Intermittent turbulence and turbulent structures in a linear magnetized plasma

Strongly intermittent turbulence is observed in the shadow of a limiter in the large plasma device at UCLA [W. Gekelman , Rev. Sci. Instrum. 62, 2875 (1991)]. The amplitude probability distribution function of the turbulence is strongly skewed, with density depletion events (or holes) dominant in the high-density region and density-enhancement events (or blobs) dominant in the low-density region. Two-dimensional cross-conditional averaging shows that the blobs are detached, outward-propagating filamentary structures with a clear dipolar potential, while the holes appear to be part of a more extended turbulent structure. A statistical study of the blobs reveals a typical size of ten times the ion sound gyroradius and a typical velocity of one-tenth the sound speed. (c) 2006 American Institute of Physics.