Status of a programme for development of ITER relevant diagnostics onFTU
Radiation hardness in ITER Diagnostics
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Transcript of Radiation hardness in ITER Diagnostics
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Radiation hardness in ITER Diagnostics
Robin Barnsley
ITER Diagnostics Division
- Overview of Fusion and ITER
- ITER Diagnostics
- Labyrinth shielding
- X-ray spectroscopy
- Plasma modelling
- Neutronics modelling
- Radiation-hard detectors
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Leading magnetic confinement device is the Tokamak
- Closed magnetic field minimizes particle losses
- Combined toroidal and poloidal fields produce helical field, that stabilizes +ve/-ve charged particle drifts.
- Plasma current induced by inner poloidal coils.
- Additional heating from neutral beams and RF/microwave
- Self-heating from fusion alphas
1 Magnetic confinement fusion research
D-T fusion requires lowest temperature
Ein + D + T -> (4He + 3.5 MeV) + (n + 14.1 MeV)
Breeding T from Li:nslow + 6Li -> 4He + Tnfast + 7Li -> 4He + T + nslow
Energy multiplication, Q: Q = Pout / Pin
Breakeven, Q=1 Palpha + Pneutron = Pin
Ignition: self-heating Palpha = Pin
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The JET Torus Hall (www.jet.efda.org)
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Inside JET without and with plasma
Remote-handling in-vessel since 1997 Visible radiation dominated by D near edgeCore radiation mostly x-raysOn JET 0.5 < Prad < 5 MW
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D-T fusion achievements to date
JET has unique D-T capability- Tritium handling plant- Remote handling- Shielded torus hall- DT compatible diagnostics- Neutral beam upgrade to ~ 40 MW- Proposed to run until ITER operational
For a JET D-T plasma,
with 20 MW input into the plasma
total output : max 16 MW
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Record: Q = 0.8 (JET)
Steady state: Q = 0.3 (JET)
JET (Joint European Torus), located near Oxford, England, is the largest Tokamak worldwide, and is a leading test-bed for ITER physics and technology
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AUG JET
ITER
Scaling to ITER from previous experiments
Physics performance can be extrapolated better than factor 2.
Technological developments ongoing for:
- First wall: blanket and divertor modules.
- Material properties under heavy neutron irradiation.
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Participating Teams all ratified by end of 2007China, Europe, India, Japan, Russia, South Korea, USA.
Construction site: Cadarache, St Paul les-Durance, Provence, France
Goals: Develop and demonstrate the physics and technology required for a fusion power plant.
Construction: 10 yrs. Began in 2008 with preparation of the site
Operations: 10 yrs. Hydrogen phase > Deuterium phase > Low-duty D-T > High duty D-T
ITER overview
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ITER (www.iter.org)
- Superconducting Tokamak
- Single-null divertor
- Elongated, triangular plasma
- Additional heating from RF, and negative-ion neutral-beams and
500Pfus(MW)
10Q (Pfus/Pin)
80+P (MW)
40-90Paux (MW)
1.85, 0.5,
5.3Bt (T)
15(17)IP (MA)
850VP (m3)
2a (m)
6.2R (m)
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
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ITER cross-section
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
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Characteristics of the plasma radiation
Main plasma
- Fuel ions D-D or D-T are diluted by impurities. Eg 2%C, 0.1% O, 0.001% Ni.
-Density ~1020 /m3 ,
-Te ~ 25 keV, Ti ~ 25 keV.
Optically thick > ~1mm:
- Emits and absorbs RF and microwave.
- Electrons orbiting in magnetic field
Optically thin < ~1mm.
- Emits quasi-blackbody Bremsstrahlung spectrum peaked at few keV.
- Many discrete spectral lines from fuel and impurity neutrals and ions.
Neutron and gamma emission from fusion reactions.
