1. Numerical investigation of H-mode threshold power by using LH transition models 8th Meeting of the ITPA Confinement Database & Modeling Topical Group 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

2. 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 ?

3. 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 (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

4. 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)

5. 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

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

7. 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

8. 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.

9. 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 ?

10. 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.

11. 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.