Title: Report on radiation effects on optical fibres at SCKCEN: H2loading, infraredfibres and fibre current
1Report on radiation effects on optical fibres at
SCK?CENH2-loading, infrared-fibres and fibre
current sensor Nuclear Belgian Research
CenterBoeretang, 2002400 Mol Belgium
Benoît Brichard, Hans Ooms, Stan van Ierschot,
Jean Pouders, Stan Hendrieckx Instrumentation
Department Tel 32 14 33 26 40 Secr 32 14
33 26 07 Fax 32 14 31 19 93 bbrichar_at_sckcen.be
www.sckcen.be
2Overview
- Progress in on-going EFDA-IRRCER fibre-related
tasks
Development Irradiation testing of
radiation-resistant fibres TW5-TPDC/IRRCER-Deliver
able 1 2
IR fibres for thermography application gamma
radiation-sensitivity TW4-TPDC/IRRCER-Deliverable
16
fiber current sensor behaviour at cryogenic
temperature TW5-TPDC/IRRCER-Deliverable 9
- New fibre optic technology for ITER a proposal
3Defects and imperfections cause photons to be
absorbed at specific wavelengths in fibres
Intrinsic spectral absorption in silica fibre
dB/km
Total intrinsic optical absorption llt 0.6 µm gt
10-2 dB/m 1.8 µm gt l gt 1 µm lt 1x10-3 dB/m
104
102
Waveguide imperfections
Rayleigh scattering l-4
1
Radiation creates additional or new defects
200
600
1000
1400
1800
2200
Wavelength nm
4Two categories of defects in SiO2
Paramagnetic Centres
Diamagnetic Centres
Oxygen Deficient Centre (ODC) Si-Si OA 5
eV PL 7.6 eV Peroxy Linkage (POL) Si-O-O-Si OA
7.1 eV ? (recent assignment)
Only indirect optical evidences
Detected by EPR/ESR spectroscopy
Can act as defect precursors for paramagnetic
defects
5Radiation affects the optical properties of
silica
- Radiation-Induced Absorption (RIA)
- Due to defect formations E,NBOHC,POR,STH,
- Radiation-Induced Luminescence (RIL)
- Due to Photoluminescence
- Due to Cherenkov effect in SiO2
- Radiation-Induced Refractive Index Change (RIRIC)
- Compaction-densification
- Colour centres
6H2-treatment drastically reduces the 2 eV RIA
band formation in all type of fibres
Fissionreactor irradiation of High OH silica
fibres 200 µm core Acrylate coated
B. Brichard, A. L. Tomashuk al., SCK?CEN, J. of
Nucl. Mat., 329, p1456, 2004
7H2 slows down the RIA growth at 600 nm while OH
content is enhanced at the same time
Low OH silica with H2
RIA dB/m
Low OH silica without H2
550
670
790
1030
1390
550
670
790
1030
1390
Wavelength nm
Wavelength nm
8At low dose the H2-STU fibre showed the best
radiation-resistance
RIA dB/m
5x1015 n/cm2 200 kGy 330 Gy/s 60C 3 MGy
(pre-ionised)
10
Radiation-hardness factor _at_ 600 nm
10
5
Ranking _at_ 600 nm
0
400
600
1000
1400
Wavelength nm
9When the H2 is exhausted RIA quickly re-increases
RIA dB/m
30
7.12x1017 n/cm2 23 MGY 80C
600
1000
1400
Wavelength nm
10- How to keep
- H2 into the glass network ?
11We follow two complementary but different
strategies
- The previous results demonstrate the clear
advantage of treating silica optical fibres with
hydrogen to improve the radiation resistance of
the optical transmission in the visible spectral
region. - However, the optical transmission start degrading
again as soon as the hydrogen is exhausted.
12SMIRNOF VI irradiation device upgrade for
handling depleted-H2 atmosphere in reactor
13A two step irradiation
Irradiation conditions in BR2-SIDONIE irradiation
channel at full power (56 MW)
Neutron flux 1.7x1014 n/cm2s Epithermal flux
4.6x1013 n/cm2s Fast neutron flux (gt1 Mev)
1.9x1013 n/cm2s Gamma Heating 3 W/gAl
14Overview
- Progress in on-going EFDA-IRRCER fibre-related
tasks
Development Irradiation testing of
radiation-resistant fibres TW5-TPDC/IRRCER-Deliver
able 1 2
IR fibres for thermography application gamma
radiation-sensitivity TW4-TPDC/IRRCER-Deliverable
16
fiber current sensor behaviour at cryogenic
temperature TW5-TPDC/IRRCER-Deliverable 9
- New fibre optic technology for ITER a proposal
15Divertor thermography with IR fibres
Divertor Cassette is a high temperature region to
be continuously monitored for machine protection
IR thermography proposed by CEA-Cadarache
Tore-Supra
IR fibre ?
Divertor Cassette
16IR-Fibres could be used to transport IR radiation
from the divertor port to the bioshield
- Low OH Silica 1-2 µm
- Sapphire 1-3.5 µm
- max 3 m
- ZrF4 1-4 µm
- Up to 250C
- Chalcogenide 1-11 µm
- Up to 150C
- Metal-coated fibres 3-17 µm
- Low NA
- PBG fibres / Bragg Fibres
- ???
Line of Sight
mirrors
Fibres
- 8.5 m up to Bioshield
- Large Wavelength Span
At the divertor port 1019 n/cm2 (Egt0.1 MeV) 1
Gy/s gt10 MGy
Cassegrain Telescope
17Experimental set up to measure on-line
radiation-induced absorption in IR fibres
Fibre
Lock-in
IR Spectrometer
Lamp
Labview DAQ
RITA Irradiation container
CEA Acquisition (R. Reichle)
18Radiation sensitivity depends on the wavelength
and type of fluoride compound material used
RIA decreases with increasing wavelength
RIA dB/m
3 kGy
Recovery 17 h
Wavelength in nm
19Similar RIA in ZrF4 fibre from other
manufacturer.
