psi 2008 toledo e.gauthier tore supra association euratom-cea 26-30/05/2008 progress in diagnostics...

26-30/05/2008PSI 2008 Toledo E.Gauthier

TORE SUPRAAssociationEURATOM-CEA

Progress in diagnostics for characterization of Progress in diagnostics for characterization of plasma-wall interaction in tokamaksplasma-wall interaction in tokamaks

E. Gauthier

Association Euratom - CEA Cadarache, IRFM

with special thanks to

C. Brosset, A. Grosman, T. Loarer, P.Monier-Garbet, R. Reichle, H. Roche,

S. Rosanvallon, J.M. Travère, E. Tsitrone, X. Courtois, M. Salami,

S. Vartanian, A. Murari, E. Joffrin, W. Fundamenski, A. Meigs, C. Lasnier,

C. Skinner, D. Whyte, K. Itami, P. Andrew, S. Ciattaglia



• Introduction

• Diagnostics for power flux control– Infrared thermography

• Diagnostics for particle control– T Retention– Dust– Erosion

• Conclusion

OutlineOutline



• ITER objectives:

– 500 MW, ~steady state (400s)

• Operate in a safe mode

• Nuclear limit

• Operational limit (safe op FPC)

• Control

– Power fluxes

– Particle fluxes– T inventory– Dust– Erosion

Measure and control the plasma edge parameters and Plasma Wall Interactions

MotivationMotivation

Plasma Core

Plasma Edge



Diagnostic routeDiagnostic route

System

ModelingCalibration Instrumentation

Real Time Control

Parameters

Measurement specification

MeasurementFunctional

specification

Maintenance

IntegrationIntegration



• Limit power flux in steady state regime at acceptable value

• Avoid Hot spots

• ELMs

• Disruptions

Thermocouples

Langmuir Probes

IR Thermography

Problematic of diagnostics for Power flux controlProblematic of diagnostics for Power flux control

IR Thermography f(x, y, z, t)

ITER requirements:

Divertor & first wall views

T : 200 - 1000 ; 1000 - 3600°C

P : 1 – 25 MW/m²; 0-5GW/m²

3 mm spatial resolution

2ms - 100 µs time resolution



Long time steady state discharge in Tore Supra IR Thermography designed for safety of PFC’s

LHCD luncher C2

LHCD luncher C3

ICRH antenna Q1

ICRH antenna Q2

ICRH antenna Q5

TPL HR Q5A

TPL Q6B

7 endoscopes

& IR cameras

Q5

Q6

Q1

Q2

Q3

Q4

LHCD

LHCD

ICRH ICRH

ICRH

TPL

IR Cameras

30°

Antenna

Limiter Views

Antenna View

IR Cameras

Endoscope

C3 Q1 Q5

Q2 C2 Q6B



Real Time Control during long time discharge

Monitoring of the heating ofspecific parts of PFC(ICRH antenna )

RT control of powerto limit PFC heating

TIR

P

100%

25%

Pro

tection

950°C 1050°C

0 20 40 600

400

800

1200

Tps (s)

T°

écra

n Q

2 (°

C)

0

25

50

75

100

100%

25%

ModulationPQ2 (%)

IR JET



ITER-like IR Thermography diagnostic on JETNeutrons : Front end mirrors and Cassegrain configuration

Visible output

Focussed IR image

Front mirror

s

Primary mirror

Secondary mirror

Cassegrain configuration allows extracting a visible view naturally without losses.

FabricationDesign R&D

Principle

Delivery


TORE SUPRAAssociationEURATOM-CEA IR and visible view images

Wide and fast visible images Wide or fast image in IR

#67689, 10 kHz, 8x128, t=20s

#66562, 100Hz, 408x512, t=300s Spatial resolution:

~2 cm

~1 cm

First time thermography in JET main chamberFirst account of power losses during disruptions

and ELMs, first detection of filaments (R. Pitts 0-8, G. Arnoux 0-36)

Similar design used for ITER (upper & equatorial views)

T range 200- 2500°C



Issues on IR thermography diagnostic

• Temperature Accuracy (Spatial resolution)

• Divertor thermography (R. Reichle P1.40)

• Measurement on metallic surface– Emissivity change Pyroreflectometry (R. Reichle P1.40)

– Reflection Photothermal effect (V. Grigorova P1.93)

• First mirror [A. Litnovsky] (M. Rubel O-12)

• Field of view vs time resolution– x2 IR cameras



Fuel– Gas balance Safety limit

– Retention

Wall particles– Dust Safety & Op limit

– Layers (hot dust) Safety & Op limit

– Erosion monitoring Op limit

• I.V.V.S.

• Speckle

• Confocal microscopy

Diagnostics for Particle Flux controlDiagnostics for Particle Flux control



Measurement of T inventory

In vessel T limit 700g in ITER ( ~14 discharges fluence)

Particle balance

(T. Loarer R-3) (B. Pégourié O-21)

Time resolved method

Large uncertainties due to pumping speed

Integrated method

T retention = Injection - burn – pump recoverySmall uncertainties, reduced by cumulative measurements

T retention in dust and layers local measurementsIon beam analysis [D. Whyte]

Laser based methods (LID) (B. Schweer P1.38)

inj = dNp/dt + burn + pump + in vessel



Dust monitoring

Dust limit in ITER 1000kg in VV

Hot Dust 6kg C + 6kg Be + 6 kg W

Dust : size 100nm to 100µm

Erosion transport dust deposition

(P. Roubin O-29)

Dust = particles + layers

Eroded material = Dust (particles + layers) Erosion Measurement



Erosion monitoring

• Vis-UV Spectroscopy Baseline ITER

First wall erosion measurement influx ≠ erosion Absolute value? Disruption ?

