Numerical investigation of H-mode threshold power by using LH transition models 8th Meeting of the ITPA Confinement Database & Modeling Topical Group 18-21 April, 2005 Kyoto University Kyoto, Japan Central Research Institute of Electric Power Industry(CRIEPI) , Tokyo, Japan R.Hiwatari High Temperature Plasma Center, University of Tokyo, Japan T.Kato, Y.Ogawa

Motivation Comparison between H-mode models and local plasma parameters in edge region For ion orbit loss model For drift alfven model For Rogers and Drake model [T.Fukuda, et al., Nucl. Fusion 37(1997)1199] [T.N.Carlstrom, et al., Nucl. Fusion 39(1999)1941] Each H-mode model seems to specify the H-mode region How about the LH transition threshold power ?

Transport code and Calculation method Core Transport (1.5D transport code) SOL-divertor Transport (two point model) This code was developed by NIFS, Univ. of Tokyo, and has passed the analytic bench mark (participant Prof.Y.OGAWA) [ITER Physics basis, Nucl.Fusion Vol. 39 (1999)2175] Usual two point model Simple particle balance model Applicable to Low-High recycling region [R.Hiwatari, et al.,J. Nucl.Mater. 337-339(2005)386] Calculation method for Pth investigation Energy Transport Energy Transport Input SOL temperature(Boudary condition) Output Heat flux across the separatrix Input Heat flux across the separatrix Output SOL temperature Divertor temperature Particle Transport Particle Transport Input (particle balance not solved.) density profile Input SOL density Output Divertor density

Outline of Transport Simulation Temperature profile(keV) Density profile(1020m-3) LH transition condition: at r/a=0.96 Thermal diffusivity Plasma configuration JT-60U like R=3.4 m a=0.9 m k=1.5 Plasma current Ip= 2.0MA Safety factor 3.0<q95<5.0 Boundary density nedge=nsol=0.667*<ne> Te LH condition Ti Normalized minor radius Normalized minor radius Heating power (MW) Ave.temperarue (keV) total NBI time (sec) time (sec) Edge density(1019m-3) Edge temperarue (keV) ndiv Tsol Tdiv nsol time (sec) time (sec)

Shaing Model Basic Concept (momentum equation for ion) Viscosity force Torque by ion orbit loss (a) (b) (c) viscosity orbit loss Low temperature High temperature Basic L-H transition condition [K.C.Shaing, et.al., Phys.Fluids B2(1990)1492] critical collisionality

Drift Alfven model LH transition condition [G.Janeschitz, et al., J. Nucl.Mater. 266-269(1999)843] Transport Coefficient

Rogers and Drake model Edge Plasma Phase Space LH Transition Condition H-Mode [B.N.Rogers, et.al., Phys. Rev. Lett. 81(1998)4396] LH Transition Condition

Bout Dependence of Pth Mainly, Bout and N20 dependences of Pth are focused Pthscal : L-H transition threshold power scaling law [T.Takizuka, et al.,PPCF 46(2004)A227] (Zeff=1.7, g=0) Pthsim : Calculated L-H transition threshold power Shaing model Drift Alfven model Roger and Drake model Pthsim/Pthscal Pthsim/Pthscal Pthsim/Pthscal Bout [T] Bout [T] Bout [T] Bout dependence is clearly reproduced by theoretical models.

N20 dependence of Pth Larger dependence than the threshold power scaling Shaing model : Pth~n201.7 Roger and Drake model : Pth~n201.7 Smaller dependence Drift Alfven model : Pth~n20-0.4 Shaing model Drift Alfven model Roger and Drake model Pthsim/Pthscal Pthsim/Pthscal Pthsim/Pthscal N20 (1020m-3) N20 (1020m-3) N20 (1020m-3) Calculation condition maybe not reasonable Density transport should be solved? boundary condition nedge~0.667*<ne>，c model? More improvement of LH model is required ?

Bt dependence of Tedge,th scaling Threshold boundary temperature is also proposed. [W.Suttrop, et al., PPFC29(1997)2051] Threshold boundary temperature is also calculated from the two-point model Note:Te,bth is at a-2 cm, but calculation result is on the separatrix. Shaing model Drift Alfven model Roger and Drake model Tedgeth (keV) Tedgeth (keV) Tedgeth (keV) ~Bt0.65 ~Bt0.9 ~Bt1.0 Bt (T) Bt (T) Bt (T) Bt dependence of Te,bth is also reproduced by theoretical models.

Summary and Future Plan Numerical investigation of H-mode threshold power is carried out by using several LH transition models. Bout dependence of Pth is clearly reproduced by the LH transition models. Bt dependence of Te,bthresh is also reproduced by using the LH transition models and the SOL-Divertor two-point model. Consistent n20 dependence is not clearly obtained yet. Future Plan Ip and Zeff dependence will be investigated. The effects of Density profile, c model, etc. are examined. Other LH transition models will be installed.