An interpretation of density holes observed by Cluster and Double Star in solar wind  

作　　者：QURESHI M N S SHI JianKui CHENG ZhengWei LIU ZhengXing 

机构地区：[1]State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China [2]Department of Physics, GC University, Lahore 54000, Pakistan

出　　处：《Chinese Science Bulletin》2012年第12期1405-1408,共4页

基　　金：supported by the National Natural Science Foundation of China(41074114,40921063,40804031);the Specialized ResearchFund for State Key Laboratories of China

摘　　要：To interpret density holes in the solar wind,which are nonlinear structures observed by Cluster and Double Star,we propose an electrostatic ion fluid model.We derive the Sagdeev potential from the magnetohydrodynamic(MHD)equations and study the characteristics of nonlinear structures in our model.The results show that density depletions(or holes)can develop from linear ion acoustic waves or ion cyclotron waves in space plasmas when parameters such as Mach number,initial electric field and ratio of ion to electron temperature satisfy certain conditions.In our model,the relative density depletion(or density holes)is from 0 to 1, and the time duration of density holes is from 2 s to more than 98 s.These are in good agreement with the observations by Cluster and Double Star in the solar wind.Our model also shows that the density holes should be accompanied by bipolar electric field solitary structures,which have also been observed by Cluster in the solar wind.To interpret density holes in the solar wind, which are nonlinear structures observed by Cluster and Double Star, we propose an electrostatic ion fluid model. We derive the Sagdeev potential from the magnetohydrodynamic （MHD） equations and study the characteristics of nonlinear structures in our model. The results show that density depletions （or holes） can develop from linear ion acoustic waves or ion cyclotron waves in space plasmas when parameters such as Mach number, initial electric field and ratio of ion to electron temperature satisfy certain conditions. In our model, the relative density depletion （or density holes） is from 0 to 1, and the time duration of density holes is from 2 s to more than 98 s. These are in good agreement with the observations by Cluster and Double Star in the solar wind. Our model also shows that the density holes should be accompanied by bipolar electric field solitary structures, which have also been observed by Cluster in the solar wind.

关 键 词：相对密度 太阳风 双星 群集 非线性结构 流体模型 磁流体动力学 空间等离子体 

分 类 号：P353.8[天文地球—空间物理学]