Optical Fiber Integration Into Bi2Sr2CaCu2Ox/Ag/AgX and
(RE)Ba2Cu3Ox Superconducting Coils—Lupine Materials and Technology (LMT), 104 Solitude Way,
Cary, NC 27518-8994
Justin
Schwartz, Principal Investigator, justin_schwartz@ncsu.edu
Golsa
Naderi, Business Official, golsa.naderi@gmail.com
Amount: $1,000,000
High-temperature
superconductors (HTS) are a vital technology for future particle accelerators,
motors, generators and other electric power systems, fusion reactors, and many
other medical and defense applications requiring high magnetic fields. One
remaining limiting factor limiting to the implementation of HTS systems is the
lack of adequate sensors to monitor the temperature and strain states of the
superconducting magnets (SCMs), and in particular for rapid and early quench
detection, as the slow normal zone propagation velocity of HTS conductors
results in a particularly difficult quench protection challenge. Without
effective quench protection, HTS magnets are likely to fail catastrophically,
so addressing this challenge is critical to technological success. Previously,
it has been shown that the quench detection challenge may be addressed by
integrating optical fibers interrogated by Rayleigh scattering into HTS SCMs,
providing a novel, fast quench detection system which is particularly impactful
on but not limited to HTS SCMs. Optical fibers can be integrated with conductor
or cables providing a distributed measurement of temperature and strain with
very high spatial and temporal resolutions. Many key questions remain, however,
for Rayleigh-interrogated optical fiber (RIOF) quench detection to become an
accepted sensor within SCMs. One of these questions was whether RIOF would
provide sufficient sensitivity at very low temperature (4.2 K); this was
successfully addressed in Phase I. In Phase I, we integrated optical fibers
into HTS coils and demonstrated effective quench detection at 4.2 K.
Small coils were wound with integrated optical fibers, voltage taps (VTs) and
embedded heaters to generate thermal instabilities, cooled in liquid helium and
tested at 4.2 K. Through these experiments RIOF performance at 4.2 K was shown
quantitatively to be effective. In Phase II, we propose to address remaining
scale-up and reliability issues, improve overall performance, and integrate
fibers into significantly larger magnets. The aim is to demonstrate that RIOF
can be implemented along every step of the way to operating a successful HTS
magnet, including integration into the winding, monitoring of
cool-down,
ramp-up, steady-state operation, and quench detection. Furthermore, we
recognize that a key non-technical issue for implementation of RIOF in magnets
is going to be customer confidence, which only comes with time and experience.
Through the Phase II objectives, the SCM community will obtain more evidence
that RIOF can be effective and reliable.
Superconducting
magnets based on high temperature superconductors are limited by the lack of an
effective distributed sensor to prevent magnet failure. Optical fiber sensors
have shown the ability to meet this need, but many challenges related to
scale-up and reliability remain; these will be addressed, opening the door for
superconducting applications.
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