A prototype accelerator cavity being used to test equipment ahead of a major project at STFC’s Daresbury Laboratory has recorded results so good that it’s had the ultimate seal of approval – reclassification!
When cavity 203 landed at Daresbury Laboratory from the US Department of Energy’s Fermi National Accelerator Laboratory (Fermilab), it was a prototype for the Particle Improvement Plan II project.
Why prototyping cavities is crucial
Accelerator projects create prototype cavities for two main reasons:
- To ensure that the cavity design is actually fit for purpose.
- To ensure that the facilities which will be testing or fitting the cavities into the cryomodules are getting the expected results – this is known as the commissioning and verification process.
In this case, the key objective was to put the cavity through the testing and cleaning process in Daresbury’s superconducting radio frequency lab (SuRF Lab) facility to cross reference test results. One key parameter was radiation readings - readying the facility for the forthcoming cavity testing programme.
In parallel the team are also prepping infrastructure for cryomodule building as part of the UK’s contribution to PIP-II.
The high pressure rinse facility at the lab is utilised for the cleaning process of non- conforming cavities and has been upgraded in order to accommodate the PIP-II cavities which are much bigger than previous models coming through the resource. This has been several months of work for the team involved before the cavity had even arrived.
After initial benchmark testing, the cavity was successfully rinsed over a 12-hour cycle, where the internal parts of the cavity are washed by ultra-pure water. It was then transferred via crane into the vertical test facility bunker where it was chilled down to two Kelvins. A series of tests, primarily checking the accelerating gradient, quality factor and any field emissions (radiation levels), were measured against the benchmark.
This commissioning process has proved a massive success, achieving a number of important project milestones, including:
- Validating the high-pressure rinse facility.
- Being the first in the collaboration to demonstrate removal of all field emission from a cavity through cavity rinsing.
- Ability to test a PIP-II cavity with comparable results to Fermilab.
- Verifying magnetic field. The magnetic hygiene process ensures that the cavity is kept within the permissible limits in the testing bunker and during module integration.
Cavity 203 arrived at Daresbury as a prototype, it’s purpose to get facilities up to scratch for when the series cavities arrive (those being build for the cryomodules), by cross checking results achieved here with a set of baseline results from Fermilab. However, the results were so good, and the High-Pressure rinse facility performed so well removing all radiation contamination, that Fermilab have revealed that the cavity will actually be the first to be integrated into one of the three cryomodules to be build at Daresbury Laboratory.
Mark Pendleton, Operations Manager in the SuRF Lab facility is thrilled at the results:
“The dedication and expertise from the team here have led us to achieving significant milestones early in the commissioning phase. The most significant could be the validation of the high-pressure rinse facility and processes, eliminating all field emission from a cavity through effective rinsing - this could prove a significant step moving forward for new assembly processes, reducing delivery times and costs. These achievements underscore excellence and our commitment to the PIP-II collaboration, and overall project success. Well done to all involved.”
Read more:
Transport tests for a PIP-II cryomodule
Daresbury Laboratory gives PIP-II cryomodule a warm welcome
PIP-II international partnerships
Image: STFC colleagues from the Technology Department and ASTeC are pictured with cavity 203 in the SuRF Lab at Daresbury Laboratory. Credit: STFC
This article was originally written and posted on STFC's LinkedIn page.
