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 O. Sauter TTF 2013, USA, 1 Outline • • • • • • 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 O. Sauter TTF 2013, USA, 2 High L-mode confinement in ohmic TCV shots q95~2.7 κ~1.5 Ip~320kA, βN~1.4 O. Sauter TTF 2013, USA, 3 High L-mode confinement in ohmic TCV shots q95~2.7 κ~1.5 Ip~320kA, βN~1.4 O. Sauter TTF 2013, USA, 4 High L-mode confinement in ohmic TCV shots O. Sauter q95~2.7 κ~1.5 Ip~320kA TTF 2013, USA, 5 High L-mode confinement in ohmic TCV shots H-mode phase O. Sauter q95~2.7 κ~1.5 Ip~320kA TTF 2013, USA, 6 Improved L-mode Thanks to H-mode phase H-98y2 O. Sauter TTF 2013, USA, 7 Improved L-mode Thanks to H-mode phase H-89P 1.6 Through H-mode phase: normal to high L-mode conf. O. Sauter TTF 2013, USA, 8 Without H-mode phase at lower Ip O. Sauter q95~3.3 κ~1.4 Ip~270kA TTF 2013, USA, 9 Without H-mode phase at lower Ip O. Sauter q95~3.3 κ~1.4 Ip~270kA TTF 2013, USA, 10 Without H-mode phase at lower Ip O. Sauter q95~3.3 κ~1.4 Ip~270kA TTF 2013, USA, 11 Without H-mode phase at lower Ip: similar H-factors: L-mode with H98y20.9 98y2 H-89P 1.6 O. Sauter TTF 2013, USA, 12 Te, Ti in low Ip IN-mode: Te~Ti (high ne) Te Te TC Ip=260kA, nel=6.3e19 TC 45870: (Wdml=13.5) We=7.0kJ Wi=5.5kJ 46178: (Wdml=10) We=4.5kJ Wi=4.0kJ O. Sauter • Both Te and Ti improve • Ti > Te in edge region • Density profiles are similar (nel control) TTF 2013, USA, 13 Without H-mode phase: Importance of early density reference O. Sauter TTF 2013, USA, 14 Without H-mode phase: Importance of early density reference O. Sauter TTF 2013, USA, 15 Without H-mode phase: Importance of early density reference refs differ only here O. Sauter TTF 2013, USA, 16 Without H-mode phase: Importance of early density reference refs differ only here H-98y2 O. Sauter TTF 2013, USA, 17 Without H-mode phase: Importance of early density reference refs differ only here H-98y2 Key role of keeping a low li O. Sauter TTF 2013, USA, 18 Back to high L-mode conf. via H-mode phase WDML XXL-mode XL-mode L-mode O. Sauter TTF 2013, USA, 19 Back to high L-mode conf. via H-mode phase WDML XXL-mode XL-mode li ↓ L-mode q(0) ↑ ST disappear Further conf. improvement consistent withTTFli2013, ↓ USA, 20 O. Sauter Aiming at same final high parameters Can reach high ohmic L-mode perf. with both approach O. Sauter TTF 2013, USA, 21 Comparison with H-mode profiles QSELM-freeH, 1MW IN-mode has high ne IN-L-mode, ohmic Needs TCV-UG NBIH Type-I-H, 1MW Type-III-H, ohmic IN-L-mode, ohmic Type-III-H, ohmic Type-I-H, 2MW • edge ne in IN-mode similar to H-modes • not edge Te O. Sauter L. Porte et al Nucl. Fusion 47 (2007) 952 A. Pitzshke et al PPCF 54 (2012) 015007 TTF 2013, USA, 22 Comparison with H-mode profiles QSELM-freeH, 1MW QSELM-freeH, 1MW IN-mode has high ne IN-L-mode, ohmic Needs TCV-UG NBIH Type-I-H, 1MW Type-I-H, 1MW Type-III-H, ohmic IN-L-mode, ohmic IN-L-mode, ohmic Type-III-H, ohmic Type-I-H, 2MW Type-III-H, ohmic • edge ne in IN-mode similar to H-modes • not edge Te • IN-L-mode in TCV close to H-mode profiles • Fills in H-mode range of profiles 0.5-1.5MW O. Sauter TTF 2013, USA, 23 IN-mode and H-mode profiles are ~self-similar • IN-mode better conf. just inside "pedestal"? (+ne(ρ=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 O. Sauter TTF 2013, USA, 24 IN-mode and H-mode profiles are ~self-similar pe/pe(0.35) • IN-mode better conf. just inside "pedestal"? (+ne(ρ=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 O. Sauter TTF 2013, USA, 25 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) O. Sauter TTF 2013, USA, 26