Electron heat transport in improved confinement discharges in DIII-D

Journal Article · Sat May 01 04:00:00 EDT 1999 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.873494· OSTI ID:344929

Stallard, B W; Rice, B W ^[1]; Greenfield, C M; Staebler, G M; Chu, M S; Baker, D R; Burrell, K H; DeBoo, J C; deGrassie, J S; Lohr, J; Miller, R L; Petty, C C; Pinsker, R I; Waltz, R E ^[2]; Rettig, C L; Doyle, E J; Peebles, W A; Rhodes, T L; Zeng, L ^[3]; Austin, M E ^[4] ; Baylor, L R ^[5]; McKee, G R ^[6]

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1. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
3. University of California, Los Angeles, California (United States)
4. University of Texas at Austin, Austin, Texas (United States)
5. Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)
6. University of Wisconsin, Madison, Wisconsin (United States)

In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. {bold 8}, 441 (1985)] tokamak plasmas with an internal transport barrier (ITB), the comparison of gyrokinetic linear stability (GKS) predictions with experiments in both low and strong negative magnetic shear plasmas provide improved understanding for electron thermal transport within the plasma. Within a limited region just inside the ITB, the electron temperature gradient (ETG) modes appear to control the electron temperature gradient and, consequently, the electron thermal transport. The increase in the electron temperaturegradient with more strongly negative magnetic shear is consistent with the increase in the ETG mode marginal gradient. Closer to the magnetic axis the T{sub e} profile flattens and the ETG modes are predicted to be stable. With additional core electron heating, FIR scattering measurements near the axis show the presence of high {ital k} fluctuations (12 cm{sup {minus}1}), rotating in the electron diamagnetic drift direction. This turbulence could impact electron transport and possibly also ion transport. Thermal diffusivities for electrons, and to a lesser degree ions, increase. The ETG mode can exist at this wave number, but it is computed to be robustly stable near the axis. Consequently, in the plasmas we have examined, calculations of drift wave linear stability do not explain the observed transport near the axis in plasmas with or without additional electron heating, and there are probably other processes controling transport in this region. {copyright} {ital 1999 American Institute of Physics.}

• OSTI ID: 344929
• Report Number(s): CONF-981127--
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 6; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CHARGED-PARTICLE TRANSPORT
ELECTRON TEMPERATURE
FLUCTUATIONS
MAGNETIC CONFINEMENT
PLASMA CONFINEMENT
PLASMA INSTABILITY
TOKAMAK DEVICES