title: Magnetic reconnection by a self-retreating X line.
abstract: Particle-in-cell simulations of collisionless magnetic reconnection are performed to study asymmetric reconnection in which an outflow is blocked by a hard wall while leaving sufficiently large room for the outflow of the opposite direction. This condition leads to a slow, roughly constant motion of the diffusion region away from the wall, the so-called "X-line retreat." The typical retreat speed is approximately 0.1 times the Alfvén speed. At the diffusion region, ion flow pattern shows strong asymmetry and the ion stagnation point and the X line are not collocated. A surprise, however, is that the reconnection rate remains the same unaffected by the retreat motion.
authors.affiliation: Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, Alabama 35805, USA. mitsuo.oka@uah.edu
authors.forename: M
authors.initials: M
authors.lastname: Oka
authors.forename: M
authors.initials: M
authors.lastname: Fujimoto
authors.forename: T K M
authors.initials: TK
authors.lastname: Nakamura
authors.forename: I
authors.initials: I
authors.lastname: Shinohara
authors.forename: K-I
authors.initials: KI
authors.lastname: Nishikawa