Abstract
The European x-ray free electron laser is under construction at Deutsches Elektronen-Synchrotron (DESY). The electron beam energy of up to 17.5 GeV will be achieved by using superconducting accelerator technology. Final prototyping, industrialization, and new infrastructure are the actual challenges with respect to the accelerating cavities. This paper describes the preparation strategy optimized for the cavity preparation procedure in industry. For the industrial fabrication and preparation, several new hardware components have been already developed at DESY. The design and construction of a semiautomated rf-measurement machine for dumbbells and end groups are described. In a collaboration among FNAL, KEK, and DESY, an automatic cavity tuning machine has been designed and four machines are under construction. The functionality of these machines with special attention to safety aspects is described in this paper. A new high pressure rinsing system has been developed and is operational.
Highlights
The European x-ray free electron laser (XFEL) [1,2] is based on a superconducting linac comprising 100 accelerator modules housing eight tesla-type cavities each
XFEL’s accelerating cavities, two final surface treatment schemes [3,4]—electropolishing and final buffered chemical polishing (BCP flash)—were studied with cavities from two different vendors
Since the cavity vendors will be supplied with the tuning machines by Deutsches Elektronen-Synchrotron (DESY), the machines have to comply with essential health and safety requirements and have to be designed, built, and documented in accordance to the machinery directive 2006/42/European Community (EC) of the European
Summary
The European x-ray free electron laser (XFEL) [1,2] is based on a superconducting linac comprising 100 accelerator modules housing eight tesla-type cavities each. The strategy to weld the cavities to their helium vessels prior to the final surface treatment was investigated. Yield curves for the different schemes (with or without helium vessel), yield curves for the different vendors being qualified for the XFEL cavity production [5], and a preparation strategy for the XFEL cavity production became available. One important step during cavity fabrication is the rf frequency tuning of dumbbells and end groups. In order to considerably shorten the tuning time and the cost, a dedicated apparatus was developed [6]. One further design goal is to set up a HPR stand prototype applicable in an industrial production line.
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