Effects of transient heating events on beryllium plasma-facing materials in a steady-state plasma environment

Abstract

In fusion tokamaks, when an edge-localized mode occurs, a considerable amount of energy can be deposited onto plasma-facing components (PFCs). This transient causes rapid heating of the surface and can result in changes to the surface and near-surface regions including material loss. We have integrated laser systems into the existing PFC research program in PISCES, a laboratory facility capable of reproducing plasma–material interactions expected during normal operation of large tokamaks. We previously showed that tungsten samples exhibit significant ‘collateral damage’ when a heat pulse is applied in a plasma background. New experiments on beryllium indicate that surfaces exposed to deuterium plasma and simultaneous laser transients undergo a change in surface morphology and retention behavior. The grassy structure often seen on the surface of plasma-exposed Be is reduced and deuterium desorption occurs at higher temperatures.