Rotation Parameters

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TRANSP can either be provided with rotation data or it can be used to calculate the rotation profile predictively. The rotation 'analysis' mode options are described here, for the predictive mode options consult the TRANSP website.

NLVPHI : Set this flag to .TRUE. in order to use rotation analysis mode. In this case rotation data must be provided. This can either be 1D axial rotation velocity data as a function of time passed using trigraph VPH, 2D rotation velocity profile data passed using trigraph VP2 or 2D angular velocity profile data passed using trigraph OMG. If both profile data (VP2 or OMG) and scalar data (VPH) are used, the profile data can be renormalised to the scalar data by setting NLRNVP to .TRUE.. This will by default happen at the plasma midpoint however the major radius used to perform the renormalisation can be set manually using the namelist variable RMJRVP. The convention is that a positive value for the velocity indicates co-current plasma rotation.

XVPHI : When using 1D rotation data, this variable is used to set the assumed shape of the rotation profile. The actual shape used has the form (1-χ²)^XVPHI i.e. this variable is the exponent applied to a quadratic profile.

Neoclassical Treatment

It is possible to use the general geometry neoclassical transport code NCLASS to determine the radial electric field given the rotation profile of a single ion species. This then allows the rotation profiles of the other ion species to be determined also. In order to do this rotation data for a single species must be provided. An angular inertia weighted average rotation profile is used for the purposes of momentum calculations. The following switches are relevant:

NLVWNC : Set this flag to .TRUE. to use NCLASS to infer the radial E field and rotation profiles of all species given a profile of 1 species as described above. In this case the user must either provide toroidal velocity profile data using trigraph VTR or angular velocity profile data using trigraph OMG. In the latter case it is necessary to set NLOMGVTR to .TRUE..

NGVTOR : This variable is used to indicate which ion species the VTR or OMG data set corresponds to. The possible options are as follows:

• NGVTOR = 100 : The input data represents a charge averaged bulk ion.
• NGVTOR = 101 : The input data corresponds to the impurity species (default).
• NGVTOR = -1 : The input data corresponds to the electrons.
• NGVTOR = i : The input data corresponds to ion species i where 1 < i < NGMAX.
• NGVTOR = 0 : The input data is identified by atomic number NVTOR_Z and atomic weight XVTOR_A.

XL1NCVPH : This sets the lower limit of χ where the full NCLASS interpretation is applied. Flat extrapolation is applied from this point to the axis. Note that if NLQLIM0 has been set to limit the axial q value to below the namelist variable QLIM0 then the lower limit of applicability of the NCLASS treatment is taken as the edge of the q liimited region. The default value is 0.10.

XL2NCVPH : This sets the upper limit of χ where the full NCLASS interpretation is applied. The magnitude of the rotation outside this point is not allowed to become greater than the value at XL2NCVPH. The default value is 0.85.

NLIVPO : Set this to .TRUE. to directly read in data for the radial electric potential (V) using trigraph VPO. Note that one cannot set both NLIVPO and NLVWNC to .TRUE. at the same time.

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