3 kGy
2.5
5.2 kGy
Zirconium Fluoride (RA6) - Polymicro
2.0
1.5
RIA dB/m
2 µm
1.0
0.5
Recovery
0.0
4
0.0
4
5
5
5
5
5
5
-5.0x10
5.0x10
1.0x10
1.5x10
2.0x10
2.5x10
3.0x10
3.5x10
Time in seconds
20Hollow Waveguide Fibre good radiation resistance
but extremely sensitive to bending
Hollow Waveguide 750 µm core 2 meters
Hollow Waveguide From Polymicro
No change observed after 27 kGy !
21Preliminary Conlusion on IR fibres
- For 1-2 µm, low-OH pure silica is a good
candidate. However, we need more data on neutron
damage at 2 µm
- Above 2 µm,
- Zirconium/ Hafnium Fibre much more
radiation-sensitive than silica - Hollow-Waveguide, good candidate but
high-intrinsic loss and difficult to handle
- Still to test Saphirre Fibre (and Chalcogenide ?)
- Also looking for PBG (Bragg) silica fibre
operating in 2-3 µm
22Overview
- Progress in on-going EFDA-IRRCER fibre-related
tasks
Development Irradiation testing of
radiation-resistant fibres TW5-TPDC/IRRCER-Deliver
able 1 2
IR fibres for thermography application gamma
radiation-sensitivity TW4-TPDC/IRRCER-Deliverable
16
fiber current sensor behaviour at cryogenic
temperature TW5-TPDC/IRRCER-Deliverable 9
- New fibre optic technology for ITER a proposal
23Optical Fiber Current sensor in ITER ?
Conventional plasma current measurement system
like Rogowski coils looses sensitivity in quasi
steady state plasma
Interest for Fibre Current Sensor ?
Faraday Effect
Magnetic Field rotates the incident polarization
state by an amount proportional to the Verdet
Constant µV.
24Few publications talking about Fibre current
sensor in TOKAMAK and
- S. Kasai, I. Sone, M. Abe, T. Nishitani, S.
Tanaka, T. Yagi, N. Yokoo and S. Yamamoto,
On-line Irradiation Tests on Sensing Fiber of
Optical-fiber Current Transformer, JAERI-Research
2002-007, p130-144 - N.M. Kozhevnikov, Y. Barmenkov, V.A. Belyakov, A.
Medvedev, G. Razdobarin, Fiber-optic sensor for
plasma current diagnostic in tokamaks, SPIE vol.
1584 Fiber Optic and Lasers IX (1991), p 138-144 - Y. Barmenkov, F. Mendoza-Santoyo, Faraday plasma
current sensor with compensation for reciprocal
birefringence induced by mechanical
perturbations, J. Appl. Research and Technology,
Vol 1, No2, 2003, p157-163
- Commercially Available System exists
- for electrical power industry
- In the US, NxtPhase http//www.nxtphase.com
- In Switzerland, ABB, Baden-Dättwil CH-5405,
- K.Bohnert, optics and lasers in Engineering, 43
(2005), 511-526
25The fibre current performance will depend on
wavelengths, temperature and radiation
Verdet constant in silica as function of
wavelengths
- We prefer to operate the fibre current sensor in
the low sensitivity region, i.e. 1.3-1.5 µm,
because at these wavelengths - we reduce the combined effect of radiation and
low temperature - we can more easily use an all-fibre optic sensor
system
A.H. Rose, JLT, Vol 15,n5,1997
26No data on Verdet Constant in Liquid Nitrogen
Mini-ITER
Liquid Nitrogen
27Fiber current sensitivity slightly decreases when
subjected to liquid nitrogen temperature
- Cryogenic Temperature induces
- decrease in sensitivity
- additional noise
28Preliminary conclusion on fibre current sensor
- Preliminary result is encouraging
- At liquid nitrogen temperature we observed a
slight decrease of the fibre sensitivity with an
increase of the noise in the measure gt need
optimizatiion - Need to verify now
- the RIA of the fibre at 1.5 µm at -77K
- if the radiation could degrade the Verdet
constant
29Overview
- Progress in on-going EFDA-IRRCER fibre-related
tasks
Development Irradiation testing of
radiation-resistant fibres TW5-TPDC/IRRCER-Deliver
able 1 2
IR fibres for thermography application gamma
radiation-sensitivity TW4-TPDC/IRRCER-Deliverable
16
fiber current sensor behaviour at cryogenic
temperature TW5-TPDC/IRRCER-Deliverable 9
- New fibre optic technology for ITER a proposal
30New fibre optic technology for ITER ?
31Photonic Crystal Fibres can be classified in two
different families
32Radiation induces Photo and Radio Luminescence in
silica based material
80
60
40
20
33High-Index Core Fibres (HICF) should reduce
Cherenkov yield while holding good light coupling
With HICF we can reduce the fibre diameter while
increasing the numerical aperture
Coupled Power P D2 NA2
Cerenkov Yield Y D2
34Fibres might simplify design and maintenance in
many diagnostic
- Small and compact space
- PMTs suffer Radiation and EMI
- gt Move away PMTs and Use fibres
35Conclusion, perspectives and expectations
- RD work will carry on
- Hydrogen-loading technique with engineering
emphasis - Outlook to new fibre technology, like Photonic
Crystal Fibres - Now, real need to interact with designers to
implement fibre pathways in ITER