Large amplitude ion-acoustic waves observed in the solar wind by the Solar Orbiter

0542776 - ÚFA 2022 DE eng A - Abstrakt
Píša, David - Souček, Jan - Santolík, Ondřej - Maksimovic, M. - Horbury, T.S. - Owen, C.
Large amplitude ion-acoustic waves observed in the solar wind by the Solar Orbiter.
EGU General Assembly 2021 (vEGU21: Gather Online). Göttingen: European Geosciences Union, 2021.
[EGU General Assembly Conference 2021. 19.04.2021-30.04.2021, online]
Institucionální podpora: RVO:68378289
Klíčová slova: Solar Orbiter * radio and plasma waves (RPW) * ion-acoustic waves * solar wind
Obor OECD: Fluids and plasma physics (including surface physics)
https://meetingorganizer.copernicus.org/EGU21/EGU21-10023.html

Electric field observations of the Time Domain Sampler (TDS) receiver, a part of the Radio and
Plasma Waves (RPW) instrument onboard Solar Orbiter, often exhibit very intense broadband
emissions at frequencies below 10 kHz in the spacecraft frame. The RPW instrument has been
operating almost continuously during the commissioning phase of the mission from March to
May, the first perihelion in June, and through the first flyby of Venus in late December 2020. Nearly
a year of observations allow us to perform a statistical study of ion-acoustic waves in the solar
wind covering an interval of heliocentric distances between 0.5 AU to 1 AU. The occurrence of lowfrequency waves peaks around perihelion in June at distances of 0.5 AU and decreases with
increasing distances, with only a few waves detected per day in late September at ~1 AU. A more
detailed analysis of triggered waveform snapshots shows the typical wave frequency at about 3
kHz and wave power about 5e-2 mV2
/m2
. The distribution of the relative phase between two
components of the projected E-field in the Spacecraft Reference Frame (SRF) shows a mostly linear
wave polarization. These waves are interpreted as strongly Doppler-shifted ion-acoustic waves,
generated by solar wind ion beams and often accompany large-scale solar wind structures. A
detailed analysis of the Doppler-shift using solar wind data from a Proton and Alpha particle
Sensor (PAS), a part of Solar Wind Analyzer (SWA), is done for several examples.
Trvalý link: http://hdl.handle.net/11104/0320121