On the generation of ion beamlets in the magnetotail: Resonant acceleration versus stochastic acceleration

Dolgonosov, M. S.; Zimbardo, G.; Perri, S.; Greco, A.

doi:10.1002/jgra.50490

Cited by 9 publications

(5 citation statements)

References 63 publications

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“…There are two most natural magnetic-field configurations, including electromagnetic turbulence, where ions can be accelerated up to high energies: the magnetic reconnection region (Onofri et al, 2006) and dipolarization fronts (Ono et al, 2009). Moreover, ions can be accelerated due to the combination of turbulent and regular mechanisms (Grigorenko et al, 2011;Artemyev et al, 2011;Dolgonosov et al, 2013). The interaction of ions with the electromagnetic turbulence can be described as the quasi-linear diffusion of ions in the energy/pitch-angle space (Dusenbery and Lyons, 1989).…”

Section: A V Artemyev Et Al: High-energy Ion Spectra In the Magnetmentioning

confidence: 99%

Formation of the high-energy ion population in the earth's magnetotail: spacecraft observations and theoretical models

et al. 2014

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Abstract.We investigate the formation of the high-energy (E ∈ [20, 600] keV) ion population in the earth's magnetotail. We collect statistics of 4 years of Interball / Tail observations (1995)(1996)(1997)(1998) in the vicinity of the neutral plane in the magnetotail region (X < −17 R E , |Y | ≤ 20 R E in geocentric solar magnetospheric (GSM) system). We study the dependence of high-energy ion spectra on the thermal-plasma parameters (the temperature T i and the amplitude of bulk velocity v i ) and on the magnetic-field component B z . The ion population in the energy range E ∈ [20, 600] keV can be separated in the thermal core and the power-law tail with the slope (index) ∼ −4.5. Fluxes of the high-energy ion population increase with the growth of B z , v i and especially T i , but spectrum index seems to be independent on these parameters. We have suggested that the high-energy ion population is generated by small scale transient processes, rather than by the global reconfiguration of the magnetotail. We have proposed the relatively simple and general model of ion acceleration by transient bursts of the electric field. This model describes the power-law energy spectra and predicts typical energies of accelerated ions.

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Section: A V Artemyev Et Al: High-energy Ion Spectra In the Magnetmentioning

confidence: 99%

Formation of the high-energy ion population in the earth's magnetotail: spacecraft observations and theoretical models

et al. 2014

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“…In particular, spacecraft observations in the Earth's magnetosphere have revealed the presence of a variety of energetic particle populations, both ions and electrons, spanning a wide range of energies [e.g., Sarafopoulos et al, 2001;Haaland et al, 2010]. The physical processes that generate suprathermal particles are not yet fully understood, although many studies, based on both spacecraft observations and numerical simulations, do exist; mechanisms such as magnetic reconnection [Litvinenko and Somov, 1993;Drake et al, 2009;Oka et al, 2010], interactions with electromagnetic fluctuations [Ambrosiano et al, 1988;Zimbardo et al, 2000;Greco et al, 2002;Ono et al, 2009;Perri et al, 2009;Greco et al, 2010;Zimbardo et al, 2010;Perri et al, 2011], resonant acceleration in the current sheet [e.g., Ashour-Abdalla et al, 2006;Dolgonosov et al, 2013], and adiabatic Fermi-like and betatron acceleration [Fu et al, 2011;Artemyev et al, 2012b;Pan et al, 2012;Fu et al, 2013b] are usually invoked. Charged particles can also be effectively accelerated by fast reconnection outflow jet propagating earthward in the magnetotail [Birn et al, 2004;Ashour-Abdalla et al, 2011;Birn et al, 2012].…”

Section: Introductionmentioning

confidence: 99%

Proton acceleration at two‐dimensional dipolarization fronts in the magnetotail

2014

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Transient reconnection events in the planetary magnetotail give rise to fast plasma jets, whose leading edges are called dipolarization fronts. We perform a test particle simulation of ion acceleration in a 2-D model of dipolarization fronts. We study the dependence of acceleration on several parameters of the model. We obtain that the interaction between the dipolarization front and particles depends on their initial energy h 0 , resulting in a moderate increase of the gained energy with h 0 . The front amplitude B max has been varied from 10 nT to 40 nT in order to study its influence on the particle gyro-radii and, in turn, on interaction with the front. As expected, the energy gained by particles increases with B max . We find that the acceleration strongly depends on the front velocity v , which we chose to vary from 200 km/s to 750 km/s. The simulations pointed out that higher energies have been reached with fast fronts, ranging from 50 to 100 keV. We also study how the average maximum energy attained by ions, ⟨h max ⟩, depends on the y extent of the front: at variance with expectations, the energy gain decreases with the increase of the y size of the front for small values of that size; increasing further, the scaling of ⟨h max ⟩ with the y size seems to indicate a slow growth. We also study the energy and velocity distributions functions of ions accelerated by dipolarization fronts and compare these distributions with spacecraft observations.

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“…This implies that their acceleration sources are located even farther downtail. Such beams lasted for several minutes and more and, thus, can be accelerated in a quasi‐steady resonant source located in the distant CS (Dolgonosov et al, ; Grigorenko et al, ). Assuming the convective velocity V Z to be 20–50 km/s, one may estimate that the equatorward displacement of an ion beam moving with | V || | ~ 2,000 km/s from X ~ −160 R E to ARTEMIS location is Δ Z ~ 1.0–3.0 R E .…”

Section: Discussionmentioning

confidence: 99%

Particle Beams in the Vicinity of Magnetic Separatrix According to Near‐Lunar ARTEMIS Observations

et al. 2019

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We study characteristics of ion and electron beams observed during 101 crossings of the near-separatrix region by Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) spacecraft in the magnetotail. We found that accelerated ion beams are observed under any level of geomagnetic activity. A duration of earthward moving ion beams is statistically longer (≤ 10 min) than a duration of tailward ion beams (≤ 4 min), which can be due to the transient character of ion acceleration in the vicinity of the near-Earth neutral line (NENL). Energetic characteristics of earthward and tailward ion beams are similar indicating similar acceleration conditions at ion kinetic scales at both sides of an X line independently of its location. Conversely, electron velocity distributions observed near magnetic separatrix earthward of the distant neutral line (DNL) differ from those observed tailward of the NENL. Earthward of the DNL a scattered and thermalized electron population without energetic field-aligned beams is observed near the separatrix. On the contrary, tailward of the NENL field-aligned electron beams accelerated to a few kiloelectron volts are detected. These observations show that near DNL the electron scattering and thermalization dominate over the direct acceleration, whereas stronger electric fields in the NENL produce substantial population of field-aligned kiloelectron volt electrons.

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On the generation of ion beamlets in the magnetotail: Resonant acceleration versus stochastic acceleration

Cited by 9 publications

References 63 publications

Formation of the high-energy ion population in the earth's magnetotail: spacecraft observations and theoretical models

Formation of the high-energy ion population in the earth's magnetotail: spacecraft observations and theoretical models

Proton acceleration at two‐dimensional dipolarization fronts in the magnetotail

Particle Beams in the Vicinity of Magnetic Separatrix According to Near‐Lunar ARTEMIS Observations

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