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Passive Diagnostic Techniques
Magnetics Pick-up coils B-fields, position, current, stored energy
RF ~ 30MHz RF antennae Ion cyclotron emission
mm-wave Waveguide Electron cyclotron emission - Te profile
IR Camera Tile thermography
Visible Filters, Gratings Edge impurity spectroscopy, vis. Brems Zeff
VUV/XUV Grating + MCP Impurity spectroscopy, machine protection
Soft x-ray camera Diode array Broadband tomography
Soft x-ray survey Crystals + GPC Impurity spectroscopy, machine protection
High res. X-ray Crystal + MWPC Doppler spectroscopy of Ti, bulk motion
Hard x-ray Scintillators Supra-thermal electrons
-ray Scintillators Fusion products
C-X neutrals Mass-spec Ion dynamics
Ions, electrons Langmuir probe Edge Te, Ne
Wide band Bolometry Total radiated power
Neutrons Imaging, counting, spectroscopy, activation
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Active Diagnostic Techniques
1 MW, 1 GHz gryrotron Collective Thomson scatt. Ion dynamicsmm-wave ~ 100 GHz Reflectometry Plasma positionFIR DCN laser 0.2 mm Interferometer Density profileRuby laser LIDAR Thomson Scattering Electron density and temp.Neutral beam 100 keV Charge exchange spectr. Ion temp, impurity densityLithium beam ~ 20 keV Spectroscopy Edge Te, NeHeavy ion beam Vis spect, Mass spect E-fieldsLaser ablation Impurity injection Impurity transport
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Diagnostics are linked to physics and operations by ITER Measurements Requirements – about 45 parameter groups.
Below are some relating to Spectroscopy
MEASUREMENT PARAMETER CONDITIONRANGE or
COVERAGERESOLUTION ACCURACY
10. Plasma Rotation
VTOR 1-200 km/s 10 ms a/30 30 %
VPOL 1-50 km/s 10 ms a/30 30 %
12. Impurity Species Monitoring
Be, C rel. conc. 1x10-4-5x10-2 10 ms Integral 10 % (rel.)
Be, C influx 4x1016-2x1019 /s 10 ms Integral 10 % (rel.)
Cu rel. conc. 1x10-5-5x10-3 10 ms Integral 10 % (rel.)
Cu influx 4x1015-2x1018 /s 10 ms Integral 10 % (rel.)
W rel. conc. 1x10-6-5x10-4 10 ms Integral 10 % (rel.)
W influx 4x1014-2x1017 /s 10 ms Integral 10 % (rel.)
Extrinsic (Ne, Ar, Kr) rel. conc.
1x10-4-2x10-2 10 ms Integral 10 % (rel.)
Extrinsic (Ne, Ar, Kr) influx 4x1016-8x1018 /s 10 ms Integral 10 % (rel.)
28. Ion Temperature Profile
Core Ti r/a < 0.9 0.5 - 40 keV 100 ms a/10 10 %
Edge Ti r/a > 0.9 0.05 - 10 keV 100 ms TBD 10 %
32. Impurity Density Profile
Fractional content, Z<=10r/a < 0.9 0.5 - 20 % 100 ms a/10 20 %
r/a > 0.9 0.5 - 20 % 100 ms 50 mm 20 %
Fractional content, Z>10r/a < 0.9 0.01 - 0.3 % 100 ms a/10 20 %
r/a > 0.9 0.01 - 0.3 % 100 ms 50 mm 20 %
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
15INDiagnostic Neutral BeamEUBolometric Array For Divertor
tbdTritium Retention MonitorsEUBolometric Array For Main Plasma
tbdDust and Erosion MonitorsBolometric System
CNLangmuir ProbesEUCollective Scatt. (LFS front end)
JAIR Thermography DivertorJAPolarimetric Syst. (Pol. Field Meas)
USResidual Gas AnalyzersUSToroidal Interferom./Polarim
EUPressure GaugesRFThomson Scat/LIF Interfaces (Div. region)
EU/JAThermocouplesJAThomson Scattering (Edge)
EU/USIR Cameras, visible/IR TVEUThomson Scattering (Core)
Plasma-Facing Comps and Operational Diagnostics
Optical Systems
USDivertor InterferometerEUHigh Res Neutron Spectr (interfaces)
EUReflectometers for Plasma PosnKONeutron Activation System
RF/USReflectometers for Main PlasmaEU/RFGamma-Ray Spect. (interfaces)
IN/USECE Diagnostics for Main PlasmaRFNeutron Flux Monitors (Divertor)
Microwave DiagnosticsCN
Neutron Flux Monitors (Ex-Vessel)
EUHard X-ray MonitorJAMicrofission Chambers
USMSE (based on heating beam)RFVertical Neutron Camera
RFNeutral Particle AnalysersEURadial Neutron Camera
INBeam Emission SpectroscopyNeutron and Fusion Product Diag.
