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

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

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