First-year ion-acoustic wave observations in the solar wind by the RPW/TDS instrument on board Solar Orbiter

0552637 - ASÚ 2022 RIV FR eng J - Journal Article
Píša, D. - Souček, J. - Santolík, O. - Hanzelka, J. - Nicolaou, G. - Maksimovic, M. - Bale, S. D. - Chust, T. - Khotyaintsev, Y. - Krasnoselskikh, V. - Kretzschmar, M. - Lorfèvre, E. - Plettemeier, D. - Steller, M. - Štverák, Štěpán - Trávníček, P. - Vaivads, A. - Vecchio, A. - Horbury, T. - O'Brien, H. - Evans, V. - Angelini, V. - Owen, C. J. - Louarn, P.
First-year ion-acoustic wave observations in the solar wind by the RPW/TDS instrument on board Solar Orbiter.
Astronomy & Astrophysics. Roč. 656, December (2021), č. článku A14. ISSN 0004-6361. E-ISSN 1432-0746
Institutional support: RVO:67985815
Keywords : waves * solar wind * plasmas
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 6.240, year: 2021
Method of publishing: Open access with time embargo
https://doi.org/10.1051/0004-6361/202140928

In this paper, we present a year-long study of electrostatic fluctuations observed in the solar wind at an interval of heliocentric distances from 0.5 to 1 AU. The RPW/TDS observations provide a nearly continuous data set for a statistical study of intense waves below the local plasma frequency. The on-board and continuously collected and processed properties of waveform snapshots allow for the mapping plasma waves at frequencies between 200 Hz and 20 kHz. We used the triggered waveform snapshots and a Doppler-shifted solution of the dispersion relation for wave mode identification in order to carry out a detailed spectral and polarization analysis. Electrostatic ion-acoustic waves are the most common wave emissions observed between the local electron and proton plasma frequency by the TDS receiver during the first year of the mission. The occurrence rate of ion-acoustic waves peaks around perihelion at distances of 0.5 AU and decreases with increasing distances, with only a few waves detected per day at 0.9 AU. Waves are more likely to be observed when the local proton moments and magnetic field are highly variable. A more detailed analysis of more than 10 000 triggered waveform snapshots shows the mean wave frequency at about 3 kHz and wave amplitude about 2.5 mV m(-1). The wave amplitude varies as R-1.38 with the heliocentric distance. The relative phase distribution between two components of the E-field projected in the Y - Z Spacecraft Reference Frame (SRF) plane shows a mostly linear wave polarization. Electric field fluctuations are closely aligned with the directions of the ambient field lines. Only a small number (3%) of ion-acoustic waves are observed at larger magnetic discontinuities.
Permanent Link: http://hdl.handle.net/11104/0327752