Title :
Field emission studies from Nb surfaces relevant to SRF cavities
Author :
Wang, T. ; Reece, C. ; Sundelin, R.
Author_Institution :
Jefferson Lab, Newport News, VA, USA
Abstract :
Enhanced field emission (EFE) presents the main impediment to higher acceleration gradients in superconducting rf (SRF) niobium (Nb) cavities for particle accelerators. A scanning field emission microscope was built at Jefferson Lab with the main objective of systematically investigating the sources of EFE from Nb surfaces. Various surface preparation techniques and procedures, including chemical etching, electropolishing, ultrasonic water rinse, high pressure water rinse, air-dry after methanol rinse, air-dry after water rinse in Class 10 cleanroom, were investigated. The capability and process variables for broad-area Nb surfaces to consistently reach field emission free or near field emission free performance at ∼140 MV/m have been experimentally demonstrated using the above techniques/procedures.
Keywords :
accelerator RF systems; accelerator cavities; beam handling techniques; electrolytic polishing; etching; particle beam diagnostics; superconducting cavity resonators; ultrasonic cleaning; Nb surfaces; SRF cavities; acceleration gradients; air-dry after methanol rinse; air-dry after water rinse; chemical etching; electropolishing; enhanced field emission; high pressure water rinse; particle accelerators; scanning field emission microscope; superconducting rf niobium cavities; surface preparation techniques; ultrasonic water rinse; Anodes; Chemicals; Conducting materials; Electron emission; Etching; Iron; Linear particle accelerator; Methanol; Niobium; Scanning electron microscopy;
Conference_Titel :
Particle Accelerator Conference, 2003. PAC 2003. Proceedings of the
Print_ISBN :
0-7803-7738-9
DOI :
10.1109/PAC.2003.1289718
