tailieunhanh - Astrophysics and Space Science Proceedings Phần 6

Tái kết nối từ ba-chiều Cơ chế sinh (sự xuất hiện hoặc phân mảnh) đã được ghi nhận, như đã được cơ chế chết (hủy bỏ, sự hóa hợp). | Three-Dimensional Magnetic Reconnection 263 were identified and then tracked in time. Their birth mechanism emergence or fragmentation was noted as was their death mechanism cancellation or coalescence . Potential field extrapolations were then used to determine the connectivity of the photospheric flux features. By assuming that the evolution of the field went through a series of equi-potential states the observed connectivity changes were coupled with the birth and death information of the features to determine the coronal flux recycling reconnection time. Remarkably it was found that during solar minimum the total flux in the solar corona completely changes all its connections in just h Close et al. 2004 2005 a factor of ten times faster than the time it takes for all the flux in the quiet-Sun photosphere to be completely replaced Schrijver et al. 1997 Hagenaar et al. 2003 . Clearly reconnection operates on a wide range of scales from kinetic to MHD. The micro-scale physics at the kinetic scales governs the portioning of the released energy into its various new forms and plays a role in determining the rate of reconnection. MHD the macro-scale physics determines where the reconnection takes place and hence where the energy is deposited and also effects the reconnection rate. In this paper we focus on macro-scale effects and investigate the behaviour of three-dimensional 3D reconnection using MHD numerical experiments. Two-dimensional 2D reconnection has been studied in detail and is relatively well understood especially in the solar and magnetospheric contexts. Over the past decade our knowledge of 3D reconnection has significantly improved Lau and Finn 1990 Priest and Demoulin 1995 Demoulin et al. 1996 Priest and Titov 1996 Birn et al. 1998 Longcope 2001 Hesse et al. 2001 Pritchett 2001 Priest et al. 2003 Linton and Priest 2003 Pontin and Craig 2006 De Moortel and Galsgaard 2006a b Pontin and Galsgaard 2007 Haynes et al. 2007 Parnell et al. 2008 . It is .