On generation of Alfv{\' e}nic-like fluctuations by drift wave-zonal flow system in Large Plasma Device experiments

POSTER

Abstract

According to recent experiments, magnetically confined fusion plasmas with ``drift wave-zonal flow turbulence'' (DW-ZF) give rise to broadband electromagnetic waves. Sharapov et al (2008) report an abrupt change in the magnetic turbulence during L-H transitions in Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. {\bf 11}, 13 (1987)] plasmas. A broad spectrum of Alfv{\'e}nic-like fluctuations appear from $\textbf{E} \times \textbf{B}$ flow driven turbulence in the Large Plasma Device (LAPD) [W. Gekelman et al., Rev. Sci. Instrum. {\bf 62}, 2875 (1991)]. We present one possible theoretical explanation of electromagnetic fluctuations in DW-ZF systems in LAPD experiments. Fluctuation modes of spectrally stable sheared flows are non-normal. The linear operators of the fluctuations modal analysis are non-normal and the corresponding eigenmodes are not orthogonal. The non-normality results in linear transient growth with bursts of the perturbations and the mode coupling, which causes electromagnetic waves. The transient growth substantially exceeds the growth of the classical dissipative trapped-particle instability.

*This work was supported by ISTC grant G-1217 and by NSF ATM-0638480.

Authors

  • C.E. Correa

    • Institute for Fusion Studies
    • Institute of Fusion Studies, University of Texas at Austin

  • W. Horton

    • Institute for Fusion Studies
    • Institute of Fusion Studies, University of Texas at Austin
    • UT Austin, IFS

  • G.D. Chagelishvili

    • Georgian National Astrophysical Observatory, The Chavchavadze State University

  • V.S. Avsarkisov

    • Georgian National Astrophysical Observatory, The Chavchavadze State University

  • J.G. Lominadze

    • Georgian National Astrophysical Observatory, The Chavchavadze State University

  • Juhyung Kim

    • Department of Physics, University of Wisconsin-Madison
    • Dept. of Physics, Univ. Wisconsin at Madison

  • Jean Carlos Perez

    • University of Wisconsin-Madison
    • Department of Physics, University of Wisconsin-Madison
    • U. Wisconsin-Madison

  • T.A. Carter

    • UCLA
    • Department of Physics and Astronomy, UCLA
    • Department of Physics, University of California, Los Angeles