L-H transition

The L-H and H-L transition time can be either set from the namelist, or calculated from power threshold.
By default, TRANSP calculates the L-H power threshold and the pedestal parameters using default settings. To disable these calculations when no needed (e.g. when running TRANSP in analysis mode), the following flag should be set in the namelist:
NLHMODE=.F.

User-defined L-H transition time

NMODEL_L2H_TRANS = 0

To impose the L-H transition time from the namelist

This option also needs the time for the L-H and H-L transition:

TIME_L2H

time (s) of transition from L-mode to H-mode

TIME_H2L

time (s) of transition from H-mode to L-mode

Model based L-H transition time

TRANSP assumes that the plasma is in H-mode when the power across the separatrix exceeds the power threshold for the L-H transition.

NMODEL_L2H_TRANS = 1

To calculate the L-H transition time from power threshold.

There are two options for the calculation of the L-H power threshold, which can be selected with LPED(1)

LPED(1) = 1

Shimomura scaling [Plasma Phys. Control. Fusion 43 (2001) A385-A394]

LPED(1) = 2

Martin scaling [Journal of Physics, Conf. Series 123 (2008) 012033].

Additional settings

CPED(6)

this parameter set the minimum time at which a L-H transition is allowed, thus CPED(6) = < time > means: "do not allow H-mode before < time >"

CPED(8)

The input variable CPED(8) can be used to adjust the power threshold, so the plasma is in H-mode if P$$_loss > CPED(8) x P$$_L-H

NOTE: The power threshold for the H-mode back transition is decreased inside TRANSP by a factor 1.25 to account for hysteresis effects.

TAU_LH_TRANS_X2

This parameter sets the minimum time(s) for factor of 2 change in the boundary condition parameters. This is used to avoid too large and fast variations in the profiles across the L-H transition and for convergence. This is independent of whether the L-H transition is calculated in TRANSP and profiles are predicted, or the density and temperature profiles are input to TRANSP. The same parameter is used also to limits excursions due to large variations in the input data when the plasma is in L-mode. Default value is 5.0 ms.