They say (in popular videos and articles) that tangled magnetic fields on Sun explode. But i don't understand why and how magnetic fields, tangled or not, explode. Could anyone explain?
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I have some amazing videos from NASA to share with you :) -- link1, link2, link3. Popular animated depictions are fine, but reality is so much more amazing. (Turn on CC by the way, there's some info in there.) – Filip Milovanović Sep 25 '22 at 00:48
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Related: https://physics.stackexchange.com/q/554566/59023 and https://physics.stackexchange.com/q/559741/59023 and https://physics.stackexchange.com/q/538661/59023. – honeste_vivere Oct 10 '22 at 12:47
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Magnetic fields in an ionized plasma have more complicated behaviors than magnetic fields in free space.
A lone charged particle in free space will undergo “cyclotron motion” in the plane which is locally perpendicular to the magnetic magnetic field. Its motion parallel to the magnetic field is not affected, so charged particles tend to follow magnetic field lines in helical paths. The stronger the field, the tighter the helix.
In a plasma, the currents associated with ionic motions are non-negligible, and these currents produce their own magnetic fields. The motions of the ions, as modified by the magnetic field, change the magnetic field environment, which in turn changes the motions of the ions. The study of this complicated self-interaction is “magnetohydrodynamics.”
One result of magnetohydrodynamics is that a region of plasma where the magnetic field has a complicated shape, and where therefore the ions have a complicated motion, has a larger energy content than a region of space where the magnetic field lines are mostly straight and mostly parallel. It is possible for the self-interaction between the fields and the ionic motions to suddenly permit a complicated field to “reconnect” into a simpler set of straight-line fields. In that event, the extra energy can be associated with an energetic mass ejection from the plasma.
rob
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Why does the reconnection follow a broken conductive path? What is the trigger level of the explosion? – Tony Stewart EE75 Sep 24 '22 at 17:25
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I'm not quite sure I understand your question, and my guess at an answer is not a good fit for a comment. Ask a follow-up question and link it here. – rob Sep 24 '22 at 23:49
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https://www.nasa.gov/feature/goddard/2019/nasa-s-sdo-sees-new-kind-of-magnetic-explosion-on-sun and https://iopscience.iop.org/article/10.3847/1538-4357/ab4a0c when the voltage has exceeded the LEL or lower explosive limit of combustible gas.
I can imagine transformer flyback properties of breaking arc sheet currents cascading with ionization delays from ionic contaminants creating stochastic random coronal emissions, but I can't explain it well. The continuous absorption of energy makes up for the detection of the solar emission to earth of 1kW/m^-2. Somewhat like a lightning tracer of cascading partial discharge, PD followed by the arc via the lowest resistance path.
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2This answer (v2) seems to draw a parallel between magnetic reconnection events in plasmas and the “lower explosive limit” associated with rapid combustion of neutral gases in an oxygen atmosphere. – rob Sep 24 '22 at 12:51
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It could be any hydrocarbon atmosphere with at least 1 molecule of oxygen. The analogy is how transformer oil explodes with a drop of water and sufficient contaminants. The result is a stochastic reduction in the breakdown voltage BDV with PD escalating into more complex gases with greater LEL and combustible energies. – Tony Stewart EE75 Sep 24 '22 at 12:58
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4Your statements are correct, but unfortunately they don't have anything to do with this question. – rob Sep 24 '22 at 14:50