Optical fiber based sensors for low temperature and ... › event › 578818 › contributions › ...• Institute of Polymers, Composites and Biomedical materials (IT) 1st access

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…


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


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


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


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


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


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


FBG characterization in the cryo cooler

Material study• Sensitivity improvement

• Design optimization

Sensors calibration• Non linearity

• Repeatability along the cycles


FBG for cryostat temperature monitoring

• Integration in the Superconducting Link horizontal cryostat• He gas cooling

• 20-m-long MgB2 cable characterization


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


• 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


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


Cernox cryostat

temperature

FBG Coil

Temperature

Publications


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


Optical fiber based sensors for low temperature and ... › event › 578818 › contributions › ...• Institute of Polymers, Composites and Biomedical materials (IT) 1st access

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