Superconducting Radio Frequency

Superconducting Radio Frequency (SRF) science and technology involves the application of electrical superconductors to radio frequency devices. The ultra-low electrical loss of the superconductor yields RF resonators with extremely high quality factors, or Q. For example, it is commonplace for a 1.3 GHz niobium SRF resonant cavity at 1.8 kelvins to obtain Q=5×1010. Such a very high Q resonator and its narrow bandwidth can then be exploited for a variety of applications.A comparison often cited to gauge the minute amount of loss in an SRF resonant cavity is that if one of the first investigators of pendulous motion, Galileo Galilei, had experimented with a 1 Hz mechanical resonator that had a Q that is achieved by today's SRF cavities, and had left one of his pendulums swinging since the early 1600s in a sepulchered lab, then it would still be swinging today with about half of its original amplitude!Photograph of the Cornell storage ring 500 MHz SRF cavity being lifted out of a cryogenic test dewar while still cold.