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Topic: Magnetic reconnection

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In the News (Mon 24 Jun 19)

  07.25.2001 - NASA's Wind spacecraft flies through Earth's magnetic tail and captures rare event in action
Reconnection is thought to occur in the atmosphere of the sun, generating solar flares, as well as in interstellar space.
When the magnetic fields of the Earth and sun interact and reconnect, particles from the sun spiraling along magnetic field lines are able to slide like beads onto the Earth's field lines, eventually making their way to the poles and generating the aurorae.
Magnetic reconnection occurs at the outer fringes of the magnetosphere, where oppositely directed field lines bump, tear and rejoin in a head-to-head hairpin configuration.
www.berkeley.edu /news/media/releases/2001/07/25_wind.html   (1029 words)

 Brief History: Reconnection   (Site not responding. Last check: 2007-10-08)
Magnetic reconnection is relevant to magnetospheric physics in two distinct ways: it makes possible a realignment of field line connections, e.g.
In regions where reconnection seems likely to occur, magnetic fields are quite variable and with isolated spacecraft it is almost impossible to extract their structure.
Reconnection was first applied to magnetospheric physics by Dungey [1961], as the key ingredient of his alternative theory of convection.
www.phy6.org /Education/bh2_5.html   (1897 words)

 Magnetic reconnection - Wikipedia, the free encyclopedia
Magnetic reconnection is the process whereby magnetic field lines from different magnetic domains are spliced to one another, changing the overall topology of a magnetic field.
Magnetic reconnection in Earth's magnetosphere is responsible for the aurora, and it is important to the science of controlled nuclear fusion because it is one mechanism preventing magnetic confinement of the fusion fuel.
This topology is approximately preserved even when the magnetic field itself is strongly distorted by the presence of variable currents or motion of magnetic sources, because effects that might otherwise change the magnetic topology instead induce eddy currents in the plasma; the eddy currents have the effect of canceling out the topological change.
en.wikipedia.org /wiki/Magnetic_reconnection   (807 words)

 Magnetism and the Sun: Magnetism on the Sun
Reconnecting Rubber Bands - Since magnetic reconnection occurs in plasmas, which cannot be feasibly produced in a high school lab, we will have to be content with an activity using rubber bands to model magnetic reconnection.
Magnetic reconnection is important to solar physicists since they think that it in part is the cause of flares and coronal mass ejections (CMEs).
One of the most significant consequences of magnetism is the coronal mass ejection (CME), a large scale and sudden expulsion of magnetized plasma from the Sun's corona, or outer atmosphere (Wagner 267).
solar-center.stanford.edu /magnetism/magnetismsun.html   (993 words)

 Spaceflight Now | Breaking News | Space probes detect enormous magnetic reconnection event
Earth's magnetic environment is to the right in the background: The blue area represents a cross-section of the bow shock formed as the solar wind hits Earth's magnetic field, the red area is a cross-section of the magnetic field produced by the Earth, and the blue sphere in the center is the Earth.
Understanding magnetic reconnection is fundamental to comprehending explosive phenomena throughout the universe, such as solar flares (billion-megaton explosions in the sun's atmosphere), gamma-ray bursts (intense bursts of radiation from exotic stars) and laboratory nuclear fusion.
The broader picture of magnetic reconnection emerged when six spacecraft — the four ESA Cluster spacecraft and NASA's ACE and Wind probes — were flying in the solar wind outside Earth’s magnetosphere on Feb. 2, 2002 and made a chance discovery.
www.spaceflightnow.com /news/n0601/12magnetic   (1474 words)

 Ph.D. Project - Magnetic Reconnection   (Site not responding. Last check: 2007-10-08)
Reconnection at the magnetopause is responsible for dynamically coupling the magnetosphere to the solar wind flow and thereby driving a global scale magnetospheric convection cycle.
Magnetic reconnection also occurs within the nightside magnetosphere, where its consequences are particularly dynamic due the large amount of energy that is available in the magnetic field of the magnetotail lobes.
Release of this energy during magnetic substorms manifests itself as dramatic auroral activity, the occurrence of strong auroral electrojet currents, significant energetic particle injection at geosynchronous orbit, particle acceleration within the tail plasma sheet and in the formation of huge plasmoids (magnetic 'bubbles') and their subsequent ejection back into the downstream solar wind.
www.mssl.ucl.ac.uk /~cjo/cjo_phd_project.php   (1097 words)

 Magnetic reconnection   (Site not responding. Last check: 2007-10-08)
The model is aimed at describing nonlinear processes in hot magnetized plasmas such as the interaction between current filaments and vortices in magnetic turbulence, and the reconnection of magnetic field lines.
Reconnection is inhibited by the electric conductivity of the plasma.
One of the other effects that lead to reconnection, the resonance of individual particles with the plasma motion, is strongly modified in the vicinity of a sizeable magnetic perturbation.
www.rijnh.nl /n3/n1/reconnection.htm   (611 words)

