Improvement of the operational performance of SRF cavities via in situ helium processing and waveguide vacuum processing

Author

Reece, C.E. ; Drury, M. ; Rao, M.G. ; Nguyen-Tuong, V.

Author_Institution

Thomas Jefferson Nat. Accel. Facility, Newport News, VA, USA

Volume

3

fYear

1997

fDate

12-16 May 1997

Firstpage

3105

Abstract

The useful performance range of the superconducting RF cavities in the CEBAF accelerator at Jefferson Lab is frequently limited by electron field emission and derived phenomena. Improvements are required to support future operation of the accelerator at higher than 5 GeV. Twelve operational cryomodules have been successfully processed to higher useful operating gradients via RF-helium processing. Progress against field emission was evidenced by improved high-field Q, reduced X-ray production and greatly reduced incidence of arcing at the cold ceramic window. There was no difficulty reestablishing beamline vacuum following the processing. Cavities previously limited to 4-6 MV/m are now operating stably at 6-9 MV/m. By applying a pulsed-RF processing technique, we have also improved the pressure stability of the thermal transition region of the input waveguide for several cavities

Keywords

accelerator RF systems; accelerator cavities; electron accelerators; linear accelerators; superconducting cavity resonators; CEBAF; He; He processing; X-ray production; arcing; beamline vacuum; field emission; high-field Q; operational performance; pressure; pulsed-RF processing; superconducting RF cavities; waveguide vacuum processing; Ceramics; Electron accelerators; Electron beams; Electron emission; Helium; Iron; Physics; Production; Thermal stability; Waveguide transitions;

fLanguage

English

Publisher

ieee

Conference_Titel

Particle Accelerator Conference, 1997. Proceedings of the 1997

Conference_Location

Vancouver, BC

Print_ISBN

0-7803-4376-X

Type

conf

DOI

10.1109/PAC.1997.753123

Filename

753123