Max-Planck-Institut für Plasmaphysik · PDF file1 Max-Planck-Institut für...

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Max-Planck-Institutfür Plasmaphysik

23rd IAEA Fusion Energy Conference, Daejon, 12 October 2010 Arne Kallenbach

Overview of ASDEX Upgrade Results

MPI für Plasmaphysik, EURATOM Assoziation, Garching bei MünchenArne Kallenbach for the ASDEX Upgrade Team

OV/3-1

223rd IAEA Fusion Energy Conference, Daejon, October 2010 Arne Kallenbach

Outline

• Status of the machine• Pedestal physics• Core transport studies with ECRH• Fast ion losses• High P/R and improved confinement with

nitrogen seeding• Abnormal events: disruption mitigation

and W melt experiments• Conclusion & outlook


Status of the machine (October 2010)

• repaired flywheel generator back in operationmeasures taken and lessons learned during its outage→ longer, higher power discharges possible

• ASDEX Upgrade with full tungsten plasma facing componentsoperational space restricted towards low ν*, low fELM domainuse of ICRF hampered by W release at antenna limiterstypical scenario: medium-high power H-mode, med-high D puff, central ECRH

• extension of ECRH system ongoing (5 MW from Dec 2010)• new ICRF antenna design – modified antenna for code validation

Noterdaeme, EXM/P7-21


ECRH operation space extended by X3- and O2 mode

Use of X2 mode (140 GHz, 2.5 T on axis) limited by cut-off density of 1.2 1020 m-3

+ X3 mode at 1.7 T for low q95+ O2 mode for high density (Ip > 1 MA)

problem: low single-path absorption

O2 mode uses holographic grating forwell-defined 2nd beam pathto reduce ECR stray radiation

Höhnle, EXW/P7-25


Pedestal physics

Pedestal profiles

• Pedestal top values largely determine plasma energy and impurity content• Plasma region with reluctance against first principle understanding


Edge transport barrier (ETB) structure

pedestal diagnostics improved in spatial and temporal resolution

negative Er well corresponds to ∇Pi/ni termin radial force balance

→ fuel ion ExB poloidal rotation ~ cancels the diamagnetic drift (low poloidal fuel rotation)

Wolfrum, subm. to PPCF


Impurity ion transport in ETB is neoclassical

experimental D, v derived by STRAHL modelling/fit to edge CXRS measurements

Pütterich,JNM in press

high frequency ELM flushing required to limit pedestal peaking of high-Z impuritiesDux, EXD/6-2


Pedestal physics

Te and ne gradients in the edge transport barrier

• determine stability and ELM behaviour• exhibit different time scales in recovery phase• subtleties in transport channels


Te and ne maximum gradient development over ELM cycle

• faster ∇ne recovery after ELM crash• after gradient re-establishment,

highly fluctuating phase starts• duration of this phase much longer

than current diffusion time

A. Burckhart, PPCF (2010)Kurzan, EXC/P3-03


Pedestal physics

Interaction of turbulence and GAMs during the L-H transition

• L-H transition not reproduced by 1st principle modelling• complicated interplay of geodesic acoustic modes (GAMs),

edge turbulence and mean flow shear• transition probed by Doppler reflectometry in dedicated experiments


GAMs as missing link for the understanding of L-H trans. ?Doppler reflectometry (DR) measures frequency spectra of Doppler shifted fluctuations- frequency shift is measure for flow speed and Er well depth

Observation and physics picture:

fluctuations in pedestal excite GAMsGAM oscillations stabilize fluctuations by shear flowpressure rises, Er well deepens, confinement rises

missing drive lets GAMs disappear, cycle restarts

or

equilibrium shear flow strong enough to suppressturbulence → H-mode, no GAMs excited any more

⇐ L ⇒ H

Conway, EXC/7-1


Central plasma transport

Transport studies using ECRH

• ECRH allows to change transport behaviour• validation of gyrokinetic calculations for normalized density gradients R/LnD,nB

• essential to use measured Te/Ti, R/LTe, νei as input


Central ECH increases the density peaking in AUG NBI heated H-modes at low plasma current

• … and flattens ion temperature and rotation

600 kA, 2.45 T, q95 = 6.6

McDermott EPS 2010


Profile fits at half radius of Te,i, vtor used as input for gyrokinetic calculations

• flat to hollow carbon profiles in H-modes also observed in JET

• boron profiles much less peaked than ne at r/a 0.5• toroidal rotation profile even partly hollow Angioni subm. to NF

Weisen NF 05 ,Giroud IAEA 06

ne

nBoron

full symb.: Te

open symb.: Ti

Ti,e

Vtor


Experimental behaviour of R/Ln reproduced by QL & NL gyrokinetic modelling (at r/a= 0.5)

• microinstabilities and turbulence are ITG• mode real frequency moves from large (NBI only) to close to zero (high ECH)• real frequency almost perfect proxi of both measured and predicted value of R/Lne• results are sensitive to input parameters ( e.g. Te/Ti, R/LTe, νei )

