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The current driven kink instability ...

Linton, Mark George.

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The current driven kink instability and its relationship to delta-spot active regions.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The current driven kink instability and its relationship to delta-spot active regions./
Author:	Linton, Mark George.
Description:	142 p.
Notes:	Co-Chairs: George Fisher; Robert Lin.
Contained By:	Dissertation Abstracts International60-03B.
Subject:	Physics, Astronomy and Astrophysics. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9922937
ISBN:	9780599225077

The current driven kink instability and its relationship to delta-spot active regions.
Linton, Mark George.

The current driven kink instability and its relationship to delta-spot active regions. - 142 p.

Co-Chairs: George Fisher; Robert Lin.

Thesis (Ph.D.)--University of California, Berkeley, 1998.

The current driven kink instability may be the cause of both the unusual morphology of solar delta-spot active regions and the tendency of these regions to be significantly more flare active than most active regions. We investigate the current driven kink instability of flux tubes in the solar interior both with a linear stability analysis and with nonlinear MHD simulations. The linear analysis shows that there is a critical twist, which depends on the axial magnetic field profile, that a flux tube needs to become kink unstable. This critical twist decreases as the tube expands, so twisted flux tubes will become increasingly unstable as they rise through the convection zone. The nonlinear simulations show that a twisted tube excited by a single unstable kink mode will evolve to a helical equilibrium state. The emergence through the photosphere of such a kinked tube would create an active region which was tilted with respect to Hale's law and which would rotate as it evolved, as delta-spots are observed to do. We then find that, when excited by multiple unstable kink modes, highly twisted flux tubes develop concentrated kinks. These concentrated kinks would produce more of the observed characteristics of delta-spot active regions. They would create active regions which, in addition to emerging tilted and then rotating, would remain compact as they evolved, and develop strong shear along their magnetic neutral line. Finally, we find that a strong concentrated kink develops a current sheet at which the magnetic field reconnects, which may be the cause of the high flare activity of delta-spots.

ISBN: 9780599225077Subjects--Topical Terms:

1019521
Physics, Astronomy and Astrophysics.

The current driven kink instability and its relationship to delta-spot active regions.
LDR:02567nam 2200289 a 45 001 939884
005 20110517
008 110517s1998 ||||||||||||||||| ||eng d
020 $a 9780599225077
035 $a (UMI)AAI9922937
035 $a AAI9922937
040 $a UMI $c UMI
100 1 $a Linton, Mark George. $3 1263995
245 1 4 $a The current driven kink instability and its relationship to delta-spot active regions.
300 $a 142 p.
500 $a Co-Chairs: George Fisher; Robert Lin.
500 $a Source: Dissertation Abstracts International, Volume: 60-03, Section: B, page: 1143.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 1998.
520 $a The current driven kink instability may be the cause of both the unusual morphology of solar delta-spot active regions and the tendency of these regions to be significantly more flare active than most active regions. We investigate the current driven kink instability of flux tubes in the solar interior both with a linear stability analysis and with nonlinear MHD simulations. The linear analysis shows that there is a critical twist, which depends on the axial magnetic field profile, that a flux tube needs to become kink unstable. This critical twist decreases as the tube expands, so twisted flux tubes will become increasingly unstable as they rise through the convection zone. The nonlinear simulations show that a twisted tube excited by a single unstable kink mode will evolve to a helical equilibrium state. The emergence through the photosphere of such a kinked tube would create an active region which was tilted with respect to Hale's law and which would rotate as it evolved, as delta-spots are observed to do. We then find that, when excited by multiple unstable kink modes, highly twisted flux tubes develop concentrated kinks. These concentrated kinks would produce more of the observed characteristics of delta-spot active regions. They would create active regions which, in addition to emerging tilted and then rotating, would remain compact as they evolved, and develop strong shear along their magnetic neutral line. Finally, we find that a strong concentrated kink develops a current sheet at which the magnetic field reconnects, which may be the cause of the high flare activity of delta-spots.
590 $a School code: 0028.
650 4 $a Physics, Astronomy and Astrophysics. $3 1019521
650 4 $a Physics, Fluid and Plasma. $3 1018402
690 $a 0606
690 $a 0759
710 2 $a University of California, Berkeley. $3 687832
773 0 $t Dissertation Abstracts International $g 60-03B.
790 $a 0028
790 1 0 $a Fisher, George, $e advisor
790 1 0 $a Lin, Robert, $e advisor
791 $a Ph.D.
792 $a 1998
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9922937