Oxygen Tweaking May Be the Key to Optimizing Particle Accelerators

Modeling the diffusion of oxygen into accelerator cavities allows scientists to tailor their properties.

The Science

Powerful particle accelerators enable the research of thousands of scientists in physics, chemistry, and biology. Many of these machines rely on superconducting radiofrequency components made of niobium. This metal becomes superconducting, and thus extremely electrically efficient, at low temperatures. Nuclear physicists found that dissolving oxygen atoms a few micrometers into niobium greatly improves the performance of components made of the metal. Now, the researchers are perfecting a model using different processes for adding oxygen. This model maps out how tweaks in the process change the material. The model also allows researchers to predict how components will perform based on how they are produced.

The Impact

The research also helps explain how oxygen changes the behavior of niobium. Magnetic vortices can form in the material due to high magnetic fields during accelerator operations. The magnetic vortices produce heat and limit performance in niobium components. The oxygenated niobium allows for stronger magnetic fields without generating the vortices and producing excess heat. The new model also shows how to improve future production processes for niobium. Teams preparing components for various accelerator projects can now use this new model to tailor a component production process that will yield a desired performance level.

Summary

State-of-the-art particle accelerators enable research into the particles that make up matter, designs for more efficient batteries, and methods to develop new medicine. Accelerator scientists and nuclear physicists are improving particle accelerators by improving the model used to leverage the special properties of niobium. By preparing samples using different component production techniques and using secondary ion mass spectrometry measurements to analyze the samples then test performance, the researchers produced data that informed a new model for accelerator facilities to use.

This new model specifies how native surface oxides dissociate and diffuse into a niobium component’s surface as a function of temperature and time during the production process. The model also links variations in surface oxygen content with both a component’s energy efficiency and its peak accelerating field. Peak accelerating field is a marker of a component’s effectiveness. The model further links all of these factors to the component’s performance and details how tuning these factors will affect future performance. This means that this model can now be used to begin tailoring accelerator component surface preparation precisely in order to get the best possible and most reliable performance.

Contact

Funding

This material is based on work supported by the Department of Energy (DOE) Office of Science, Office of Nuclear Physics and Office of High Energy Physics and by a DOE Office of Nuclear Physics Early Career Award.

Publications

Lechner, E.M., et al., Oxide dissolution and oxygen diffusion scenarios in niobium and implications on the Bean–Livingston barrier in superconducting cavities. Journal of Applied Physics 135, 13 (2024). [DOI: https://doi.org/10.1063/5.0191234]

Lechner, E.M., et al., RF surface resistance tuning of superconducting niobium via thermal diffusion of native oxide. Applied Physics Letters 119, 8 (2021). [DOI: https://doi.org/10.1063/5.0059464]

Related Links

Oxygen Tweaking May Be Key to Accelerator Optimization, Jefferson Lab news release

Accelerators May Get a Boost from Oxygen, Jefferson Lab news release

Smoother Surfaces Make for Better Accelerators, Jefferson Lab news release

Cooking Up a New Theory for Better Accelerators, Jefferson Lab news release

Highlight Categories

Program: NP

Performer: University , DOE Laboratory , LCLS , SNS , CEBAF