Xolotl: A New Plasma Facing Component Simulator

Scott Forest Hull II

Jr. Software Developer

Oak Ridge National Laboratory

hullsf@ornl.gov

2 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Project Overview:

The overall goal of the project:

•Develop and deploy high performance simulations capable of predicting the lifetime and durability of tungsten-based plasma-facing components in a “hot” fusion plasma environment.

•Modeling surface morphology evolution in erosion or re-deposition regimes.

•Recycling of hydrogenic species.

•Xolotl (SHO-lottle) – new code to simulate 3D continuum reaction-diffusion for long-time morphological and chemical evolution.

3 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Project Overview (Continued)

• This code is being built from scratch!

• ORNL tasked with Xolotl Development.

• Funded by Fusion Energy Sciences

(FES) and Advanced Scientific Computing

Research ASCR/SciDAC.

• Participants of various institutions and PI, including Oak Ridge National Laboratory (ORNL), Los Alamos National Lab (LANL), Pacific Northwest National Laboratory (PNNL), Argonne National Laboratory (ANL), and others.

• Proposal funding is for Fiscal Year 2012-2016.

4 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Science Lesson

• Develop a new simulator to predict PFC lifetime and performance.

• Integrating and applying discrete particle-based, as well as continuum-based, multi-scale modeling techniques to provide scientific discovery of the mechanism controlling PFC and bulk materials evolution under fusion plasma and 14-MeV neutron exposure.

• Will work on various HPC machines, including Jaguar/Titan – targeting HPC CPU/GPU hybrids as a main focus.

• Solving coupled reaction-diffusion problem.

5 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Parallel Programming Model

Exact model determined during design phase, but some ideas:

•OpenMP, MPI, Pthreads – also investigating OpenACC.

•Languages: C++

•Runtime libraries and frameworks include Integrated Plasma Simulator (IPS) and Mesh-Oriented datABase (MOAB).

•Parallel build with CMake and Ctest

•OpenCL and CUDA – explored for new data structures and reveal tasks within a timestep.

•Hybrid MPI + X – expand spatial scales of the problems.

6 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Performance and Scaling

• Since this is a new project, bottlenecks and scaling can only be predicted.

• The programs will scale to a height of the largest available systems on the current and future market.

• Collect application-specific data at a relatively coarse-grained level.

• Use tools, like HPCToolKit and mpiP, for application analysis.

7 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Tools

• Debug with logging and GDB. Valgrind as necessary.

• VisIt and ParaView for visualization tools.

• NEAMS integrated Computational Environment (NiCE) for leveraging an existing system for data and workflow management.

• Eclipse IDE, IBM’s Rational Software Architecture (RSA) for programming environment and development.

• Development Techniques:– Unified Modeling Language (UML) – Test Driven Development (TDD)

8 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Roadmap

• Release 1.0 on Sourceforge of Plasma Facing Components (PFC) Code within the first year.

• Code Refinement in sequential years for Xolotl: – Xolotl simulations for PFC surface and near surface

evaluations.– Xolotl simulations to evaluate bulk neutron-induced defect

cluster and gas bubble response.

• Work on 10,000 cores by year three.

9 Managed by UT-Battellefor the U.S. Department of Energy Presentation_name

Questions

Questions? Email me: hullsf@ornl.gov

THANK YOU!