CS21 – Alloy K-500 – Science & Technology Facilities Council

Left – drift tube installed in vacuum chamber

Right – schematic of drift tube showing mounting rod fabricated using Alloy K-500

The Science & Technology Facilities Council (STFC) is one of Europe’s largest multidisciplinary research organisations, supported by the UK Government. They employ more than 1700 people, split across two main sites, the Rutherford Appleton Laboratory at Harwell and Daresbury Laboratory near Runcorn, supporting around 800 PhD researchers at any point in time.

STFC supports research in many fundamental fields such as particle physics, nuclear physics and astronomy, with the objective of understanding how the universe works, and ultimately supporting the UK economy.

The linear accelerator is an extremely large vacuum chamber used to conduct experiments in particle physics. Within this 12m long and 1m diameter tank, particles are accelerated to great speeds by a Radio Frequency generator and collided with each other. The particles are focused by passing through so-called drift tubes that contain a powerful magnet – these drift tubes appear in the image as the rugby ball-shaped units hanging from the wall.

STFC approached Langley Alloys looking for a suitable material to fabricate the inner sleeve of the mounting rod. Alloy K-500 was selected for this application due to its performance against a number of key criteria:

• Non-magnetic over the wide range of operating temperatures, so that it does not influence the particle focusing process
• Compatible with other materials used in the fabrication, specifically the thermal expansion coefficient of Alloy 304 stainless steel and copper sheet
• High strength and stiffness to robustly support the suspended magnet with a relatively thin support
• Resistance to general degradation, as units cannot subsequently be repaired due to the presence of radiation in the chamber