CERN Accelerating science

Article
Report number	IPAC-2013-WEPFI058
Title	Breakdown Localization Studies on the SwissFEL C-band Test Structures
Author(s)	Klavins, J (PSI, Villigen) ; Dementjevs, S (PSI, Villigen) ; Le Pimpec, F (European XFEL, Hamburg) ; Locans, U (PSI, Villigen) ; Shipman, N (Manchester U ; CERN) ; Stingelin, L (PSI, Villigen) ; Wohlmuther, M (PSI, Villigen) ; Zennaro, R (PSI, Villigen)
Publication	2013
Imprint	2013
Number of pages	3
In:	4th International Particle Accelerator Conference, Shanghai, China, 12 - 17 May 2013, pp.2824
Subject category	Accelerators and Storage Rings
Abstract	The SwissFEL main LINAC will consist of 104 Cband structures with a nominal accelerating gradient of 28MV/m. First power tests were performed on short constant impedance test-structures composed of eleven double-rounded cups. In order to localize breakdowns, two or three acoustic emission sensors were installed on the test-structures. In order to localize breakdowns we have analysed, in addition to acoustic measurements, the delay and phase of the RF power signals. Parasitic, acoustic noise emitted from the loads of the structure complicated the data interpretation and necessitated appropriate processing of the acoustic signals. The Goals of the experiments were to identify design and manufacturing errors of the structures. The results indicate that breakdowns occur mostly at the input power coupler, as also confirmed by vacuumevents at the same location. The experiments show that the LINAC test-structures fulfil the requirements in breakdown probability. Moreover developing a detection system based on acoustic emission sensors for breakdown localization for our C-band structure seems reasonable given the results obtained.