Presentation on theme: "Max-Planck-Institut für Plasmaphysik"— Presentation transcript:
1Max-Planck-Institut für Plasmaphysik Report from IPP Garching on work related to the EU PWI Task Force: Oct Oct 2006*With contributions fromW. Bohmeyer, A. Chankin, D. Coster, R. Dux, T. Eich, A. Herrmann, C. Hopf, W. Jacob,A. Kallenbach, C. Linsmeier, M. Mayer, H.-W. Müller, R. Neu, R. Pugno,V. Rohde, J. Roth,K.Schmid,T. Schwarz-SelingerCompiled by Arne Kallenbach* + Berlin +JET+ PISCES-B
2Topics investigated in IPP from Nov 2005 – Oct 2006 Chemical erosion (see also talk S. Brezinsek)Tungsten tokamak (see also talk R. Neu)Decay and migration of carbon in ASDEX UpgradeELM power deposition characteristics in outer midplaneELM in-out divertor asymmetryHe retention in W-coated surfacesChemical erosion by N ions and simultaneous neutral impact (non-scavenging)Be-W alloyingPISCES-B measurements on D retention and pulsed power with Be seedingEdge modelling with B2.5 (AUG) and DIVIMP (ITER)SOL transport and parallel flow
3Tungsten erosion at LFS limiters on ASDEX Upgrade R. DuxICRH: strongest W erosion by sheath accelerationNBI: Loss of ripple trapped fast ions identified asdominant W sputtering mechanism byMonte Carlo simulations of pitch angle dependencefor both ICRH and NI, W limiter source dominated by ELMsabout 70 % of time-averaged sputtered W during ELMs
4Tungsten erosion at LFS limiters on ASDEX Upgrade: ICRH sheath potential from measured W yield
5Tungsten erosion at LFS limiters on ASDEX Upgrade: pitch angle dependence form ripple loss of fast NBI ions
6x 40 x 5 x 9 x 4 Tungsten erosion at LFS limiters on ASDEX Upgrade Effect of type-I ELMsx 40x 5x 9x 4
7Structure and radial decay of ELM filaments in the omp A. Herrmann, A. Schmiddedicated diagnostic setupenergy carried predominantly by ions
8experiment migration modelling Decay of carbon concentration with increasing W PFC coatingFraction in ASDEX Upgrade A. Kallenbachexperimentmigration modellingscatter due to boronisations,Exp.imerfections, calibrations,…slow decay of the carbon concentration with increasing W surface fractionnet divertor source becomes important with diminishing C PFC area
9Divertor becomes important net carbon source with W PFCs recovery of C after boronisation allows to estimate net sourcenet outer divertorC source:1.5e19 ions/sC part of divertornot coated by boronLFS limiter fluxes and C concentration closely coupledheat shield lags behind (1 ML C on heat shield 30 plasma C content)
10Erosion measurements with markers and long term samples Matej MayerErosion of tungsten in the outer divertor of JETTungsten erosion was determined with a marker stripe fromLarge erosion at outer strike point, outer baffle and apronErosion at strike point >> 2.4 µmInhomogeneous erosion due to surface roughnessErosion of Be, C, Ni and W at the inner vessel wall of JETErosion was determined with long term samples fromWhole inner vessel wall is erosion dominated,erosion of C is about 10 times larger than erosion of BeErosion of carbon and tungsten in the outer divertor of ASDEX UpgradeCarbon and tungsten erosion were determined with marker stripes fromLargest erosion at strike points, both for carbon and tungstenErosion of carbon times larger than erosion of tungsten2.8 g C eroded during the campaignfactor 3 larger than migration modeluncertainties, direct losses to inner div
11Deposition in inner divertor Matej Mayer2002 – 20034800 s2004 – 20053050 s2005 – 20062900 s6A6B549CDecrease of C-deposition on divertor tiles by factor 7 from 2004/2005 to 2005/2006Decrease of C-deposition below roof baffle by factor from 2004/2005 to 2005/2006 Outboard limiters are main carbon source
12SOL plasma flow in upper-SN H-mode at outer midplane Hans-Werner Müller
14Shot resolved gas balance in ASDEX Upgrade Volker Rohde
15Implications of Tungsten on Helium Gas Recycling Klaus SchmidHigh He plasma concentrations encountered in AUG since the transition from a C to a W first wallHe plasma concentration linked to He glow duration and number of discharges since last boronizationRetained He in different C and W materials (NRA)Dedicated laboratory experiments show:W retains ~10 times more He compared to C or boronization layersHe release due to plasma load similar for W and CThermal release starts at 400K for both C and WHigh He plasma concentrations in AUG are due to higher retention of He in W compared to C – effect expected to vanish at higher wall temp.
