3D MHD Coronal Oscillations About a Magnetic Null Point: Application of WKB Theory

Details 3D MHD Coronal Oscillations About a Magnetic Null Point: Application of WKB Theory 3D MHD Coronal Oscillations About a Magnetic Null Point: Application of WKB Theory

2007-12-11

arxiv.org/abs/0712.1731v1

Astronomy and Astrophysics

Astrophysics

26 pages, 12 figures

Scientific paper

10.1007/s11207-007-9107-2

This paper is a demonstration of how the WKB approximation can be used to help solve the linearised 3D MHD equations. Using Charpit's Method and a Runge-Kutta numerical scheme, we have demonstrated this technique for a potential 3D magnetic null point, ${\bf{B}}=(x,\epsilon y -(\epsilon +1)z)$. Under our cold plasma assumption, we have considered two types of wave propagation: fast magnetoacoustic and Alfv\'en waves. We find that the fast magnetoacoustic wave experiences refraction towards the magnetic null point, and that the effect of this refraction depends upon the Alfv\'en speed profile. The wave, and thus the wave energy, accumulates at the null point. We have found that current build up is exponential and the exponent is dependent upon $\epsilon$. Thus, for the fast wave there is preferential heating at the null point. For the Alfv\'en wave, we find that the wave propagates along the fieldlines. For an Alfv\'en wave generated along the fan-plane, the wave accumulates along the spine. For an Alfv\'en wave generated across the spine, the value of $\epsilon$ determines where the wave accumulation will occur: fan-plane ($\epsilon=1$), along the $x-$axis ($0<\epsilon <1$) or along the $y-$axis ($\epsilon>1$). We have shown analytically that currents build up exponentially, leading to preferential heating in these areas. The work described here highlights the importance of understanding the magnetic topology of the coronal magnetic field for the location of wave heating.

Affiliated with

Also associated with

No associations

Rating

3D MHD Coronal Oscillations About a Magnetic Null Point: Application of WKB Theory does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with 3D MHD Coronal Oscillations About a Magnetic Null Point: Application of WKB Theory, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and 3D MHD Coronal Oscillations About a Magnetic Null Point: Application of WKB Theory will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-474433