Nonlocal k-space interaction and the rare existence of coherent structures in the tokamak edge plasma
The relation between turbulent density fluctuations occurring at two wave numbers is investigated at the plasma edge of the Tore Supra tokamak. To achieve this goal, light scattering is used with two laser beams performing a Fourier transform about two given wave vectors. Consequently a band-pass filter is applied to the spatial turbulent density fluctuations about each wave vector. When the separation is small between the analyzing wave numbers, it is found that the cross correlation between the two channels is dominated by the autocorrelation caused by the diagnostic resolution in the wave number space. For large separations, the instrumental resolution contribution is negligible but a cross correlation amplitude of about 1% to 2% is still detected. It reflects nonlocal coupling in the k space caused by eddy organization rarely taking place. In agreement with this behavior, a rather small deviation of the probability distribution from a Gaussian is reported.
Bibliographic Reference: An article published in: Physics of Plasmas, Vol. 9 (2002), N°4, p 1255-1261
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Record Number: 200518142 / Last updated on: 2005-06-06
Original language: en
Available languages: en