H. Urano, H. Takenaga, T. Fujita, Y. Kamada, K. Kamiya, Y. Koide, N. Oyama, M. Yoshida and the JT-60 Team Japan Atomic Energy Agency JT-60U Tokamak: p. 1 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 Japan Atomic Energy Agency Naka Fusion Institute Dependence of H-mode pedestal and heat transport on toroidal rotation in JT-60U

JT-60U has 11 PNBs (~85keV) and 2 NNBs (~ keV). Widely variations in combination of tang. (co/bal/ctr) and perp. injection. After the installation of FSTs, accessible dynamic range of V T has become extended towards co- direction. Introduction H. Shirai et al, NF 39 (1999) 1713 H. Urano et al, NF 47 (2007) 706 -NBI T-NBI P-NBI P-NBI P-NBI CO dir. CTR dir. #2 #3, 4 #6 #7, 8 #9, 10 #12 #13, 14 I p 2 co-tang. NNB (4MW) 7perp.PNBs (~15.75MW) 2ctr-tang.PNBs (~4.5MW) 2 co-tang. PNBs (~4.5MW) JT-60U Tokamak: p. 2 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 Energy confinement is improved with toroidal rotation in co-direction during conventional ELMy H-mode plasmas. However, the mechanism how this confinement improvement is obtained with the change of toroidal rotation is not yet clear.

Objectives Clarify the mechanism of energy confinement improvement with co-toroidal rotation in conventional ELMy H-modes. (1) Dependence of H-mode pedestal and ELMs on edge toroidal rotation (2) Dependence of heat transport in the plasma core on toroidal rotation profile. JT-60U Tokamak: p. 3 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 Pedestal boundary condition p, T ETB T(r)  T ped 01 r/a stiffness heat fluxQ(r) V T (r) ?  pol ELM W th =W ped +W core B.C. V T (r) n ped,T, ,… core pedestal  (r),T(r),n(r),…  pol ? e.g. L T,… Locally affected in H-modes? resilience ELM

[MW] [10 20 m -2 ] [MJ] [a.u.] P NBI neTLneTL W DIA  pol DD DD DD time [s] (co-NBI) (bal-NBI) (ctr-NBI) P ABS [MW] W th [MJ] bal-inj. co-inj. ctr-inj. Experiments on power scan with the variation of toroidal momentum source co-NBIbal-NBIctr-NBI Total and thermal stored energy become higher when co-NBI is applied. tangential NB perp. NBs Line-averaged n e does not change in the variation of tang. NBs. LH transition occurs with lower heating power in case of ctr-NBI. JT-60U Tokamak: p. 4 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, [Hz] f ELM

ELM frequency becomes lower and ELM energy loss becomes larger with co-toroidal rotation At a given P sep, ELM frequency f ELM is clearly reduced as the toroidal rotation increases in co-direction. 01 V T ped [10 5 m/s] f ELM [Hz] co-NBI bal-NBI ctr-NBI P sep ~ 5MW,n e ~ 2x10 19 m -3 JT-60U Tokamak: p. 5 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, V T PED [10 5 m/s]  W ELM / W ped [%] P sep ~ 5MW, n e ~ 2x10 19 m -3 co-NBI bal-NBI ctr-NBI With increasing toroidal rotation towards co-direction, ELM energy loss  W ELM clearly becomes larger with the decrease of f ELM.

Large ELM affected area in case of co-NBI ELM affected area also extends more inward in case of co-NBI. JT-60U Tokamak: p. 6 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 In case of co-NBI, ELM frequency is lower and drop of edge T e profile becomes larger.

co-NBI P NBI neTLneTL W DIA DD pp TeTe nene time [s] [keV] [a.u.] [10 20 m -2 ] [MW] [MJ] [10 19 m -3 ] AB CD JT-60U Tokamak: p. 7 Pedestal pressure enhanced with increased  pol during type-I ELMy H-mode Enhanced  pol with sufficient central heating can increase the height of the H-mode pedestal during type-I ELMy H-mode phase. I p = 1.2MA, B T = 2.6T, q 95 ~ 4,  ~ 0.35 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 P. B. Snyder et al, H-mode WS (2007)

JT-60U Tokamak: p. 8 Reduced heat diffusivity at the plasma core in case of co-NBI TG becomes larger at the plasma core when co-NBI is applied. Heat diffusivity is reduced at a given P abs in case of co-NBI. Core heat transport given by Q/(n  T) in a steady state is enhanced when ctr-NBI is applied dT i /dr [keV/m] Q i /n i [W  m 3 ] co-NBI bal-NBI ctr-NBI  CTR  CO r/a = Is core TG scale length shortened by enhanced V T in co-direction? r/a  i [m 2 /s] co-NBI bal-NBI ctr-NBI r/a Heat Flux Q i [MW] co-NBI bal-NBI ctr-NBI The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007

