Force-free magnetic fields attain more and more energy as the footpoints of field lines are driven by flows on the surface. However, the energy is never able to exceed an upper limit which is set by the field with all the field lines open to the outer space. This property of the force-free fields has so far been discussed based on analytic studies using integral relationships (virial relations, Aly 1984) about the magnetic field, and also based on numerical simulations. In this study, we use a simple solution for the force-free fields derived by Low and Lou (1990) and show the above-mentioned property most directly.
Cool Stars, Stellar Systems, and the Sun
- Pub Date:
- SOLAR CORONA;
- SOLAR MAGNETIC FIELD