Magnetic holes in the solar wind

Turner, J. M.; Burlaga, L. F.; Ness, N. F.; Lemaire, J.

doi:10.1029/ja082i013p01921

Cited by 252 publications

(255 citation statements)

References 11 publications

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“…From solar wind observations, these structures have sizes of tens to hundreds of proton thermal gyroradii, and are found predominantly in regions where the conditions are marginally mirror stable. 2 Similar MH structures, either as isolated events or as trains of structures, have now been observed across a wide range of plasma environments, in planetary magnetosheaths, 3,4 cometary environments, 5 the solar wind 1,6 and in the heliosheath. 7 The association of magnetic holes with regions of flow compression and enhanced perpendicular temperature anisotropy, such as the magnetosheath downstream of planetary bow shocks, indicates an association with the linear mirror instability with threshold b ?…”

Section: Introductionmentioning

confidence: 76%

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Electron vortex magnetic holes: A nonlinear coherent plasma structure

et al. 2015

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We report the properties of a novel type of sub-proton scale magnetic hole found in two dimensional particle-in-cell simulations of decaying turbulence with a guide field. The simulations were performed with a realistic value for ion to electron mass ratio. These structures, electron vortex magnetic holes (EVMHs), have circular cross-section. The magnetic field depression is associated with a diamagnetic azimuthal current provided by a population of trapped electrons in petal-like orbits. The trapped electron population provides a mean azimuthal velocity and since trapping preferentially selects high pitch angles, a perpendicular temperature anisotropy. The structures arise out of initial perturbations in the course of the turbulent evolution of the plasma, and are stable over at least 100 electron gyroperiods. We have verified the model for the EVMH by carrying out test particle and PIC simulations of isolated structures in a uniform plasma. It is found that (quasi-)stable structures can be formed provided that there is some initial perpendicular temperature anisotropy at the structure location. The properties of these structures (scale size, trapped population, etc.) are able to explain the observed properties of magnetic holes in the terrestrial plasma sheet. EVMHs may also contribute to turbulence properties, such as intermittency, at short scale lengths in other astrophysical plasmas. V C 2015 AIP Publishing LLC.

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Section: Introductionmentioning

confidence: 76%

“…The term "magnetic hole" (MH) was first used by Turner et al 1 who identified large dips in the magnetic field amplitude in the solar wind, in an otherwise undisturbed background. For a subclass of such events, sometimes described as "linear," the magnetic field direction remains unchanged through the event.…”

Section: Introductionmentioning

confidence: 99%

Electron vortex magnetic holes: A nonlinear coherent plasma structure

et al. 2015

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“…Observations of magnetic holes in the solar wind were first discussed by Turner et al (1977) and Fitzenreiter & Burlaga (1978) based on observations made at 1 au. These structures are ubiquitous in the solar wind, and they have been extensively studied (e. A model by Avinash et al (2009) that best describes the observations of magnetic holes and humps observed in the distant heliosphere and heliosheath identifies magnetic holes and humps as soliton-like structures.…”

Section: Magnetic Humps and Magnetic Holesmentioning

confidence: 99%

Heliosheath Magnetic Field and Plasma Observed by Voyager 2 During 2012 in the Rising Phase of Solar Cycle 24

Burlaga

Ness

Richardson

et al. 2016

ApJ

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We discuss magnetic field and plasma observations of the heliosheath made by Voyager 2 (V2) during 2012, when V2 was observing the effects of increasing solar activity following the solar minimum in 2009. The average magnetic field strength B was 0.14 nT and B reached 0.29 nT on day 249. V2 was in a unipolar region in which the magnetic polarity was directed away from the Sun along the Parker spiral 88% of the time, indicating that V2 was poleward of the heliospheric current sheet throughout most of 2012. The magnetic flux at V2 during 2012 was constant. A merged interaction region (MIR) was observed, and the flow speed increased as the MIR moved past V2. The MIR caused a decrease in the >70 MeV nuc −1 cosmic-ray intensity. The increments of B can be described by a q-Gaussian distribution with q=1.2±0.1 for daily averages and q=1.82±0.03 for hour averages. Eight isolated current sheets ("PBLs") and four closely spaced pairs of current sheets were observed. The average change of B across the current sheets was a factor of ≈2, and B increased or decreased with equal probability. Magnetic holes and magnetic humps were also observed. The characteristic size of the PBLs was ≈6 R L , where R L is the Larmor radius of protons, and the characteristic sizes of the magnetic holes and humps were ≈38 R L and ≈11 R L , respectively.

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“…[2] Magnetic holes (MHs) [Turner et al, 1977;Winterhalter et al, 1994Winterhalter et al, , 2000Fränz et al, 2000] and magnetic decreases (MDs) [Tsurutani and Ho, 1999;Neugebauer et al, 2001] are decreases in the magnitude of the interplanetary magnetic field that can be relatively short (seconds) or can last as long as tens of minutes or even hours in duration. It has recently been shown by Tsurutani et al [2002] that MHs and MDs are presumably the same phenomenon (with MDs longer and with discontinuities bounding an edge), and that they often occur at the edges of phase steepened Alfvén waves.…”

Section: Introductionmentioning

confidence: 99%

Phase‐steepened Alfvén waves, proton perpendicular energization and the creation of magnetic holes and magnetic decreases: The ponderomotive force

Tsurutani

Dasgupta

Galvan

et al. 2002

Geophysical Research Letters

112

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[1] Solar wind protons detected within Magnetic Holes (MHs) and Magnetic Decreases (MDs) are found to be preferentially heated perpendicular toB 0 . The MHs/MDs are associated with the phase-steepened edges of nonlinear Alfvén waves. The proton anisotropies can lead to the proton cyclotron and mirror mode plasma instabilities. We examine the Ponderomotive Force (PF), a phenomenon due to wave pressure gradients, and show that for this plasma regime and for phase-steepened Alfvén waves, the PF proton acceleration/energization will primarily be orthogonal to B 0 . It is suggested that accelerated ions create the MHs/MDs by a diamagnetic effect.

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Magnetic holes in the solar wind

Cited by 252 publications

References 11 publications

Electron vortex magnetic holes: A nonlinear coherent plasma structure

Electron vortex magnetic holes: A nonlinear coherent plasma structure

Heliosheath Magnetic Field and Plasma Observed by Voyager 2 During 2012 in the Rising Phase of Solar Cycle 24

Phase‐steepened Alfvén waves, proton perpendicular energization and the creation of magnetic holes and magnetic decreases: The ponderomotive force

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