Professional Presentations

A Portable Version of EFIT with Toroidal Rotation for VMS and UNIX Environments, S.J. Thompson et al., General Atomics

A portable, easily-maintained version of the reconstruction code, EFIT, is being developed for use in both VMS and UNIX environments. Initial benchmark calculations indicate a 5- to 6-fold improvement in computational speed on an HP 9000/730 UNIX workstation when compared with a VAX 4000/3000 or a Sun SPARCstation 1. Early results suggest between-shot MHD analysis, reconstructing fully the time evolution of a discharge with as many as 50-70 time slices, is possible and requires less than 5 minutes of CPU time. A model for equilibrium reconstruction incorporating toroidal flow in an axially symmetric torus is also being developed. With toroidal flow, the constant pressure surfaces do not coincide with the magnetic surfaces (relative displacement depending on flow velocity), nor do surfaces of constant density, in general, coincide with flux or pressure surfaces. In this case, the centrifugal force due to toroidal rotation balances the pressure variation along a flux surface. To reconstruct equilibria, magnetic data must be supplemented by toroidal rotation data from charge exchange recombination spectroscopy. Results of analysis using experimental DIII-D data will be presented.

  • Supported by the U.S. Department of Energy (Contract DE-AC03-89ER51114)

  • Presented at the 34th Annual American Physical Society Conference on Controlled Fusion and Plasma Physics, Nov. 16-20, Seattle, WA, and published in the Bulletin (Abstract) 37 (1992) 1511

Profile Analysis of High Performance Discharges in the DIII-D Tokamak, S.J. Thompson et al., General Atomics

Experimental results from the DIII-D tokamak indicate that improved stability and confinement regimes may be obtained in shaped discharges with detailed pressure and current profile control. In this work we present accurate, self-consistent reconstructions of the tokamak current profile and the associated magnetic topology using the MHD equilibrium constraint from external magnetic measurements, kinetic profile measurements, local internal measurements of the magnetic field pitch angle from multi-channel motional Stark effect diagnostics, and topological information from soft X-ray measurements. Detailed results for several high performance shaped tokamak discharges (high normalized toroidal beta, high internal inductance, confinement enhancement factor, H ~ 4, and high poloidal beta) will be presented.

  • Supported by the U.S. Department of Energy (Contracts DE-AC03-89ER51114 and W-7405-ENG-48)

  • Presented at the 35th Annual American Physical Society Conference on Controlled Fusion and Plasma Physics, Nov. 1-5, St. Louis, MO, and published in the Bulletin (Abstract) 38 (1993) 2066