Experimental study on melting and evaporation of metal exposed to intense hydrogen ion beam

This report describes experimental studies on melting and evaporation of metals, mainly stainless steels, subjected to high heat flux simulating a plasma disruption in a thermonuclear fusion reactor. The test pieces were heated by an intense hydrogen ion beam. The heated area was about 70 mm in diameter. The peak heat flux on the surface ranged from 68 to 261 MW/m2, and the heating duration from 40 to 250 ms. The melting and evaporating process was observed by using a high-speed video camera. The melt layer convected from the center of the piece to the periphery and the thickness of the piece was decreased not only by the evaporation but also by the convection in the melt layer. (orig.)