1. How to do wall conditioning in ITER ? # B tor cycles is limited GDC inefficient in B Drawbacks of ECWC, Taylor Ion cyclotron wall conditioning (ICWC) J. Roth General aims of wall conditioning: Plasma initiation - Impurities, fuel removal Control of discharge content - Isotopic ratio ITER : Tritium removal Ion Cyclotron Wall Conditioning (ICWC) on JET V. Philipps, A. Lyssoivan, D. Douai, R. Pitts, C. Schueller, T. Loarer, G. Sergienko, S. Brezinsek, J. Ongena, M. Mayoral … ICWC compatible with permanent magnetic field ICWC seems suitable – at least in C machines – for removal of impurities and tritium control by isotope exchange (TEXTOR, Tore Supra and AUG)

2. RF plasma production : He-D 2 ICWC Simulate D 2 -ICWC in ITER full field conditions using JET A2 ICRF antennas : BT=3.3 T and frequencies ~25 MHz and ~29 MHz thus simulating ITER operation at BT=5.3 T and 40 MHz and 46.6 MHz Simulate ITER RF conditions at full field JET only! - Optimise poloidal homogeneity (and penetration of the ICWC-plasma into the divertor throat) using a second frequency - Optimise RF power coupling (phasing of antenna straps, gas pressure and composition, antenna phasing, in particular for safe antenna operation - Check consistency with codes (deposition profile by TOMCAT/METS ) PWI : pure D 2 ICWC 1) Assess the efficiency of ICWC for T-removal on large size tokamak with divertor 2) Compile a reference dataset with a C-based PFCs for later comparison with the ILW JET : only machine with Be operation unique information for active phase in ITER! - Optimise isotopic exchange efficiency : pressure, gas-composition, RF-power waveform after breakdown - Optimize duty-cycle (RF on/ RF off). - Test plasma re-start after ICWC ITER DCR-080 (2007) : ICWC as a functional requirement for the main ICRH system ITPA experiment-2009 - SOL/Div group Goals and rationales

5. ICWC discharge optimisation (RF part + preparation of PWI experiment) Reference ICWC discharge Preloading by 2 hours H 2 -GDC with H + )=6.10 13 cm -2.s -1 total fluence = 4,4.10 17 H/cm 2 ~ accessible reservoir in JET: 10 23 D Reference H 2 -ohmic shot [H]/([H]+[D]) 10 D 2 -ICWC shots to perform change-over Reference D 2 ohmic shots [H]/([H]+[D]) - test of ohmic plasma initiation after ICWC - repeated for changeover H D Diagnostics - Neutral Particle Analyser : CX neutrals + isotopic ratio in ref ohmic shots - OES - Detailed exhaust gas composition by mass spectrometry - AGHS after cryo-pumps regeneration - pressure gauges - + others : Langmuir, Penning gauges,… Present strategy