USER model in TRANSP

The USER Model set the profiles for anomalous diffusivity that change linearly between boundaries of the axial, confinement and boundary regions. The model can be enabled by setting pt_[area]%user%active=.True. in the pt_solver namelist. For example, setting
pt_confinement%user%active=.True.
enables the UserModel in the confinement region.
The diffusivity values at the boundaries in $cm^2/s$ are set using the variables USER_CHI0 and USER_CHI1 for six channels of anomalous transport. These channels are:

1. Electron energy channel
2. Ion energy channel
3. Toroidal angular momentum channel
4. Main plasma ion particle channel
5. Impurity ion particle channel
6. Electron particle channel
All channels are disabled by default. In order to enable a channel, NCHAN needs to be used. For example, the settings

NCHAN=1,1,4*0 USER_CHI0=1.e4,5e3,4*0. USER_CHI1=1.e3,5e2,4*0.

will set the diffusivity profiles for the electron and ion energy channels only and these profile will have the shapes as in the figures below.