17Mixed materials formation: Be-W alloying Ch. Linsmeier, A. Wiltner, F. KostW on Bestable Be12W above 1000 K Tm < 2000 K no W in surface zoneBe on W (ITER divertor!)< 800 KBe metal layer deposition Tm ~1560 K> 1000 KBe2W surface alloy only (~nm)no bulk diffusion, sublimation faster Tm ~2500 Kdepth profileFuture workReactivity of Be/W alloys with carbonFormation of ternary surface layersReactivity of different surface layers with atomic oxygen
18Power pulsing experiments in PISCES-B R. Pugno, PISCES-B team under EFDA contract TW5-TPP-CARWBERA transitory positive voltage biasing system has been installed on PISCES-B to simulate the heat pulses associated with ELMs.A new infra-red diagnostic system has been installed to measure the target surface temperature during the heat pulses.From visible spectroscopy and mass loss measurements, the formation time of the Be2C protective coating on graphite samples exposed to beryllium-seeded deuterium plasmas, is reduced in presence of power transients.The deuterium retention is increased in presence of power transients for both pure deuterium (+30%) and Be-seeded plasmas (+60%).The infra-red measurements evidence a change in emitting area due to a surface morphology modification during plasma exposure (both for pure carbon and Be2C surfaces) in agreement with previous observations by SEM electron micrographs.
19Work done at PISCES-B in the frame of the EFDA contract TW5-TPP-CARWBER R. Pugno, PISCES-B teamSaturation of the surface is observed in CFC target for fluences higher than 1e26 ion/m2 and target temperature of 1100 K.No change in deuterium retention in CFC is observed between pure deuterium plasmas and Be seeded plasmas in that conditions.Earlier onset of thermal desorption is observed for mixed material surface i.e. after exposure to Be seeded plasmas as already observed in PISCES-BThe scaling law for the suppression time of chemical erosion in Be seeded plasmas obtained with FGG target seems to be valid also for CFC target.
20SOLPS work, development and benchmarking D. Coster, A. Chankin, C SOLPS work, development and benchmarking D. Coster, A.Chankin, C. Konz, M. WischmeierIn addition to other activities, the members of the edge group took part in the Edge Modelling Campaign at JETCosterEdge transport Code-Code Verification/Validation/BenchmarkingChankinEDGE2D runs: adding drifts to JET H-mode pulsesKonzSimulation of disruption thermal quenches with B2 SOLPSWischmeierSOLPS5 modelling of ohmic plasmas with C13 injection at the top of the machine
21Dicrepancy in code-experiment comparisons Detailed comparison between B2.5-EIRENE (SOLPS) edge modelling and experiment shows that the code overestimates plasma density and underestimated electron temperature in the divertor, especially near the strike point position.The example shown above demonstrates a large discrepancy between simulated and experimental Ha radiation profiles, which is the consequence of the overestimate of the plasma density in the divertor.
22code-code comparison Edge code benchmarking / ITPA activity EDGE2D D+CEDGE2D DSOLPSD+Ccode-code comparisonPhase I: pure D, no driftsPhase II: pure D, driftsPhase III: D+C, no driftsPhase IV: D+C, driftsSOLPS-EDGE2D/NIMBUS Phase I completed successfully (reported on at PSI 2004)Phases II and III in progressSOLPS-UEDGEPhase I underwayPhase II expected to start soonAdditional code-experimentJET: SOLPS-EDGE2D/NIMBUSAUG/D3D: SOLPS-UEDGESOLPSEDGE2D
23Association Euratom–Tekes Using MDSplus for SOLPS to ASCOT2D background (ne, Te, Ti, …) written as MDSplus tree by SOLPS (IPP-Garching) [modelled by Chankin] provides input to ASCOT Due to open field lines, special care must be taken with the Monte Carlo collisionsPlanned: output of ASCOT to be saved to a MDSplus treeITPA standard pedestal MDSplus tree created based on AUG shot (provides the equilibrium data)ASCOT:T. Kurki-Suonio, L. Aho-Mantila, J. Heikkinen, V. Hynönen, T. Kiviniemi, A. Salmi, S. Sipilä, V. TulkkiDistribution of electrons reaching outer targetAssociation Euratom–Tekes
24Divertor in-out power asymmetry during ELMs depends on ion grad-B drift direction T. Eich
25In-out power asymmetry connected to charge flow asymmetry charge sign suggests ions to carry excess powerAUG upper SN
26TW4-TPP-TRIDEPHumboldt Universitätzu BerlinW. BohmeyerBeginning of the project 08/2004intermediate report 12/2004(end 12/2005) prolongated / 2006 *Main topics:1. Analysis of Cx Hy mixture produced by chemical erosion2. Study of the influence of the target temperature3. Influence of impurities on chemical erosionIR absorption, QMS, cavities4. Determination of the balance between deposition and erosion for areasnot exposed directly to the plasma ( ITER pumping duct).Experiments and ERO-Modellingdensity of atomic hydrogenimprovement of experimental data for modelling(spectroscopic data, cavities,...)* delayed start of the experiments (reason: no permission to use hydrogen)-
27CH4 injection into a He-Plasma Humboldt Uinversitätzu BerlinCH4 injection into a He-Plasma2D-CH-emission at 430 nm7 cmnozzleNe=2*1018 m-3Ne=1017 m-3Ne=3*1017 m-31.Clear shift from global to local decomposition with increasing el.-density2.Decomposition and excitation length is not in agreement with atomic data