CNRadial X-Ray CameraEUHalo Current Sensors
IN/USX-Ray Crystal SpectrometersEUDiamagnetic Loop
JAVisible & UV Imp Mon (Div)EUContinuous Rogowski Coils
KOVUV Imp Mon (Main Plas and Div)EUDivertor Magnetics
RFH Alpha SpectroscopyEUIn-Vessel Magnetics
EU/RFCXRS Active Spectr. (based on DNB)EUOuter-Vessel Magnetics
Spectroscopic and NPA SystemsMagnetic Diagnostics
INDiagnostic Neutral BeamEUBolometric Array For Divertor
tbdTritium Retention MonitorsEUBolometric Array For Main Plasma
tbdDust and Erosion MonitorsBolometric System
CNLangmuir ProbesEUCollective Scatt. (LFS front end)
JAIR Thermography DivertorJAPolarimetric Syst. (Pol. Field Meas)
USResidual Gas AnalyzersUSToroidal Interferom./Polarim
EUPressure GaugesRFThomson Scat/LIF Interfaces (Div. region)
EU/JAThermocouplesJAThomson Scattering (Edge)
EU/USIR Cameras, visible/IR TVEUThomson Scattering (Core)
Plasma-Facing Comps and Operational Diagnostics
Optical Systems
USDivertor InterferometerEUHigh Res Neutron Spectr (interfaces)
EUReflectometers for Plasma PosnKONeutron Activation System
RF/USReflectometers for Main PlasmaEU/RFGamma-Ray Spect. (interfaces)
IN/USECE Diagnostics for Main PlasmaRFNeutron Flux Monitors (Divertor)
Microwave DiagnosticsCN
Neutron Flux Monitors (Ex-Vessel)
EUHard X-ray MonitorJAMicrofission Chambers
USMSE (based on heating beam)RFVertical Neutron Camera
RFNeutral Particle AnalysersEURadial Neutron Camera
INBeam Emission SpectroscopyNeutron and Fusion Product Diag.
CNRadial X-Ray CameraEUHalo Current Sensors
IN/USX-Ray Crystal SpectrometersEUDiamagnetic Loop
JAVisible & UV Imp Mon (Div)EUContinuous Rogowski Coils
KOVUV Imp Mon (Main Plas and Div)EUDivertor Magnetics
RFH Alpha SpectroscopyEUIn-Vessel Magnetics
EU/RFCXRS Active Spectr. (based on DNB)EUOuter-Vessel Magnetics
Spectroscopic and NPA SystemsMagnetic Diagnostics
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
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ITER diagnostics are port-based where possible
Each diagnostic port-plug contains an integrated instrumentation package
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
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In-Vessel
Distributed Diagnostics
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Divertor, Equatorial & Upper Port Diagnostics
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Ports contain several diagnostics
Common features:
High fluxes onto plasma-facing mirrors
- Nuclear radiation - 0.5 MW / m2
- Heat, peaking in x-rays
- Escaping neutrals and ions
Mirror/waveguide labyrinths for shielding
- Require extensive neutronics analysis
- Performance compromised
- No fibres, lenses or windows in port
Some systems cannot use labyrinths
- X-ray camera, spectroscopy
- Neutron and gamma cameras
Some systems require vacuum extensions
- VUV spectroscopy
- Neutral particle analyser
High electromagnetic loads
- Plasma current of 15MA can disrupt in 40ms
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
211st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
LocationNeutron
flux/cm2.s
Suitable technology Issues
Plasma - facing ~1014
Metal mirrorsRetro-reflectorsWaveguides
Deposition and erosion by plasma.Maintenance: - possible if in-port - almost impossible if in-vessel
In-vesselBehind blanket
~1012
Mineral-insulated cablePick-up coils for magnetics
Radiation induced, EMF, currents, insulation breakdownMaintenance almost impossible
Inside port-plug
~108 - 1012
MirrorsReplaceable detectors
Some maintenance possible
Behind port-plug
< ~108
Optical fibres, lenses, CCD detectors, conventional electronics.“Almost anything”
Easily maintainable
Radiation issues according to location
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Mirror labyrinth collection optics on ITER upper port #3Neutronics by G.E.Shatalov, S.V.Sheludiakov, Kurchatov Inst. Moscow
The neutron environment ranges from mild behind the port-plug to severe at the blanket. StSt:H2O 80:20,Allowable activation
at Flange <100 uSv/hrbehind BioSh <10 uSv/hr
Normalized to 500 MW fusion power Neutron flux at flange ~ 1. 107 n/cm2 s-1 This is less than inside JET torus hall.
