Behavior of current sheets at directional magnetic discontinuities in the solar wind at 0.72 AU

Zhang, T. L.; Russell, C. T.; Zambelli, W.; Vörös, Z.; Wang, Chao; Cao, Jinbin; Jian, L. K.; Strangeway, R. J.; Balikhin, M. A.; Baumjohann, W.; Delva, M.; Volwerk, M.; Glaßmeier, K.‐H.

doi:10.1029/2008gl036120

Cited by 37 publications

(41 citation statements)

References 21 publications

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“…The existence of magnetic holes in space plasmas has been known for many years. Examples in the solar wind were first reported by Turner et al [1977], and subsequent studies have shown that these cover a range of scale sizes, with the observed depressions sometimes as short as 5 s, or in other events lasting for hours or more [e.g., Turner et al, 1977;Tsurutani et al, 1992;Winterhalter et al, 1994;Zurbuchen et al, 2001;Zhang et al, 2008;Xiao et al, 2010]. Similar structures have also been observed in other space environments, such as the magnetosheaths of Earth, Jupiter, and Saturn [e.g., Kaufmann et al, 1970;Tsurutani et al, 1982;Erdős and Balogh, 1996;Chisham et al, 1999].…”

Section: Introductionmentioning

confidence: 59%

Properties and origin of subproton‐scale magnetic holes in the terrestrial plasma sheet

2015

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Electron-scale magnetic depressions in the terrestrial plasma sheet are studied using Cluster multispacecraft data. The structures, which have an observed duration of~5-10 s, are approximately 200-300 km wide in the direction of propagation, and they show an average reduction in the background magnetic field of 10-20%. A majority of the events are also associated with an increase in the high-energy high pitch angle electron flux, which indicates that the depressions are presumably generated by electrons with relatively high velocity perpendicular to the background magnetic field. Differences in the recorded electron spectra in the four spacecraft indicates a possible nongyrotropic structure. Multispacecraft measurements show that a subset of events are cylindrical, elongated along the magnetic field, and with a field-parallel scale size of at a minimum 500 km. Other events seem to be better described as electron-scale sheets, about 200-300 km thick. We find that no single formation mechanism can explain this variety of events observed. Instead, several processes may be operating in the plasma sheet, giving rise to similar magnetic field structures in the single-spacecraft data, but with different 3-D structuring. The cylindrical structures have several traits that are in agreement with the electron vortex magnetic holes observed in 2-D particle-in-cell simulations of turbulent relaxation, whereas the sheets, which show nearly identical signatures in the multispacecraft data, are better explained by propagating electron solitary waves.

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Section: Introductionmentioning

confidence: 59%

Properties and origin of subproton‐scale magnetic holes in the terrestrial plasma sheet

2015

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“…The occurrence rate remains constant within 1 AU but decreases beyond 2 AU with increasing heliocentric distance, with no clear radial dependence observed between 1 and 2 AU. Zhang, Russell, Zambelli, et al (2008) examined solar wind data from the Venus Express spacecraft for MHs identified as the minimum field strength within a 300 s rolling window with at least 50% decrease below the background field and found that at 0.72 AU, the duration of rotational holes associated with a reconnection current sheet is generally less than 30 s, and their thickness is about 2,000 km, comparable to observations at 1 AU. Other studies at 1 AU have reported ∼39% of all MHs are of linear type (Briand et al, 2010;Stevens & Kasper, 2007), while over the solar poles, nearly half of the magnetic depressions are linear MHs (Fränz et al, 2000;Tsurutani et al, 2011).…”

