how to do wall conditioning in iter ? # b tor cycles is limited gdc inefficient in b drawbacks of...
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How to do wall conditioning in ITER ?
# Btor cycles is limitedGDC inefficient in BDrawbacks 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 fieldICWC seems suitable – at least in C machines – for removal of impurities and tritium control by isotope exchange (TEXTOR, Tore Supra and AUG)
RF plasma production : He-D2 ICWC
Simulate D2-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 MHzSimulate 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 D2 ICWC
1) Assess the efficiency of ICWC for T-removal on large size tokamak with divertor2) Compile a reference dataset with a C-based PFCs for later comparison with the ILWJET : 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
ICWC discharge optimisation (RF part + preparation of PWI experiment)
Reference ICWC discharge
Preloading by 2 hours H2-GDC
with H+)=6.1013 cm-2.s-1 total fluence = 4,4.1017 H/cm2
~ accessible reservoir in JET: 1023 D
Reference H2-ohmic shot [H]/([H]+[D])
10 D2-ICWC shots to perform change-over
Reference D2 ohmic shots [H]/([H]+[D])
- test of ohmic plasma initiation after ICWC
- repeated for changeover HD
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
-5 0 5 10 15 200
0.1
0.2
0.3
0.4
0.5
0.6
0.7
time (sec.)
n H/[
n H+
n D]
#43447
#43485
nH/[nH+nD] in ohmic shots (by means of NPA)
after 15+3’ ICWC
Reference ohmicshot before ICWC
-5 0 5 10 15 200
0.1
0.2
0.3
0.4
0.5
0.6
0.7
time (sec.)
n H/[
n H+
n D]
#43447
#43485
nH/[nH+nD] in ohmic shots (by means of NPA)
-5 0 5 10 15 200
0.1
0.2
0.3
0.4
0.5
0.6
0.7
time (sec.)
n H/[
n H+
n D]
#43447
#43485
nH/[nH+nD] in ohmic shots (by means of NPA)
after 15+3’ ICWC
Reference ohmicshot before ICWC