Characterization of RF plasma cleaning protocols for removal of contaminants in high voltage beam diodes

Summary form only given, as follows. Contaminants have been shown to be a contributing factor to parasitic losses in ion beam diodes. Probable primary contaminants are CO, CO/sub 2/, H/sub 2/O, H/sub 2/, and C/sub n/H/sub m/ complexes. Experiments are underway at the University of Michigan to characterize effective cleaning protocols for high voltage A-K gaps. RF cleaning techniques using Ar and Ar/O/sub 2/ mixtures are being investigated. Optical emission spectroscopy is being used to view the effects of cleaning on neutral and ion contaminants during the high voltage diode pulse and to characterize the cleaning discharge. Experiments utilize the Michigan electron long beam accelerator (MELBA) at parameters: V=-0.7 to -1.0 MV, I/sub diode/=1-10 kA, and /spl tau//sub e-beam/=0.4-1.0 /spl mu/s. MELBA is used to study thermal and stimulated desorption of contaminants from A-K surfaces due to electron deposition. Pre-analysis and post-analysis of contaminants (e.g. CO, CO/sub 2/, H/sub 2/, H/sub 2/, C/sub n/H/sub m/) is performed using a residual gas analyzer.