Possible coexistence of kinetic Alfv\'en and ion Bernstein modes in sub-ion scale compressive turbulence in the solar wind.

摘要: We investigate compressive turbulence at sub-ion scales with measurements from the Magnetospheric MultiScale Mission. The tetrahedral configuration and high time resolution density data obtained by calibrating spacecraft potential allow an investigation of turbulent fluctuations in solar wind their three-dimensional structure range. wave-vector associated highest energy each frequency is application Multi-point signal resonator technique to four-point data. show a strong anisotropy $k_{\perp}\gg k_{\parallel}$ where parallel perpendicular symbols are respect mean magnetic field direction. plasma frame frequencies two populations, one below proton cyclotron $\omega \Omega_{ci}$ consistent ion Bernstein wave (IBW) turbulence. Alternatively, these may constitute KAWs that have undergone multiple wave-wave interactions causing broadening frequencies. scale-dependent kurtosis this region shows reduction intermittency small which can also be explained presence activity. Our results suggest small-scale exhibits linear-wave properties kinetic Alfven possibly ion-Bernstein/magnetosonic waves. Based on our results, we speculate waves play role describing observed sub scales.