Alper, B.

Angioni, C.

Baruzzo, M.

Belo daSilva, P.

Buratti, P.

Carraro, L.

Coffey, I.

Garzotti, L.

Giroud, C.

Lerche, E.

Mantica, P.

Naulin, Volker

Predebon, I.

Puiatti, M.E.

Tala, T.

Taroni, L. Lauro

Tsalas, M.

Valisa, M.

Van Eester, D.

Online Research Database In Technology

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Downloaded from orbit.dtu.dk on: Dec 20, 2017Metal Impurity transport control in JET H-mode plasmas with central Ion CyclotronRadiofrequency HeatingValisa, M.; Carraro, L.; Predebon, I.; Puiatti, M.E.; Angioni, C.; Coffey, I.; Giroud, C.; Taroni, L. Lauro;Alper, B.; Baruzzo, M.; Belo daSilva, P.; Buratti, P.; Garzotti, L.; Van Eester, D.; Lerche, E.; Mantica, P.;Naulin, Volker; Tala, T.; Tsalas, M.Publication date:2010Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Valisa, M., Carraro, L., Predebon, I., Puiatti, M. E., Angioni, C., Coffey, I., ... Tsalas, M. (2010). Metal Impuritytransport control in JET H-mode plasmas with central Ion Cyclotron Radiofrequency Heating [Sound/Visualproduction (digital)]. 15th EU-US Transport Task Force Meeting and 3rd EFDA Transport Topical Groupmeeting, Cordoba, Spain, 07/09/2010TTG-TTF meeting, Cordoba September 2010 1    L. Carraro1, I  Predebon1,,  C. Angioni2, I Coffey3, C.Giroud4,   L. Lauro Taroni1, B Alper4,  M Baruzzo1, P . Belo daSilva5, P. Buratti6, L.Garzotti4, D.Van Eester7,  E. Lerche7, P. Mantica8, V. Naulin9, T Tala10 , M.Tsalas11  and JET-EFDA contributors12 1 Consorzio RFX – Associazione EURATOM-ENEA sulla Fusione, Padova, Italy  2 Max Planck Institut fur Plasmaphysik, EURATOM-IPP Association, D-85748 Garching, Germany  3 Department of Physics, Queen’s University, Belfast, United Kingdom    4 EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, UK  5 EURATOM/IST 5Fusion Association, Instituto de Plasmas e Fusão Nuclear, Av. Rovisco Pais 1049-001 Lisbon Portugal  6 EURATOM-ENEA Association, C.R. Frascati, CP 65, 00044 Frascati, Italy  7 Association EURATOM-Belgian State, LPP-ERM/KMS, Partner in TEC, B-1000 Brussels, Belgium 8 Associazione EURATOM-ENEA sulla Fusione, Via Cozzi,  Milano, Italy  9 Association EURATOM - Risoe DTU, Frederiksborgvej 399, 4000 Roskilde, Denmark  10 Association Euratom-Tekes, VTT, P.O. Box 1000 FI-02044 VTT –Finland  11 EFDA CSU Culham, Culham Science Centre, Abingdon,OX14 3DB, UK 12 See Appendix of F Romanelli et al., Proc. 22nd IAEA Fusion Energy Conf. 2008,Geneva, Switzerland Metal Impurity Transport Control in JET  H-modePlasmas with Central ICRH M. Valisa, M.E. Puiatti TTG-TTF meeting, Cordoba September 2010 2 !   We need to fully understand the behaviour of impurities in reactor relevant plasmas as  in ITER and Demo plasma dilution in the core will be a figure of merit ( including fusion ashes).  !   Also, as for many other parameters, impurities will need an active control system to guarantee stationarity of plasma conditions  Motivation TTG-TTF meeting, Cordoba September 2010 3 •  Source mechanisms  and transport across  SOL and pedestal  important but beyond the scope of this work, focused on core aspects.  •  For impurities in the core  what really matters is the relationship between D_impurities  , D fuel and χe,i , since the relevant parameter is dilution. Here we concentrate on D_impurities To measure impurity  transport one powerful means is to create impurity density perturbations as with laser ablation. Modelling of the transient evolutions of the appropriate signals  provides an estimate of the transport coefficients. Method  + accurate atomic physics to describe all  of the  ionization stages.  