Theory Weekly Highlights for August 1999

August 20, 1999

The MHD stability of a thin layer of liquid lithium supported against a conducting wall by a current flow in the direction of the fluid motion was examined. The slab geometry approximates the configuration being considered for the magnetic propulsion concept of L. Zakharov and R. Woolley (PPPL), as well as the liquefied inner surface of an imploding metallic liner for Magnetized Target Fusion applications. . A variational formulation for the normal surface displacement, assuming an ideally conducting fluid indicates that the liquid layer is stable due to line bending effects.

A new Fortran 90 software package, designed to parallelize finite-difference and Monte-Carlo Fortran codes for porting to parallel facilities was developed. The package is structured as a hierarchy of high-level modules encapsulating typical concurrent implementation of finite difference and particle solvers. Two simulation programs, written specifically to demonstrate the usefulness of this software, were successfully parallelized and tested on the GA parallel cluster, Luna.

August 13, 1999

The time-dependent transport solver PTOR has been extracted from the Cray Basis version of the MLT transport code and ported to a Pentium II based Linux machine. Using the MPI library, the GLF23 transport model was then parallelized, incorporated into the workstation version of PTOR and ported to the GA Luna linux cluster. The performance using 10 CPU's was found to be more than a factor of 8 faster than the single processor runs. This represents an important step toward achieving practical use of the GLF23 model in the Onetwo code.

August 06, 1999

Several ORBIT-RF runs have been carried out with constant and localized power sources to study minority-ICRH induced plasma rotation. Sheared radial current profiles were found in both cases. The collision drag force was measured to be small compared to the RF scattering effect in producing toroidal torque.

The full (nonzero Bθ) FRC formation simulations indicate presence of a substantial azimuthal magnetic field inside the separatrix. This was found to be an important tilt-stabilizing factor.

Schissel, McHarg, and Casper visited Polycom in San Jose this week. Polycom manufactures the ShowStation IP which has been successfully used during meetings the last several months. Discussions centered around Polycom's solution to video conferencing and web based streaming video. The knowledge gained will be used to finalize DIII-D's plan to enhance our support for remote communication during both on-site meetings and tokamak operations.

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