Survey of Langmuir and beam-mode waves observed by WHISPER instruments on Cluster spacecraft inside terrestrial foreshock

0477987 - ÚFA 2018 BE eng C - Konferenční příspěvek (zahraniční konf.)
Píša, David - Santolík, Ondřej - Souček, Jan
Survey of Langmuir and beam-mode waves observed by WHISPER instruments on Cluster spacecraft inside terrestrial foreshock.
Papers from URSI: XXXIInd General Assembly and Scientific Symposium (URSI GASS). Ghent: URSI, 2017, č. článku H33-2..
[URSI General Assembly and Scientific Symposium (URSI GASS) 2017 /32./. Montreal (CA), 19.08.2017-26.08.2017]
Grant CEP: GA ČR GJ16-16050Y
Institucionální podpora: RVO:68378289
Klíčová slova: planetary shocks * plasma waves * Langmuir waves * beam-mode waves * WHISPER observations
Kód oboru RIV: BL - Fyzika plazmatu a výboje v plynech

In the upstream region of planetary shocks, intense Langmuir and beam-mode waves are typically observed. Electron beams accelerated at the shock front generate electrostatic waves via beam instability. Waves often occur as narrowband bursts at a frequency close to the local plasma frequency. Broadband emissions at frequencies above and below the plasma frequency are observed deeper in downstream. We present a survey of Langmuir and beam-mode waves in upstream of the terrestrial bow shock from Cluster 2 measurements between years 2002 and 2010. We have used an automated method to identify intense spectral peaks in measured spectra obtained from the WHISPER instrument. Using solar wind data and bow shock positions from OmniWeb, as well as in-situ measurements of interplanetary magnetic field from the fluxgate magnetometer, we have mapped all available observations into foreshock coordinates. We show that the peak intensity increases steeply behind the foreshock boundary and then decreases downstream into the foreshock. We found narrowband emissions at frequencies equal to or above the local plasma frequency in the vicinity of the foreshock boundary. We often detected broadband emissions with the normalized spectral width >40% and down-shifted below the plasma frequency deeper inside the foreshock and close to the bow.

Trvalý link: http://hdl.handle.net/11104/0274217