Smoothing RF cavities with gas cluster ions to mitigate high voltage breakdown

D. R. Swenson, E. Degenkolb, Z. Insepov, L. Laurent, G. Scheitrum

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Many studies have demonstrated that improving the surface smoothness and cleanliness of high voltage electrodes increases the voltage standoff capability, but none have specifically investigated the role of nano-scale and atomic level surface roughness. Using AFM imaging, we have studied the effect of gas cluster ion beams (GCIB) on oxygen-free Cu electrode material that is used in high gradient RF cavities. Using Ar clusters accelerated by 30 kV, with a dose of 6 × 1014 e cm-2, we have effectively removed an asperity that was 3500 Å wide and 350 Å high. Subsequent processing with 5 kV acceleration reduced the surface roughness from an Ra value of 13.2 Å to 4.8 Å. This demonstrates the effectiveness of GCIB for reducing sub-micron roughness to atom level smoothness.

Original languageEnglish
Pages (from-to)641-644
Number of pages4
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Issue number1-4
Publication statusPublished - Dec 1 2005
Externally publishedYes


  • Cluster beam
  • Cluster-surface interactions
  • Kilpatrick limit
  • RF breakdown

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

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