PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Progress in diagnostics for characterization of plasma-wall interaction in tokamaks Progress in diagnostics for characterization of plasma-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

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Introduction Diagnostics for power flux control –Infrared thermography Diagnostics for particle control –T Retention –Dust –Erosion Conclusion Outline

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 Motivation Plasma Core Plasma Edge

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Diagnostic route System Modeling Calibration Instrumentation Real Time Control Parameters Measurement specification Measurement Functional specification Maintenance Integration

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 control  IR Thermography f(x, y, z, t) ITER requirements: Divertor & first wall views T : ; °C P : 1 – 25 MW/m²; 0-5GW/m² 3 mm spatial resolution 2ms µs time resolution

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 LHCD ICRH TPL IR Cameras 30° Antenna Limiter Views Antenna View IR Cameras Endoscope C3Q1Q5 Q2C2Q6B

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Real Time Control during long time discharge Monitoring of the heating of specific parts of PFC (ICRH antenna ) RT control of power to limit PFC heating T IR P 100% 25% Protection 950°C1050°C Tps (s) T° écran Q2 (°C) % 25% Modulation P Q2 (%) IR JET

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 ITER-like IR Thermography diagnostic on JET Neutrons : Front end mirrors and Cassegrain configuration Visible output Focussed IR image Front mirrors Primary mirror Secondary mirror Cassegrain configuration allows extracting a visible view naturally without losses. Fabrication Design R&D Principle Delivery

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 IR and visible view images Wide and fast visible imagesWide or fast image in IR #67689, 10 kHz, 8x128, t=20  s #66562, 100Hz, 408x512, t=300  s Spatial resolution: ~2 cm ~1 cm First time thermography in JET main chamber First 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 °C

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Issues on IR thermography diagnostic Temperature Accuracy (Spatial resolution) Divertor thermography (R. Reichle P1.40) Measurement on metallic surface –Emissivity changePyroreflectometry (R. Reichle P1.40) –ReflectionPhotothermal effect (V. Grigorova P1.93) First mirror [A. Litnovsky] (M. Rubel O-12) Field of view vs time resolution –x2 IR cameras

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 control

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 recovery Small uncertainties, reduced by cumulative measurements T retention in dust and layers  local measurements Ion beam analysis [D. Whyte] Laser based methods (LID) (B. Schweer P1.38)  inj = dNp/dt +  burn +  pump +  in vessel

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Dust monitoring Dust limit in ITER1000kg 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

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Erosion monitoring In Vessel Viewing System [ENEA] Baseline ITER Amplitude modulated laser radar, scan = 1.55 µm, f = 80 MHz  a,   Imaging and range Accuracy ~mm  Angle 0-30° R&D needed to improve resolution Tested in laboratory conditions Vibrations ? [C. Neri]

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Erosion measurements by means of Speckle Interferometry Phase Image  = 1600 µm ITER Divertor W C Visible image 1 cm Altitude [µm] X [cm] Y [cm] Shape variation Image Depth crater ~ 10 to 40 µm (accuracy ~ 5µm) X [cm] Altitude [µm] X [cm] Altitude [µm] mirror surface Ablation Laser CCD camera beamsplitter Shape measurements by means of Speckle Interferometry I(1)=I 0 +I m cos(φ) I(2)=I 0 +I m cos(φ+2π/3)=I 0 +I m sin(φ) I(3)=I 0 +I m cos(φ+4π/3)=I 0 -I m cos(φ) I(4)=I 0 +I m cos(φ+3π/2)=I 0 -I m sin(φ) φ(x,y)=arctan ITER Mock-up Phase image CFC & W material Tunable pulsed laser

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008  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

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 : Flat surface Leading edge Light source Diaphragm Beamsplitter Surface

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Net erosion TPL Q6a Sector ~1 mm ~800µm Shape measurements ≠ Erosion measurements Variation of shape + ref-modeling  Erosion measurements

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 resolution First 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

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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 inventory B. 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

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Dust monitoring Electrostatic gridslocal dust deposition rate metal ?[C. Skinner] (D. Boyle P1.42) Capacitive Diaphragm microbalancelocal mass deposition rate [G. Counsell] scale local  global ? Light scatteringdensity, size [DIII-D, FTU, TS…] Light extinctiondensity, 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 Spectroscopychemical composition Laser Induced Breakdown Spectroscopychemical composition

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 Shot 39743, 115s Cooling loop = 120°C Active cooling : Tsurf = cte “Hot dust” determination from IR imaging Deposition zone : Thick deposits ~ 1000 °C Erosion zone : Tile surface ~ °C Erosion Thick Coating Thick coating Thin coating

PSI 2008 Toledo E.Gauthier TORE SUPRA Association EURATOM-CEA 26-30/05/2008 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