Sensitive Fiber Optic Sensor for Rapid Hot-Spot Detection at Cryogenic Temperatures
Xiyong Huang, Mike Davies, Dominic A. Moseley, Jofferson T. Gonzales, H.W. Weijers, Rodney A. Badcock
Abstract
The incredible current density and high magnetic field generation possible with high-temperature superconductors (HTS) have the potential to revolutionize energy generation, e.g. high-power generators, and compact fusion energy devices. However, an open issue that limits the applications of this class of superconductors is the challenge of rapidly detecting a hot spot which can lead to a quench. Owing to the inherent advantages of fibre optic sensors, they are promising candidates to be integrated in HTS magnets for hot-spot detection. In this paper, closely spaced fibre Bragg gratings (FBG) with the same Bragg wavelength are used to establish an ultra-long FBG (ULFBG) for distributed hot-spot monitoring. We investigate the capability of a 10m ULFBG to detect a small temperature rise at the end of the sensor. The results show that a 10 m long ULFBG can rapidly detect a small hot spot within 1 K temperature rise at 80 K. It is expected that ULFBG can be wavelength-division multiplexed and integrated to superconducting coils to achieve long-distance hot-spot monitoring with extremely high spatial resolution and fast response.