 CMPD - Center for Multiscale Plasma Dynamics (reconnection)
The inability to model the reconnection of large scale flux and the evolution of magnetic islands, while at the same time including an accurate kinetic description of the currents and transport, is inhibiting the development of a predictive capability to model the performance of future fusion experiments such as ITER.
The conversion of magnetic energy to energetic electrons and ions is widely observed during reconnection in laboratory fusion experiments, dedicated reconnection experiments, the Earth's magnetosphere and the solar corona.
This is the case for the reconnection issues that are central to the CMPD mission.
www.cscamm.umd.edu /cmpd/reconnection.htm   (730 words)

 Direct Observation Of 3D Magnetic Reconnection
Magnetic reconnection on the Earth's magnetopause is considered to be the most efficient mechanism for solar material to penetrate the Earth's magnetic shield.
This phenomenon, known as magnetic reconnection, was imagined in the 50's as a large scale steady-state process, as illustrated by Animation 1.
This 3D magnetic topology of inter-linked magnetic structures is recalled in the middle of Image 4, where the blue plane symbolises the magnetopause.
www.spacedaily.com /news/earth-magnetic-05c.html   (2384 words)

 01.11.2006 - NASA/ESA space probes detect enormous magnetic annihilation event
Understanding magnetic reconnection is fundamental to comprehending explosive phenomena throughout the universe such as solar flares, which are billion-megaton explosions in the sun's atmosphere; gamma-ray bursts, which are intense bursts of radiation from exotic stars; and laboratory nuclear fusion.
However, "this discovery settles a long-standing debate concerning whether reconnection is intrinsically patchy, or whether instead it can operate across vast regions in space," said Dr. Jack Gosling of the University of Colorado, a co-author of the paper and a pioneer in research on reconnection in space.
Another 27 large-scale reconnection events were identified by ACE and Wind, so the team could conclude that reconnection in the solar wind is to be looked at as an extended phenomenon.
www.berkeley.edu /news/media/releases/2006/01/11_Phannasa.shtml   (1016 words)

 INI Programme MRT
Magnetic reconnection is a fundamental process in a magnetized plasma or fluid at high magnetic Reynolds number, whereby magnetic field lines are broken and reconnected in an electric current singularity that is resolved by magnetic diffusion.
Reconnection is responsible for many dynamic processes in the Sun, the Magnetosphere, the laboratory and many astrophysical bodies, but in this Programme we shall be focusing on the fundamentals of the process and on the first two fields.
In addition, reconnection is likely to be heating the solar corona in many small current sheets to several million degrees by comparison with the solar surface temperature of only 6000 degrees.
www.newton.cam.ac.uk /programmes/MRT/mrt.html   (435 words)

The U-shaped reconnected magnetic field lines are seen to snap upward and downward, away from the point at which the reconnection occurred.
Magnetic reconnection can happen in the solar atmosphere because it is hot enough to separate electrons from atoms, producing a gas of electrically charged particles called plasma.
Magnetic reconnection could power a solar flare by heating the Sun's atmosphere to tens of millions of degrees and accelerating electrically charged particles that comprise the plasma (electrons and ions) to almost the speed of light.
www.nasa.gov /centers/goddard/news/topstory/2003/1209rhessi.html   (1340 words)

 Physics Division | Research Highlights | Los Alamos National Laboratory
A structure that generates magnetic fields from conductive-fluid flow is called a dynamo, and the annihilation of a magnetic field is called magnetic reconnection.
During five decades of study, researchers have largely regarded magnetic reconnection as a “fl-box” process that begins with the dissipation of magnetic-field energy and ends in plasma-particle acceleration and/or thermal heating.
Magnetic reconnection is thought to convert magnetic-field energy into particle, beam, and thermal energy.
www.lanl.gov /p/rh03_intrator.shtml   (1659 words)

 Magnetic reconnection between a magnetic cloud and the solar wind magnetic field
This paper presents a numerical study of magnetic reconnection processes between magnetically organized structures in the solar wind (e.g., magnetic clouds or plasma bubbles) and the solar wind magnetic field.
Magnetic reconnection occurs at points along the surface bounding the two flux systems where antiparallel field lines are forced together.
For a magnetic cloud moving outward in an unidirectional radial magnetic field, the reconnection occurs asymmetrically, the location depending on the sense of rotation of the cloud's magnetic field.
www.agu.org /pubs/crossref/2003/2002JA009325.shtml   (302 words)

 First 3-D magnetic reconnection measurements
Magnetic reconnection is the phenomenon in which magnetic energy in a plasma is rapidly converted to heat and jets of energetic particles.
Magnetic reconnection is also an important process in some experimental fusion energy reactors that use magnetic fields to confine the plasma.
The physical picture of magnetic reconnection is of two strands of magnetized plasma with oppositely directed magnetic field merging together.
www.eurekalert.org /pub_releases/2002-11/aps-f3m110702.php   (291 words)

