Study of the spatial structure of drift-wave turbulence in the torsatron TJ-K
Résumé
The structure and scaling properties of drift-wave turbulence has been studied using a $8\times$8 Langmuir-probe matrix. Quasi-coherent structures drift into the electron-diamagnetic direction. The scalings of correlation lengths and times with the drift scale parameter $\rho_s$ and other dimensionless parameters are investigated. Using five different gases from hydrogen to argon, $\rho_s$ could be varied by a factor of 10. A scaling weaker than Bohm-like has been found for the correlation length. The study of $\rho_s$ scaling on the diffusivity turns out to be misleading since residual dependencies on other parameters are present and the cross-phase between poloidal electric field and density fluctuations is also a function of $\rho_s$. The measured turbulent diffusivity is consistent with typical values reported for the edge of fusion plasmas.
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