Final Design and Prototyping of the Superconducting Magnet Package for the Linear Accelerator of the European XFEL

Abstract—The electron beam of the European XFEL will beaccelerated to an energy up to 17 GeV in a linear acceleratorwhich is divided into 101 modules. Each module will be equippedwith eight superconducting cavities and a superconductingmagnet package. That package consists of a main superferricquadrupole and two nested corrector dipoles, horizontal andvertical, enclosed in a stainless steel vessel. Conduction cooledcurrent leads are used.Up to four prototypes were produced between 2005 and 2009.Some problems were detected which may complicate the seriesproduction, mainly that the wire diameter was too small for thewinding process, the solid iron yoke was too expensive to bemachined and the magnetization effects on the magnet transferfunction were too high. Therefore, it was decided to revisit thedesign to ease fabrication. The new magnet design is presented inthis paper. The fabrication process and test results of theprototype are reported as well.Finally, the helium vessel around the magnet needs to satisfythe European Standard for Pressure Vessels, namely PED97/23/EC. This paper also describes the modifications necessaryin the original design to achieve that specification

Experience on Series Production of the Superconducting Magnet Package for the Linear Accelerator of the European XFEL

Abstract—The procurement of 103 superconducting magnetpackages is part of the Spanish in-kind contribution to theEuropean X-FEL. Each package consists of a main superferricquadrupole and two steerers, vertical and horizontal, fed byconduction-cooled current leads and enclosed in a stainless steelvessel. The operation temperature is 2 K, as they are embeddedin a superfluid helium bath. The magnetic and mechanicaldesigns are published elsewhere. The magnets are beingproduced in the Spanish company ANTEC, while the vessels arefabricated by another Spanish company, Trinos Vacuum-Projects, which is also responsible for the integration, under thesupervision of CIEMAT. The helium vessel manufacturer needsto accomplish the requirements given by the European PressureEquipment Directive, namely PED 97/23/EC. This paperdescribes the series fabrication techniques, the production followup,the quality assurance and the magnet testing at themanufacturer site. Cold tests are realized at DESY premises. Themain problems found during the fabrication of the first half ofthe series are also reported: a) the reproducibility of thequadrupole coil dimensions; b) the accuracy of the beam positionmonitor housing after final welding of the vessel; and c) theminimization of the magnetization effects on the transfer functionof the magnets