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:

κi = XKFAC × κNeo

where κNeo 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:

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 χi to Bohm-like : Rosenbluth 1994 IAEA-CN-60/E-P-2
13 GLF23 χe predictive model
14 MMM95 χe predictive model
15 WEILAND χe transport model
19 MMM7_1 χe transport model
21 CDBM χe transport model
22 MMM8_1 χe 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:

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:

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'.