NCLASS [Houlberg et al, Phys. Plasmas 4 3230 (1997) ] is a module for the calculation of plasma resistivity, bootstrap current and radial electric field within the plasma via inclusion of neoclassical effects. NCLASS uses a full multi-species representation of plasma profiles valid for arbitrary geometry and collisionality regimes. It maintains separate velocity profiles for each species and when given a toroidal rotation velocity profile for one species can calculate the rotation profiles for all species as well as the radial electrostatic potential.
TRUEto use NCLASS to analyze the input rotation data and compute the radial electrostatic potential profile. A full analysis is performed in the range XL1NCVPH < r/a < XL2NCVPH with a simple extrapolation outside this region. The defaults are
TRUEin order to use the average ion temperature for all species in the NCLASS calcuation. This is the default. When set to
FALSENCLASS will use the impurity and majority temperatures estimated by the SLVTX routine (See PPPL website).
TRUEin order to specify the that the rotation profile for the NCLASS diagnostic species should be taken from the rotational data input specified by trigraph
NCLASS is sensitive to noise in temperature and pressure gradients. The following options can be used to reduce the impact of this:
TRUEto activate temperature and density profile smoothing. This recommended.
TRUEto reinitialize the time convolutions after each sawtooth event.
Once the smoothing has been performed, the resulting profiles are renormalised to preserve the total particle and energy content of each species.
TRUEto use NCLASS to calculate the plasma resistivity.
TRUEto include bootstrap currents in the solution of the poloidal field diffusion equation. By default a neoclassical model based on an aspect ratio approximation is used.
NLBOOTis set to
TRUEthis can also be set to
TRUEto calculate the neoclassical bootstrap currents using the NCLASS neoclassical code. This is what is commonly done at JET.