Parallel flows and turbulence in a linear plasma machine

Abstract

Experimental evidence of parallel flows dynamically coupled to radial turbulent transport is reported in a linear plasma machine (SLPM). Probability density functions (PDFs) for parallel flows and transport are different. PDFs for transport show clear non-gaussian features with large and sporadic bursts and PDFs of parallel flows are rather gaussian. Plasma profiles of parallel Mach number (in the range 0.1–0.3) show gradients dM||/dr comparable to 1/Ln. Experimental results show that the dynamical coupling between transport and flows shows differences at different plasma radii. The degree of coupling also shows variations with plasma heating conditions. These findings suggest that, although turbulence can be considered as quasi-bidimensional in magnetized plasmas, parallel dynamics still play an important role in the regulation of radial transport.