Mode Analysis with Poincaré Plots
- Science Problem
- Tokamak magnetic fusion reactors, such as ITER, have been relying upon the magnetic separatrix surface as the last confinement tool during the quiescent fusion production phase without external perturbation.
- There has been a continued concern and experimental observation that a significant loss of electron energy occurs across the separatrix surface by an unknown mechanism.
- There has also been skepticism by mathematicians about the confinement property of tokamak magnetic separatrix surface based on the homoclinic tangle theories.
- Technical Solution
- The Poincaré puncture plot tool developed in VTK-m allowed for very fast visualization and deep analysis of the sub-grid homoclinic tangles that destroy the tokamak magnetic separatrix surface.
- The significant speedups provided by the VTK-m implementation allowed for a quick study of the magnetic field structures across hundreds of timesteps and over all the mode structures within the plasma.
- Science Impact
- The VTK-m Poincaré tool provided the capability to perform unprecedented analysis of new sub-grid electromagnetic turbulence physics in plasmas inside of tokamaks over all the physically relevant timesteps and mode numbers.
- Before this VTK-m tool, physicists were spending an impractical amount of time.
Visualization of homoclinic tangle features (the lobes denoted with arrows) for Wide Pedestal case. Mode 2 (top) is an example of a mode that does not contribute, while mode 14 (bottom) shows a strong mechanism for feature development.
Homoclinic tangle features