Comparison of the density fluctuation spectrum and amplitude in TEXT with expectations for electron drift waves

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Abstract
Modifications to the spectrum and magnitude of turbulent density fluctuations in the Texas Experimental Tokamak (TEXT) [Plasma Phys. Controlled Fusion 27, 1335 (1985)], measured by far-infrared scattering, are related to changes in plasma profiles (e.g., density and potential) induced by naturally occurring magnetic islands (i.e., m=2) of varying amplitude. The statistical dispersion relation of the microturbulence that propagates in the electron diamagnetic drift direction is observed to be consistent with expectations for electron drift-wave turbulence when a spectral shift due to E×B plasma rotation is included. Observed spectral widths are several times larger than the linear mode frequency. The fluctuation amplitude is found to scale inversely with the electron density scale length.