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The IN-mode in the TCV tokamak

The IN-mode in the TCV tokamak. O. Sauter, A. N. Karpushov, S. Coda, B. P. Duval, L. Federspiel, D. Kim and the TCV team Ecole Polytechnique Fédérale de Lausanne (EPFL) Centre de Recherches en Physiques des Plasmas (CRPP) Lausanne, Switzerland. High L-mode confinement in ohmic TCV shots

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The IN-mode in the TCV tokamak

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  1. The IN-mode in the TCV tokamak O. Sauter, A. N. Karpushov, S. Coda, B. P. Duval, L. Federspiel, D. Kim and the TCV team Ecole Polytechnique Fédérale de Lausanne (EPFL) Centre de Recherches en Physiques des Plasmas (CRPP) Lausanne, Switzerland

  2. High L-mode confinement in ohmic TCV shots Proximity to L-H transition Role of density in early phase of the discharge Comparison with H-mode profiles Similarity of core profiles, role of edge properties Conclusions Outline

  3. High L-mode confinement in ohmic TCV shots q95~2.7 k~1.5 Ip~320kA, bN~1.4

  4. H-mode phase High L-mode confinement in ohmic TCV shots q95~2.7 k~1.5 Ip~320kA

  5. Improved L-mode Thanks to H-mode phase H-98y2

  6. Improved L-mode Thanks to H-mode phase H-89P 1.6 Through H-mode phase: normal to high L-mode conf.

  7. Without H-mode phase at lower Ip q95~3.3 k~1.4 Ip~270kA

  8. Without H-mode phase at lower Ip q95~3.3 k~1.4 Ip~270kA

  9. Without H-mode phase at lower Ip: similar H-factors: L-mode with H98y20.9 98y2 H-89P 1.6

  10. Te, Ti in low Ip IN-mode: Te~Ti (high ne) Te Ip=260kA, nel=6.3e19 45870: (Wdml=13.5) We=7.0kJ Wi=5.5kJ 46178: (Wdml=10) We=4.5kJ Wi=4.0kJ TC Te TC • Both Te and Ti improve • Ti > Te in edge region • Density profiles are similar (nel control)

  11. Good-bad profiles, low Ip case Ip=260kA, nel=6.3e19 45870: (Wdml=13.5) We=7.0kJ Wi=5.5kJ 46178: (Wdml=10) We=4.5kJ Wi=4.0kJ • vtor follows Ti profile changes

  12. Without H-mode phase: Importance of early density reference

  13. H-98y2 Without H-mode phase: Importance of early density reference refs differ only here Key role of keeping a low li

  14. li  q(0) ↑ ST disappear Back to high L-mode conf. via H-mode phase XXL-mode WDML XL-mode L-mode Further conf. improvement consistent with li

  15. Aiming at same final high parameters Can reach high ohmic L-mode perf. with both approach

  16. QSELM-freeH, 1MW Type-I-H, 1MW IN-L-mode, ohmic Type-III-H, ohmic Comparison with H-mode profiles IN-mode has high ne Needs TCV-UG NBIH QSELM-freeH, 1MW IN-L-mode, ohmic Type-I-H, 1MW Type-III-H, ohmic Type-III-H, ohmic IN-L-mode, ohmic Type-I-H, 2MW • edge ne in IN-mode similar to H-modes • not edge Te • IN-L-mode in TCV close to H-mode profiles L. Porte et al Nucl. Fusion 47 (2007) 952 A. Pitzshke et al PPCF 54 (2012) 015007 • Fills in H-mode range of profiles 0.5-1.5MW

  17. IN-mode and H-mode profiles are ~self-similar pe/pe(0.35) • IN-mode better conf. just inside "pedestal"? (+ne(r=1)) • Edge L-modes are not stiff => wide variety of scenarios On the non-stiffness of edge transport in L-modes, O. Sauter et al, TTF2013

  18. Conclusions • IN-mode is "another" improved L-mode • IN-mode reached H98y~0.9-1 in stationary ohmic L-mode • It has low edge Te (<100eV) and relatively high edge ne • A) Limited H-modes was triggered when forming IN-mode • B) High ne request from t=0 helped creating IN-mode • In both A and B series, li is lower with good confinement • With both A, B series, similar paremeters were obtained • Stationary improved confinement does not depend on initial conditions but needed to "create" good confinement • It shows that L-modes can have a very wide range of edge and core profiles: namely "I-family" (edge non-stiff)

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