Roberts, OW;
Verscharen, D;
Narita, Y;
Nakamura, R;
Vörös, Z;
Plaschke, F;
(2020)
Possible coexistence of kinetic Alfvén and ion Bernstein modes in sub-ion scale compressive turbulence in the solar wind.
Physical Review Research
, 2
, Article 043253. 10.1103/PhysRevResearch.2.043253.
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Abstract
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 the turbulent density fluctuations in the solar wind and their three-dimensional structure in the sub-ion range. The wave-vector associated with the highest energy density at each spacecraft frequency is obtained by application of the multipoint signal resonator technique to the four-point density data. The fluctuations show a strong wave-vector anisotropy k⊥ k� where the parallel and perpendicular symbols are with respect to the mean magnetic-field direction. The plasma frame frequencies show two populations, one below the proton cyclotron frequency ω<ci consistent with kinetic Alfvén wave (KAW) turbulence. The second component has higher frequencies ω>ci consistent with ion Bernstein wave turbulence. Alternatively, these fluctuations may constitute KAWs that have undergone multiple wave-wave interactions, causing a broadening in the plasma frame frequencies. The scale-dependent kurtosis in this wavevector region shows a reduction in intermittency at the small scales which can also be explained by the presence of wave activity. Our results suggest that small-scale turbulence exhibits linear-wave properties of kinetic Alfvén and possibly ion-Bernstein (magnetosonic) waves. Based on our results, we speculate that these waves may play a role in describing the observed reduction in intermittency at sub-ion scales.
| Type: | Article |
|---|---|
| Title: | Possible coexistence of kinetic Alfvén and ion Bernstein modes in sub-ion scale compressive turbulence in the solar wind |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/PhysRevResearch.2.043253 |
| Publisher version: | http://dx.doi.org/10.1103/PhysRevResearch.2.043253 |
| Language: | English |
| Additional information: | Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10113227 |
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