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Center for Nonlinear Studies |
Sudden changes in the efficiency of plasma confinement mark transitions to the so-called H (high) mode of operation in tokamaks, stellarators and other devices where plasma is confined by magnetic field. H-mode is a highly desirable regime for the future plasma fusion reactor. Such transitions are always correlated with the development of strong sheared flows and reduction in turbulence. Physics of L-H transitions remains a topic of vigorous research in fusion plasma community. Recently we suggested that physical mechanisms underlying and accompanying spectral condensation of 2D turbulence may be very similar to those occurring during L-H transitions in plasma. Experimental studies of spectral condensation in 2d fluid turbulence reveal several of such similarities, namely, condensation of spectral energy in large coherent structures, transition to a monopole vortex flow and the suppression of turbulent eddies by self-generated shear flow. Evolution of spectra in plasma and in fluids and the dynamics of the systems diffusion are discussed.
Host: Misha Chertkov