On generation of Alfvénic-like fluctuations by drift wave–zonal flow system in large plasma device experiments

Horton, W.; Correa, C.; Chagelishvili, G. D.; Avsarkisov, V. S.; Lominadze, J. G.; Perez, J. C.; Kim, J.-H.; Carter, T. A.
September 2009
Physics of Plasmas;Sep2009, Vol. 16 Issue 9, p092102
Academic Journal
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. [Europhysics Conference Abstracts, 35th EPS Conference on Plasma Physics, Hersonissos, 2008, edited by P. Lalousis and S. Moustaizis (European Physical Society, Switzerland, 2008), Vol. 32D, p. 4.071] reported an abrupt change in the magnetic turbulence during L-H transitions in Joint European Torus [P. H. Rebut and B. E. Keen, Fusion Technol. 11, 13 (1987)] plasmas. A broad spectrum of Alfvénic-like (electromagnetic) fluctuations appears from E×B flow driven turbulence in experiments on the large plasma device (LAPD) [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] facility at UCLA. Evidence of the existence of magnetic fluctuations in the shear flow region in the experiments is shown. We present one possible theoretical explanation of the generation of electromagnetic fluctuations in DW-ZF systems for an example of LAPD experiments. The method used is based on generalizing results on shear flow phenomena from the hydrodynamics community. In the 1990s, it was realized that fluctuation modes of spectrally stable nonuniform (sheared) flows are non-normal. That is, the linear operators of the flows 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 the generation of electromagnetic waves from the drift wave–shear flow system. We consider shear flow that mimics tokamak zonal flow. We show that the transient growth substantially exceeds the growth of the classical dissipative trapped-particle instability of the system.


Related Articles

  • Coupled azimuthal and radial flows and oscillations in a rotating plasma. Karimov, A. R.; Stenflo, L.; Yu, M. Y. // Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p062313 

    Nonlinear coupling between the radial, axial, and azimuthal flows in a cold rotating plasma is considered nonperturbatively by first constructing a basis solution for a rotating flow. Simple but exact solutions that describe an expanding plasma with oscillatory flow fields are then obtained....

  • Ray tracing simulation for radiation trapping of the He I resonance transitions in a linear plasma device. Kajita, Shin; Nishijima, Daisuke; Hollmann, Eric M.; Ohno, Noriyasu // Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p063303 

    A ray tracing code combined with a He I collisional-radiative (CR) model has been developed to investigate effects of radiation trapping on the population distribution of He atoms in a weakly ionized plasma. The code accurately reproduces experimentally observed vertical profiles of emission...

  • Mirror instability in space plasmas: Solitons and cnoidal waves. Istomin, Ya. N.; Pokhotelov, O. A.; Balikhin, M. A. // Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p062905 

    The nonlinear theory of magnetic mirror instability (MI) in space plasmas is revisited. The nonlinear dynamics of the MI is analyzed using the perpendicular plasma pressure balance condition and the drift kinetic equation for the ion distribution function as the starting point. In contrast with...

  • On the modulational stability of magnetic structures in electron drift turbulence. Jucker, Martin; Pavlenko, Vladimir P. // Physics of Plasmas;Oct2007, Vol. 14 Issue 10, p102313 

    The generation of large-scale magnetic fields in magnetic electron drift mode turbulence is investigated. In particular, the mechanism of modulational instability caused by three-wave interactions is elucidated and the explicit increment is calculated. Also, a stability criterion similar to the...

  • BRIEF COMMUNICATIONS. Hahm, T.S.; Burrell, K.H. // Physics of Plasmas;Jan1996, Vol. 3 Issue 1, p427 

    Indicates that the radial correlation length of the turbulence responsible for transport can have a different gyroradius scaling in low-mode and high-mode plasma due to E x B flow shear effects. Two-point nonlinear analysis in general tokamak geometry; Model of confinement improvement through E...

  • Structure function analysis of long-range correlations in plasma turbulence. Yu, C. X.; Gilmore, M.; Peebles, W. A.; Rhodes, T. L. // Physics of Plasmas;Jul2003, Vol. 10 Issue 7, p2772 

    Long-range correlations (temporal and spatial) have been predicted in a number of different turbulence models, both analytical and numerical. These long-range correlations are thought to significantly affect cross-field turbulent transport in magnetically confined plasmas. The Hurst exponent,...

  • Oscillating two stream instability of electromagnetic pump in the ion cyclotron range of frequency in a plasma. Ahmad, Nafis; Tripathi, V. K.; Rafat, M.; Husain, Mudassir M. // Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p062308 

    An analytical formalism of oscillating two stream instability of a large amplitude electromagnetic wave in the ion cyclotron range of frequency in a plasma is developed. The instability produces electrostatic ion cyclotron sidebands and a driven low frequency mode. The nonlinear coupling arises...

  • On the estimation by Kadomtsev of coefficients of turbulent transport in magnetized plasma. Nedospasov, A. V. // Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p060501 

    The behavior of plasma in magnetic field is, as a rule, defined by nonlinear interaction of numerous oscillations and exhibits a complex turbulent pattern. Such state of plasma cannot described by linear and quasilinear theories. This paper reflects on the history of studying turbulence in...

  • Whistler wave radiation from a loop antenna located in a cylindrical density depletion. Kudrin, Alexander V.; Bakharev, Pavel V.; Krafft, Catherine; Zaboronkova, Tatyana M. // Physics of Plasmas;Jun2009, Vol. 16 Issue 6, p063502 

    Electromagnetic radiation from sources in a magnetoplasma containing a radially nonuniform cylindrical density depletion is considered. Using a rigorous solution for the total field comprising both the discrete and continuous parts of the spatial spectrum of excited waves, the radiation...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics