dorsal/arxiv
View SchemaWhy current-carrying magnetic flux tubes gobble up plasma and become thin as a result
| Authors | P. M. Bellan |
|---|---|
| Categories | |
| ArXiv ID | physics/0301037 |
| URL | https://arxiv.org/abs/physics/0301037 |
| DOI | 10.1063/1.1558275 |
Abstract
It is shown that if a current-carrying magnetic flux tube is bulged at its axial midpoint z=0 and constricted at its axial endpoints z=+h,-h, then plasma will be accelerated from z=+h,-h towards z=0 resulting in a situation similar to two water jets pointed at each other. The ingested plasma convects embedded, frozen-in toroidal magnetic flux from z=+h,-h to z=0. The counter-directed flows collide and stagnate at z=0 and in so doing (i) convert their translational kinetic energy into heat, (ii) increase the plasma density at z~0, and (iii) increase the embedded toroidal flux density at z~0. The increase in toroidal flux density at z~0 increases the toroidal field Bphi and hence increases the magnetic pinch force at z~0 and so causes a reduction of the flux tube radius at z~0. Thus, the flux tube develops an axially uniform cross-section, a decreased volume, an increased density, and an increased temperature. This model is proposed as a likely hypothesis for the long-standing mystery of why solar coronal loops are observed to be axially uniform, hot, and bright.
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"abstract": "It is shown that if a current-carrying magnetic flux tube is bulged at its\naxial midpoint z=0 and constricted at its axial endpoints z=+h,-h, then plasma\nwill be accelerated from z=+h,-h towards z=0 resulting in a situation similar\nto two water jets pointed at each other. The ingested plasma convects embedded,\nfrozen-in toroidal magnetic flux from z=+h,-h to z=0. The counter-directed\nflows collide and stagnate at z=0 and in so doing (i) convert their\ntranslational kinetic energy into heat, (ii) increase the plasma density at\nz~0, and (iii) increase the embedded toroidal flux density at z~0. The increase\nin toroidal flux density at z~0 increases the toroidal field Bphi and hence\nincreases the magnetic pinch force at z~0 and so causes a reduction of the flux\ntube radius at z~0. Thus, the flux tube develops an axially uniform\ncross-section, a decreased volume, an increased density, and an increased\ntemperature. This model is proposed as a likely hypothesis for the\nlong-standing mystery of why solar coronal loops are observed to be axially\nuniform, hot, and bright.",
"arxiv_id": "physics/0301037",
"authors": [
"P. M. Bellan"
],
"categories": [
"physics.plasm-ph",
"physics.space-ph"
],
"doi": "10.1063/1.1558275",
"title": "Why current-carrying magnetic flux tubes gobble up plasma and become thin as a result",
"url": "https://arxiv.org/abs/physics/0301037"
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