NERSC Initiative for Scientific Exploration (NISE) 2010 Awards

Modeling plasma surface interactions for materials under extreme environments

Brian Wirth, University of California, Berkeley

Associated NERSC Project: Ab-initio modeling of the energetics and structure of nanoscale Y-Ti-O cluster precipitates in ferritic alloys (m916), Principal Investigator: Brian Wirth

The detailed atomistic understanding of plasma-surface interaction will provide a way to predict the material performance and further enable the design of new plasma facing materials with an extraordinary tolerance under extreme fusion environment towards the realization of nuclear fusion energy.

Plasma - surface interactions (PSI) pose an immense scientific challenge in magnetic confinement fusion. These challenges are related to the large-scale modification of plasma facing surfaces via erosion, fuel retention, and mixing, which will begin to limit the operational viability and availability of the device.

Despite the vastly different physical length scales for the surface (~nm) and plasma processes (~mm), the plasma and material surface are strongly coupled to each other, mediated by an electrostatic and magnetic sheath. Also the intense radiation environment (ions, neutrons, photons) ensures that the material properties are modified and dynamically coupled to the PSI processes.

To capture such complex and fast kinetics associated with low-energy ion impingement and entrainment at or near the surface, in combination with point defect mediated evolution from higher energy ion and neutron irradiation, we propose to employ large scale molecular dynamics (MD) and molecular statics (MS) simulations using the parameters (e.g., atomic forces, displacement fields, defect energetics, and electronic bonding character) provided by density functional theory (DFT) in the W-He-H system. These studies, which will incorporate energetics and semi-empirical potentials developed from DFT calculations, will be able to investigate the structure and fast kinetic structural evolution of much larger scale systems and topological complexity.