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Association Euratom-CEA

Association Euratom-CEA. TORE SUPRA. Status of Particle Transport Studies at Cadarache G.T. Hoang, C. Bourdelle, N. Dubuit, X. Garbet R. Guirlet, P. Hennequin, T. Parisot R. Sabot, A. Sirinelli Association Euratom-CEA CADARACHE. OUTLINE. Experimental Conditions Codes for analysis

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Association Euratom-CEA

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  1. AssociationEuratom-CEA TORE SUPRA Status of Particle Transport Studies at CadaracheG.T. Hoang, C. Bourdelle, N. Dubuit, X. GarbetR. Guirlet, P. Hennequin, T. ParisotR. Sabot, A. SirinelliAssociation Euratom-CEACADARACHE

  2. OUTLINE • Experimental Conditions • Codes for analysis • Main experimental results • Main modeling results • Perspectives

  3. Tore Supra Can Offer Ideal Conditions For Particle Transport Studies No central fuelling (RF heating) VWare suppressed in steady-state by RT control. Various heating schemes: LHCD, FWEH, H-min • parametric dependence studies: q-profile, Te, Ti/Te, collisionality Various fuelling systems: Supersonic Molecular Beam Injection (Mach number 5); Pellet injection from 4 poloidal locations (LFS/HFS, 10Hz speed 100-600m/s, adjustable size). Laser blow off (various metallic impurities Cr, Ni, Pd, Ge..) Accurate measured profiles: Te (32-channel ECE), ne (3 reflectometers), current density (CD profile by Hard-X tomography, polarimetry, MSE) Fluctuation measurements (k from 3cm-1 – 20cm-1)

  4. 2 X-mode Reflectometers Measure the Whole ne Profile • 50-75 & 75-110 GHz for edge profile • 105-155 GHz for core measurement R (m) Plasma core can be diagnosed with high spatial resolution (relative error ~ mm) and high time resolution: 25ms – 105ms Impact of MHD on the density profile is being studied

  5. Fluctuation measurements by reflectometers • 3 methods to measure dn properties • classical fixed frequency method • dn(r) from frequency steps • high frequency modes (few 100’s kHz) Fast swept reflectometers • dn(r) • low (m,n) MHD modes Doppler reflectometry (O-mode) • dn = f(kq) Perp. Fluctuation velocity dn ( r ) • complementary dn measurements from low to high k, from MHD to µ-instabilities

  6. Main Experimental Results Hoang, PRL 90 (03) Hoang, PRL 93 (04) Demonstration of turbulent pinch in steady-state (two orders of magnitude higher than Vneo) Roles of Te & q profiles • - Both the thermodiffusion & curvature pinches co-exist • - Gradient zone: • Inward curvature pinch, neprofile varies as 1/q0.5 • Weak outwardthermodiffusion pinch correlated with TEM dominant • - Core ( r/a < 0.3): • Inward thermodiffusion correlated with dominant ITG

  7. q/q (m-1) - Te/Te (m-1) - ne/ne (m-1) Density peaking versus colisionality Saturation? Data from 3 full LHCD shots @ r/a =0.55 Preliminary Density gradient weakly increases with collisionality Similar behavior in FTU

  8. Modeling of turbulent transport Garbet, PRL 91 (03) Dubuit, TTF Napa (05) Non linear gyrofluid code results (TRB) electrostatic, no collisions, fixed-flux coherent with a quasi linear approach - Curvature pinch always directed inward - Thermodiffusion” pinch direction without passing electrons and without collisions ITG dominant: inward for electrons, outward for impurities. TEM dominant: outward for electrons,inward for impurities. TEM impurities ITG TEM ITG electrons

  9. Modeling of pinch driven by non-inductive CD sources Helander & Peysson EPS 2005 Location of absorption • Convective transport induced by non-inductive CD computed using a Green’s function formalism • Inward pinch, smaller than Vware, for LHCD and ECCD • Pinch  VWare with NBI: Inward for counter-injection. Outward for co-injection - 610-3 m/s (~ 0.1x Vware) Pinch driven by LHCD in Tore Supra

