Electromagnetic Energy Conversion at Reconnection Fronts

Angelopoulos, V.; Runov, A.; Zhou, X.‐Z.; Turner, D. L.; Kiehas, S. A.; Li, Shumei; Shinohara, I.

doi:10.1126/science.1236992

Cited by 260 publications

(367 citation statements)

References 35 publications

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“…The spatial scale of B Z pulses, L pulse , is typically of the order of a few ρ T , while the L F is less than ρ T for all analyzed pulses. This is in agreement with previous results reported for the DFs (e.g., Angelopoulos et al, 2013;Balikhin et al, 2014).…”

Section: The Dynamics and Acceleration Of Suprathermal Protons Duringsupporting

confidence: 83%

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

et al. 2018

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Abstract. The fortunate location of Cluster and the THEMIS P3 probe in the near-Earth plasma sheet (PS) (at X ∼ −7-−9 R E ) allowed for the multipoint analysis of properties and spectra of electron and proton injections. The injections were observed during dipolarization and substorm current wedge formation associated with braking of multiple bursty bulk flows (BBFs). In the course of dipolarization, a gradual growth of the B Z magnetic field lasted ∼ 13 min and it was comprised of several B Z pulses or dipolarization fronts (DFs) with duration ≤ 1 min. Multipoint observations have shown that the beginning of the increase in suprathermal (> 50 keV) electron fluxes -the injection boundary -was observed in the PS simultaneously with the dipolarization onset and it propagated dawnward along with the onset-related DF. The subsequent dynamics of the energetic electron flux was similar to the dynamics of the magnetic field during the dipolarization. Namely, a gradual linear growth of the electron flux occurred simultaneously with the gradual growth of the B Z field, and it was comprised of multiple short (∼ few minutes) electron injections associated with the B Z pulses. This behavior can be explained by the combined action of local betatron acceleration at the B Z pulses and subsequent gradient drifts of electrons in the flux pile up region through the numerous braking and diverting DFs. The nonadiabatic features occasionally observed in the electron spectra during the injections can be due to the electron interactions with high-frequency electromagnetic or electrostatic fluctuations transiently observed in the course of dipolarization.On the contrary, proton injections were detected only in the vicinity of the strongest B Z pulses. The front thickness of these pulses was less than a gyroradius of thermal protons that ensured the nonadiabatic acceleration of protons. Indeed, during the injections in the energy spectra of protons the pronounced bulge was clearly observed in a finite energy range ∼ 70-90 keV. This feature can be explained by the nonadiabatic resonant acceleration of protons by the bursts of the dawn-dusk electric field associated with the B Z pulses.

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Section: The Dynamics and Acceleration Of Suprathermal Protons Duringsupporting

confidence: 83%

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

et al. 2018

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“…In addition to the configuration shown in Fig. 6, times when THEMIS is in the near tail and Artemis is in the deep tail will be especially valuable as shown in the study by Angelopoulos et al (2013).…”

Section: Discussionmentioning

confidence: 99%

“…If similar extensions occur in the mainly symmetric reconnection of the magnetotail then they could be important for generation of the reconnection fronts observed by Angelopoulos et al (2013). These recent observations suggest a larger target for MMS as well as different reconnection and dissipation regimes for it to explore.…”

Section: (A)mentioning

confidence: 99%

“…As discussed by Angelopoulos et al (2013) for bursty bulk flows and reconnection fronts and by Biernat et al (1987) for flux transfer events, reconnection is often unsteady. While MMS is designed to make rapid plasma and field measurements within moving reconnection sites, its capabilities will apply equally well to the unsteady or time-varying reconnection.…”

Section: (A)mentioning

confidence: 99%

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Magnetospheric Multiscale Overview and Science Objectives

et al. 2015

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Magnetospheric Multiscale (MMS), a NASA four-spacecraft constellation mission launched on March 12, 2015, will investigate magnetic reconnection in the boundary regions of the Earth's magnetosphere, particularly along its dayside boundary with the solar wind and the neutral sheet in the magnetic tail. The most important goal of MMS is to conduct a definitive experiment to determine what causes magnetic field lines to reconnect in a collisionless plasma. The significance of the MMS results will extend far beyond the Earth's magnetosphere because reconnection is known to occur in interplanetary space and in the solar corona where it is responsible for solar flares and the disconnection events known as coronal mass ejections. Active research is also being conducted on reconnection in the laboratory and specifically in magnetic-confinement fusion devices in which it is a limiting factor in achieving and maintaining electron temperatures high enough to initiate fusion. Finally, reconnection is proposed as the cause of numerous phenomena throughout the universe such as comet-tail disconnection events, magnetar flares, supernova ejections, and dynamics of neutron-star accretion disks. The MMS mission design is focused on answering specific questions about reconnection at the Earth's magnetosphere. The prime focus of the mission is on determining the kinetic processes occurring in the electron diffusion region that are responsible for reconnection and that determine how it is initiated; but the mission will also place that physics into the context of the broad spectrum of physical processes associated with reconnection. Connections to other disciplines such as solar physics, astrophysics, and laboratory plasma physics are expected to be made through theory and modeling as informed by the MMS results.

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“…Recent spacecraft observations (e.g., Angelopoulos et al, 2013;Fu et al, 2013a) and numerical models (e.g., Sitnov et al, 2009Sitnov et al, , 2013 suggest that the significant part of the released magnetic energy is evacuated from the reconnection region by fast plasma flows. The leading edge of such flows is characterized by the specific magnetic-field configuration: the so-called dipolarization front.…”

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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Electromagnetic Energy Conversion at Reconnection Fronts

Cited by 260 publications

References 35 publications

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

Contrasting dynamics of electrons and protons in the near-Earth plasma sheet during dipolarization

Magnetospheric Multiscale Overview and Science Objectives

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

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