JT-60U Tokamak: p. 9 Self-similar temperature profile raised with co-NBI leading to highly sustained energy Core temperature increases throughout minor radius when co-NBI is applied. Heat transport varies with sustaining self-similar temperature profiles in the variations of toroidal rotation. Does increased pedestal temperature with co-toroidal rotation play a role as a key factor for better confinement? r/a T i [keV] Logarithmic plot The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007

JT-60U Tokamak: p. 10 Pedestal structure varies together with edge toroidal rotation The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, Distance from separatrix [cm] T i [keV] V T ped [10 5 m/s] p ped [kPa] co-NBI bal-NBI ctr-NBI P abs ~ 8MW Pedestal temperature is increased with toroidal rotation. co-NBI bal-NBI ctr-NBI Steep dT/dr in the ETB layer might be caused by increased  pol in case of co- NBI. Examine heat transport in the plasma core when boundary condition is fixed in cases of co-and ctr-NBI.  pol = 1.3  pol = 1.1 Pedestal pressure increases weakly with the increase of V T ped into co-direction.

JT-60U Tokamak: p. 11 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 Identical temperature profiles for cases of co- and ctr-NBI at fixed T ped adjusted by density When density is raised in co-case to reduce T ped to the level of ctr-case, identical T profiles are obtained in spite of totally different V T profiles. Heat diffusivities are also similar at Q/n ~ const. because of similar T profiles (dT/dr = const.).

 T i /T i [m -1 ] Q i / n i [ W  m 3 ] Difference of TG scale length is small in the variations of V T profiles co-NBI bal-NBI ctr-NBI r/a = r/a T i [keV] Heat flux is enhanced while sustaining self- similar T i profile in the variations of toroidal rotation. High pedestal temperature is a key factor for confinement improvement with toroidal rotation. TG scale length does not clearly change with V T and remains roughly constant in core region. JT-60U Tokamak: p. 12 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007

JT-60U Tokamak: p. 13 Summary: Schematic view of H-mode confinement When V T increases in co-direction, pedestal pressure becomes larger. Heat transport in the core is reduced with toroidal rotation while sustaining self-similar temperature profile with higher T ped. Energy confinement in the variation of V T is determined by increased pedestal and reduced transport brought on by stiffness in standard H-mode plasmas. The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007 Pedestal boundary condition p, T ETB T(r)  T ped 01 r/a stiffness heat fluxQ(r)  pol ELM W th =W ped +W core B.C. V T (r) n ped,T, ,… core pedestal  (r),T(r),n(r),…  pol e.g. L T,… resilience ELM very weak in standard H-mode

V T (r=0.2a) [10 5 m/s] n e (r=0.2a) / n e U V T (r=0.2a) [10 5 m/s] n e U2 [10 19 m -3 ] V T (r=0.2a) [10 5 m/s] n e U2 [10 19 m -3 ] V T (r=0.2a) [10 5 m/s] n e (r=0.2a) / n e U2 co-NBI bal-NBI ctr-NBI Electron density profiles are insensitive to torodial rotation except outward shifted case Density profiles or peaking factor does not largely change with V T at the plasma core. However, in case of outward shifted large volume plasma, density profile tends to be peaked at the center when ctr- NBI is applied. Operational range of n e remains roughly constant. Effect of fast ion loss? Er, impurity, … JT-60U Tokamak: p. 14 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007

co-NBI X Y X Y X Y bal-NBI ctr-NBI T i 0.2a – T i ped X = 0.7a x 0.5 x (T i 0.2a + T i ped ) Y = P abs – P rad – dW/dt JT-60U Tokamak: p. 15 ~ 1 / L Ti TG scale length in DB analysis Enhanced heat flux at global TG boundary in the plasma core is similar in the variations of the direction of tang-NBI. Larger volume plasmas have more stiff T i profiles against heating power. Remove the effect of mean dT/dr caused by power deposition. The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, 2007

Height and width of the H-mode pedestal of T i profile becomes greater when co-NBI is applied. Compare the pedestal profiles with V T ped into co- and ctr-direction. JT-60U Tokamak: p. 16 The 13 th ITPA meeting on Pedestal and Edge Physics, Oct 1-3, distance from separatrix [m] T i ped [ keV ] pedestal shoulder (A) co-NBI (B)ctr-NBI n e ped ~ 1.5x10 19 m V T ped [10 5 m/s] p ped [ kPa ] (A) (B) Pedestal pressure tends to increase weakly with toroidal rotation into co-direction Pedestal pressure increases weakly with the increase of V T ped into co-direction at fixed power. P sep ~ 5MW Type-I ELMs