1. In-situ Visualization and Analysis of Plasma Surface Interaction Simulations Wathsala Widanagamaachchi SCI Institute, University of Utah Mentors : Li-Ta Lo, Chris Sewell & Jim Ahrens

2. What are PSI simulations? Tungsten in future nuclear fusion reactors When exposed to helium & hydrogen plasmas, – Surface defects and bubbles form Molecular dynamics (MD) simulations Data : – LAMMPS simulation of Plasma Surface Interaction

3. What is in-situ visualization & analysis? “In-situ” is a Latin phrase – “on site” or “in position” Motivation – Ever-increasing sizes of simulation data – Post-processing is challenging disk I/O and the network bandwidths – Data reduction method to the output data Apply visualization & analysis during runtime

5. ParaView pipeline Reproduce existing ParaView pipeline Using … – Threshold – Gaussian Splatter – Isosurface – Box Clip – Glyph Tungsten Cavities Helium Bubbles

6. LAMMPS + VTK Pipeline Collocate simulation with visualization & analysis LAMMPS as an external library within C++ At each time step, – Simulation – Visualization & analysis Lessons learnt : Working with LAMMPS & VTK

7. LAMMPS + VTK Pipeline

8. Serial & Parallel versions – Serial : complete – Parallel : technical issues with some VTK filters Gaussian Splatter Fast Splatter Lessons learnt : Creating a ParaView plugin Filters are not parallel

9. Visualization Feedback from a domain scientist – Definitions of Helium bubbles & Tungsten cavities “all Helium atoms reachable through links shorter than the lattice unit (within the simulation) is considered to be in one bubble” – Realistic parameters to be used – Helium atoms clustering in LAMMPS – Evolution of bubbles & cavities – Details to output (Data files & images) – Running an entire simulation – Larger dataset Karl Hammond, Department of Nuclear Engineering, University of Tennessee

10. Visualization Feedback from an artist Better color maps Francesca Samsel, Los Alamos National Laboratory Lessons learnt : Importance of color in visualizations

11. Visualization Camera movement, Timers Rendering issues – depth ordering Correct image

12. Analysis Helium clustering using LAMMPS Evolution of Helium bubbles – Volume overlap of bubbles – New color map to show evolution Displaying of statistics – Percentage of atoms – Helium bubbles, splits & merges

13. Video

15. Thank you.