Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations

A. E. White; W. A. Peebles; T. L. Rhodes; C. H. Holland; G. Wang; L. Schmitz; T. A. Carter; J. C. Hillesheim; E. J. Doyle; L. Zeng; G. R. McKee; G. M. Staebler; R. E. Waltz; J. C. Deboo; C. C. Petty; K. H. Burrell

doi:10.1063/1.3323084

Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations

A. E. White, W. A. Peebles, T. L. Rhodes, C. H. Holland, G. Wang, L. Schmitz, T. A. Carter, J. C. Hillesheim, E. J. Doyle, L. Zeng, G. R. McKee, G. M. Staebler, R. E. Waltz, J. C. Deboo, C. C. Petty, K. H. Burrell

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Abstract

This paper presents new measurements of the cross-phase angle, α n_e T_e, between long-wavelength (k_θ ρ _s <0.5) density, ñ_e, and electron temperature, T̃ _e, fluctuations in the core of DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak plasmas. The coherency and cross-phase angle between ñ _e and T̃ _e are measured using coupled reflectometer and correlation electron cyclotron emission diagnostics that view the same plasma volume. In addition to the experimental results, two sets of local, nonlinear gyrokinetic turbulence simulations that are performed with the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] are described. One set, called the pre-experiment simulations, was performed prior to the experiment in order to predict a change in α n_e T _e given experimentally realizable increases in the electron temperature, T_e. In the experiment the cross-phase angle was measured at three radial locations (ρ =0.55, 0.65, and 0.75) in both a "Base" case and a "High T_e " case. The measured cross-phase angle is in good qualitative agreement with the pre-experiment simulations, which predicted that ñ _e and T̃ _e would be out of phase. The pre-experiment simulations also predicted a decrease in cross-phase angle as T_e is increased. Experimentally, this trend is observed at the inner two radial locations only. The second set of simulations, the postexperiment simulations, is carried out using local parameters taken from measured experimental profiles as input to GYRO. These postexperiment simulation results are in good quantitative agreement with the measured cross-phase angle, despite disagreements with transport fluxes. Directions for future modeling and experimental work are discussed.

Original language	English
Article number	056103
Journal	Physics of Plasmas
Volume	17
Issue number	5
DOIs	https://doi.org/10.1063/1.3323084
State	Published - May 2010
Externally published	Yes

Funding

This research was supported by the U.S. Department of Energy under Grant Nos. DE-AC05-06OR23100, DE-FG03-08ER54984, DE-FG02-07ER54917, DE-FG03-95ER54309, and DE-FC02-04ER54698. The research of A.E.W. was performed under an appointment to a DOE ORISE FES postdoctoral fellowship. J.C.H. is supported by a DOE ORISE FES graduate fellowship. A.E.W. wishes to thank the tokamak operators for this experiment, J. R. Ferron and B. Hudson, and would like to acknowledge insightful input from D. Mikkelson and R. Prater. A.E.W. also thanks R. J. Groebner for CER analysis and C. Holcomb for MSE analysis. We thank the entire DIII-D team for their support of these experiments. The GYRO simulations reported here were performed on FRANKLIN at NERSC.

Funders	Funder number
U.S. Department of Energy	DE-FC02-04ER54698, DE-FG03-95ER54309, DE-FG02-07ER54917, DE-AC05-06OR23100, DE-FG03-08ER54984

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White, A. E., Peebles, W. A., Rhodes, T. L., Holland, C. H., Wang, G., Schmitz, L., Carter, T. A., Hillesheim, J. C., Doyle, E. J., Zeng, L., McKee, G. R., Staebler, G. M., Waltz, R. E., Deboo, J. C., Petty, C. C., & Burrell, K. H. (2010). Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations. Physics of Plasmas, 17(5), Article 056103. https://doi.org/10.1063/1.3323084

@article{1bc50625f48c4826bb351c954c297df1,

title = "Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations",

abstract = "This paper presents new measurements of the cross-phase angle, α ne Te, between long-wavelength (kθ ρ s <0.5) density, {\~n}e, and electron temperature, {\~T} e, fluctuations in the core of DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak plasmas. The coherency and cross-phase angle between {\~n} e and {\~T} e are measured using coupled reflectometer and correlation electron cyclotron emission diagnostics that view the same plasma volume. In addition to the experimental results, two sets of local, nonlinear gyrokinetic turbulence simulations that are performed with the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] are described. One set, called the pre-experiment simulations, was performed prior to the experiment in order to predict a change in α ne T e given experimentally realizable increases in the electron temperature, Te. In the experiment the cross-phase angle was measured at three radial locations (ρ =0.55, 0.65, and 0.75) in both a {"}Base{"} case and a {"}High Te {"} case. The measured cross-phase angle is in good qualitative agreement with the pre-experiment simulations, which predicted that {\~n} e and {\~T} e would be out of phase. The pre-experiment simulations also predicted a decrease in cross-phase angle as Te is increased. Experimentally, this trend is observed at the inner two radial locations only. The second set of simulations, the postexperiment simulations, is carried out using local parameters taken from measured experimental profiles as input to GYRO. These postexperiment simulation results are in good quantitative agreement with the measured cross-phase angle, despite disagreements with transport fluxes. Directions for future modeling and experimental work are discussed.",

