Generation of Magnetic Fields: Various Multipolar Seed Fields
The exact solution for the kinematic dynamo in spherical coordinates r,θ,(φ) is given by Callebaut 1 when the azimuthal velocity is supposed to be a given, but arbitrary, function of r and θ only. Using a bipolar seed field yielded a qualitative agreement with the sunspot butterfly diagram and the polar faculae butterfly diagram. Next we have investigated the case that a quadrupolar seed field resides in the Sun (Callebaut and Khater, 2006) as some observations reveal a quadrupolar and even an octupolar contribution to some surface and interplanetary phenomena. A combination of a bipolar, a quadrupolar and an octupolar field may yield a fairer agreement with observations. However, the ratio of the various components is still a problem: determination from the solar surface or from interplanetary space gives approximate values. The separation between the sunspot region and the polar faculae, although both are generated by the same mechanism, is manifest: the region where the radial variation of the angular frequency of the rotation vanishes. One serious drawback: as for other models the agreement near the poles is poor, although it was improved much in comparison with a bipolar field alone by realizing that the coefficients of bipolar and quadrupolar field have opposite signs.
D. K. Callebaut H. Kikuchi
Physics Department, CGB University of Antwerp Antwerp B-2020, Belgium Institute for Environmental Electromagnetics Tokyo B-2020, Japan
国际会议
Progress in Electromagnetics Research Symposium 2007(2007年电磁学研究新进展学术研讨会)(PIERS 2007)
北京
英文
965-969
2007-03-26（万方平台首次上网日期，不代表论文的发表时间）