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Cavity testing results show promising start

In a project managed through Daresbury Laboratory, high beta cavities destined for the European Spallation Source (ESS) have started to be tested, with very positive results. Cavity validation testing is one of many work packages STFC is involved with as part of the UK’s in-kind contribution to the international project. This specific work package includes testing to qualify the performance of the cavities against a specification set by ESS, before shipping them with the relevant quality control paperwork.

In total, 88 high beta superconducting accelerating cavities will be built in Europe for the ESS – a crucial component because they will determine how fast the protons will travel in the accelerator. ESS is hoping to accelerate protons at around 90% the speed of light, so it is vitally important that the cavities are fully functional and clean when they are fitted.

The first cavity test, a ‘pre-series’ unit took place at DESY laboratory, Hamburg, as part of the qualification of all the production processes and equipment at the cavity manufacturer’s facility, also in Germany. Testing includes radio frequency (RF) assessments in cryogenic conditions. In this case, cooling the cavities down to 2 kelvin (-271°C) by immersing them in liquid helium, inputting RF power, and measuring the electric fields achieved.

What is a pre-series cavity?

Pre-series cavities are those made early in the manufacturing process. They are subject to additional analysis to prove that the way they are being constructed is up to the required standards. For this project, there will be four pre-series cavities in total. 

The first run of tests has ended on a positive for the team involved, as results showed it was testing at a higher performance than the ESS specification required, and results were able to be correlated against prototype testing carried out by other contributors involved in the ESS programme. Work has now begun on the remaining three pre-series cavities.

In parallel, commissioning testing has also been progressing very well in the new vertical test facility. The new test facility has been designed and built by Daresbury Laboratory experts and will ensure that all production cavities can be tested while maintaining cleanliness to a particulate level.

These achievements mark a very significant phase shift in the work package from planning to delivery, with the full series cavities beginning to arrive at Daresbury Laboratory for validation from January 2020 and will continue to arrive and be tested throughout the year.

Find out more about the Accelerator Science and Technology Centre at Daresbury Laboratory.  


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Last updated: 07 August 2019


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