Turbulent Density Fluctuations and Proton Heating Rate in the Solar Wind from 9–20 R_⊙

Abstract

We obtain scatter-broadened images of the Crab nebula at 80 MHz as it transits through the inner solar wind in June 2016 and 2017. These images are anisotropic, with the major axis oriented perpendicular to the radially outward coronal magnetic field. Using these data, we deduce that the density modulation index (δN e /N e ) caused by turbulent density fluctuations in the solar wind ranges from 1.9 ×10 −3 to 7.7 ×10 −3 between 9 -20 R ⊙ . We also find that the heating rate of solar wind protons at these distances ranges from 2.2 × 10 −13 to 1.0 × 10 −11 erg cm −3 s −1 . On two occasions, the line of sight intercepted a coronal streamer. We find that the presence of the streamer approximately doubles the thickness of the scattering screen.

Global Solar Magnetic Field and Interplanetary Scintillations During the Past Four Solar Cycles

“…Recent reports using angular-broadening observations show that various turbulent parameters (e.g. amplitude of turbulence, density modulation index) correlate well with the solar cycle (Bisoi et al, 2014;Sasikumar Raja et al, 2016, 2017. In this article, we attempted to explore the relationship between the global magnetic-field strength and the turbulence parameters.…”

“…amplitude of the turbulence, density, velocity and magnetic-field fluctuations, dissipation scales, and heating rates etc.) are related (Bisoi et al, 2014;Sasikumar Raja et al, 2016, 2017. The recently launched Parker Solar Probe may provide valuable insights in understanding the relationship between the magnetic-field and the turbulent parameters (Fox et al, 2016).…”