Spatiotemporal Splitting of Global Eigenmodes due to Cross-Field Coupling via Vortex Dynamics in Drift Wave Turbulence

C. Brandt, S. C. Thakur, A. D. Light, J. Negrete, Jr., and G. R. Tynan

Phys. Rev. Lett. 113, 265001 – Published 29 December 2014

Abstract

Spatiotemporal splitting events of drift wave (DW) eigenmodes due to nonlinear coupling are investigated in a cylindrical helicon plasma device. DW eigenmodes in the radial-azimuthal cross section have been experimentally observed to split at radial locations and recombine into the global eigenmode with a time shorter than the typical DW period ( $t ≪ f_{DW}^{- 1}$ ). The number of splits correlates with the increase of turbulence. The observed dynamics can be theoretically reproduced by a Kuramoto-type model of a network of radially coupled azimuthal eigenmodes. Coupling by $E \times B$ —vortex convection cell dynamics and ion gyro radii motion leads to cross-field synchronization and occasional mode splitting events.

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Received 21 March 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.265001

Authors & Affiliations

C. Brandt^1,*, S. C. Thakur^1,2, A. D. Light^2,3, J. Negrete, Jr.⁴, and G. R. Tynan^1,2

¹Center for Energy Research, University of California—San Diego, La Jolla, California 92093-0417, USA
²Center for Momentum Transport and Flow Organization, La Jolla, California 92093-0417, USA
³Center for Integrated Plasma Studies, Department of Physics, University of Colorado at Boulder, Boulder, Colorado 80309, USA
⁴Max-Planck-Institut für Dynamik und Selbstorganisation (MPIDS), Am Faßberg 17, 37077 Göttingen, Germany

^*c.brandt@fz-juelich.de

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Vol. 113, Iss. 26 — 31 December 2014

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