magnetic structure of the disk corona
Download
Skip this Video
Download Presentation
Magnetic structure of the disk corona

Loading in 2 Seconds...

play fullscreen
1 / 11

Magnetic structure of the disk corona - PowerPoint PPT Presentation


  • 94 Views
  • Uploaded on

Magnetic structure of the disk corona. Slava Titov, Zoran Mikic, Alexei Pankin, Dalton Schnack SAIC , San Diego Jeremy Goodman, Dmitri Uzdensky Princeton University CMSO General Meeting , October 5-7, 200 5 Princeton. 2D case : field line connectivity and topology. BP separtrix

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Magnetic structure of the disk corona' - emilie


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
magnetic structure of the disk corona

Magnetic structureof the disk corona

Slava Titov, Zoran Mikic,Alexei Pankin, Dalton Schnack

SAIC, San Diego

Jeremy Goodman,Dmitri Uzdensky

Princeton University

CMSO General Meeting, October 5-7, 2005

Princeton

slide2

2D case: field line connectivity and topology

BP separtrix

field line

NP separtrix

field line

normal

field line

disk

  • Flux tubes enclosing separatrices split at null pointsor "bald-patch" points.
  • They are topological features, because splitting cannot be removed by a

continous deformation of the configuration.

  • Current sheets are formed at the separatrices due to footpoint displacements

or instabilities.

All these 2D issues can be generalized to 3D!

slide3

Extra opportunity in 3D: squashing instead of splitting

  • Differences compared to nulls and BPs:
        • squashing may be removed by a continuous deformation,
        • => QSL is not topological but geometrical object,
        • metric is needed to describe QSL quantitatively,
        • => topological arguments for the current sheet formation at QSLs are notapplicable;
        • other approach is required.

Nevertheless, thin QSLs are as importantas genuine separatrices for this process.

slide4

Squashing factor Q

  • Geometrical definition:
        • Infinitezimal flux tube such that a cross-section at one foot is curcular, then circle  ==>   ellipse:
    • Q = aspect ratio of the ellipse;
    • Q is invariant to direction of mapping.

(Titov, Hornig & Démoulin, 2002)

  • Definition of Q in coordinates:
  • where a, b, c and d are the elements of the Jacobian matrix
  • D and then Q can be determined by integrating field line equations.
slide5

Expansion-contraction factor K

  • Geometrical definition:
        • Infinitezimal flux tube such that a cross-section at one foot is curcular, then circle  ==>   ellipse:
    • K = lg(ellipse area / circle area);
    • K is invariant (up to the sign) to the direction of mapping.
  • Definition of K in coordinates:
  • where a, b, c and d are the elements of the Jacobian matrix
  • D and then Q can be determined by integrating field line equations.
what can we obtain with the help of q and k
What can we obtain with the help of Q and K?
  • Identify the regions subject to boundary effects.
  • Understand the effect of resistivity.
  • Identify the reconnecting magnetic flux tubes.
example t 238
Example (t=238)

Numerical MHD

log Q

From the initial B(r)

and vdsk(rdsk,t) only!

From the

computed B(r,t).

1 2

Exact ideal MHD

-10 0 10

example t 2381
Example (t=238)

Numerical MHD

K

-1 0 1

Exact ideal MHD

-10 0 10

example t 2382
Example (t=238)

Numerical MHD

log Q

K

1 2

-1 0 1

Exact ideal MHD

-10 0 10

helical qsl t 238
Helical QSL (t=238)

Magnetic field lines

Launch footpoints

conclusions
Conclusions

Evolving Q and K distributions make possible:

  • to identify the regions subject to boundary effects,
  • to understand the effect of resistivity,
  • to identify the reconnecting magnetic flux tubes (helical QSL).
ad