Fully developed (three-dimensional) turbulence is characterized by a self-similar distribution of kinetic energy over the different spatial scales. Here, the injected kinetic energy is transferred to smaller and smaller scales. This is called the turbulent cascade. Due to the free particle motion along the magnetic field, the turbulence in magnetically confined plasmas is quasi-two-dimensional on the surface perpendicular to the magnetic field. Quasi-two-dimensional turbulence is also relevant for atmospheres. In these systems, the turbulence tends to form larger structures. This is called an inverse cascade. We find non-local interaction in the wave number space in the region of the direct entropy-cascade. The vortices interacting with each other are of different sizes. This contradicts the picture of the cascade, where stepwise (locally in the wave number space) the energy is transferred between similarly sized vortices.  

relevant publications

P. Manz et al. 'Bispectral experimental estimation of the nonlinear energy transfer in two-dimensional plasma turbulence' 2008 Plasma Phys. Control. Fusion 50 035008 (2008)

P. Manz, M. Ramisch, U. Stroth 'Experimental estimation of the dual cascade in two-dimensional drift-wave turbulence' Plasma Phys. Control. Fusion 51 035008 (2009)

P. Manz, M. Xu, S.C. Thakur G.R. Tynan ^'Nonlinear energy transfer during the transition to drift-interchange turbulence' Plasma Phys. Control. Fusion 53 095001 (2011)

P. Manz, G. Birkenmeier, M. Ramisch, U. Stroth 'A link between nonlinear self-organization and dissipation in drift-wave turbulence' Physics of Plasmas 19, 082318 (2012)