 Plasma: Magnetic reconnection
After the reconnection the plasma is expelled in the direction of the original orientation of the magnetic field lines.
The reconnection of magnetic field lines can happen even in the case when the interplanetary field is parallel to the direction of the field lines in the day side.
The magnetic reconnection of the field lines is then reached sidewards with respect to the magnetosphere, not at all at the zone of the local noon.
www.aldebaran.cz /astrofyzika/plazma/reconnection_en.html   (1464 words)

 Magnetic reconnection
Magnetic reconnection is a phenomenon which is of particular importance in solar system plasmas.
In the Earth's magnetosphere, magnetic reconnection in the magnetotail is thought to be the precursor for auroral sub-storms.
Assuming that each plasma is frozen to its own magnetic field, and that cross-field diffusion is absent, we conclude that the two plasmas will not mix, but, instead, that a thin boundary layer will form between them, separating the two plasmas and their respective magnetic fields.
farside.ph.utexas.edu /teaching/plasma/lectures/node74.html   (745 words)

 NASA - Space Probes Detect Enormous Natural Particle Accelerator
Just as a rubber band can suddenly snap when twisted too far, magnetic reconnection is a natural process by which the energy in a stressed magnetic field is suddenly released when it changes shape, accelerating particles (ions and electrons).
Some previous reconnection events measured in Earth’s magnetosphere suggested that the phenomenon was intrinsically random and patchy in nature, extending not more than a few tens of thousands of kilometers (miles).
The broader picture of magnetic reconnection emerged when six spacecraft – the four European Space Agency Cluster spacecraft and NASA's Advanced Composition Explorer (ACE) and Wind probes – were flying in the solar wind outside Earth’s magnetosphere on 2 February 2002 and made a chance discovery.
www.nasa.gov /centers/goddard/solarsystem/2006_mag_recon.html   (1166 words)

 Cluster hits the magnetic bull's-eye
This reconnection of magnetic fields generates jets of particles and heats the plasma.
At the very heart of a reconnection event, there must be a three dimensional zone where the magnetic fields break and reconnect.
Throughout the Universe, magnetic reconnection is thought to be a fundamental process that drives many powerful phenomena, such as the jets of radiation seen escaping from distant fl holes, and the powerful solar flares in our own Solar system that can release more energy than a billion atomic bombs.
www.eurekalert.org /pub_releases/2006-07/esa-cht071806.php   (505 words)

 Satellites Catch Earth Reconfiguring Its Magnetic Field
Magnetic reconnection occurs when the bubbles are pushed together and their magnetic fields break and reconnect, creating a more stable magnetic relationship.
The process, called magnetic reconnection, is a transitional phase involving the interaction of plasma filled magnetic "bubbles," and is thought to be responsible for driving a variety of extremely powerful celestial phenomena.
This is the first time that magnetic reconnection has been observed, and the data collected from the mission, appearing in Nature Physics, will be invaluable to astronomers and nuclear scientists.
www.scienceagogo.com /news/20060619213743data_trunc_sys.shtml   (1010 words)

 Fast magnetic reconnection
We conclude that the reconnecting layer is extremely narrow, assuming that the Lundquist number of the plasma is very large.
He pointed out that magnetic energy can be converted into plasma thermal energy as a result of shock waves being set up in the plasma, in addition to the conversion due to the action of resistive diffusion.
Clearly, since the maximum reconnection rate depends inversely on the logarithm of the Lundquist number, rather than its square root, it is much larger than that predicted by the Sweet-Parker model.
farside.ph.utexas.edu /teaching/plasma/lectures/node77.html   (1143 words)

 ESA Science & Technology: New Microscopic Properties of Magnetic Reconnection Derived by Cluster
Magnetic reconnection is considered to be the most efficient mechanism for solar material to penetrate the Earth's magnetic shield and to convert magnetic energy to particle energy (generating plasma jets and plasma heating).
In the atmosphere of the Sun, magnetic reconnection is indeed believed to contribute to the heating of the solar corona (outer layer of the solar atmosphere).
It is indeed a mechanism preventing magnetic confinement of the fusion fuel.
sci.esa.int /jump.cfm?oid=39246   (1192 words)

 Magnetic Reconnection
A magnetic reconnection can release vast amounts of energy, and is responsible for explosive events on the sun, such as flares, that can cause communication and power system disruptions on Earth.
Reconnection is a process by which magnetic fields reconfigure themselves, releasing energy that can be converted to particle energies and bulk flows.
Reconnection plays an essential role in several phenomena in magnetic confinement devices, such as sawtooth-like oscillations seen in the core electron temperature or magnetic islands induced by field-errors.
www.magnetictherapy.co.uk /Resources/magnetic---expressions-magnetic-reconnection.htm   (385 words)

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