Electron heat transport in improved confinement discharges in DIII-D

B. W. Stallard; C. M. Greenfield; G. M. Staebler; C. L. Rettig; M. S. Chu; M. E. Austin; D. R. Baker; L. R. Baylor; K. H. Burrell; J. C. DeBoo; J. S. DeGrassie; E. J. Doyle; J. Lohr; G. R. McKee; R. L. Miller; W. A. Peebles; C. C. Petty; R. I. Pinsker; B. W. Rice; T. L. Rhodes; R. E. Waltz; L. Zeng

doi:10.1063/1.873494

Electron heat transport in improved confinement discharges in DIII-D

B. W. Stallard, C. M. Greenfield, G. M. Staebler, C. L. Rettig, M. S. Chu, M. E. Austin, D. R. Baker, L. R. Baylor, K. H. Burrell, J. C. DeBoo, J. S. DeGrassie, E. J. Doyle, J. Lohr, G. R. McKee, R. L. Miller, W. A. Peebles, C. C. Petty, R. I. Pinsker, B. W. Rice, T. L. RhodesR. E. Waltz, L. Zeng

Fusion Energy Division

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94 Scopus citations

Abstract

In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 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_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 k fluctuations (12 cm^-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.

Original language	English
Pages (from-to)	1978-1984
Number of pages	7
Journal	Physics of Plasmas
Volume	6
Issue number	5 I
DOIs	https://doi.org/10.1063/1.873494
State	Published - May 1999

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Stallard, B. W., Greenfield, C. M., Staebler, G. M., Rettig, C. L., Chu, M. S., Austin, M. E., Baker, D. R., Baylor, L. R., Burrell, K. H., DeBoo, J. C., DeGrassie, J. S., Doyle, E. J., Lohr, J., McKee, G. R., Miller, R. L., Peebles, W. A., Petty, C. C., Pinsker, R. I., Rice, B. W., ... Zeng, L. (1999). Electron heat transport in improved confinement discharges in DIII-D. Physics of Plasmas, 6(5 I), 1978-1984. https://doi.org/10.1063/1.873494

@article{a7b84d80d0804976b955b13304cab958,

title = "Electron heat transport in improved confinement discharges in DIII-D",

abstract = "In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 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 Te 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 k fluctuations (12 cm-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.",

author = "Stallard, {B. W.} and Greenfield, {C. M.} and Staebler, {G. M.} and Rettig, {C. L.} and Chu, {M. S.} and Austin, {M. E.} and Baker, {D. R.} and Baylor, {L. R.} and Burrell, {K. H.} and DeBoo, {J. C.} and DeGrassie, {J. S.} and Doyle, {E. J.} and J. Lohr and McKee, {G. R.} and Miller, {R. L.} and Peebles, {W. A.} and Petty, {C. C.} and Pinsker, {R. I.} and Rice, {B. W.} and Rhodes, {T. L.} and Waltz, {R. E.} and L. Zeng",

year = "1999",

month = may,

doi = "10.1063/1.873494",

language = "English",

volume = "6",

pages = "1978--1984",

journal = "Physics of Plasmas",

issn = "1070-664X",

publisher = "American Institute of Physics",

number = "5 I",

}

Stallard, BW, Greenfield, CM , Staebler, GM, Rettig, CL, Chu, MS, Austin, ME, Baker, DR, Baylor, LR, Burrell, KH, DeBoo, JC, DeGrassie, JS, Doyle, EJ, Lohr, J, McKee, GR, Miller, RL, Peebles, WA, Petty, CC, Pinsker, RI, Rice, BW, Rhodes, TL, Waltz, RE & Zeng, L 1999, 'Electron heat transport in improved confinement discharges in DIII-D', Physics of Plasmas, vol. 6, no. 5 I, pp. 1978-1984. https://doi.org/10.1063/1.873494

TY - JOUR

T1 - Electron heat transport in improved confinement discharges in DIII-D

AU - Stallard, B. W.

AU - Greenfield, C. M.

AU - Staebler, G. M.

AU - Rettig, C. L.

AU - Chu, M. S.

AU - Austin, M. E.

AU - Baker, D. R.

AU - Baylor, L. R.

AU - Burrell, K. H.

AU - DeBoo, J. C.

AU - DeGrassie, J. S.

AU - Doyle, E. J.

AU - Lohr, J.

AU - McKee, G. R.

AU - Miller, R. L.

AU - Peebles, W. A.

AU - Petty, C. C.

AU - Pinsker, R. I.

AU - Rice, B. W.

AU - Rhodes, T. L.

AU - Waltz, R. E.

AU - Zeng, L.

PY - 1999/5

Y1 - 1999/5

N2 - In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 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 Te 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 k fluctuations (12 cm-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.

AB - In DIII-D [J. L. Luxon and L. G. Davis, Fusion Technol. 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 Te 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 k fluctuations (12 cm-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.

UR - http://www.scopus.com/inward/record.url?scp=0001175786&partnerID=8YFLogxK

U2 - 10.1063/1.873494

DO - 10.1063/1.873494

M3 - Article

AN - SCOPUS:0001175786

SN - 1070-664X

VL - 6

SP - 1978

EP - 1984

JO - Physics of Plasmas

JF - Physics of Plasmas

IS - 5 I

ER -

Electron heat transport in improved confinement discharges in DIII-D

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