Arcing at the cold ceramic RF window was first recognized as a major limitation on CEBAF performance in 1994. Repetitive arcing at the ceramic is due to charge/discharge cycles driven by field emission in the cavities. Statistical analysis of the fault dependence on gradient using the Fowler-Nordheim and exponential models of field emission has been developed. The analysis method and results of the analysis of faults recorded through January 2001 will be presented. 212 of the 320 linac cavities installed have sufficient fault data for field emission models. These models are input to the code used to set the gradient of each cavity in the linacs for minimum total arc rate. The modeling effort is second only to helium processing in its contribution to improved CEBAF accelerator availability for physics.



Publication: CASA Tech Note 01011