Collisional Scaling of the Energy Transfer in Drift-Wave Zonal Flow Turbulence

B. Schmid, P. Manz, M. Ramisch, U. Stroth

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26 Scopus citations

Abstract

The collisionality scaling of density and potential coupling together with zonal flow energy transfer and spectral power is investigated at the stellarator experiment TJ-K. With a poloidal probe array, consisting of 128 Langmuir probes, density and potential fluctuations are measured on four neighboring flux surfaces simultaneously over the complete poloidal circumference. By analyzing Reynolds stress and pseudo-Reynolds stress, it is found that, for increasing collisionality, the coupling between density and potential decreases which hinders the zonal flow drive. Also, as a consequence, the nonlinear energy transfer, as well as the zonal flow contribution to the complete turbulent spectrum, decreases the same way. This is in line with theoretical expectations and is a first experimental verification of the importance of collisionality for large-scale structure formation in magnetically confined toroidal plasmas.

Original languageEnglish
Article number055001
JournalPhysical Review Letters
Volume118
Issue number5
DOIs
StatePublished - 31 Jan 2017

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