Article

# Phase Diagram for Magnetic Reconnection in Heliophysical, Astrophysical and Laboratory Plasmas

(Impact Factor: 2.14). 09/2011; 18(11). DOI: 10.1063/1.3647505
Source: arXiv

ABSTRACT

Recent progress in understanding the physics of magnetic reconnection is
conveniently summarized in terms of a phase diagram which organizes the
essential dynamics for a wide variety of applications in heliophysics,
laboratory and astrophysics. The two key dimensionless parameters are the
Lundquist number and the macrosopic system size in units of the ion sound
collisionless phases, multiple X-line reconnection phases arise due to the
presence of the plasmoid instability either in collisional and collisionless
current sheets. In particular, there exists a unique phase termed "multiple
X-line hybrid phase" where a hierarchy of collisional islands or plasmoids is
terminated by a collisionless current sheet, resulting in a rapid coupling
between the macroscopic and kinetic scales and a mixture of collisional and
collisionless dynamics. The new phases involving multiple X-lines and
collisionless physics may be important for the emerging applications of
magnetic reconnection to accelerate charged particles beyond their thermal
speeds. A large number of heliophysical and astrophysical plasmas are surveyed
and grouped in the phase diagram: Earth's magnetosphere, solar plasmas
(chromosphere, corona, wind and tachocline), galactic plasmas (molecular
clouds, interstellar media, accretion disks and their coronae, Crab nebula, Sgr
A*, gamma ray bursts, magnetars), extragalactic plasmas (Active Galactic Nuclei
disks and their coronae, galaxy clusters, radio lobes, and extragalactic jets).
Significance of laboratory experiments, including a next generation
reconnection experiment, is also discussed.

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• "To maintain pressure anisotropy, the time between electron collisions must be long compared with the full transit time of a fluid element through the reconnection layer (Egedal et al. 2013; Le et al. 2015). As a valuable tool for displaying the various regimes of reconnection and their transitions , Daughton & Roytershteyn (2012) developed the reconnection phase diagram spanned by the Lundquist number S and the normalized system size λ with respect to the ion sound Larmor radius, ρ s = m i (T e + T i )/eB, or the ion skin depth, d i = c/ω pi , for strong and weak guide-field reconnection, respectively (Ji & Daughton 2011). A convenient way of representing the constraint for anisotropic pressure on a system is the condition S > 10(m i /m e )(L/d i ). "
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##### Article: Preface to Special Topic: Advances in Magnetic Reconnection Research in Space and Laboratory Plasmas. III
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Preview · Article · Nov 2011 · Physics of Plasmas
• ##### Article: Magnetic Reconnection, a Key Self-Organization Process in Laboratory and Astrophysical Plasmas: Recent Research Progress
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ABSTRACT: Magnetic reconnection is a phenomenon of nature in whichmagnetic field lines change their topology and convert magnetic energy to plasma particles by acceleration and heating. The process can stretch out over time or occur quite suddenly. It is one of the most fundamental processes at work in laboratory and astrophysical plasmas. Magnetic reconnection occurs everywhere: In solar flares; coronal mass ejections; the earth's magnetosphere; in the star forming galaxies; and in plasma fusion devices. This paper reviews the most recent progress in the research of magnetic reconnection.
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