地球磁层极尖区场向电子事件期间能量特性研究

Study on Energy Features during a Field-aligned Electron Events in the Cusp Region

根据Cluster卫星2001年9月30日在北半球极尖区观测到的一次强扰动场向电子事件数据,分析研究了这次事件期间场向电子的能量特性,讨论了场向电子对太阳风能量向磁层的传输和磁层-电离层耦合过程中能量传输的作用.分析认为,这次电子扰动事件期间电子速度和密度都具有很强的扰动变化,电子速度增加是一个主要特点.本次事件中低能段5~200 eV和500~1500 eV内的能谱分析结果表明,上行电子通量大于下行电子通量,上行电子主要来源于电离层,说明电离层上行电子在本次事件中具有非常活跃的作用.根据电离层中带电粒子的能量特征分析结果可知,这次事件中电离层起源的上行电子在上行过程中得到了加速.关于加速机制问题还有待深入研究.

By focusing on an extremely disturbed field-aligned electrons event observed with Cluster in the northern cusp region on 30 September 2001,the energy features of the field-aligned electrons in the event is analyzed and the roles of the field-aligned electrons on the transmission of solar wind energy to the magnetosphere and on the magnetosphere-ionosphere coupling are discussed.The results show that the velocities and densities of the electrons have strong disturbances during the event,and the velocity is a main factor to enhance the electron flux.The electron energy spectrum in 5~200eV and 500~1500eV show that the up-flowing electron flux is higher than that of downflowing,which means the up-flowing electrons mainly come from the ionosphere and play an active role in this event.The energy features show that the ionospheric electrons have been accelerated during the up-flowing.However,the accelerating physical mechanism still needs to be further studied.