4 years ago

MOTOREX Magazine 2014 102 EN

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REPORT CONTINUED 1 Injector The electrons are generated and pre-accelerated. 2. Linear accelerator The electrons are accelerated to almost the speed of light. Quadrupole magnet This component guides the electron beam along the path. Cavities The linear accelerator consists of 104 cavities, each composed of 113 annular copper disks. It has an overall length of 335 meters. UTMOST PRECISION FOR THE UNDULATOR For scientists to forge ahead into new dimensions, they’ll need not just theoretical knowledge, but also the requisite infrastructure. In the case of the SwissFEL, this represents a further ambitious construction and engineering challenge. The undulators are a good example of the effort required to achieve the necessary precision. The devices are four meters long, 1.4 meters high, two meters wide and weigh 20 tonnes, but must achieve an accuracy in the 1/1000 range. Close collaboration between the PSI’s specialists and the capable contractors employed on the project has meant breakthroughs into new dimensions of production engineering for the latter as well. Laser measurements are used to determine the precise difference in dimensions between an installed part and a loose part. NOT FOR THE FAINT OF HEART Tackling a project like the SwissFEL takes a good deal of ambition and motivation. The PSI commissioned Max Daetwyler AG, famous for its precision mechanical engineering capabilities, to build prototypes and the twelve undulators for the project. That was in 2010. The first nearly production-ready undulator was completed by Daetwyler Industries at its Ursenbach plant just recently and delivered to Villigen in a special refrigerated and air-cushioned container. The job involved a number of unique design and production engineering solutions. SPECIALISTS AT WORK Daetwyler Industries has many decades of experience in precision mechanical engineering. Milling and grinding machine frames and workpieces weighing as much as 30 tonnes and measuring up to 12×2.5×2 meters is among the company’s core competencies. To handle these multi-tonne machine beds with the necessary precision, the machines used to produce them are mounted on unstressed concrete foundations of extremely generous dimensions (average size 40×20×25 meters) in the air-conditioned factory. The machine beds of the SwissFEL undulators are made of a mineral composite material that best meets the strength, 12

The undulator is situated in a vacuum chamber, allowing the magnets to be brought as close as possible to the electron beam. Text excerpts © PSI 4. Experiments Optical elements transport the extremely brief and intense X-ray flashes to the measuring stations, where a wide range of experiments can be conducted. Neodymium magnets 3. Undulator The undulators are composed of ultra-strong neodymium magnets. Magnets of alternating polarity (north-south) force the electrons to follow a slalom-shaped path, generating the X-ray light. weight, and temperature and dimensional stability requirements. Simply rotating the six-tonne workpieces, which have to be machined on both sides, is no small challenge. Taking several runs and measuring constantly, the milling and grinding specialists bring the undulator structural components to their specified ultra-precise dimensions. CONTINUOUSLY AIR-CONDITIONED The Ursenbach plant has a specially equipped, fully air-conditioned assembly department for building the undulators. Temperature differences at every height within the space are kept within a range of +/– 0.3 °C. With the horizontal tolerance for the four-meter undulator cross-section set at 20 µm (0.002 mm), the room temperature and assembly position of the undulators are crucial for ensuring precise measurements during assembly. PSI developed special measuring procedures and devices for the job. The twelve undulators needed for the SwissFEL are scheduled for completion by fall 2015. NUMEROUS AND VARIED BENEFITS SwissFEL will open the door to entirely new discoveries, expand our understanding of processes in nature and lead to practical applications such as new drugs, more efficient processes in the chemical industry, new materials in electronics and alternative energy production methods. These brilliant prospects for the future reveal the value of PSI’s research efforts for our entire society. They also clearly demonstrate how cuttingedge research depends on industry partners with the capabilities to carry out these spectacular projects in wholly new dimensions. • HOW FAST IS “ULTRA-FAST”? To observe ultra-fast processes, we need ultra-short X-ray flashes such as those that the SwissFEL will produce, lasting about 10 femtoseconds (0.00000000000001 s). The exposure time of an ordinary camera is 10 milliseconds (0.01 s). Thus at 10 femtoseconds, the SwissFEL’s exposure time is one thousand billion (one trillion) times faster! The SwissFEL will make it possible to “photograph” how molecules form a new compound. Text excerpts © PSI MOTOREX MAGAZINE 102 I JULY 2014 13

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