Spontaneous Brillouin Scattering Temperature/Strain Sensors for CICC Superconductors

A real-time distributed sensor is needed for superconductivity quench detection in large superconducting magnets, such as those used in plasma fusion confinement systems. This project will use spontaneous Brillouin backscattering to achieve simultaneous spatially-resolved temperature and strain determination in real time in cryogenic environments, by measuring the Brillouin frequency shift and the gain bandwidth simultaneously. The innovation involves the coherent radio frequency (RF) detection of spontaneous Brillouin scattering (SBS) in fiber by using a CW single-frequency Brillouin fiber laser as a frequency-shifted local oscillator. The approach optically moves the coherent Brillouin beat signal from the conventional microwave range into the radio frequency range, enabling a system that can measure the Brillouin frequency shift and the gain bandwidth in real time with advanced digital techniques (such as DSP and FPGA). The immunity of the fiber optic sensor to electromagnetic fields will make it an ideal candidate for a quench detection system and for a general superconducting magnet diagnostic during heat treatment, charging, running, and even during the quenches. Commercial Applications and other Benefits as described by the awardee: The successful accomplishment of this project should revolutionize sensor technologies used for temperature and strain sensing in cryogenic environments. In addition to the fusion application, the technology should find wide use in large facilities such as power plants and particle accelerators. Finally, a real-time distributed temperature/stain sensor could provide an advance warning capability and eventually generate countermeasures that minimize the effects of terrorism, or of natural and accidental events.