Statistical analysis of turbulent flux and intermittency in the nonfusion magnetoplasma Blaamann

Turbulent particle flux due to correlated fluctuations of density and (E) over right arrowx (B) over right arrow -drift velocity has been statistically characterized in the simple magnetized torus Blaamann [F. J. Oynes, O. M. Olsen, H. L. Pecseli, A. Fredriksen, and K. Rypdal, Phys. Rev. E 57, 2242 (1998)]. The shape and width of the probability distribution functions (PDF) and how they change as a function of time resolution tau upon coarse-graining have been analyzed. The shape of the PDF is non-Gaussian with a sharp central peak and is strongly asymmetric. The resulting width, sigma, scales as a power-law over about two decades in tau, sigmasimilar totau(H), for tau>100 mus. As tau decreases the width tends to flatten, i.e., the effective Hurst exponent H increases continuously in the interval 0.5<1. The behavior of the PDF at small time scales seems to be ascribed to the presence of coherent structures, living in the torus generated by flux instability. (C) 2003 American Institute of Physics.