QL GS2, NL GYRO

Fable PPCF 2010

Angioni subm. to NFalso quite good reproduction of R/LnB dependence on boron Mach number


Core physics

MHD induced fast ion losses• can lead to a reduction of fusion power• may damage plasma facing components


SXR SXR CameraCamera

ECEECE

MirnovMirnov

FILD

Combination of various fast core diagnostics (SXR, ECE, reflectometry) allowsto disentangle complicated mode structre

MHD induced fast ion losses – lost ion detection with FILD

Fast Ion Loss Detector (FILD)resolves pitch angle and gyroradius (energy)

Garcia-Munoz, EXW/P7-7


MHD spectra during reversed shear, high power ICRH:FILD spectra closely follow MHD signatures

Mirnov prove

Central soft X-ray diode

FILD

TAE modes and Alfven cascades


MHD induced fast ion losses:detection with FILD and correlation with magnetic probes

0.0 0.2 0.4 0.6 0.8 1.00.0

0.5

1.0

1.5

0.0

0.5

1.0

1.261.24 1.28 1.30 1.320

1

2

Time (s)

FILD (10 V)-2

dB (10 T)-2

dB (10 T)-2

FIL

D (

10

V)

-2

2 3 4 5

3

4

5

6 FILD (10 V)-2

dB (10 T)-4

1.42 1.44 1.46 1.48 1.50Time (s)

3

4

5

6

2

3

4

5

6

dB (10 T)-4

FIL

D (

10

V)

-2

r~70 mm

TAE n=5

#23824

r~70 mm

TAE n=3

#23824(b)

(a)coherent ion loss ∝ δB

incoherention loss ∝ δB2

direct wave-particleinteraction

diffusive losses,stochastization

δB thresholdAnalysis with HAGIS code:Lost ions are not those which dominate the drive

Lauber, THW/2-2Ra


Power exhaust

High P/R discharges with nitrogen seeding

• nitrogen very successfully used for radiative cooling• improvement of energy confinement• radiative characteristics better suited for divertor cooling than noble gases


High P/R discharge with nitrogen seeding

Neu, EXW/10-2Ra


Confinement improvement with N seeding

Schweinzer, EXC/P2-07

N seeding results in increasedpedestal and core temperatures and τE


Confinement improvement with N seeding

Schweinzer, EXC/P2-07

N seeding results in increasedpedestal and core temperatures and τE

Improvement correlates with Zeff risehollow N profiles deduced from bremsstrahlung

Rathgeber, PPCF 52 (2010)


Power exhaust and plasma-wall interaction

Tungsten divertor pin melt experiment

• under normal conditions, no problems with power exhaust in W divertor• pin melt experiment to simulate abnormal behaviour• EMC-3 Eirene calculations started to interprete and predict W penetration


Tungsten pin inserted into divertor with manipulator

Krieger, Lunt PSI 2010, to appear in JNM

Well diagnosed experiment, with midplane W-ablation for reference in core tungsten increase

small W pin ~ 1⊗1⊗3 mmcompletely molten/evaporatedby H-mode divertor plasma

0.4 % of evaporated W pin atoms enter core plasma (droplets !)9 % of midplane LBO W atoms enter


Tungsten pin inserted into divertor with manipulator:modelling with EMC3-Eirene to benchmark divertor W retention

Lunt, Krieger, PSI 2010, to appear in JNM

midplane W injection divertor W injection

high divertor screening of W reproduced, but strong dependence on distance of injection point to strike point→ further experiments & modelling required


Power exhaust and plasma-wall interaction

Disruption mitigation• MGI disruption mitigation system used routinely for Ip ≥ 1 MA• dedicated valve used for physics investigations: approach Rosenbluth-density,

impurity penetration• fast AXUV bolometry installed to determine temporal-spatial development of

radiation


Radiation distribution during disruption mitigationwith massive gas injection (MGI)

MGI trig. @ 2.98 s

+ radiation distribution strongly asymmetric (peaks around injection port), filaments travelling over top+ strong high field side radiation caused by energy flux of thermal quench

ECRH as alternative disruption delay/avoidance scheme in AUG: Esposito, EXW/10-2Ra

Pautasso, P9-1


Conclusions and outlook

• routine operation in full-tungsten ASDEX Upgrade with up to 20 MW heating• central heating and sufficiently high ELM frequency are key elements for

low central tungsten concentration • nitrogen seeding routinely used for target power load control -

energy confinement improved by up to 25 %• not covered in this overview: dust, fuel retention, turbulent edge transport

• operation from Nov 2010 with 8 newly installed RMP coils (next +8 coils in 2011)Balden, EXD/P3-03 Rohde, EXD/P3-28 Müller,EXD/P3-23