Equivalent to local dose <5 uSv/h (10 days after s/d)
Total nuclear heating power to:BSM 420 kWA 58 kWB 0.43 kWC 9W
Addition power deposition in TFC ~10WM1 Heating ~2W/cc Total Neutron flux ~6.1013 n/cm2 s-1
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ArXVII spectrum from NSTX - Manfred Bitter
Te = 0.58 keV from all diel. satellites & line w; Ti = 0.45 keV
3000
2000
1000
03.94 3.95 3.96 3.97 3.98 3.99 4.00
Ph
oto
n C
ou
nts
/ C
ha
nn
el
Wavelength (Å)
(c) w
x y q r a k
n >
3 s
ate
llite
s
z
j
n
High-resolution x-ray spectroscopyExtensively, but not exclusively, He-like ions.
~Te/Z: 250eV: Ne, 500eV,:Ar, 2keV: Fe-Ni, 10keV:Kr
Requires/ >~ 5000, hence < 1.3 nm for crystals
Ti: Doppler broadening
Vtor/pol: Doppler shift
Te Dielectronic satellite ratio
ne Forbidden line ratio z/(x+y) (sometimes)
Zeff Continuum imp Impurity injection
nimp Absolute calibration
Simple and reliable - bent crystal & pos. sens. detector.
Crystals are cheap dispersive elements, eg Si < 1kEur
Energy resolving detector makes it doubly dispersive, with excellent signal-to-noise ratio.
All crystal-window-detector processes are volume effects, leading to calculable and stable calibration. (1 mm Carbon ~ transparent at 10 keV).
Detector developments have been the key to progress:
1st gen. Photographic film
2nd gen. Multiwire prop. counter, ~ 3 - 25 m radiius
3rd gen. Solid state eg CCD, 0.5 - 2 m radius
4th gen. Imaging with fast 2-d detector
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High resolution imaging crystal spectrometers
Recent advances in active pixel detectors such as Pilatus and Medipix have enabled a new generation of imaging crystal spectrometer.
The technique has moved quickly from demonstration, to routine production of a wide range of new physics results (Matt Reinke, John Rice, this meeting)
The ITER design has been based on this principle since 2003
Extensive analysis and modelling has been performed:- Plasma emission modelling- Spectrometer sensitivity and signal estimates- Neutronics analysis to optimize the forward position of detectors
Fig.14a. Spherical crystal optics Fig.14b. Toroidal crystal optics
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Advances in detector technology enable new measurement capability CERN-led Medipix 3 – in development
Active pixel detector- Each pixel has analog pulse processing, thresholds, and digital counter- 256 x 256 array. Pixels 55 um square - Multiple enrgy windows- 1 us pulse-process time per pixel - Radiation-hard to ~1014 neutron/cm2
Diagnostic applications- X-ray spectroscopy and imaging - Particle detection and spectroscopy - Fast visible and VUV framing (with MCP)- Neutron and gamma spectroscopy
27 September 2004 Michael Campbell
MEDIPIX2 Hybrid Pixel DetectorMEDIPIX2 Hybrid Pixel Detector
Detector and electronics readout are optimized separately
27 September 2004 Michael Campbell
Charge sensitive preamplifier with individual leakage current compensation2 discriminators with globally adjustable threshold3-bit local fine tuning of the threshold per discriminator1 test and1 mask bitExternal shutter activates the counter13-bit pseudo-random counter1 Overflow bit
Medipix2 Cell SchematicMedipix2 Cell Schematic
Preamp
Disc1
Disc2
Double Disc logic
VthLow
VthHigh
13 bits
Shift Register
Input
Ctest
Testbit
Test Input
Maskbit
Maskbit
3 bits threshold
3 bits threshold
Shutter
Mux
Mux
ClockOut
Previous Pixel
Next Pixel
Conf
8 bits configuration
Polarity
Analog Digital
Preamp
Disc1
Disc2
Double Disc logic
VthLow
VthHigh
13 bits
Shift Register
Input
Ctest
Testbit
Test Input
Maskbit
Maskbit
3 bits threshold
3 bits threshold
Shutter
Mux
Mux
ClockOut
Previous Pixel
Next Pixel
Conf
8 bits configuration
Polarity
Analog Digital
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3 PILATUS II Detectors Provide Continuous Spatial Coverage of He-like Ar Spectra
Bottom
Core
Top
Crystal
Detector
C-Mod Plasma(Height =72 cm)