  10. Perspectives: Experiments scheduled 2005-2006 • Fluctuation measurements to identify nature of • microturbulence and check if quasi linear • prediction for thermodiffusion direction is correct • Ti/Te scaling using FWEH and H minority allowing to test its predicted impact on thermodiffusion • Dedicated experiments testing q impact on density profile • Beta and collisionality impact (PhD thesis) • To characterize particle source, D and V: use of RF power modulation, SMBI and pellets (PhD thesis) • Impurity transport studies: Z = 7-32, compared with turbulent predictions by TRB (PhD thesis)

  11. Perspectives: Modeling 2005-2006 • Gyro fluid fixed flux TRB (PhD thesis) • improved version with effects of parallel impurity flow • Ti/Te impact on transport using non linear gyro kinetic GYRO • TRB, GYRO versus quasi linear theory • TRB, GYRO versus fluctuation measurements • Consitent calculation of pinch driven by non-inductive CD sources (RF, NBI) • Implementation of Impurity Transport code in CRONOS for consistent analysis

  12. Peaked density profile in absence of Ware pinch Radial ne profiles from 40 – 350s six-minute discharge LH Power (MW) ne (x1019m-3) Zeff Transformer flux (Wb) Neoclassical pinch Including impurities LCFS Before RF Te(0) (keV) Magnetic axis Line density (x1019m-2) Ti(0) (keV) - n /n (m-1) During RF Density peaking VWare = 0 over the whole plasma volume Ej (V/m) @ r/a = 0.2, 0.4, 0.6 Inward pinch >> Vneo V/D = -n /n ~ 1(m-1) In the gradient region Support Materials

  13. Inward thermodiffusion pinch when ITG q/q 2m-1 - n/n (m-1) Maximum linear growth rate (s-1) With KINEZERO ITG &TEM CT 0.2 Cq  -0.1 Assuming no trapped elec. (Purely ITG) - Te/ Te (m-1) TEMs more and more dominant when moving from the core to the outer plasma Support Materials r/a  0.3 predicted by turbulent simulations Garbet PRL91, 035001 (2003) From a set of 7 discharges @ various Te (Te(0) = 4- 8keV), and q (qedge = 8.9-14), in condition n/n =- Cqq/q + CTTe/Te

  14. Outward thermodiffusion pinch correlated with dominant TEM q/q 3.5m-1 - n/n (m-1) CT -0.2 Cq  0.8 - Te/ Te (m-1) Support Materials 0.3  r/a  0.6 Consistent with turbulence simulations Garbet, PRL91 (03)

  15. Weak thermodiffusion, in the core region, can only be identified when suppresing VWare Flattening of n when Ware pinch decreases n/nincreases with Te/Tewhen Vware=0 nl (x1019m-2) Te/Te(m-1) 2 min. combined LHCD/ICRH discharge Te/Te(m-1) nl (x1019m-2) nl (x1019m-2) LH (MW) ICRH (MW) n/n (m-1) n/n (m-1) q/q (m-1) q/q (m-1) Vneo(x10-2 m/s) Vneo(x10-2 m/s) r/a = 0.3 r/a = 0.3 Support Materials

  16. Density peaking increases with magnetic field shear in the gradient region • Te/ Te • (m-1) - n/n (m-1) Circles: Te/Ti =1.3 Diamonds: Te/Ti =2.1 CT -0.15 Cq  0.8 q/q (m-1) 0.3 r/a 0.6 Similar observation at JET & TCV [H. Weisen, PPCF 46 (2004) 751] Support Materials Dominant inward curvature pinchcorrelated with dominant TEM, consistent with turbulence simulations e.g., X. Garbet, PRL 91 (2003); C. Angioni, Phys. Plasmas 10 (2003)

  17. Density peaking varies with q-profile Normalized profile to the value @ r/a =0.6 50 profiles from 10 shots. Slightly under estimated using Isichenko’s formula based on ITGs (fits TFTR L-mode) PRL74,1995 Isichenko Nycander Yankov Model 1/q Exp. Exp. Over estimated by model 1/q (fits TFTR supershots) PoP 2 1995 Model Boucher&Rebut&Watkins qedge ~14 qedge ~ 9 Empirical model, n ~1/q0.5, reproduces better experiments also fits JET and ITER database CR Acad. Sci. T315, Ser. II, 273 (92) Exp. Model 1/q0.5 Model 1/q0.5 Exp. Support Materials

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