Density fluctuations associated with turbulence and waves

We use the plasma density based on measurements of probe-to-spacecraft potential in combination with magnetic field by MAG to study fields and fluctuations solar wind observed Solar Orbiter during first perihelion encounter ($\sim$0.5~AU away from Sun). In particular we polarization wave field, phase between compressible compressibility ratio (the normalized B) characterize waves turbulence. find that are out-of-phase component for intervals turbulence, while they circular-polarized around proton cyclotron frequency. analyze detail two specific events simultaneous presence left- right-handed at different frequencies. compare properties a prediction three-fluid (electrons, protons alphas) model. limit wavenumbers, $10^{-6} < k 7 \times 10^{-6}$~m$^{-1}$, which corresponds wavelength $7 10^6 >\lambda > 10^6$~m. conclude most likely both correspond low-wavenumber part (close cut-off $\Omega_{c\mathrm{He}++}$) proton-band electromagnetic ion (left-handed frame confined frequency range $\Omega_{c\mathrm{He}++} \omega \Omega_{c\mathrm{H}+}$) propagating outwards inwards directions respectively. The fact polarizations same time identified mode has low group velocity suggests double-banded occur source regions waves.