As for the present situation of coronal mass ejection （CME） triggering models, the distributions of Alfv@n waves in flux ropes are different from model to model, and thus examining those distributions in interplanetary coronal mass ejection （ICME） is an effective way to connect ICME observations with these theoretical models of CME triggering. However, previous observations of Alfv@nic fluctuations in ICMEs were rare with locations ranging from 0.3 AU to 0.68 AU only, which is usually explained as rapid dissipation of those remnant waves. Here we present an observation of Alfv@n waves in a magnetic cloud （MC） near 1 AU, in situ detected by WIND in February 17,-~20, 2011. The MC was generated by a CME accompanied with the first X-class flare in the 24th solar cycle. The slope of the power spectral densities of magnetic fluctuation in the MC, are similar to those modes in ambient solar wind, but more anisotropic. The results will also be helpful for studies of CME theories and ICME thermodynamics.
As an essential mechanism in large scale fast magnetic energy releases and field reconfigurations processes in space,astrophysical, and laboratory plasmas,magnetic reconnection,particularly collisionless magnetic reconnection,has been studied for more than 65 years.Many progresses have been achieved in recent years and basic features of the process have been well understood,largely due to more and more satellite observation data available in the last decade.However,a few outstanding issues are still remained unresolved.We in the paper review the development of collisionless magnetic reconnection studies and major achievements in recent years,and also briefly discuss the open questions remained to be answered in studies of collisionless magnetic reconnection.