The ASDEX Upgrade Team (2008-10)J. Adamek1, L. Aho-Mantila2, S. Äkäslompolo2, C. Angioni, C.V. Atanasiu3, M. Balden, K. Behler, E. Belonohy, A. Bergmann, M. Bernert, R. Bilato, V. Bobkov, J. Boom, A. Bottino, F. Braun, M. Brüdgam, A. Buhler, A. Burckhart, A. Chankin, I.G.J. Classen4, G. Conway, D.P. Coster, P. de Marne, R. D’Inca, R. Drube, R. Dux, T. Eich, N. Endstrasser, K. Engelhardt, B. Esposito5, E. Fable, H.-U. Fahrbach, L. Fattorini6, R. Fischer, A. Flaws, H. Fünfgelder, J.C. Fuchs, K. Gál7, M. García Munoz, B. Geiger, M. Gemisic Adamov, L. Giannone, C. Giroud8, T. Görler, S. da Graca6, H. Greuner, O. Gruber, A. Gude, S. Günter, G. Haas, A.H. Hakola2, D. Hangan, T. Happel9, T. Hauff, B. Heinemann, A. Herrmann, N. Hicks, J. Hobirk, H. Höhnle10, M. Hölzl, C. Hopf, L. Horton11,M. Huart, V. Igochine, C. Ionita12, A. Janzer, F. Jenko, C.-P. Käsemann, A. Kallenbach, S. Kálvin7, O. Kardaun, M. Kaufmann, A. Kirk8, H.-J.Klingshirn, M. Kocan, G. Kocsis7, H. Kollotzek, C. Konz, R. Koslowski13, K. Krieger, T. Kurki-Suonio2, B. Kurzan, K. Lackner, P.T. Lang, P. Lauber, M. Laux, F. Leipold14, F. Leuterer, A. Lohs, T. Lunt, A. Lyssoivan15, H. Maier, C. Maggi, K. Mank, M.-E. Manso5, M. Maraschek, P.Martin16, M. Mayer, P.J. McCarthy17, R. McDermott, H. Meister, L. Menchero, F. Meo14, P. Merkel, R. Merkel, V. Mertens, F. Merz, A. Mlynek, F. Monaco, H.W. Müller, M. Münich, H. Murmann, G. Neu, R. Neu, B. Nold10, J.-M. Noterdaeme, G. Pautasso, G. Pereverzev, Y. Podoba, F. Pompon, E. Poli, K. Polochiy, S. Potzel, M. Prechtl, M.J. Püschel, T. Pütterich, S.K. Rathgeber, G. Raupp, M. Reich, B. Reiter, T. Ribeiro, R. Riedl, V. Rohde, J. Roth, M. Rott, F. Ryter, W. Sandmann, J. Santos6, K. Sassenberg17, P. Sauter, A. Scarabosio, G. Schall, K. Schmid, P.A. Schneider, W. Schneider, G. Schramm, R. Schrittwieser12, J. Schweinzer, B. Scott, M. Sempf, F. Serra6, M. Sertoli, M. Siccinio, A. Sigalov, A. Silva6, A.C.C. Sips11, F. Sommer, A. Stäbler, J. Stober, B. Streibl, E. Strumberger, K. Sugiyama, W. Suttrop, G. Tardini, C. Tichmann, D. Told, W. Treutterer, L. Urso, P. Varela6, J. Vincente6, N. Vianello16, T. Vierle, E. Viezzer, C. Vorpahl, D. Wagner, A. Weller, R. Wenninger, B. Wieland, C. Wigger, M. Willensdorfer18, M. Wischmeier, E. Wolfrum, E. W¨ursching, D. Yadikin, Q. Yu, I. Zammuto, D. Zasche, T. Zehetbauer, Y. Zhang, M. Zilker, H. Zohm

Max-Planck-Institut f. Plasmaphysik, EURATOM Association, Garching,GERMANY1 Institute of Plasma Physics, Praha, Czech Republic2 Asscociation EURATOM-Tekes, Helsinki, Finland3 Institute of Atomic Physics, EURATOMAssociation-MEdC, Romania4 FOM-Institute for Plasma Physics Rijnhuizen, EURATOM Association, TEC, Nieuwegein, The Netherlands5 C.R.E ENEA Frascati, EURATOMAssociation, CP 65, 00044 Frascati, Italy6 CFN, EURATOMAssociation-IST Lisbon, Portugal7 KFKI, EURATOMAssociation-HAS, Budapest, Hungary8 EURATOM/CCFE Fusion Association, Culham Science Centre, UK9 Ciemat, Madrid, Spain

10 Institut f. Plasmaforschung, Universität Stuttgart, Germany11 EFDA-JET, Culham, United Kingdom12 University of Innsbruck, EURATOMAssociation-AW, Austria13 Forschungszentrum J¨ulich, Germany14 Riso, EURATOMAssociation-RIS, Roskilde, Denmark15 LPP-ERM/KMS, EURATOM Association-Belgian State, Brussels, Belgium16 Consorzio RFX, EURATOM Association-ENEA, Padova, Italy17 Physics Department, University College Cork, Association EURATOM-DCU, Ireland18 IAP, TU Wien, EURATOM Association-AW, Austria

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