Laboratory Study of Magnetic Reconnection with Variable Collisionality and its Application to Space Astro-physics

The fundamental physics of magnetic reconnection derived from the recent MRX experiment [1] is presented focusing on the different dynamics of electrons and ions during reconnection. Both local and global physics issues for reconnection and magnetic field dissipation are discussed. In the MRX scaling [1], the reconnection rate increases rapidly when the ion skin depth becomes larger than the Sweet-Parker width; the rate depends linearly on $\lambda_{mfp}/L$, a ratio of the electron mean free path to the scale length. This scaling can guide comparisons between laboratory results and astrophysical plasmas [2]. The recent experimental study of the global dynamics of line-tied solar flux ropes in a half-toroid plasma arc is also presented. \\[4pt] [1] M. Yamada et al, Phys. Plasmas, 13, 052119 (2006)\\[0pt] [2] D. A. Uzdensky, Phys. Rev. Lett., v.99, 261101 (2007).