Report on radiation effects on optical fibres at SCKCEN: H2loading, infraredfibres and fibre current

1
Report 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 [phone] Secr 32 14
33 26 07 Fax [phone] bbrichar_at_sckcen.be
www.sckcen.be
2
Overview

• 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

3
Defects 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
4
Two 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)

• E
• NBOHC
• POR (SPOR)
• STH

Only indirect optical evidences
Detected by EPR/ESR spectroscopy
Can act as defect precursors for paramagnetic
defects
5
Radiation 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

6
H2-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
7
H2 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
8
At 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
9
When 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 ?

11
We 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.

12
SMIRNOF VI irradiation device upgrade for
handling depleted-H2 atmosphere in reactor
13
A 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
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Overview

• 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

15
Divertor 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
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IR-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
17
Experimental 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)
18
Radiation 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
19
Similar 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
20
Hollow 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 !
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Preliminary 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

22
Overview

• 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

23
Optical 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.
24
Few 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

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The 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
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No data on Verdet Constant in Liquid Nitrogen
Mini-ITER
Liquid Nitrogen
27
Fiber current sensitivity slightly decreases when
subjected to liquid nitrogen temperature

• Cryogenic Temperature induces
• decrease in sensitivity
• additional noise

28
Preliminary 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

29
Overview

• 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

30
New fibre optic technology for ITER ?
31
Photonic Crystal Fibres can be classified in two
different families
32
Radiation induces Photo and Radio Luminescence in
silica based material
80
60
40
20
33
High-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
34
Fibres might simplify design and maintenance in
many diagnostic

• Small and compact space
• PMTs suffer Radiation and EMI
• gt Move away PMTs and Use fibres

35
Conclusion, 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