Regimes of improved confinement and stability in DIII-D obtained through current profile modifications
- General Atomics, San Diego, CA (United States)
- California Univ., Los Angeles, CA (United States)
- Lawrence Livermore National Lab., CA (United States)
- Oak Ridge National Lab., TN (United States)
- Max-Planck-Institut fuer Plasmaphysik, Garching (Germany)
Several regimes of improved confinement and stability have been obtained in recent experiments in the DIII-D tokamak by dynamically varying the toroidal current density profile to transiently produce a poloidal magnetic field profile with more favorable confinement and stability properties. A very peaked current density profile with high plasma internal inductance, {ell}{sub i}, is produced either by a rapid change in the plasma poloidal cross section or by a rapid change in the total plasma current. Values of thermal energy confinement times nearly 1.8 times the JET/DIII-D ELM-free H-mode thermal confinement scaling are obtained. The confinement enhancement factor over the ITER89-P L-mode confinement scaling, H, is as high as 3. Normalized toroidal beta, {beta}{sub N}, greater than 6%-m-T/MA and values of the product {beta}{sub N}H greater than 15 have also been obtained. Both the confinement and the maximum achievable {beta} vary with {ell}{sub i} and decrease as the current profile relaxes. For strongly shaped H-mode discharges, in addition to the current density profile peakedness, as measured by {ell}{sub i} other current profile parameters, such as its distribution near the edge region, may also affect the confinement enhancement.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC03-89ER51114; AC05-84OR21400; W-7405-ENG-48
- OSTI ID:
- 10103288
- Report Number(s):
- GA-A-21053; CONF-920913-21; ON: DE93002674
- Resource Relation:
- Conference: 14. international conference on plasma physics and controlled nuclear fusion research,Wurzburg (Germany),30 Sep - 7 Oct 1992; Other Information: PBD: Sep 1992
- Country of Publication:
- United States
- Language:
- English
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