Abstract
Based on previous experience with conditioning of vessels for plasma experiments by a dc glow discharge, a very simple, safe, and effective technique was developed for ASDEX. It is characterized by a low working pressure of 5 × 10 −3 mb of H 2 at which no violent arcing or damaging parasitic discharges occur and it utilizes anodes in a fixed position well within the limiter shadow. The efficiency of the glow discharge is monitored by a differentially pumped mass spectrometer. The results show a high efficiency in removing carbon from the vessel. Total amounts pumped out mainly as CO and CH 4 are of the order of grams corresponding to hundreds of monolayers. Surface analysis of samples yield less than 30% of a monolayer after several hours glow discharge conditioning, but recontamination is seen to be significant. We also find a water production rate corresponding to the removal of one monolayer per hour during the glow discharge. An investigation of the current and pressure dependence of the impurity removal rates show that the chosen conditions are quite optimal.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
