Negative transferred arc cleaning: A method for roughening and removing surface contamination from beryllium and other metallic surfaces

TA cleaning has been investigated for preparing the surface of beryllium pl asma facing components (PFC's) inside of the International Thermonuclear Ex perimental Reactor (ITER) prior to depositing beryllium by plasma spraying. Plasma spraying of beryllium was evaluated during the ITER Engineering Des ign Activity (EDA) for in-situ repair and initial fabrication of the beryll ium first wall armor. Results have shown that surface roughening of berylli um, during the TA cleaning process, can result in bond strengths greater th an 100 MPa between beryllium surfaces and plasma sprayed beryllium. In addi tion, the TA cleaning process was shown to be an effective method for remov ing contaminate layers of carbon and tungsten from the surface of beryllium . Investigations have been performed to characterize the different are-type s that occur during the TA cleaning process (Type I, II and III arcs) and t he effectiveness of the TA cleaning process for potentially removing co-dep osited layers of carbon and deuterium from the surface of beryllium, stainl ess steel and tungsten.