Transition from ion-coupled to electron-only reconnection: Basic physics and implications for plasma turbulence

• DOI: 10.1063/1.5090403
• Publication Date: 2019-08-16T13:56:43Z
• Authors: P. Sharma Pyakurel; M. A. Shay; T. D. Phan; W. H. Matthaeus; J. F. Drake; J. M. TenBarge; C. C. Haggerty; K. G. Klein; P. A. Cassak; T. N. Parashar; M. Swisdak; A. Chasapis
• Keywords: Gyroradius; Magnetosheath

Using kinetic particle-in-cell (PIC) simulations, we simulate reconnection conditions appropriate for the magnetosheath and solar wind, i.e., plasma beta (ratio of gas pressure to magnetic pressure) greater than 1 low shear (strong guide field). Changing simulation domain size, find that ion response varies greatly. For reconnecting regions with scales comparable Larmor radius, ions do not respond dynamics leading ''electron-only'' very large quasi-steady rates. The transition more traditional ''ion-coupled'' is gradual as size increases, becoming frozen-in in exhaust when island width normal direction reaches many inertial lengths. During this transition, rate decreases until are fully coupled, ultimately reaching an asymptotic value. scaling outflow velocity during electron-only ion-coupled found be consistent a theoretical model newly reconnected field line. In order have flows Alfv\'en speed, at least several lengths needed. turbulent systems occurring between bubbles associated fluctuations, using geometric arguments estimate requires bubble length tens