Power balance

This section details the settings used to solve the ion power balance equation to determine the ion temperature. This is only done if NLTIPRO=.FALSE. (which is the default value of NLTIPRO so if this is unset in the namelist then this section is relevant) indicating that the ion temperature is not being read from data or set based on the electron temperature. When this is the case the ion temperature is calculated based on a prescribed form for the ion thermal conductivity:

κ_i = XKFAC × κ_Neo

where κ_Neo is a fit to the neoclassical ion thermal conductivity and XKFAC is an anomalous multiplier. This multiplier can be set directly in the namelist file by the user or specified via Ufile input in one of the following ways:

Set NLXKFI to TRUE and use trigraph XKF to read in 1D data for the anomalous multiplier.

Set NLXKFI to TRUE and use trigraph KF2 to read in 2D data for the anomalous multiplier.

Set NKIMOD=0 and use trigraph KI2 to read in 2D data for the ion conductivity itself. In this case the above equation is not used.

Set NLXKIE to TRUE to set the ion conductivity equal to XKFAC × κ_e where κ_e is the electron thermal conductivity.

The fit to the neoclassical conductivity which is used is specified using the switch NKIMOD. Many models are available and only a few are listed here. For more details see the Ion Power Balance section of the PPPL website.

NKIMOD	Description
2	Hazeltine-Hinton fit
3	Ware-Bolton fit
4	Chang-Hinton fit
5	Chang-Hinton fit with impurity correction
10	IFS-PPPL Gyrofluid model fit
11	Rebut-Lalia-Watkins predictive model : P.H. Rebut, et al., Phys. Fluids, B3,(1991)2209.
12	Rebut-Lalia-Watkins model with Boucher's modification of χ_i to Bohm-like : Rosenbluth 1994 IAEA-CN-60/E-P-2
13	GLF23 χ_e predictive model
14	MMM95 χ_e predictive model
15	WEILAND χ_e transport model
19	MMM7_1 χ_e transport model
21	CDBM χ_e transport model
22	MMM8_1 χ_e transport model

Time Variation

It is possible to transition between up to 8 of the regimes for solving the power balance equation over the course of a simulation by using the following switches. Be aware that using these switches will overwrite the settings in the previous section:

TKIMOD(i) : This specifies the time at which one transitions from regime i to i+1. This must be a strictly ascending list of values each of which is greater than 0.0.

NKIMODA(i) : This specifies the scheme to be used to determine the ion temperature between TKIMOD(i-1) and TKIMOD(i). The options for each time interval are as follows:

NKIMODA(i)=2,3,4 or 5 to specify one of the neoclassical models listed above. NKIMOD is set to NKIMODA(i), NLTI2 and NLXKIE are set to FALSE

NKIMODA(i)=-2,-3,-4 or -5 to specify one of the neoclassical models listed above with feedback on the anomalous multiplier to match input ion temperature data which must have been provided. NKIMOD is set to |NKIMODA(i)|, NLTI2 is set to TRUE and NLXKIE is set to FALSE

NKIMODA(i)=0 to use χ_i Ufile data which must have been provided as described in the section above. NKIMOD is set to 0, NLTI2 and NLXKIE are set to FALSE

NKIMODA(i)=99 to use χ_i=XKFAC × χ_e. NKIMOD is set to 4, NLTI2 is set to TRUENLXKIE is set to FALSE

NKIMODA(i)=100 to set NLTIPRO=TRUE from TKIMOD(i-1) to TKIMOD(i) in order to use ion temperature data or to set the ion temperature based on the electron temperature during this period. See the Ion Temperature Controls section for details of further options in this case.

NKIMODA(i)=11,12,13.... to use one of the predictive models listed in the section above.

DTISAVE : This specifies the timescale over which the ion temperature profile is smoothly merged from being predicted to being taken from input data when using NKIMODA(i)=100.

XKIMOD(i) : This specifies the value of the anomalous multiplier XKFAC for the interval between TKIMOD(i-1) and TKIMOD(i) if NKIMODA(i)>0.

Boundary Conditions

The boundary conditions to be used when solving the ion power balance equation are set using the switch MODIEDG as follows:

MODIEDG=1 : Use the same boundary condition for the edge ion temperature as for the recycling neutrals at the edge (Default)

MODIEDG=2 : Use the value of the TIEDGE namelist input as the boundary value (Default = 10 eV)

MODIEDG=3 : Use the edge value of the electron temperature data as a boundary condition on the ion temperature

MODIEDG=4 : Use the edge ion temperature data as a boundary condition

MODIEDG=5 : Use the NTCC PEDESTAL module to determine a boundary condition (See section titled 'NTCC PEDESTAL module' on the PPPL website)

If option 1 is chosen then the ion temperature boundary condition is determined by the boundary condition for the recycling neutrals which is set by the switch MOD0ED described in the Neutrals section under 'Temperature Settings'.