Proton and Helium Ion Acceleration at Magnetotail Plasma JetsShow others and affiliations
2022 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 127, no 8, article id e2022JA030430Article in journal (Refereed) Published
Abstract [en]
We investigate two flow bursts in a series of Earthward bursty bulk flows (BBFs) observed by the Magnetospheric Multiscale spacecraft in Earth's magnetotail at (-24, 7, 4) R-E in Geocentric Solar Magnetospheric coordinates. At the leading edges of the BBFs, we observe complex magnetic field structures. In particular, we focus on one BBF which contains large-amplitude magnetic field fluctuations on the time scale of the proton gyroperiod, and another with a large scale dipolarization. For both events, the magnetic field structures are associated with flux increases of supra-thermal ions with energies greater than or similar to 100 keV. We observe that helium ions dominate the ion flux at energies greater than or similar to 150 keV. We investigate the ion acceleration mechanism and its dependence on the mass and charge state of H+ and He2+ ions. We show that for both events, the ions with gyroradii smaller than the dawn-dusk scale of the structure are accelerated by the ion bulk flow. For ions with larger gyroradii, the acceleration is likely due to a localized spatially limited electric field for the event with a large-scale dipolarization. For the event with fluctuating magnetic field, the acceleration of ions with gyroradii comparable with the scale of the magnetic fluctuations can be explained by resonance acceleration.
Place, publisher, year, edition, pages
American Geophysical Union (AGU) , 2022. Vol. 127, no 8, article id e2022JA030430
Keywords [en]
2744, 2764, 2114
National Category
Astronomy, Astrophysics and Cosmology Fusion, Plasma and Space Physics Geology
Identifiers
URN: urn:nbn:se:kth:diva-316792DOI: 10.1029/2022JA030430ISI: 000838191300001Scopus ID: 2-s2.0-85136884484OAI: oai:DiVA.org:kth-316792DiVA, id: diva2:1691335
Note
QC 20220830
2022-08-302022-08-302023-05-15Bibliographically approved