Model based on 1D continuity  equation  with  TTG-TTF meeting, Cordoba September 2010 4 Theory : several mechanisms can affect impurities in the plasma •  Turbulence and impurity radial transport  - Curvature pinch (Perp Dynamics) : inward         f(Z) - Parallel Compressibility : Outward for TEM     Inward for ITG - Thermodiffusion :             Inward for TEM     Outward for ITG ~ Z/A ~ 1/Z  lower for high Z impurities - Curvature pinch changes sign with magnetic shear (Futatani) -  Rotation and shear rotation inward for TEM and Outward for ITG (Camenen) -  Centrifugal and Coriolis forces : outward advection (Clements/ Romanelli ) -  Electromagnetic effects ~ 10% of electrostatic ones (Hein) -  RF induced  ponderomotive forces  - affect similarly D and v ( Nordman) -  High Impurity concentration: significant in case of TEM (Fulop/ Moradi) •  vneo / Dneo = Zi• (1/n• dn/dr  - H• 1/T• dT/dr) ; H approx 1 •  Neoclassical radial transport  TTG-TTF meeting, Cordoba September 2010 5 Experiment: central RF power and impurity pump out RF ( electron heating) pump out effect observed in several other experiments: C-mod, DIII-D, JT-60, TCV  and  also in non axisymmetric devices (W7-AS) ...but only few example of successful explaniation of radial flow reversal from the theory   - AUG : TEM (Angioni et al. PPCF 2007)  TTG-TTF meeting, Cordoba September 2010 6 M.E. Puiatti et al  PoP 13 2006 JET: RF power is a means to control heavy impurities Steady state Ni profiles, calculated from exp v and D  JET discharges 58143 and 58142  Similar results obtained also in high density JET discharges  M.E. Puiatti et al .Plas. Phys.Contr. Fus. 44(2002)1863  TTG-TTF meeting, Cordoba September 2010 7 This work:  ICRH Power scan in JET A series of dedicated H mode discharges with a RF power scan  + LBO of Ni and Mo have been performed on JET to systematically analyze  the effect of Central RF heating Main feature:  •  ICRH heating: H minority, 5% concentration to heat electrons •  low collisionality (νeff< 0.2)  •  about 12 MW NBI  •  high central q to avoid sawteeth •  no total power (NBI + RF )  conservation  effect of the RF scan on q, Te, Ti , ω profiles •  no significant MHD activity TTG-TTF meeting, Cordoba September 2010 8 Main plasma profiles  The RF power modifies the target plasma affecting mostly Ti , Te , bulk  toroidal rotation and q              (MW) 74354 0 74355 1 74356 2 74359 3 74360 3 74363 3 TTG-TTF meeting, Cordoba September 2010 9 ICRH power  RF scan in Jet :  V’s and D’s of Ni TTG-TTF meeting, Cordoba September 2010 10 Mo( 42)  and Ni ( 28) have similar behaviour  Average between ρ = 0.2 and ρ = 0.3 OUTWARD INWARD TTG-TTF meeting, Cordoba September 2010 11 Ni profiles extrapolated to stationary conditions 3 MW ICRH 1 MW ICRH NO ICRH TTG-TTF meeting, Cordoba September 2010 12 New data fit  wider JET database 68383 – marginal H mode Low collisonality,  Similar triangularity  and elongation   TTG-TTF meeting, Cordoba September 2010 13 Average between ρ = 0.2 and ρ = 0.3 Good  correlation of v/D(Ni)   with R/LTe TTG-TTF meeting, Cordoba September 2010 14 Average between ρ = 0.2 and ρ = 0.3 Still better correlation of v/D(Ni)   with R/LTi Neoclassical effect? TTG-TTF meeting, Cordoba September 2010 15 No dependence on ICRH power at ρ=0.5 TTG-TTF meeting, Cordoba September 2010 16 Turbulence induced flow:  no agreement with experiment  GS2 (linear, electrostatic) analysis shows trends in the right direction, but never provides an inversion of v/D (which may occur  for  ITG  TEM dominant mode transition,obtainable  for instance with  much lower Ti gradients than in JET experiments - see e.g. Angioni et al. PPCF 49, 2007);  Tested also  the  addition of a hot H species (to simulate energetic ion tails after ICRH injection).  