Theory Weekly Highlights for February 2002

February 15 2002

A computational module that accounts for arbitrarily pulsed fast ion neutral beam sources was implemented in the Onetwo transport code. Hybrid Monte Carlo deposition and analytic fast ion slowing results are combined to produce a much faster running module than would be possible if a pure Monte Carlo approach were used. Applied to DIII-D, it is expected that better agreement with time dependent neutron rates, fast ion charge exchange, stored energy densities, thermalization rates, etc. will be obtained.

February 08 2002

A utility to convert GYRO simulation data to netCDF format has been developed. The resultant filetype is compatible with the GKV analysis tool developed by W. Nevins (LLNL). A simulation repository has been established at and presently includes exhaustive data for the DIII-D Cyclone base case.

February 01 2002

In a sawtoothing, Elming H-mode discharge, the linear 3/2 tearing index calculated from kinetic EFITs between sawtooth events, was shown to increase on the approach to the onset of a 3/2 mode. The amplitudes of the magnetic fluctuations from the 3/2 seed islands show a corresponding decrease in their damping rate, in agreement with the Rutherford model and a decreasing neoclassical threshold. Simulations with the nonlinear resistive code NIMROD, using these kinetic EFITs as initial conditions, show initially 1/1 and 2/2 components growing, with a 3/2 mode being driven by coupling. This is promising because these are the same group of modes observed in the experiment. The differences in evolution of the 3/2 islands from each kinetic equilibrium will be compared to the experimental data and linear tearing results. This may explain why this particular sawtooth triggered the 3/2 mode, while the several similar preceding sawteeth did not.

These highlights are reports of research work in progress and are accordingly subject to change or modification