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1 Max-Planck-Institut für Plasmaphysik 9th ITPA Meeting on Divertor and SOL Physics, 10/5/07 Initial operation of ASDEX Upgrade with 100 % tungsten PFCs Rudolf Neu With contributions from: V. Bobkov, R. Dux, A. Kallenbach, T. Pütterich, H. Greuner, Ch. Hopf, C.F. Maggi, H. Maier, M. Mayer, V. Rohde, ASDEX Upgrade Team
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2 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Operation with 100 % W PFCs Transition to W PFCs in ASDEX Upgrade Boundary Conditions for Experimental Campaign Arguments on boronisation First Results of initial operation
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3 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Steps in ASDEX Upgrade towards a full W device guard/ ICRH limiter aux. limiter hor. plate lowerPSL roof baffle 2007 W-coatingstarting withcampaign 2003/2004 2004/2005 2005/2006 guard/ ICRH limiter aux. limiter hor. plate lowerPSL roof baffle 2007 W-coatingstarting withcampaign 2003/2004 2004/2005 2005/2006 Steady increase of area of main chamber W PFCs since 1999 Rationales: -risk minimisation -physics investigations -partitioning of installation time -production capacity
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4 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Optimisation of VPS coatings / HHF tests in GLADIS 200 µm W VPS (Plansee) on SGL R6710 Thermal Screening: surface temperatures > 2000°C no macroscopic defects
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5 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Optimisation of VPS coatings / HHF tests in GLADIS Cyclic Loading: 200 pulses @ - 10.5 MW/m² - 3.5 s - T surf > 1600°C coatings qualified for use in the lower divertor
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6 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Steps in ASDEX Upgrade towards a full W device
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7 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Steps in ASDEX Upgrade towards a full W device
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8 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Operation with 100 % W PFCs Transition to W PFCs in ASDEX Upgrade Boundary Conditions for Experimental Campaign Arguments on boronisation First Results of initial operation
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9 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu AUG is operated with the help of three flywheel generators: –EZ2 (1.45 GJ / 167 MVA): toroidal field –EZ3 (500 MJ /144 MVA) + EZ4 (650MJ/220MVA): OH, pol.field, aux. heating Reconfiguration of power supplies necessary: less power, less energy available Ip 1.0 MA, pulse length 3-4 s, P aux 7.5 MW, intermediate densities / triangularities (@ 1 MA) Constraints imposed by damage of EZ4 0 5 10 15 20 New-EZ3 (kA) 0.40.60.81.01.2 I p (MA) EZ3 > 11 kA EZ3 ≤ 11 kA Limit: 11 kA
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10 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Setup of program for 2007 campaign I. Exploration of W compatibility (discharges in agreement with general boundary conditions) II. Extension of working space - rad. cooled plasmas - impr. H-Mode (high low density) III. Other ITER related physics investi- gations, compatible with above results and requirements envisaged rel. weight (whole campaign) priority 30% 20% 50%
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11 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Guidelines during initial operation Boundary conditions set by W-PFCs (during phase I., to be refined): density: 7e19/m³ (gas puff rate > 6e21/s) q-edge: > 3.2 f(ELM): > 60 Hz dominant central heating (no pure off axis heating) P heat 2xH-Mode threshold power/energy limits for upper divertor (5 MW 4s, 10MW 1s) monitoring of limiter (and divertor) glow (restrictions on shape, power, energy: to be adjusted) power/energy limits for lower divertor from operation / results of radiatively cooled plasmas
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12 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Research Topics of W-programme at AUG for the upcoming campaign(s) Investigation will concentrate on: transition to C-(low-Z) free machine: - radiatively cooled (integrated) scenarios by simultaneous use of noble gas puff, central heating and ELM pacemaking - optimization of gas species/injection evolution of hydrogen retention: - influence on gas balance and D inventory in PFCs disruption characteristics: - differences in current decay / run-aways optimization of ICRF: - is the simultaneous use of with high-Z PFCs possible
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13 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Operation with 100 % W PFCs Transition to W PFCs in ASDEX Upgrade Boundary Conditions for Experimental Campaign Arguments on boronisation First Results of initial operation
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14 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Reminder: Unboronized start-up with W HS successful H ~ 1, P rad ~ 30 % main
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15 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Why Boronisation Conditioning - large O getter (even in non plasma exposed areas): easier break down higher density limit facilitates start up - use of BD6 pre-loading of wall, strong pumping larger D puffing rates easier transition to D: Coating of surfaces - suppression of W influx - suppression of other intrinsic metallic impurities
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16 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Estimates for B Erosion Thickness of boron layer Main chamber:50 nm 3e21/m² Limiter:50 nm 3e21/m² Divertor:10 nm 5e20/m² Particle fluxes / Particle temperatures (energies) / B Yield Main Chamber: 1e21 / (E 100 eV) / 1e-2 Limiter: 1e22 / T= 20 eV / 1e-2 Divertor: 1e23 / T=5 eV / 5e-4 Live-time of boron layer Main chamber:300 s (100 disch) Limiter:30 s (10 disch) Divertor: 10 s (3 disch)
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17 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Effect of boronisation strong reduction of W influx and concentrations for ICRH only, H-Mode threshold increases stronger than for NBI for aged boronisation time constants shorter than typical distance between boronisations recovery of W influx depends on particle and energy load 800 kA 1.8MW ICRH
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18 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Effect of boronisation strong reduction of W influx and concentrations for ICRH only, H-Mode threshold increases stronger than for NBI for aged boronisation time constants shorter than typical distance between boronisations recovery of W influx depends on particle and energy load
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19 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Benefits of start-up without boronization Operation/investigation of W machine without (any) intrinsic low-Z radiator Comparison of boronised / un-boronised machine: maybe able to proof of hypothesis on B influence D retention ‚without‘ low-Z (C,B) contamination Comparison of D pumping W wall / boronised W wall and H-D transition
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20 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Aims for the unboronized phase Milestone: Steady state H-Mode at intermediate density and heating power with H~1 Specific Investigations: Exposure of deposition probes to measure: evolution B,C,W impurities, D retention Particle Balance (in co-op. TS) Influence of ICRH Documentation of edge plasma parameters / radiative cooling (if applicable/necessary)
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21 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Operation with 100 % W PFCs Transition to W PFCs in ASDEX Upgrade Boundary Conditions for Experimental Campaign Arguments on boronisation First Results of initial operation
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22 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Conditioning by baking - He / He-D glow 10 days baking @ 150°C overnight glow in He (He+10%D 2, 500V, 4x1.8A) Strong pumping of C and O (through CO and CO 2 )
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23 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu First Results of initial operation Re-start since 24/4/07 (5 days of operation) Reconfiguration of power supplies for OH/V-coils main issue Reliability of break-down not yet satisfactory (low-Z impurities, gas release) Divertor configuration succes- fully acchieved W contamination not important
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24 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu First Results of initial operation Re-start since 24/4/07 (5 days of operation) Reconfiguration of power supplies for OH/V-coils main issue Reliability of break-down not yet satisfactory (low-Z impurities, gas release) Divertor configuration succes- fully acchieved W contamination not important
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25 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Long term evolution of W concentrations reduced c W at relevant auxiliary heating power and densities
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26 9th ITPA Meeting on Div/SOL Physics, 10/5/07 R.Neu Classification of proposals Pprerequistefirst few weeks Rrelatedfirst half of campaign Eextendedend of first half of campaign Ccompatiblefirst few months (lower priority) Oorthogonalsecond half of campaign Priority within categories by TFs
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