资源环境科技发展态势分析平台

We investigate an exhaust crossing of asymmetric guide‐field reconnection observed by Magnetospheric Multiscale (MMS) mission at Earth's dayside magnetopause. One MMS spacecraft (MMS 4) observes multi‐component electron distributions, including two counter‐streaming electron beams, while the other three MMS spacecraft, with a separation of ∼ 30 km, record nearly isotropic electron distributions. As counter‐streaming electrons are unstable for the electron two‐stream instability (ETSI), our observations suggest that the electrostatic waves generated by the fast‐growing ETSI can contribute to the rapid isotropization of electron distributions in the reconnection exhaust, indicating that wave‐particle interactions play an important role in electron dynamics.