Investigation on the Effect of Temperature Excursion on the Helium Defecis of Tungsten Surface by using Compact Plasma Device

Abstract

The effects of temperature excursion on the helium defects of tungsten surface have been investigated by using compact plasma device AIT-PID. An initial stage of bubble formations has been identified with an order of smaller (sub-micron) bubbles and holes than those in the past in which the micron size is the standard magnitude. The radiation cooling has been detected when a blacking of tungsten surface coming from nanostructure formation is proceeding due to an increase in the emissivity up to almost 1.0 in the final stage. The temperature increase to the domain (～1600K) in bubble/hole formation from that in nanostructure formation has been found to bring a constriction in diameter and a reduction in length of fiber-form nanostructure.