Characterization of cross-section correction to charge exchange recombination spectroscopy rotation measurements using co- and counter-neutral-beam views

Solomon, W. M.; Burrell, K.H.; Feder, R.; Nagy, A.; Gohil, P.; Groebner, R. J.

doi:10.1063/1.2957841

Cited by 25 publications

(33 citation statements)

References 9 publications

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“…The profiles of ion temperature, T i , and radial electric field, E r , were measured by charge exchange recombination spectroscopy. 37 The measured experimental profiles at t = 1525 ms for reference shots 138 038 ͑red-grey͒ and 138 040 ͑black͒ are shown in Fig. 4.…”

Section: Resultsmentioning

confidence: 99%

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

White¹,

Peebles²,

Rhodes³

et al. 2010

Physics of Plasmas

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This paper presents new measurements of the cross-phase angle, αneTe, between long-wavelength (kθρs<0.5) density, ñe, and electron temperature, T̃e, fluctuations in the core of DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak plasmas. The coherency and cross-phase angle between ñe and T̃e 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 αneTe 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 ñe and T̃e 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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Section: Resultsmentioning

confidence: 99%

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

White¹,

Peebles²,

Rhodes³

et al. 2010

Physics of Plasmas

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“…These data are collected by Thomson scattering, 107 electron cyclotron emission (ECE), and chargeexchange emission spectroscopy (CER). 108 Solid lines represent the best-fit splines to the individual measurements, and the resulting reduced-v 2 (hereafter written v Figure 7 plots power spectra of electron temperature fluctuations in which the fluctuation level approaches dT e =T e % 1%. Density fluctuations are observed with comparable spectra and slightly lower amplitude.…”

Section: Results During Off-axis Nbcdmentioning

confidence: 99%

Energetic ion transport by microturbulence is insignificant in tokamaks

et al. 2013

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Energetic ion transport due to microturbulence is investigated in magnetohydrodynamic-quiescent plasmas by way of neutral beam injection in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)]. A range of on-axis and off-axis beam injection scenarios are employed to vary relevant parameters such as the character of the background microturbulence and the value of E b =T e , where E b is the energetic ion energy and T e the electron temperature. In all cases, it is found that any transport enhancement due to microturbulence is too small to observe experimentally. These transport effects are modeled using numerical and analytic expectations that calculate the energetic ion diffusivity due to microturbulence. It is determined that energetic ion transport due to coherent fluctuations (e.g., Alfvén eigenmodes) is a considerably larger effect and should therefore be considered more important for ITER. V C 2013 AIP Publishing LLC.

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“…The profile diagnostic views intersect neutral beams which inject both in the co-current and counter-current direction. With independent views of the co and counter beams at the same major radius, the true toroidal rotation velocity and associated charge-exchange cross section correction can be calculated, 19 and the sign and magnitude of the correction can be compared to atomic modeling. Each neutral beam has two ion sources directed at different angles, identified by "RT" and "LT" for right or left ion source.…”

Section: Experimental Configuration and Diagnostic Specificationsmentioning

confidence: 99%

Measurements of the deuterium ion toroidal rotation in the DIII-D tokamak and comparison to neoclassical theory

et al. 2012

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Bulk ion toroidal rotation plays a critical role in controlling microturbulence and MHD stability as well as yielding important insight into angular momentum transport and the investigation of intrinsic rotation. So far, our understanding of bulk plasma flow in hydrogenic plasmas has been inferred from impurity ion velocity measurements and neoclassical theoretical calculations. However, the validity of these inferences has not been tested rigorously through direct measurement of the main-ion rotation in deuterium plasmas, particularly in regions of the plasma with steep pressure gradients where very large differences can be expected between bulk ion and impurity rotation. New advances in the analysis of wavelength-resolved D a emission on the DIII-D tokamak [J. L. Luxon et al., Fusion Sci. Technol. 48, 807 (2002)] have enabled accurate measurements of the main-ion (deuteron) temperature and toroidal rotation. The D a emission spectrum is accurately fit using a model that incorporates thermal deuterium charge exchange, beam emission, and fast ion D a (FIDA) emission spectra. Simultaneous spectral measurements of counter current injected and co current injected neutral beams permit a direct determination of the deuterium toroidal velocity. Time-dependent collisional radiative modeling of the photoemission process is in quantitative agreement with measured spectral characteristics. L-mode discharges with low beam ion densities and broad thermal pressure profiles exhibit deuteron temperature and toroidal rotation velocities similar to carbon. However, intrinsic rotation H-mode conditions and plasmas with internal transport barriers exhibit differences between core deuteron and carbon rotation which are inconsistent with the sign and magnitude of the neoclassical predictions. V C 2012 American Institute of Physics. [http://dx

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Characterization of cross-section correction to charge exchange recombination spectroscopy rotation measurements using co- and counter-neutral-beam views

Cited by 25 publications

References 9 publications

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

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

Energetic ion transport by microturbulence is insignificant in tokamaks

Measurements of the deuterium ion toroidal rotation in the DIII-D tokamak and comparison to neoclassical theory

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