The LHC has been busy generating data for the past couple of years in order to find the Higgs boson. But now it has it is taking a well earned rest and in the meantime a Lancaster student is helping to increase its energy reach for when it returns. Up to now LHC has not been able to reach its full 14 TeV energy due to problems in the interconnections on the superconducting magnets. A failure in one of these resulted in a catastrophic explosion nine days after start-up. The CERN staff were able to recover from this but they have waited till now to repair it.
During the break (known as Long Shutdown 1 or LS1), the interconnections will be repaired on 10,000 magnets. To do so they need to punch a hole in the thermal shields around the magnets at the interconnections. All the welds will then be replaced with bolts for future ease of access and maintenance. However no current hole punch is small enough to fit while having enough force to puncture the shield, and using a hand drill is both awkward and time costly, hence a new hole punch was required. The task for designing this fell to Loren Wright, a 4th year mechanical engineering student at Lancaster University, who is currently taking a year at CERN to gain experience.
Loren says “For the design, we ran into a few problems; I had to do a lot of stress analysis and modifying of the original design in order to reduce stress intensities as we need each hole punch to do around 1000 cycles, and therefore cannot have extreme plasticisation within the material as this would lead to earlier failure. This meant employing several techniques such as filleting sharp edges and reducing large jumps in material thickness through the component etc. The design itself is now complete and the technical drawings have been approved for manufacture, so now it is just a case of battling with French suppliers over ordering some of the components!”
For more on the LHC LS1 work please visit
http://cerncourier.com/cws/article/cern/52361
Figure 1: CAD model of final design (some connection components, such as bolts and the encircling front plate, have been omitted for easier viewing)