It is important to ensure that there are no collisions between cyclists when observing the European XFEL. At lunchtime, in particular, cyclists pass through the tunnel system linking the site of the German electron synchrotron research centre (Deutsches Elektronen-Synchrotron – DESY) in Hamburg with the research campus in Schenefeld in the state of Schleswig-Holstein, where the underground X-ray facility is being developed. At 3.4 kilometres in length, it is no wonder that the on-site technicians prefer to go by bike rather than on foot. But even the fastest cyclists among them only manage to achieve a fraction of the speed of the facility lining their path.
In the facility's particle accelerator of around two kilometres in length, electrons (round elementary particles) are accelerated up to almost the speed of light. As they fly through a magnetic zig-zag course, they generate very short and very bright X-ray laser pulses. “The European XFEL produces ultra-short laser-light pulses in the X-ray range up to 27,000 times per second – with billions of times more luminosity than that of conventional sources of X-ray radiation,” explains Torsten Böckmann from DESY’s cryogenics (low-temperature technologies) division. DESY is a majority shareholder in the project, which involves eleven European countries, and is working together with international partners to construct components such as the accelerator. “Just like a gigantic microscope, the laser will make it possible to see even the smallest of atoms and molecules, which will provide scientists and industrial users with completely new research possibilities from 2017,” Böckmann explains.
To speed up particles to almost the speed of light, DESY uses a specially developed technology concept. Super-conducting, high-frequency resonators (cavities) transfer the energy of the supplied electromagnetic fields to the particle beam – in an almost loss-free, and therefore extremely efficient, process.
Loss-free acceleration needs a cold environment
“In order to ensure that the electromagnetic fields can oscillate in the HF resonators without any losses, they need an extremely cold environment. This is why they are located in thermally insulated tubes, where helium is used to create a temperature of two kelvin, which is around minus 271 °C,” Böckmann continues. “We use special cooling systems to produce the necessary
Jochen Bonfigt of Weidmüller (left-hand side) with Torsten Böckmann (centre) and Olaf Korth of DESY
amounts of superfluid helium-2. These cooling systems use a two-stage process to cool down the helium, which starts off in gas form, before it can then be distributed in its fluid state”.
For precise temperature control, specially developed Cernox and TVO cryogenic temperature sensors with customised characteristic curves are used. And in order to ensure that measurements can still be performed without interruption in the event of a defect, all sensors feature a double or triple redundant design.
There are around 2,000 marshalling panels using the PRV from Weidmüller to ensure order and safety when it comes to sensor wiring
Application-specific terminal block solution for DCS marshalling
“Due to the reserve sensors, direct connection of the 0.14-mm² temperature lines would lead to a large number of open wire ends. The people at DESY therefore opted for wiring via marshalling panels,” explains Weidmüller sales representative Jochen Bonfigt, who has been assisting in the development of the European XFEL project for many years. “Around 2000 panels are required, and these are produced in series production according to industrial standards. We use our application-specific terminal block PRV, which enables the most compact marshalling solution with PUSH IN technology on the market”.
The 1.5-mm² terminal block with up to 16 layers boasts a space-optimised format, and has plenty of space for reserve inputs thanks to its high signal density. The identification aids on the product deliver yet another planning benefit, as the coloured matrix structure with “checkerboard design” allows for fault-free signal allocation.
“Wiring is performed before installation. For service work in the control cabinets, which are located in a rather confined space behind the acceleration modules in the European XFEL tunnel, the easy orientation is hugely beneficial,” confirms Bonfigt. “The same applies to the tool-less operation of our PUSH IN terminal blocks. The option of performing re-wiring work without any special tools makes the PRV a particularly maintenance-friendly solution in ensuring ongoing operation”.
The signals are subsequently distributed to the central control room in the refrigeration hall, where all processes relating to the cooling system are monitored 24 hours a day, 365 days a year. As a system failure would mean interruptions to ongoing experiments, maintaining availability is of the highest priority.
In addition to the PRV terminal blocks, active Weidmüller components also play a role here. Power-over Ethernet switches are used for the oscillation sensors, for example, and the parallel data and energy transfer noticeably reduces the amount of wiring work between the networked devices.
Contribution to major research
Weidmüller is involved with the pioneering European XFEL project thanks to its marshalling and data transmission solutions, meaning that individual components are helping to contribute to major research. This seems particularly fitting in light of the major riddles the research facility will solve in the future using the very smallest particles. From the decoding of biomolecular structures to the filming of chemical reactions, through to the investigation of matter in extreme conditions, the XFEL X-ray laser will be leading the way. And who knows, maybe the new materials or technologies developed as a result will be able to give the cyclists in the European-XFEL tunnel a bit of a speed boost in the future too.
Control room in the refrigeration hall: the signals routed via the PRV meet here
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Weidmüller terminal blocks
Published in November 2015