The prototype, which was manufactured in China by order of the IHEP institute in Beijing, consists of the outer vacuum vessel and the “cold mass” inside it. It is currently being prepared for the planned tests in DESY hall III. After completion to a full-fledged accelerator module, it will be tested on the Cryomodule Test Bench (CMTB) at -271 degrees Celsius starting in June. In addition, two other cryostat prototypes are being manufactured – one in Spain and one in France – within the frame of the international accelerator consortium, which is coordinated by DESY. “This is a good example of the successful work of the consortium,” acknowledges DESY director Reinhard Brinkmann.

Preparation of the cryostat prototype manufactured in China for the first tests. Heiko Hintz from the DESY machine group Cryogenics and Superconductivity (MKS) is installing a vacuum-tight cover. The crane is operated by Luise Kohlmeyer.

　　China is one of the 13 international partner countries participating in the construction and operation of the European XFEL alongside Germany. The People’s Republic offered to deliver 25 cryostat elements as in-kind contribution. To that end, they now first sent a prototype manufactured under their own direction to DESY for testing.

　　A total of 101 superconducting modules will have to be produced in industry for the 1.7-kilometre-long linear accelerator of the European XFEL. Each module is 12 metres long, weighs around 10 tonnes and comprises several components. One of these is the yellow outer iron cylinder, a vacuum vessel isolating the cold interior from the warm environment. Two additional shields cooled with helium gas also serve as heat insulation. In addition, the vessel encloses various helium processing pipes, the suspension for the string of eight niobium resonators and one magnet unit. All together, they form the cryostat element PXFEL1, which was now delivered from China.

　　The module components will be mass-produced by different manufacturers, the selection of which is currently being prepared. This is why DESY commissioned two other companies in Spain and France, in addition to the already existing Italian supplier, to manufacture one prototype of a cryostat unit each – PXFEL2 and PXFEL3 – modelled on the modules used in FLASH. Both prototypes should be delivered soon, joining the Chinese cryostat element PXFEL1 which is the first to undergo testing at DESY. The module fitted with PXFEL1 will be inserted into FLASH as ACC7 at the end of the year in order to ascertain its quality under regular accelerator operation conditions, i.e. with electron beam.

　　The results of these intense prototype tests together with the projected manufacturing costs will finally form the basis for the decision on the mass production of the cryostat units, which is planned to begin in 2010.

These two pictures were taken in February 2009 at the company Aerosan in Nanjing (China), which manufactured the cryostat prototype. Top: Experts from Germany and Italy (Kay Jensch from DESY at the right laptop, with Carlo Pagani from INFN Milano sitting on the right beside him) discussing matters with their colleagues from IHEP, Beijing (in front on the right: project leader Ge Rui). Bottom: Final work on the prototype before its journey to Europe.

Source: EXFEL Website