author = "White, {A. E.} and Peebles, {W. A.} and Rhodes, {T. L.} and Holland, {C. H.} and G. Wang and L. Schmitz and Carter, {T. A.} and Hillesheim, {J. C.} and Doyle, {E. J.} and L. Zeng and McKee, {G. R.} and Staebler, {G. M.} and Waltz, {R. E.} and Deboo, {J. C.} and Petty, {C. C.} and Burrell, {K. H.}",

year = "2010",

month = may,

doi = "10.1063/1.3323084",

language = "English",

volume = "17",

journal = "Physics of Plasmas",

issn = "1070-664X",

publisher = "American Institute of Physics",

number = "5",

}

White, AE, Peebles, WA, Rhodes, TL, Holland, CH, Wang, G, Schmitz, L, Carter, TA, Hillesheim, JC, Doyle, EJ, Zeng, L, McKee, GR, Staebler, GM, Waltz, RE, Deboo, JC, Petty, CC & Burrell, KH 2010, 'Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations', Physics of Plasmas, vol. 17, no. 5, 056103. https://doi.org/10.1063/1.3323084

TY - JOUR

T1 - Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations

AU - White, A. E.

AU - Peebles, W. A.

AU - Rhodes, T. L.

AU - Holland, C. H.

AU - Wang, G.

AU - Schmitz, L.

AU - Carter, T. A.

AU - Hillesheim, J. C.

AU - Doyle, E. J.

AU - Zeng, L.

AU - McKee, G. R.

AU - Staebler, G. M.

AU - Waltz, R. E.

AU - Deboo, J. C.

AU - Petty, C. C.

AU - Burrell, K. H.

PY - 2010/5

Y1 - 2010/5

N2 - This paper presents new measurements of the cross-phase angle, α ne Te, between long-wavelength (kθ ρ s <0.5) density, ñe, and electron temperature, T̃ e, fluctuations in the core of DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak plasmas. The coherency and cross-phase angle between ñ e and T̃ e are measured using coupled reflectometer and correlation electron cyclotron emission diagnostics that view the same plasma volume. In addition to the experimental results, two sets of local, nonlinear gyrokinetic turbulence simulations that are performed with the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] are described. One set, called the pre-experiment simulations, was performed prior to the experiment in order to predict a change in α ne T e given experimentally realizable increases in the electron temperature, Te. In the experiment the cross-phase angle was measured at three radial locations (ρ =0.55, 0.65, and 0.75) in both a "Base" case and a "High Te " case. The measured cross-phase angle is in good qualitative agreement with the pre-experiment simulations, which predicted that ñ e and T̃ e would be out of phase. The pre-experiment simulations also predicted a decrease in cross-phase angle as Te is increased. Experimentally, this trend is observed at the inner two radial locations only. The second set of simulations, the postexperiment simulations, is carried out using local parameters taken from measured experimental profiles as input to GYRO. These postexperiment simulation results are in good quantitative agreement with the measured cross-phase angle, despite disagreements with transport fluxes. Directions for future modeling and experimental work are discussed.

AB - This paper presents new measurements of the cross-phase angle, α ne Te, between long-wavelength (kθ ρ s <0.5) density, ñe, and electron temperature, T̃ e, fluctuations in the core of DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak plasmas. The coherency and cross-phase angle between ñ e and T̃ e are measured using coupled reflectometer and correlation electron cyclotron emission diagnostics that view the same plasma volume. In addition to the experimental results, two sets of local, nonlinear gyrokinetic turbulence simulations that are performed with the GYRO code [J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)] are described. One set, called the pre-experiment simulations, was performed prior to the experiment in order to predict a change in α ne T e given experimentally realizable increases in the electron temperature, Te. In the experiment the cross-phase angle was measured at three radial locations (ρ =0.55, 0.65, and 0.75) in both a "Base" case and a "High Te " case. The measured cross-phase angle is in good qualitative agreement with the pre-experiment simulations, which predicted that ñ e and T̃ e would be out of phase. The pre-experiment simulations also predicted a decrease in cross-phase angle as Te is increased. Experimentally, this trend is observed at the inner two radial locations only. The second set of simulations, the postexperiment simulations, is carried out using local parameters taken from measured experimental profiles as input to GYRO. These postexperiment simulation results are in good quantitative agreement with the measured cross-phase angle, despite disagreements with transport fluxes. Directions for future modeling and experimental work are discussed.

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U2 - 10.1063/1.3323084

DO - 10.1063/1.3323084

M3 - Article

AN - SCOPUS:77953007440

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JO - Physics of Plasmas

JF - Physics of Plasmas

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Measurements of the cross-phase angle between density and electron temperature fluctuations and comparison with gyrokinetic simulations

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