Simulation in Fusion Tokamaks, Submitted to: Computer Physics Communications, (July 2022).