Theory Weekly Highlights for October 1999

October 29, 1999

The FREYA neutral beam heating package in the ONETWO transport code has been parallelized using MPI (Message Passing Interface) and tested on the LUNA PC Linux cluster. Running FREYA in a stand-alone code, the CPU time needed to calculate the neutral beam deposition profile and orbit losses for a single beamline using 100,000 source particles was found to be nearly a factor of fourteen faster comparing the performance of Hydra to LUNA running 16 processors. This represents an important step in improving the performance of the ONETWO code by taking advantage of modern high speed computing techniques.

October 22, 1999

The DIII-D Brainstorming meeting was broadcast over the Web using a PC and RealNetworks technology. This hardware/software configuration replaced the Polycom StreamStation that was used during the Year End Summary meeting that was broadcast last month. Although minor hardware problems did delay the start of the broadcast on the first day, these were resolved and the remainder of the meeting was streamed over the Web.

October 15, 1999

The GATO ideal MHD stability code has been extended successfully to compute growth rates of MHD modes using ballooning transformed variables. This new version will enable the GATO code to compute intermediate and possibly higher toroidal mode number n global ideal kink modes (n ~ 5-20) for general axisymmetric equilibria. Results from the new code have been obtained for internal modes with toroidal mode numbers up to n = 20.

October 08, 1999

It was shown previously that a central plasma rotation could be sustained by ICRF, which transfers no net torque to the plasma, provided finite banana width effects of the ICRF-energized particles produced separated regions of positive and negative torque density. However, calculations from the ORBIT code, done in collaboration with PPPL, showed that torque density arising from jr x Bp effects was almost cancelled by mechanical angular momentum transfer by collisions to the background plasma. It has now been shown that this result appears to be specific to the particles' initial conditions and that other initial conditions will result in separated torque density regions. ORBIT calculations are planned to investigate a variety of initial conditions representative of ICRF-energized particles.

October 01, 1999

The NCLASS neoclassical transport model has been implemented in the XPTOR transport code and tested on the Luna beowolf system. NCLASS calculates the transport fluxes, neoclassical resistivity, viscosities, and bootstrap current for a multi-species plasma of arbitrary aspect ratio, geometry and collisionality. It is currently being installed in the ONETWO code whereby the user is given the option of writing the relevant geometric quantities to iterdb files required for use in XPTOR. The ONETWO version should be available for general use within the next few weeks.

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