• I.V.V.S.

• Speckle Interferometry

• Confocal microscopy

ITER needs :

Erosion rate : 1-10µm/s +/-30% : 2s

Erosion range : 3 mm +/- 12µm pulse



Erosion monitoring

In Vessel Viewing System[ENEA]

Baseline ITERAmplitude modulated laser radar, scan

= 1.55 µm, f = 80 MHz a, Imaging and rangeAccuracy ~mm Angle 0-30°R&D needed to improve resolutionTested in laboratory conditionsVibrations ?

[C. Neri]



Erosion measurements by means of Speckle Interferometry

Phase Image = 1600 µm

ITER Divertor

W

C

Visible image

1 cmAltitude [µm]

X [cm]

Y [

cm]

Shape variation Image

Depth crater ~ 10 to 40 µm (accuracy ~ 5µm)

X [cm]

Alt

itu

de

[µ

m]

X [cm]

Alt

itu

de

[µ

m]

mirror

surface

Ablation

Laser

CCD camera

beamsplitter

Shape measurements by means of Speckle Interferometry

•I(1)=I0+Im cos(φ)

•I(2)=I0+Im cos(φ+2π/3)=I0+Imsin(φ)

•I(3)=I0+Im cos(φ+4π/3)=I0-Imcos(φ)

•I(4)=I0+Im cos(φ+3π/2)=I0-Imsin(φ)

• φ(x,y)=arctan 13

24

II

II

ITER Mock-up

Phase image

CFC & W material

21

21

22

i),(2

),( yxi

yxz

Tunable pulsed laser



Speckle Interferometry at two wavelenths can provide

-Shape measurements

-Erosion/redeposition measurements on divertor & First wall: Localisation of Erosion/Redeposition areas hot dust Quantitative inventory of eroded redeposited material

Erosion/redeposition successfully measured in presence of vibrations

Speckle Interferometry in lab fulfills ITER requirements

Need to be integrated

Speckle Interferometry



Confocal Microscopy

• Spatial resolution : 75 nm in z, 5 µm in x-y

Measurements on a limiter sector :• 30° of TPL :• Zones : 200 mm (radial) x 100 mm (toroidal)• Resolution 20 x 65 µm

2 optical systems :2 optical systems :Flat surface Flat surface Leading edgeLeading edge

Light source

Diaphragm

Beamsplitter

Surface



Net erosion

TPL Q6a SectorTPL Q6a Sector

~1 mm~800µm

Shape measurements ≠ Erosion measurements

Variation of shape + ref-modeling Erosion measurements



Summary

Perspectives

Diagnostics in ITER are essential for operation, safety and scientific results

Diagnostic for Power flux control have already reached very good status•R&D still needed on divertor IR thermography

IR on metal (pyroreflectometry, photothermal, multi )

Spatial resolutionFirst mirror

Diagnostic for Particle flux control have not been developed enough for ITER

• Accurate Gas balance diagnostic is required during H phase

• Diagnostics based on laser for local T measurement must be developed

• Dust & layer effects are important and diagnostics are not developed enough by now

• Diagnostics measuring dust formation should be implemented on today tokamaks

• Erosion must be measured in Real Time for safe operation in ITER

• Diagnostics for erosion measurement must urgently be developed



Dust

F. Onofri, “Development of an in situ ITER dust diagnostic…” P1.80

S. Rosanvallon, “Dust limit management strategy in tokamaks…” P1.8

C. Grisolia, ”From eroded material to dust:…” P1.07

P. Roubin, “Tore Supra carbon deposited layers: characterization and growth process” O-29

D. Boyle, “Electrostatic dust detector with improved sensitivity” P1.42

T inventoryB. Pegourié, “Overview of the deuterium inventory campaign in Tore Supra”

I-21 T. Loarer, “Fuel retention in tokamak” R-3

D. Schweer, “In-situ detection of hydrogen retention in TEXTOR by LID” P1.38

IR Thermography

R. Reichle, “Concept and development of ITER divertor thermography diagnostic” P1.40

V. Grigorova, “Active Pyrometry by pulsed Photo-thermal method” P1.93

G. Arnoux, “Divertor heat load in ITER-like advanced tokamak scenarios” O-36

R. Pitts, “The impact of large ELMs on JET” O-8

Some related contributions at this conference



Dust monitoring Electrostatic grids local dust deposition rate

metal ? [C. Skinner] (D. Boyle P1.42)

Capacitive Diaphragm microbalance local mass deposition rate[G. Counsell]

scale local global ?

Light scattering density, size [DIII-D, FTU, TS…]

Light extinction density, size (F. Onofri P1.80)

Fast cameras (IR-vis) velocity, trajectory [NSTX]

Not relevant for dust safety limit (S. Rosanvallon P1.8)

IR camera qualitatif, localisation layer, hot dust

Laser Induced Ablation Spectroscopy chemical composition

Laser Induced Breakdown Spectroscopy chemical composition



Shot 39743, 115s

Cooling loop = 120°CActive cooling : Tsurf = cte

“Hot dust” determination from IR imaging

Deposition zone :Thick deposits ~ 1000 °C

Erosion zone :Tile surface ~ 200-300 °C

Erosion

Erosion

ThickCoating

Thickcoating Thin

coating



Laser Induced Spectroscopy (LIBS)

Chemical composition of layers

Quantitative ?

LIBS diagnostic can be coupled

with T & layers removal technics[A. Semerok]

LIBS retained for Mars exploration In 2010

psi 2008 toledo e.gauthier tore supra association euratom-cea 26-30/05/2008 progress in diagnostics...

Documents