Surface composition changes of samples during ECR discharge cleaning of JIPP T-IIU and RFC-XX-M.

Abstract

In order to investigate the cleaning effect on the wall surfaces, samples were exposed to ECR discharge cleaning of JIPP T-IIU and RFC-XX-M, and their surface composition changes were observed by means of AES. After long exposure to ECR plasma, surface composition ratios were reached an equilibrium condition independent of sample position but dependent on sample material. On the surfaces of stainless steel and nickel samples, carbon and oxygen decreased with discharge?cleaning time and iron and nickel became dominant in surface composition. On the surfaces of silicon samples, oxygen was main component of surface even after ECR discharge cleaning. Also the deposition of small amount of impurities was observed during the ECR discharge cleaning on the sample surfaces exposed to ion flow along the magnetic lines.