Third-moment descriptions of the interplanetary turbulent cascade, intermittency and back transfer

Abstract

One contribution of 11 to a theme issue 'Dissipation and heating in solar wind turbulence' . We review some aspects of solar wind turbulence with an emphasis on the ability of the turbulence to account for the observed heating of the solar wind. Particular attention is paid to the use of structure functions in computing energy cascade rates and their general agreement with the measured thermal proton heating. We then examine the use of 1 h data samples that are comparable in length to the correlation length for the fluctuations to obtain insights into local inertial range dynamics and find evidence for intermittency in the computed energy cascade rates. When the magnetic energy dominates the kinetic energy, there is evidence of anti-correlation in the cascade of energy associated with the outward-and inward-propagating components that we can only partially explain.

Anisotropy in solar wind plasma turbulence

“…Instead, however, the solar wind is a strongly ionized plasma and this range may involve dissipation processes that are more complicated than viscous diffusion. For example, dissipation might occur via wave-particle interactions, wave damping and/or further cascades [7][8][9][10][11]. These processes are expected to become relevant at scales near (and smaller than) the proton gyroradius (ρ i ) and/or proton inertial length (d i = V A /Ω ci ).…”

“…This review is intended to complement existing reviews on solar wind anisotropy and related matters [2][3][4][5][6], and also other papers appearing in this theme issue [7][8][9][10][11]. Thus, we do not attempt a complete review of the literature.…”

Dissipation and heating in solar wind turbulence: from the macro to the micro and back again

“…The logic of this approach is simple: in the absence of dissipation in the inertial range, any energy that is cascaded through it will eventually be dissipated at the smaller scales-the exact process of the dissipation need not be known. The research article of Coburn et al [22] reviews the main tool in calculating these energy cascade rates, third-moment theory and proceed to compare these with thermal proton heating using a very large ensemble of 1 h field and particle data intervals from 12 years of ACE spacecraft observations. One of the most interesting results of this study are that the measured energy cascade rates show highly intermittent values and statistics.…”

Intermittency, nonlinear dynamics and dissipation in the solar wind and astrophysical plasmas

“…To δb r ? More properly, based on the structure of the third-order law for MHD [17,18], perhaps relations analogous to equation (2.6) should be written separately for two local dissipation functions + r and − r , in terms of the increment combinations (δz + |δz − | 2 ) 1/3 and (δz − |δz + | 2 ) 1/3 [19]. There have also been suggestions that even more information could be embedded in the primitive increment functions entering the MHD KRSH, for example by allowing for a scaling of alignment angles between v and b [20].…”