Collisionless Magnetic Reconnection in Space Plasmas
Magnetic reconnection, the merging of oppositely directed magnetic fields that leads to field reconfiguration, plasma heating, jetting and acceleration, is one of the most celebrated processes in collisionless plasmas. It requires the violation of the frozen-in condition which ties gyrating charged...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2013-12-01
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| Series: | Frontiers in Physics |
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| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fphy.2013.00031/full |
| _version_ | 1818587046316343296 |
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| author | Rudolf A. Treumann Wolfgang eBaumjohann |
| author_facet | Rudolf A. Treumann Wolfgang eBaumjohann |
| author_sort | Rudolf A. Treumann |
| collection | DOAJ |
| description | Magnetic reconnection, the merging of oppositely directed magnetic fields that leads to field reconfiguration, plasma heating, jetting and acceleration, is one of the most celebrated processes in collisionless plasmas. It requires the violation of the frozen-in condition which ties gyrating charged particles to the magnetic field inhibiting diffusion. Ongoing reconnection has been identified in near-Earth space as being responsible for the excitation of substorms, magnetic storms, generation of field aligned currents and their consequences, the wealth of auroral phenomena. Its theoretical understanding is now on the verge of being completed. Reconnection takes place in thin current sheets. Analytical concepts proceeded gradually down to the microscopic scale, the scale of the electron skin depth or inertial length, recognizing that current layers that thin do preferentially undergo spontaneous reconnection. Thick current layers start reconnecting when being forced by plasma inflow to thin. For almost half a century the physical mechanism of reconnection has remained a mystery. Spacecraft in situ observations in combination with sophisticated numerical simulations in two and three dimensions recently clarified the mist, finding that reconnection produces a specific structure of the current layer inside the electron inertial (also called electron diffusion) region around the reconnection site, the X line. Onset of reconnection is attributed to pseudo-viscous contributions of the electron pressure tensor aided by electron inertia and drag, creating a complicated structured electron current sheet, electric fields, and an electron exhaust extended along the current layer. We review the general background theory and recent developments in numerical simulation on collisionless reconnection. It is impossible to cover the entire field of reconnection in a short space-limited review. The presentation necessarily remains cursory, determined by our taste, preferences, and kn |
| first_indexed | 2024-12-16T09:02:38Z |
| format | Article |
| id | doaj.art-6eb42ee7786844bfb1dc2baa4bbfcbad |
| institution | Directory Open Access Journal |
| issn | 2296-424X |
| language | English |
| last_indexed | 2024-12-16T09:02:38Z |
| publishDate | 2013-12-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Physics |
| spelling | doaj.art-6eb42ee7786844bfb1dc2baa4bbfcbad2022-12-21T22:37:09ZengFrontiers Media S.A.Frontiers in Physics2296-424X2013-12-01110.3389/fphy.2013.0003175075Collisionless Magnetic Reconnection in Space PlasmasRudolf A. Treumann0Wolfgang eBaumjohann1Austrian Academy of SciencesAustrian Academy of SciencesMagnetic reconnection, the merging of oppositely directed magnetic fields that leads to field reconfiguration, plasma heating, jetting and acceleration, is one of the most celebrated processes in collisionless plasmas. It requires the violation of the frozen-in condition which ties gyrating charged particles to the magnetic field inhibiting diffusion. Ongoing reconnection has been identified in near-Earth space as being responsible for the excitation of substorms, magnetic storms, generation of field aligned currents and their consequences, the wealth of auroral phenomena. Its theoretical understanding is now on the verge of being completed. Reconnection takes place in thin current sheets. Analytical concepts proceeded gradually down to the microscopic scale, the scale of the electron skin depth or inertial length, recognizing that current layers that thin do preferentially undergo spontaneous reconnection. Thick current layers start reconnecting when being forced by plasma inflow to thin. For almost half a century the physical mechanism of reconnection has remained a mystery. Spacecraft in situ observations in combination with sophisticated numerical simulations in two and three dimensions recently clarified the mist, finding that reconnection produces a specific structure of the current layer inside the electron inertial (also called electron diffusion) region around the reconnection site, the X line. Onset of reconnection is attributed to pseudo-viscous contributions of the electron pressure tensor aided by electron inertia and drag, creating a complicated structured electron current sheet, electric fields, and an electron exhaust extended along the current layer. We review the general background theory and recent developments in numerical simulation on collisionless reconnection. It is impossible to cover the entire field of reconnection in a short space-limited review. The presentation necessarily remains cursory, determined by our taste, preferences, and knhttp://journal.frontiersin.org/Journal/10.3389/fphy.2013.00031/fullmagnetosphereSolar windSpace weatherReconnectionMagnetic mergingFlux tubes |
| spellingShingle | Rudolf A. Treumann Wolfgang eBaumjohann Collisionless Magnetic Reconnection in Space Plasmas Frontiers in Physics magnetosphere Solar wind Space weather Reconnection Magnetic merging Flux tubes |
| title | Collisionless Magnetic Reconnection in Space Plasmas |
| title_full | Collisionless Magnetic Reconnection in Space Plasmas |
| title_fullStr | Collisionless Magnetic Reconnection in Space Plasmas |
| title_full_unstemmed | Collisionless Magnetic Reconnection in Space Plasmas |
| title_short | Collisionless Magnetic Reconnection in Space Plasmas |
| title_sort | collisionless magnetic reconnection in space plasmas |
| topic | magnetosphere Solar wind Space weather Reconnection Magnetic merging Flux tubes |
| url | http://journal.frontiersin.org/Journal/10.3389/fphy.2013.00031/full |
| work_keys_str_mv | AT rudolfatreumann collisionlessmagneticreconnectioninspaceplasmas AT wolfgangebaumjohann collisionlessmagneticreconnectioninspaceplasmas |