Scaling Laws for Magnetic Reconnection when Electron Pressure Anisotropy is near the Firehose Threshold

Magnetic reconnection in weakly-collisional, a process linked to solar flares, coronal mass ejections, and magnetic substorms, has been widely studied through fluid and kinetic simulations. While two-fluid models often reproduce the fast reconnection rate of kinetic simulations, significant differences are observed in the structure of the reconnection regions [1]. Recently, new equations of state that accurately account for the development of anisotropic electron pressure due to the electric and magnetic trapping of electrons have been developed [2]. Guide-field, fluid simulations using these equations of state have been shown to reproduce the detailed reconnection region observed in kinetic simulations [3]. Implementing this two-fluid simulation using the HiFi framework [4], we describe a mechanism for regulation of electron pressure anisotropy as well as study force balance of the electron layers in guide-field reconnection. Scaling laws for the heating observed in these layers based on upstream conditions are derived.\\[4pt] [1] Daughton W et al., Phys. Plasmas 13, 072101 (2006).\\[0pt] [2] Le A et al., Phys. Rev. Lett. 102, 085001 (2009).\\[0pt] [3] Ohia O, et al., Phys. Rev. Lett. In Press (2012).\\[0pt] [4] Lukin VS, Linton MG, Nonlinear Proc. Geoph. 18, 871 (2011)