Dynamics of cold ions in the magnetic reconnection jet and magnetosheath boundary layer

Li, Wenya

Dynamics of cold ions in the magnetic reconnection jet and magnetosheath boundary layer

Friday, 14 July 2017: 09:30

Furong Room (Cynn Hotel)

Wenya Li¹, Mats Andre¹, Yuri V Khotyaintsev¹, Andris Vaivads¹, Stephen A Fuselier², Daniel Bruce Graham¹, Sergio Toledo-Redondo³, Cecilia Norgren¹, Binbin Tang⁴, Chi Wang⁴, Per-Arne Lindqvist⁵, Drew L Turner⁶, David T Young², Michael O Chandler⁷, Barbara L Giles⁸, Craig J Pollock⁹, Robert Ergun¹⁰, Benoit Lavraud¹¹, Christopher T Russell¹², Roy B Torbert¹³, Thomas Earle Moore⁸ and James Burch², (1)IRF Swedish Institute of Space Physics Uppsala, Uppsala, Sweden, (2)Southwest Research Institute, San Antonio, TX, United States, (3)European Space Astronomy Centre, Madrid, Spain, (4)NSSC National Space Science Center, CAS, Beijing, China, (5)KTH Royal Institute of Technology, Stockholm, Sweden, (6)Aerospace Corporation El Segundo, El Segundo, CA, United States, (7)NASA Marshall Space Flight Center, Huntsville, AL, United States, (8)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (9)Denali Scientific, Healy, AK, United States, (10)University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (11)IRAP, Toulouse, France, (12)University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (13)University of New Hampshire Main Campus, Durham, NH, United States

Abstract:

Magnetosheath plasma usually determines many properties of asymmetric magnetic reconnection at the subsolar region of Earth's magnetopause. However, cold plasma originating from the ionosphere can also reach the magnetopause, and modify the kinetic physics of asymmetric reconnection. On 1 November 2015, the Magnetospheric Multiscale (MMS) spacecraft observed a magnetopause crossing with high-density (10-60 cm^-3) cold ions and ongoing reconnection. The magnetopause crossing is estimated to be 300 ion-inertial lengths south of the X line. He⁺ is used to trace the cold ions in the reconnection jet and magnetosheath boundary layer. The cold ions are quickly heated and accelerated in the jet region, and mix with the magnetosheath ions. On the magnetosheath edge of ion jet, we observe two separate ion populations with distinct velocities. One population with 200-300 km/s parallel velocities is identified to be cold ion beams, and the other is the magnetosheath ions. Walén test shows that the magnetosheath ions are field-aligned and Alfvénic in the deHoffman-Teller frame, and the field-aligned cold ion beams have a much smaller velocity. These cold ion beams on the magnetosheath edge of the ion jet are suggested to be from the cold ion inflow close to the X line.