Proton and Helium Ion Acceleration at Magnetotail Plasma Jets

Richard, LouisUppsala universitet,Rymd- och plasmafysik,Institutet för rymdfysik, Uppsalaavdelningen (författare)

QC 20220830
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.

Khotyaintsev, Yu, VSwedish Inst Space Phys, Uppsala, Sweden. (författare)
Graham, Daniel B.Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen(Swepub:uu)dangr618 (författare)
Vaivads, AndrisKTH,Rymd- och plasmafysik,KTH Royal Inst Technol, Space & Plasma Phys, Sch Elect Engn, Uppsala, Sweden.(Swepub:kth)u167dmzs (författare)
Nikoukar, R.Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. (författare)
Cohen, I. J.Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. (författare)
Turner, D. L.Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA. (författare)
Fuselier, S. A.Southwest Res Inst, San Antonio, TX USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA. (författare)
Russell, C. T.Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA. (författare)
Khotyaintsev, Yuri V.Uppsala universitet,Institutet för rymdfysik, Uppsalaavdelningen(Swepub:uu)ykh28990 (författare)
Uppsala universitetRymd- och plasmafysik (creator_code:org_t)

Ingår i:Journal of Geophysical Research - Space Physics: American Geophysical Union (AGU)127:82169-93802169-9402

Av författaren/redakt...: Richard, Louis; Khotyaintsev, Yu ...; Graham, Daniel B ...; Vaivads, Andris; Nikoukar, R.; Cohen, I. J.; visa fler...; Turner, D. L.; Fuselier, S. A.; Russell, C. T.; Khotyaintsev, Yu ...; visa färre...

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