1B. PégouriéDITS progress report 27/04/07 Euratom EXPERIMENTAL CAMPAIGN No reliable estimation of the wall inventory WI ~ ??? D atoms (Tsitrone, IAEA2004) Requirement: WI >> estimated present WI For good accuracy : WI ~ 4x10 24 D (~ 5 x WI) i.e. such that (WI / WI) ~ accuracy of particle balance Retained flux ~ 2x10 20 /s -> 2x10 4 s of LD (equivalent to a year of operation) 1- Motivation

2B. PégouriéDITS progress report 27/04/07 Euratom 2x10 4 of plasma: Modification of the LPT surface (erosion-redeposition) marker to identify the surface at t=0 Carbonization 13 C ( 2h glows He + 15% 13 CH 4 ) then Boronization ( 2h glows He + 15% B 2 D 6 ) Total thikness Å Association of the 2 markers easy to detect 2- Surface identification at the beginning of the experiment

3B. PégouriéDITS progress report 27/04/07 Euratom 3- Plasma scenario Long duration required for an effective wall loading MHD-free scenario, i.e. with V loop 0 Routine LD scenario: nl ~ 2.5x10 19 m -2 I p = 0.6 MA; B T = 3.4 T P LH ~ 2.5 MW (V loop ~ 75 mV) plasma duration ~ 2 min 2x10 4 s of plasma = 160 LD of 2 min 8h – 18h operation t between 2 successive discharges ~ 30 min 16 LD/day ~ 10 days of operation May 11 th : scenario optimization May 24 th – June 7 th : LPT D-loading experiment

4B. PégouriéDITS progress report 27/04/07 Euratom 4- Special features Two main points: - LH power Feedback control on V loop Better repartition of the power on the different modules in case of loss of a klystron - Prevent the density from uncontrolled increasing Operation with active pumping Two independent measurements of the exhausted flux Active pumping : no effect on wall retention but offset on gas injection

5B. PégouriéDITS progress report 27/04/07 Euratom 5- Diagnostics 160 times the same discharge, steady state or slow evolution Adapted acquisition strategy to limit the amount of data (1/2 n point of measurement recorded in the data base to be optimized on May, the 11 th ) In addition to global diagnostics required for operation & safety (density and temperature profiles, Z eff and radiated power…..) 3 key points : Gaz balance : manometers pressure gauges mass spectrometer Erosion / redeposition : IR imaging (deposits on LPT surface) optical fibers (neutralisers) CCD camera + Spectrometer (C, CD, D ) (filters can be changed in between discharges) Scrape-off layer :Probes (density, electron and ion temperatures) During & in between discharges

6B. PégouriéDITS progress report 27/04/07 Euratom 6- Unexpected events Fatigue of klystrons (cathode outgassing) : Shorter discharges (particle balance accurate enough to measure the changes in th WI as soon as the plasma duration is longer than 30s) Loss of LH power : experiment stopped openning of the vacuum chamber collect of samples Particle balance recorded during cleaning / conditionning phases Wall saturation : Good news!! Size of the reservoir discharge at natural density (no gas puffing) pulsed discharge cleaning if necessary Disruption due to increase of impurity content : Boronisation (amont of injected D << few expected from the D loading experiment) No other experiment before dismantling

7B. PégouriéDITS progress report 27/04/07 Euratom 7- Expected results No dismantling only if analysis impossible : Major water leak… [D]/[C] + localization N < 40 [D]/[C] + localization Comparison WI from tiles analysis & from part. Balance (lower accuracy) 120 < N < 40 [D]/[C] + localization Comparison WI from tiles analysis & from part. Balance (accuracy 20 %) 160 > N > 120N 160 [D]/[C] + localization (detection easy) Comparison WI from tiles analysis & from part. Balance (accuracy 20 %)