Section: Introductionmentioning

confidence: 70%

Magnetic Holes Upstream of the Martian Bow Shock: MAVEN Observations

et al. 2020

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Magnetic holes (MHs) are pressure-balanced structures characterized by distinct decreases in the interplanetary magnetic field strength in otherwise unperturbed solar wind. In this paper we present an analysis of MHs upstream of the Martian bow shock based on 3 months of observations by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. Plasma properties within and around these structures as well as their shape characteristics are examined. We find an occurrence rate of around 2.1 events per day. About 51% of all events are of linear type with magnetic field rotation across the hole less than 10 • . We observe linear MHs both as isolated events and as part of a train of MHs. The proton temperature anisotropy inside MHs increases, while alpha particles remain mostly isotropic. The average electron temperature inside MHs modestly increases with increasing hole depth. The duration of linear holes at 1.5 AU shows an increase compared to durations at smaller heliocentric distances, but the structures remain asymmetrical and ellipsoid. A case study of MHs accompanied by a population of heavy pickup ions is also discussed. Plain Language SummaryThe solar wind, a supersonic flow of electrons and ions flowing radially outward from the Sun, carries a magnetic field. Magnetic holes are structures with reduced magnetic field strength that last between a few seconds to a few minutes. These structures have been observed at many places throughout the solar system. A common formation mechanism for magnetic holes is a wave mode instability that converts magnetic energy into ion thermal energy, known as the mirror mode. Mirror mode instabilities grow when the temperature of ions moving perpendicular to the magnetic field is higher than that of ions moving in the parallel direction. Mirror waves alter the magnetic field and the spatial structure of the plasma. In this paper, we use observations from the Mars Atmosphere and Volatile EvolutioN spacecraft to study magnetic holes in the space environment around Mars.

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“…Finding #3 in Table points out that the profiles of solar wind current sheets determine the high‐frequency magnetic spectra. As noted in Table , physical concepts that are important to the spatial profiles of current sheets are current sheet structuring (Gekelman et al, ; Ng et al, ; Schindler & Birn, ; Schindler & Hesse, ), plasma expansion and compression (Schindler & Hesse, , ), Bohm and gyro‐Bohm diffusion (Borovsky & Gary, ; Pecseli & Mikkelsen, ; Vahala & Montgomery, ), finite‐gyroradii effects (Schindler & Hesse, ), ion versus electron current carriers (Aunai et al, ; Sasunov et al, ; Schindler & Birn, ), Alfvén wave nonlinear processes (Gomberoff, ; Tsurutani et al, ), plasma waves in current sheets (Huang et al, ; Malaspina et al, ; Verscharen & Marsch, ; Zelenyi et al, ), pressure balance (Riazantseva et al, ; Tu et al, ; Zhang et al, ), and three‐dimensional reconnection (Huang & Bhattacharjee, ; Wyper & Hesse, ).…”

Section: Discussionmentioning

confidence: 99%

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

Borovsky

Burkholder

2020

JGR Space Physics

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The hypothesis is explored that the high‐frequency magnetic spectral power of the solar wind is associated with the spatial profiles of strong current sheets (directional discontinuities) in the solar wind plasma. This hypothesis is based on previous findings about current sheets and the solar wind's magnetic power spectra (1) that the amplitude distribution and waiting time distribution of strong current sheets determines the amplituic composition and the electron strade and spectral slope of the “inertial range” of frequencies and (2) that the thicknesses of strong current sheets in the solar wind determine the breakpoint frequency that ends the inertial range. Solar wind current sheets are collected from the WIND 0.09375‐s and MMS 7.8 × 10−3‐s magnetic data sets, and the current sheets are individually Fourier transformed. At frequencies above the solar wind breakpoint (1) the shape of the magnetic power spectra of the current sheets resembles the shape of the magnetic power spectra of the solar wind and (2) the current sheets occur frequently enough to account for the magnetic power of the solar wind above the breakpoint. This has implications for the physics underlying the high‐frequency magnetic power spectral density of the solar wind, supplementing the energy‐cascade description of the high‐frequency spectrum.

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Behavior of current sheets at directional magnetic discontinuities in the solar wind at 0.72 AU

Cited by 37 publications

References 21 publications

Properties and origin of subproton‐scale magnetic holes in the terrestrial plasma sheet

Properties and origin of subproton‐scale magnetic holes in the terrestrial plasma sheet

Magnetic Holes Upstream of the Martian Bow Shock: MAVEN Observations

On the Fourier Contribution of Strong Current Sheets to the High‐Frequency Magnetic Power SpectralDensity of the Solar Wind

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