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Lower Hybrid Wave Induced Rotation on Alcator C-ModMeasured by imaging crystal spectrometer (Ken Hill et al)
New measurement capability for non-NBI discharges
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High resolution imaging crystal spectrometer for ITER
Plasma coverage by toroidal viewsPlasma coverage by radial views
Crystal
• Yellow represents view tunnel within the port plug and its virtual extension into the plasma• Aim is to view the tangent to all plasma flux surfaces• Spatial coverage drives detector height
View from top of plug
radial
toroidal
Detector
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ITER impurity line emission and spectrometer signals
Top left Modelled ITER radial profiles
Top right Local emissivity of impurity spectral lines
(O’Mullane, ADAS-SANCO)
Bottom Simulated signals for imaging x-ray crystal spectrometer
Incremental radiated powers for added impurity concentrations of 10-5.ne are:
Ar 0.25 MW Fe 0.8 MW Kr 1.4 MW
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Z-plane cross section of the neutron flux, modelled in Attila finite-element neutron transport code
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Neutron spectra at the detector locations
1.0E+00
1.0E+01
1.0E+02
1.0E+03
1.0E+04
1.0E+05
1.0E+06
1.0E+07
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02
energy (MeV)
ne
utr
on
flu
x (n
/cm
2s)
d1 d2d3 d4d5 d6
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Photon spectra at the detector locations
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E+07
1.E+08
1.E+09
1.E+10
1.E+11
1.E+12
1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02
energy (MeV)
ph
oto
n fl
ux
(n/c
m2
s)d1 d2
d3 d4
d5 d6
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Background and lifetime for a Medipix-like detector
Detector location within port-plug
Rear Mid Front
X-ray – gamma background
Total gamma flux
(ph/cm2 .s)3 .104 9 . 106 1 . 1012
Fractional dead-time for 1% QDE
1 . 10-8 4 . 10-5 0.33
Neutron background Neutron flux > 1 keV
(n/cm2 .s)6 . 106 1.5 . 108 5 . 1011
Fractional dead-time for 1% QDE
2 . 10-6 5 . 10-4 0.18
Detector life
(ITER life ~ 2.107 s)
Time to reach fluence of 1014 n/cm2 (s) 2 . 1010 2 . 107 500
Saturation rate: 3 . 1010 /cm2 .s (106 /s per 55 um pixel)
Lifetime fluence of 1 MeV neutrons: 1014 /cm2
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High energy physics requires radiation-hard detectorsSLHC core neutron fluence >10^16/cm^2 over 10 yrs
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Estimated detector lifetimes along the line between front and rear detectors
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E+09
1.00E+10
1 3 5 7 9
Line between front detector d5 (1) and rear detector d2 (10)
Det
ecto
r lif
etim
e (s
)
Fluence 10^14 / cm^2
Fluence 10^16 / cm^2
ITER lifetime
Maintainable
KU-1 glass
1st EIROforum School on Instrumentation, CERN, 11-15 May 2009, R Barnsley
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Imaging Crystal Spectrometer Layout, with overlap between upper and equatorial views
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Neutron and Neutron and -cameras for ITER-cameras for ITER
Radial camera
- 20 Views total
- 12 ex-vessel
- 8 in-vessel – dictated by narrow port
Vertical camera
- Required to detect in-out asymmetry
- Difficult to integrate
- Divertor location favoured
Instrumentation
- Counters and spectrometers
- Fission chambers for neutrons
- Scintillators for gammas and neutrons
- Natural and CVD diamonds
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Summary- The ITER diagnostic system deals with radiation in a number of ways:
- Real hardness: waveguides, mirrors, mineral-insulated cables- Shielding: optical labyrinths, remote detectors- Use of radiation-hard detectors: x-ray spectroscopy and imaging
- Neutronics modelling is essential to optimize diagnostic designs
- ITER Diagnostics are entering the detailed design phase.
- Construction time for a complete diagnostic system: ~ 6 yrs