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EuCARD-2 is co-funded by the partners and the European Commission under Capacities 7th Framework Programme, Grant Agreement 312453
Optical fiber based sensors for low temperature and superconductors
Antonella Chiuchiolo
4th EuCARD-2 Annual MeetingGlasgow 28 – 30 March 2017
Outline
• Fiber Optic Sensors for the TNA
• Fiber integration in the test facility SM18
• FOS for cryogenic temperatures
• FOS for superconducting magnets
• Conclusions
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 2
Fiber Optic Sensors for TNA
• Fiber Optic Sensors FOR CRYogenic ApplicatiOns and Superconducting Magnets
• University of Sannio (IT)
• University of Napoli, Federico II (IT)
• University of Padova (IT)
• University of Debrecen (HU)
• Institute of Polymers, Composites and Biomedical materials (IT)
1st access granted 20th of November 2013
…to develop a non intrusive technology based on FOS for
strain and temperature monitoring in the new generation of
superconducting magnet and cryogenic devices…
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 3
Horizon 2020
4Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow
UniversitiesIndustries
Research Institutes
Fiber Optic Sensors for TNA
• Assessed Technology
Small size and lightweight
Immunity to electromagnetic interference
Intrinsic electrical insulation
Radiation hardness capability
Wide operating temperature range
Multiplexing
5Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow
Innovation
no commercial available FOS for cryogenic applications and superconducting magnets
• Fiber Bragg grating (FBG) sensors
• Rayleigh scattering distributed sensors
Wiring reduction in a complex environmentRemote monitoring
No heat-leak into the cryogenic bath
Fiber Bragg Grating sensor
• FBG: longitudinal periodic variation of the refractive index in the optical fiber core
6Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow
DlB (T, e)
Cladding
CoreBroadband light
BlBl
Strain and Temperature sensitive:
Ta
B
B DDD
)()1( el
l : photo elastic coefficient
: thermo-optic coefficient
: thermal expansion coefficient
a
effB n2l
lB: Bragg Wavelength
neff : effective refractive index of the core
Λ: grating period
FBG for Cryogenic
The thermal response of a bonded or
embedded FBG is dominated by the thermal expansion/contraction of the host material
[H. Zhang et al. IEEE Transactions oh applied superconductivity,
VOL. 18, NO. 2, 2008]
Bare FBG
Coated FBG
Commercial Polyimide
30 mm thickness
12 mm
2 mm
5 mm
25 mm
Customized PMMA
5 mm thickness
Customized Epoxy
2 mm thickness
30 mm
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 7
FBG temperature sensitivity:
8 - 12 pm/K @ room T
< 0.1 pm/K below 50 K
Bare FBG no suitable for cryogenic temperature!
Fiber integration in the test facility SM18
• Sensors- Single Mode fiber
- Commercial sensors
- Customized sensors
• Data Acquisition System– Optical Interrogators: sm125, sm130
and Hyperion modules
– 4 channels , 2 Hz - 1 KHz, 90 – 160 nm
• Connections- Fusion Splice Machine for fiber reparation
- Optical connectors and feedthrough to equip the test facility
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 8
Fiber integration in the test facility SM18
Horizontal cryostat for HTS cable
of 20 to 60 meter length:
Helium Gas cooling
Vertical cryostat for testing
magnets down to 4.2 K
and 1.9 K:
Liquid and
Superfluid Helium
Horizontal benches
RF test area
Visitors
Cryogenics
Visito
rsVertical cryostats
SC - Link
Fiber Lab
Cluster D
For magnet cold
powering
up to 30 kA
Cryogen free cryostat for testing
FOS with 4.2 K
Pulse Tube Refrigerator
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 9
Vertical cryostat for
testing mechanical properties of
large magnet structures down to
77 K:
Liquid Nitrogen
FBG characterization in the cryo cooler
• Dedicated cryogen- free test station• He gas cooling down to 4 K with
Pulse Tube refrigerator
• Temperature control
FBG and reference sensors set-up
Material study
Sensors Calibration
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 10
FBG characterization in the cryo cooler
Material study• Sensitivity improvement
• Design optimization
Sensors calibration• Non linearity
• Repeatability along the cycles
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 11
FBG for cryostat temperature monitoring
• Integration in the Superconducting Link horizontal cryostat• He gas cooling
• 20-m-long MgB2 cable characterization
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 12
He gas temperature monitoring over 20 mwith calibrated FBGs anddistributed Rayleigh scattering based sensors
Wiring reduction:• 4 CCS: 16 wires • 4 FBG: 2 wires
Connection side
He gas temperature monitoring over 20 m with calibrated FBGs and distributed Rayleigh scattering based sensors
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 13
• FBGs: agreement with CCS within 1 K at 30 K
• Rayleigh scattering: map over distance with spatial resolution of 5 cm
FBG for cryostat temperature monitoring
FBG for superconducting magnets
• Integration in the magnet structures and coils• Nb3Sn racetrack short model coils
and quadrupoles
• High Temperature Superconducting magnets(H.Bajas talk)
Temperature monitoring
Strain monitoring during magnet fabrication and operation
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 14
Nb3Sn Racetrack coil Magnet assembly
FBG for superconducting magnets
Temperature monitoring inside the coil• Magnet cool down from
300 to 1.9 K
Strain monitoring inside the coil• Magnet powering to 15 kA @ 1.9 K
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 15
Cernox cryostat
temperature
FBG Coil
Temperature
Publications
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 16
Conclusions
• The SM18 test facility is now fully equipped for FOS integration and tests at
cryogenic temperature
software integration in the facility needs further development
• FBG for cryogenic temperature monitoring have been developed
material study is still needed to enhance the sensitivity at 4 K
• FBG and Rayleigh scattering based sensors can be integrated in the facility
cryostats for temperature monitoring
Sensors packaging solution needs further development
• FBG can monitor the magnet thermo-mechanical behaviour of the magnet from
fabrication to operation
Integration needs to be improved
Distributed sensors solution needs to be implemented
Antonella Chiuchiolo - 4th EuCARD-2 Annual Meeting - Glasgow 17