Cryogenic distributed temperature monitoring (Cryo-DSS)

To insure safe operation of new cryogenic superconducting degaussing cables , used to cloak the magnetic signatures naval vessels, distributed temperature measurements are needed every 1 m over 200 m lengths from 25K to 300K. Present electronic temperature sensors conduct heat into the cables, which can cause catastrophic failure in superconductors. Therefore, distributed fiber optic temperature sensors are sought that overcome the lack of thermal sensitivity in silica fibers at the cryogenic operating temperatures of high temperature superconductors. Luna will monitor temperatures along specially designed optical fibers without needing to write fiber Bragg Gratings into the fibers. Luna’s approach will decrease the fabrication cost of the distributed fiber sensors. During Phase I, the thermal sensitivity and optical properties of custom glass compositions will be demonstrated, so that in Phase II the full system will demonstrate distributed cryogenic temperature measurements. A key benefit of Luna’s approach is that it enables high spatial resolution to monitor the growth of non-superconducting zones in a winding, whereas alternative discrete fiber Bragg gratings can only monitor the proper operation of the cryostat.