1. Seminar PPPL, 25 January 2011 Association Euratom-Cea 1 Interplay between neoclassical and turbulent transport on Tore Supra Acknowledgements: J. Abiteboul, F. Clairet, C. Fenzi, S. Futatani 1, V. Grandgirard, R. Guirlet, O. Gürcan 2, P. Hennequin 2, S. Heuraux 3, H. Lütjens 4, R. Sabot, Y. Sarazin, E. Trier 2, L. Vermare 2, D. Villegas, and the Tore Supra Team X. Garbet IRFM, CEA Cadarache 1 Iter Organisation, 2 LPP Ecole Polytechnique, 3 IJL Nancy, 4 CPhT Ecole Polytechnique

2. Seminar PPPL, 25 January 2011 Association Euratom-Cea 2 Motivation and outline Usual statement : perpendicular transport is turbulent, parallel dynamics is collisional. When axisymmetry is lost, competition between turbulence and collisional processes is exacerbated. Outline Large scale flows : competition between turbulence Reynolds stress and viscous damping Particle transport : competition between Ware and turbulent pinch velocities – Perp. diffusion is enhanced in presence of helical perturbations.

3. Seminar PPPL, 25 January 2011 Association Euratom-Cea 3 Turbulence diagnostics and codes on Tore Supra k i k s k Cut-off layer 2 Doppler and 2 fast sweeping reflectometers: profile of turbulence intensity, frequency and wavenumber spectra Numerical tools: global (GYSELA) local (GYRO, GENE) gyrokinetic codes, integrated modelling (CRONOS)

4. Seminar PPPL, 25 January 2011 Association Euratom-Cea 4 Large scale flows : interplay between turbulence generation and collisional damping On Tore Supra, magnetic field corrugation (ripple) is large (7%) Leads to magnetic braking in toroidal direction – controls radial electric field. Competes with turbulence Reynolds stress

5. Seminar PPPL, 25 January 2011 Association Euratom-Cea 5 Flow dynamics Radial force balance equation Reynolds stress + collisional viscous damping Smolyakov 09  determine V , V , et E r Reynolds stress  Viscous damping

6. Seminar PPPL, 25 January 2011 Association Euratom-Cea 6 Rotation measurements Doppler reflectometry Assumption : V ph « -E r /B - supported by simulations  direct measurement of E r CXRS: measurements of V  22.22.42.62.833.21.81.6 Z (m) R (m) CXRS Doppler reflectometry

7. Seminar PPPL, 25 January 2011 Association Euratom-Cea 7 Radial electric field Radial electric field is negative : controlled by thermal ripple losses Local trapping k rip =3.37 Connor 73. Ripple-plateau k rip =1.5 Boozer 80, Kovrizhnykh 99 Trier 08 r/a=0.6

8. Seminar PPPL, 25 January 2011 Association Euratom-Cea 8 Intrinsic toroidal rotation Counter-rotation in Ohmic plasmas. Co-rotation with smaller ripple. Fenzi 10 ripple VV Co-rotation Cntr Consistent with competition between ripple friction and turbulent Reynolds stress.

9. Seminar PPPL, 25 January 2011 Association Euratom-Cea 9 Neoclassical viscous damping Strong collisional friction at the passing/trapped boundary Poloidal flow scales with  T: [Kim '91] Dif-Pradalier 08 Collisionality k neo

10. Seminar PPPL, 25 January 2011 Association Euratom-Cea 10 Poloidal rotation agrees with neoclassical theory in global simulations Consistent with poloidal viscous damping However: large corrugations due to turbulent Reynolds stress. v  Total v  Neo Dif-Pradalier 09

11. Seminar PPPL, 25 January 2011 Association Euratom-Cea 11 Reynolds stress important for shear flow Even if V   V neo, velocity shear is different ExB shear not the same with or w/o turbulence Sarazin 10

12. Seminar PPPL, 25 January 2011 Association Euratom-Cea 12 Is the poloidal rotation neoclassical on Tore Supra? Doppler reflectometry  E r always agrees with  ripple =0 in the core CXRS  V  changes from cntr to co-rotation when ripple becomes weaker Radial force balance equation  V   V neo Not impossible (e.g. JET Crombé 06, DIII-D Kim 94 TFTR transient Bell 98 ) but surprising : turbulence simulations find V   V neo + turbulence corrugations

13. Seminar PPPL, 25 January 2011 Association Euratom-Cea 13 Particle and impurity transport in the plasma core (q<1) Usual form of particle transport  =-D  n+Vn Usually D,V >> D neo,V neo Not always true in the core, where values get closer to neoclassical (“neoclassical”=axisymmetric value)

14. Seminar PPPL, 25 January 2011 Association Euratom-Cea 14 Modelling of transient confirm the diffusion/convection model Futatani 10

15. Seminar PPPL, 25 January 2011 Association Euratom-Cea 15 Particle pinch is usually turbulent on Tore Supra Long pulses (6mn) with LHCD  E ind  0  Ware pinch=0 Ionization source localised in the edge, pinch due to waves is small.  V (electrons) is turbulent Diffusion and pinch velocity vs radius - TORE SUPRA - G.T. Hoang 04

16. Seminar PPPL, 25 January 2011 Association Euratom-Cea 16 Transport during sawtoothing ohmic plasmas Pinch velocity close to Ware value, diffusion is not neoclassical Guirlet 08

17. Seminar PPPL, 25 January 2011 Association Euratom-Cea 17 Fluctuation level is low inside q=1  D turb is small R

18. Seminar PPPL, 25 January 2011 Association Euratom-Cea 18 0 0.2 0.4 0.6 -6 -4 -2 0 2 r/a V trans+stat 0 0.2 0.4 0.6 0 0.5 1 1.5 D trans+stat Guirlet 08 What about impurities? Supersonic impurity gas injection. Both transient and steady profiles are used to assess fluxes  =-D  n+Vn Allows to reduce error bars on D and V by a large factor.

19. Seminar PPPL, 25 January 2011 Association Euratom-Cea 19 Sabot 10 Level of fluctuations Guirlet 10 D and V for electrons and Nickel vs neoclassical Impurities are neoclassical in the core, electrons are not V nickel and D nickel are neoclassical How is is possible to get D e >>D Ni  D Ni,neo >>D e,neo Simplest theory  c,Ni <<  c,e ???

20. Seminar PPPL, 25 January 2011 Association Euratom-Cea 20 m=1,n=1 activity part of the time Estimation of magnetic field amplitude  a few 10 -3 Is the internal kink mode responsible for high D e ? Sabot 10

21. Seminar PPPL, 25 January 2011 Association Euratom-Cea 21 Orders of magnitude Ellectrons: banana-drift regime Nickel: ripple-plateau regime In summary: - Neoclassical electron transport is enhanced–still off by a factor 3-5 - Ni neoclassical transport is unchanged

22. Seminar PPPL, 25 January 2011 Association Euratom-Cea 22 Conclusions GK simulations show that V   V neo but corrugations due to turbulence are not negligible. E r and V  agree with neoclassical theory in ohmic plasmas, with strong ripple. Situation at low ripple is unclear: looks like V  departs from V neo. Some evidence that in the core, collisional transport due to n=1,m=1 helical perturbation can be important