Rosetta measurements of lower hybrid frequency range electric field oscillations in the plasma environment of comet 67P. Issue 4 (22nd February 2017)

• Record Type: Journal Article
• Authors: Karlsson, T.; Eriksson, A. I.; Odelstad, E.; André, M.; Dickeli, G.; Kullen, A.; Lindqvist, P.‐A.; Nilsson, H.; Richter, I.
• Is Part Of: Geophysical research letters. Volume 44:Issue 4(2017)
• Page Start: 1641
• Page End: 1651
• Publication Date: 2017-02-22
• Subjects: Rosetta -- electric field -- lower hybrid waves -- LAP -- comet -- ionosphere; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL072419
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Electric field measurements from cometary environments are very rare but can provide important information on how plasma waves help fashion the plasma environment. The long dwelling time of the Rosetta spacecraft close to comet 67P/Churyumov‐Gerasimenko promises to improve this state. We here present the first electric field measurements from 67P, performed by the Rosetta dual Langmuir probe instrument LAP. Measurements of the electric field from cometocentric distances of 149 and 348 km are presented together with estimates of plasma density changes. Persistent wave activity around the local H2 O + lower hybrid frequency is observed, with the largest amplitudes observed at sharp plasma gradients. We demonstrate that the necessary requirements for the lower hybrid drift instability to be operating are fulfilled. We suggest that lower hybrid waves are responsible for the creation of a warm electron population, the origins of which have been unknown so far, by heating ambient electrons in the magnetic field‐parallel direction. Key Points: We present first electric field measurements from the inner coma of comet 67P Churyumov‐Gerasimenko Persistent wave activity at lower hybrid frequency is collocated with plasma density gradients The waves can heat both electrons and ions and may explain hot plasma populations