Dynamics of a guide-field reconnection layer: Pathway to collisionless dissipation

Lower-hybrid-drift (LHD) vortices driving non-gyrotropic electron heating have recently been discovered in the electron-scale reconnection layer with a guide field in the terrestrial magnetotail. The observation presents a new regime of electron interaction with LHD waves. In this talk, a physical pathway of how the vortices facilitate dissipation to smaller spatiotemporal scales is discussed based on measurements from the Magnetospheric Multiscale Mission and particle-in-cell simulations. In the observation, electron distribution functions are modified by the lower-hybrid-wave fields, and unstable to whistler, upper hybrid, and Langmuir waves, presenting a cascade of dissipation to higher frequencies and finer spatial scales. Particle-in-cell simulations produce lower-hybrid-drift vortices, but the wave field is too weak to demagnetize electrons as in the observations. The electrostatic potential along the vortex tube in the PIC simulation exhibits features suggestive of slippage reconnection. The new regime of strong electron-wave interaction, the dissipation cascade, and the possibility of further reconnection within the vortex tubes call for concerted laboratory, simulation, and space investigations.