October 22, 2015
MIT Plasma Science and Fusion Center (PSFC) Mechanical Engineer Jeff Doody received a “Best Paper Award” on October 9 at the COMSOL Conference 2015. The paper, “Structural Analysis of the Advanced Divertor eXperiment’s Proposed Vacuum Vessel,” describes how Doody used COMSOL Multiphysics modeling software to predict loads and stresses on the vacuum vessel in the initial design for the Advanced Divertor eXperiment (ADX), a proposed high field, high-power-density fusion tokamak. Collaborating with him at the PSFC were Chief Mechanical Engineer Rui Viera, Senior Research Scientist Brian LaBombard, Principal Research Scientist Bob Granetz, Mechanical Design and Fabrication Specialist Rick Leccacorvi, and Principal Research Engineer Jim Irby.
Doody describes the importance of modeling physics scenarios to generate engineering solutions. “All the components of ADX must be able to survive a plasma disruption - when we lose control of the plasma and it moves off its equilibrium position, losing all of its current in a few milliseconds. This creates rapidly changing magnetic fields, which then induce eddy currents and Lorenz forces in conductive structures (like the inconel vacuum vessel). To determine if our design can withstand these loads, I use COMSOL to model the plasma movement and current quench. COMSOL predicts the magnetic fields, eddy currents, Lorenz forces and mechanical stresses the vessel will see, and we can then use those results to suggest reinforcements.”
Doody continues to evaluate the effect of various scenarios on ADX structures. He has analyzed the structural loads on ADX antennas, and is currently expanding his analysis of the vessel to include halo currents, large currents that flow from the scrape-off layer of the plasma into the vessel and then back to the plasma, which can cause significant forces in the vessel.