What is SRF used for?

Superconducting radiofrequency (SRF) technology is a means of accelerating subatomic or atomic particles like electrons, protons, or ions. Acceleration via SRF offers the advantage of immense power savings, though at the cost of the ultra-low-temperature refrigeration that is required for superconducting operation. In general, after accounting for refrigeration, particle acceleration with SRF nets better than two orders of magnitude in power savings—and also yields important benefits in the quality of the accelerated beams.

As both a science and a technology, SRF is a complex multidisciplinary field that is still advancing. Not all of SRF’s limits or applications are yet known, and it has not reached a technological plateau. To engage SRF in all its research-and-development dimensions requires work in overlapping areas that include solid-state physics, surface science, low-temperature physics, electromagnetism, materials science, RF and microwave technologies, feedback and control systems, interactions between radio waves and the beams they accelerate, vacuum science, mechanical engineering, and cryogenics.

Worldwide, SRF is used in or planned for a number of existing, impending, or envisioned facilities for research in high-energy physics, nuclear physics, nuclear astrophysics, life sciences, and materials science, as well as in facilities or equipment for applied research, industrial processing, and directed-energy weapons.

Most of SRF’s best-known actual or prospective applications fall into four categories:

• Low- to medium-current continuous-wave (CW) accelerators like CEBAF (the Continuous Electron Beam Accelerator Facility at Jefferson Lab) and the envisioned U.S. Rare-Isotope Accelerator ( RIA) for nuclear astrophysics.
• Pulsed high-current proton or ion accelerators like the proton accelerator that Jefferson Lab built at the heart of the new Spallation Neutron Source ( SNS) at Tennessee’s Oak Ridge National Laboratory. The SNS will provide the most intense pulsed neutron beams in the world for scientific research and industrial development.
• Pulsed high-energy linear accelerators for electrons and other leptons, including linear colliders like the International Linear Collider ( ILC), muon colliders, and neutrino factories.
• Energy-recovering linear accelerators (ERLs) in electron coolers and in light sources, including the SRF ERL that drives Jefferson Lab’s free-electron laser ( FEL)—the world’s most powerful source of tunable laser light. Cornell University and England’s Daresbury Laboratory are building SRF ERLs based on the Jefferson Lab FEL’s proof of the energy-recovery principle.