Formation Condition of Fiberform Nanostructured Tungsten by Helium Plasma Exposure

Abstract

Tungsten samples were irradiated with high density helium plasma in the divertor plasma simulator NAGDIS to investigate the formation condition of the fiberform nanostructured tungsten. Experimental results indicated that the surface temperature threshold for the formation of nanostructure was approximately 1000 K when the incident ion energy was 50 eV. When the surface temperature was above 1000 K, the width of the nanostructure increased with the surface temperature. Three tungsten samples manufactured by different procedures (ultra fine grained tungsten, ITER-reference tungsten grade and powder metallurgy tungsten) were exposed to the helium plasma. The nanostructure was formed on all samples.