Current structure and nonideal behavior at magnetic null points in the turbulent magnetosheath

Wendel, D. E.; Adrian, M. L.

doi:10.1002/jgra.50234

Cited by 36 publications

(56 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Helical field lines of the fans connect the nulls with the external magnetic field. Such topology is very similar to the one deduced from the Cluster observations of a null pair in the Earth's magnetosheath by Wendel & Adrian (2013). Another null pair, observed by Deng et al (2009), has shown quite alarge angle between the spines of the two nulls, as well asa fan-fan separator line.…”

Section: Results: "Multiple Nulls"supporting

confidence: 83%

“…Isolated magnetic nulls have been studied by means of MHD ) and kinetic particle-in-cell (PIC; Baumann & Nordlund 2012) simulations. Observations, however, have suggested that nulls often concentrate in clusters (Deng et al 2009;Wendel & Adrian 2013). Several 3D MHD simulations addressed multiple null points (Galsgaard & Nordlund 1997;Wyper & Pontin 2014a, 2014b.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Olshevsky

Deca

Divin

et al. 2016

ApJ

View full text Add to dashboard Cite

We present a systematic attempt to study magnetic null points and the associated magnetic energy conversion in kinetic particle-in-cell simulations of various plasma configurations. We address three-dimensional simulations performed with the semi-implicit kinetic electromagnetic code iPic3D in different setups: variations of a Harris current sheet, dipolar and quadrupolar magnetospheres interacting with the solar wind,and a relaxing turbulent configuration with multiple null points. Spiral nulls are more likely created in space plasmas: in all our simulations except lunar magnetic anomaly (LMA) and quadrupolar mini-magnetosphere the number of spiral nulls prevails over the number of radial nulls by a factor of 3-9. We show that often magnetic nulls do not indicate the regions of intensive energy dissipation. Energy dissipation events caused by topological bifurcations at radial nulls are rather rare and short-lived. The so-called X-lines formed by the radial nulls in the Harris current sheet and LMA simulations are rather stable and do not exhibit any energy dissipation. Energy dissipation is more powerful in the vicinity of spiral nulls enclosed by magnetic flux ropes with strong currents at their axes (their crosssections resemble 2D magnetic islands). These null lines reminiscent of Z-pinches efficiently dissipate magnetic energy due to secondary instabilities such as the two-stream or kinking instability, accompanied by changes in magnetic topology. Current enhancements accompanied by spiral nulls may signal magnetic energy conversion sites in the observational data.

show abstract

Section: Results: "Multiple Nulls"supporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Olshevsky

Deca

Divin

et al. 2016

ApJ

View full text Add to dashboard Cite

show abstract

“…2.7.4). Wendel and Adrian (2013) derived the topological degree, or Poincaré index, and discovered magnetic nulls associated with many of the current filaments. The Poincaré index is a measure of the number of roots, 'or magnetic nulls' in a region (Greene 1992).…”

Section: Plasma Phenomena As Measured In Three Dimensionsmentioning

confidence: 99%

“…The determinant and eigenvalues of ∇B studied by Wendel and Adrian (2013) revealed that the null pair consisted of spiral A s and B s nulls. From the eigenvalues of ∇B one can determine the nature of a spine and fan of a null.…”

Section: Plasma Phenomena As Measured In Three Dimensionsmentioning

confidence: 99%

Multipoint observations of plasma phenomena made in space by Cluster

et al. 2015

Self Cite

View full text Add to dashboard Cite

Plasmas are ubiquitous in nature, surround our local geospace environment, and permeate the universe. Plasma phenomena in space give rise to energetic particles, the aurora, solar flares and coronal mass ejections, as well as many energetic phenomena in interstellar space. Although plasmas can be studied in laboratory settings, it is often difficult, if not impossible, to replicate the conditions (density, temperature, magnetic and electric fields, etc.) of space. Single-point space missions too numerous to list have described many properties of near-Earth and heliospheric plasmas as measured both in situ and remotely (see http://www.nasa.gov/missions/#.U1mcVmeweRY for a list of NASA-related missions). However, a full description of our plasma environment requires three-dimensional spatial measurements. Cluster is the first, and until data begin flowing from the Magnetospheric Multiscale Mission (MMS), the only mission designed to describe the three-dimensional spatial structure of plasma phenomena in geospace. In this paper, we concentrate on some of the many plasma phenomena that have been studied using data from Cluster. To date, there have been more than 2000 refereed papers published using Cluster data but in this paper we will, of necessity, refer to only a small fraction of the published work. We have focused on a few basic plasma phenomena, but, for example, have not dealt with most of the vast body of work describing dynamical phenomena in Earth's magnetosphere, including the dynamics of current sheets in Earth's magnetotail and the morphology of the dayside high latitude cusp. Several review articles and special publications are available that describe aspects of that research in detail and interested readers are referred to them (see for example, Escoubet et al.

show abstract

“…To model an encounter with a magnetic null by MMS, we used four-point Cluster data to test techniques for detecting these three-dimensional structures in the dayside magnetosheath (Wendel and Adrian 2013). Nulls are associated with the filamentary substructure of current sheets where reconnection is occurring.…”

Section: Locating Magnetic Nulls In the Magnetosheathmentioning

confidence: 99%

Mission Oriented Support and Theory (MOST) for MMS—the Goddard Space Flight Center/University of California Los Angeles Interdisciplinary Science Program

et al. 2015

View full text Add to dashboard Cite

The MOST IDS team was tasked with focusing on two general areas: The first was to participate with the Fast Plasma Investigation (FPI) team in the development of virtual detectors that model the instrument responses of the MMS FPI sensors. The virtual instruments can be "flown through" both simulation data (from magnetohydrodynamic, hybrid, and kinetic simulations) and Cluster and THEMIS spacecraft data. The goal is to determine signatures of magnetic reconnection expected during the MMS mission. Such signatures can serve as triggers for selection of burst mode downloads. The chapter contributed by the FPI team covers that effort in detail and, therefore, most of that work has not been included here. The second area of emphasis, and the one detailed in this chapter, was to build on past and present knowledge of magnetic reconnection and its physical signatures. Below we describe intensive analyses of Cluster and THEMIS data together with theoretical models and simulations that delineate the plasma signatures that surround sites of reconnection, including the effects of turbulence as well as the detailed kinetic signatures that indicate proximity to reconnection sites. In particular, we point out that particles are energized in several regions, not only at the actual site of reconnection.

show abstract

Current structure and nonideal behavior at magnetic null points in the turbulent magnetosheath

Cited by 36 publications

References 83 publications

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Magnetic Null Points in Kinetic Simulations of Space Plasmas

Multipoint observations of plasma phenomena made in space by Cluster

Mission Oriented Support and Theory (MOST) for MMS—the Goddard Space Flight Center/University of California Los Angeles Interdisciplinary Science Program

Contact Info

Product

Resources

About