October 1, 2009Janos Marki: IR measurements at TCV1/14 IR measurements during ELM experiments on TCV (collaboration with MAST) J. Marki, R. A. Pitts, B.P. Duval and TCV Team 2009 Joint Annual Meeting of the Special Expert Working Groups: Transient Loads and High-Z Materials, IST, Ljubljana

October 1, 2009Janos Marki: IR measurements at TCV2/14 History Original idea: EPS 2007 Discussions, s, etc EU Priority support received end spring 2008 PSI 2008: discussion of details Trigger unit + support structure built by end summer 2008 (thanks to MAST workshop in great part) Original date for start – mid-August, nearly shipped but got stuck – postponed until end IAEA (October) TCV: beginning of November - flywheel generator breaks down, reparation by April TCV: Wait until summer for ECRH operation July 2009 Camera arrives!!!! September 2009 Camera leaves

October 1, 2009Janos Marki: IR measurements at TCV3/14 Experimental Setup Detector typeCMT 256 M HS (TCV) CMT 256 L HS (MAST) FPA size256 x 256 Spectral range μm μm Frame rate880 Hz Subframe mode25 16 x 8 Integration time1 μs -2 ms Measure IR photon flux digital signal Apply blackbody calibration apparent temperature Assuming real surface temperature T Spatio-temporal evolution of T + simple model of deposited surface layer power flux P IR (THEODOR 2D code = inverse solution of heat conduction equation) Thermosensorik CMT256 M HS 1.5 – 5.1 μm FOV VIR FOV HIR Thermosensorik CMT256 L HS (MAST) μm

October 1, 2009Janos Marki: IR measurements at TCV4/14 Full frame chamber views

October 1, 2009Janos Marki: IR measurements at TCV5/14 Experimental Programme Main goal: characterise FWD- & REV-B ELMs (target temperatures, power fluxes, divertor wetted areas, temporal shape of heat deposition, statistics, power balance, in-out assymetries) in ohmic and X3 ECRH-heated scenarios Secondary objective: measure ITER- relevant filamentary losses at the top of the machine by making use of TCVs flexibility in terms of plasma geometry

Shot parameters A-scenario REV-BFWD-B scenarioB-scenario REV-B

October 1, 2009Janos Marki: IR measurements at TCV7/14 Shot parameters FWD-B #37513 REV-B A #37649 REV-B B #37638 nene 5 – 6e195.8 – 6e196.4 – 7.4e19 IpIp -370 kA410 kA420 kA f ELM 70 Hz140 Hz200 Hz dW ELM 1.2 ± 0.2 kJ0.85 ± 0.25 kJ0.43 ± 0.13 kJ W Plasma kJ24 kJ30.5 – 32 kJ dW/W ELM ~6%~3.5%~1.25%

October 1, 2009Janos Marki: IR measurements at TCV8/14 IR data VERY preliminary analysis suggests similar in-out ELM heat deposition ratios REV-B outerREV-B inner FWD-B innerFWD-B outer

October 1, 2009Janos Marki: IR measurements at TCV9/14 Diagnostics Langmuir probes (colum, floor, outer wall) in I sat mode of operation (particle flux) Fast visible camera (information on filament propagation) Thomson scattering with denser edge channels (pedestal density & temperature) BOLO and AXUX N/A – full power balance needs to be done using earlier discharges

October 1, 2009Janos Marki: IR measurements at TCV10/14 Second separatrix exp. ITER worry: ELM energy fluxes arriving at the upper dump plates in far SOL. If substantial, would require blanket modules in upper dump area to become high heat flux components needs verification By using TCV versatility, turning the plasma upside down moves interesting deposition region into the vertical systems field of view in REV-B, corresponds to FWD-B upper deposition

October 1, 2009Janos Marki: IR measurements at TCV11/14 First results Inter – ELM, a bit of a dim flash visible from time to time, otherwise, no sign of heat deposition In every ELM, a number of filaments make it to the top (usually at least 7-10) Many more filaments visible than for the outer divertor (remark – not so pretty on TCV in general on outer, but still, some even visible on inner divertor The existence of filaments is easy to observe, with some luck, even the mode number, however, calculating their energy content, even with a large number of assumptions, is not easy (possibly not feasible with a restricted view like this

October 1, 2009Janos Marki: IR measurements at TCV12/14 Last planned experiments (1) Goal is to have a better understanding of surface layer temperature response 3 LP tiles left uncleaned, larger temperature response than cleaned tiles, seems to grow over time (larger for 1.5 kJ ohmic ELMs in 2008 than for 7.5 kJ X3 ELMs in 2007)

October 1, 2009Janos Marki: IR measurements at TCV13/14 Last planned experiments (2) attempt L-mode X2 ECRH power steps (worry: shot (<2s) not long enough for near-asymptotic behaviour at target + low-density strike point splitting) 1 session to characterise detector behaviour with various filters (transients needed, most easily done by repetition of ohmic L-mode) – hoping to understand layer behaviour better from this

October 1, 2009Janos Marki: IR measurements at TCV14/14 Layers: regrowth after cleaning During TCV shutdown, all tiles have been removed from TCV and grit-blasted, with the exception of 3 LP tiles Photographs taken after 112 2s discharges (start-up, most disrupted early) regions of co-deposition can clearly be seen as a blue tinge on the cleaned tiles interference colour method by Wienhold and Littmark [1]: TCV: bluish hue = carbon co-deposited layer thicknesses 60 – 100 nm or 180 – 200 nm (first two interference bands, assuming C and Si layer behaviour similar)