Turbulence, small-scale structures, and dissipation in the solar wind
Thursday, 26 May 2016: 4:00 PM
Melvyn L. Goldstein, Space Science Institute, Baltimore, MD, United States, Silvia Perri, Departmento de Fiscia, Arcavacata di Rende, Italy, Antonella Greco, Dipartimento di Fisica, Universita della Calabria, Calabria, Italy, Sergio Servidio, University of Calabria, Cozenza, Italy, Chris A Gurgiolo, Bitterroot Basic Research Inc, Hamilton, MT, United States and Adolfo F. Vinas, NASA Goddard Space Flight Center, Greenbelt, MD, United States
Abstract:
The observed magnetic field and velocity fluctuations in the solar wind are indicative that the magnetofluid is turbulent. Although the fluctuations often resemble an ensemble of Alfvénic fluctuations, the power spectrum of those fluctuations resembles closely that of ordinary Navier-Stokes fluid turbulence. However, unlike Navier-Stokes turbulence, which dissipates via viscosity at molecular scales, the mechanisms by which solar wind turbulence dissipates are not well understood. As the magnetic fluctuations approach the scale of the proton Larmor radius, power spectrum steepens, which may result from wave dispersion effects or from insipient dissipation. As the scale of the fluctuations approaches electron scales, the slope of the power spectrum changes again. The turbulence at these small scales has been studied using a variety of techniques including single-point power spectra, multi-point k-filtering, and Partial Variance of Increments (PVI). At small scales the plasma appears to contain very small-scale structures that may be the source of dissipation and plasma heating. This talk will discuss some recent studies of this small-scale regime using data from a variety of spacecraft.