TTG-TTF meeting, Cordoba September 2010 17 vneo / Dneo = Zi• (1/n• dn/dr  - H• 1/T• dT/dr) ;     H approx 1 Neoclassical transport? The impressive good correlation between v/D and R/LTi suggest a strong  neoclassical contribution  Flat density profiles and peaked ion temperature profiles screen impurities out  TTG-TTF meeting, Cordoba September 2010 18 However: neoclassical V and D  - from NCLASS – are small TTG-TTF meeting, Cordoba September 2010 19 Sensitivity study on neoclassical v  Exp V and D D exp + V neoclassical V neo + v/D as from exp  74360 3 MW ICRH Experimental  SXR central channel (J5 Camera ch10) Time differences well beyond the analysis uncertaintes  LBO Simulation of SXR emission with various combinations of transport parameters TTG-TTF meeting, Cordoba September 2010 20 Summary and conclusions •  Ni and Mo feature peaked profiles in JET  H mode plasmas at low collisionality without sawthooth activity •  Ni and Mo profiles may be made flat-hollow by applying  2-3 MW ICRH  •  Impurity pump out has not been explained by turbulence calculations by GS2 ( too large R/LTi to get outward turbulent flux)  •  Very good correlation between v/D (Ni) and R/LTi ,  however absolute neoclassical values do not fit the experiment   TTG-TTF meeting, Cordoba September 2010 21 Effect also of q and ω on v/D Toroidal rotation  TTG-TTF meeting, Cordoba September 2010 22 Control of central W transport AUG (Courtesy of T. Pütterich, EFPW 2009, Hungary) Central power and impurity pump out RF ( electron heating) pump out effect observed in several other experiments: C-mod, DIII-D, JT-60, TCV  and  also in non axisymmetric devices (W7-AS) TTG-TTF meeting, Cordoba September 2010 23  RF SCAN in Jet: Mo discharges. Similar result as with Ni ICRH power 74357 NO ICRH 74362 3 MW  ICRH TTG-TTF meeting, Cordoba September 2010 24 For the experimental ne and Te profiles of #68383 at r=0.35 ,  R/LTi < 3 would be necessary for the flow inversion. L Carraro, C Angoni et al  EPS 2007 Warsaw TTG-TTF meeting, Cordoba September 2010 25 •  GS2 (linear, electrostatic) scan analysis shows trends in the right direction, but never provides an inversion of v/D (which it can be for  ITG  TEM dominant mode transition reachable, for instance, for much lower Ti gradients - see e.g. Angioni et al. PPCF 49, 2007); •  Tested the  addition of a hot H species (to simulate energetic ion tails after ICRH injection). The nature of turbulence remains ITG-dominated: the dominant mode frequency only slightly decreases for increasing beam energies, it never changes sign. 4 6 8 100.450.50.550.60.650.7R/LTeïv/D  (mï1)74354r274354r574355r274355r574359r274359r574360r274360r5Gyrokinetic analysis (GS2)  ρ=0.2 (●)  ρ=0.5 (►) 5 10 15 20 25 30ï0.2ï0.100.10.20.30.40.50.60.7Zïv/D  (mï1)74354r274354r574355r274355r574359r274359r574360r274360r5TTG-TTF meeting, Cordoba September 2010 26  RF control of heavy impurities profile  also in !JET  Elmy H mode / HIGH DENSITY and Ar puffing !! 	•  Core diffusion decreases	•  Core convection also decreases  and may become outward 	NO ICRH 	Shot 52136: Strong inward convection	Shots 53548 , 53015 WITH ICRH:	convection may become outward	M.E. Puiatti et al .Plas. Phys.Contr. Fus. 44(2002)1863 	TTG-TTF meeting, Cordoba September 2010 27 Impurity Accumulation in the Center  Dux et al., PPCF 45, 2003 !   Turbulent transport in center small, dependent on heating  !   Central ECH increases diffusion and reduces inward pinch !   Outward convection with ECH real? !   Effect of ICRH similar but less pronounced Courtesy of T. Pütterich @ EFPW 2009, Hungary Impurity pump out in AUG TTG-TTF meeting, Cordoba September 2010 28 Soft-X rays: a vertical camera with 34 l-o-s (250µ filter) and a horizontal camera with 17 channels (350µ  filter). JET SXR L-O-S geomketry 

Metal Impurity transport control in JET H-mode plasmas with central Ion Cyclotron Radiofrequency Heating

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Metal Impurity transport control in JET H-mode plasmas with central Ion Cyclotron Radiofrequency Heating

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