Study of gas cluster ion beam surface treatments for mitigating RF breakdown

Gas cluster ion beam surface treatments for reducing field emission and breakdown of electrodes and SRF cavities

“…4 [14]. It should also be noted that the processing of this electrode included treatments with O 2 clusters which increased the thickness of surface oxide layer from 1.5 nm to >10 nm [7]. The treated surface was also measured to be twice as hard as the untreated surface [7].…”

“…It should also be noted that the processing of this electrode included treatments with O 2 clusters which increased the thickness of surface oxide layer from 1.5 nm to >10 nm [7]. The treated surface was also measured to be twice as hard as the untreated surface [7]. The relative contributions of smoothing, oxide thickness and surface hardening to the reduction in field emission are receiving further study.…”

“…An earlier study concluded that NF 3 + O 2 clusters can significantly etch Nb and blunt the angles of the grains that protrude from the surface [7]. The conclusion was based on multiple AFM measurements of the grain edges and SEM images.…”

“…1-3 [7]. The field emission was measured at the Jefferson Laboratory Large Area Electrode Test Chamber.…”

“…GCIB treatments are used industrially in the production of thinfilm optical coatings, fixed disk memory technology, EUV lithography masks, and for the manufacture of semiconductor devices [5]. Previous papers have reported results of GCIB treatments of OFE-Cu, stainless steel, Ti and Nb electrode surfaces [6,7]. This paper contains additional data for stainless steel electrodes and reports the direct measurements of the suppression of field emission by GCIB treatments of Nb SRF cavity material.…”