地球同步轨道航天器在地磁亚暴环境下处于向光面和背光面的两侧会产生电位差。本文利用高能电子和高能离子的双麦克斯韦分布拟合同步轨道环境等离子体并加入二次电子和光电子的影响,建立了航天器的三维计算模型,利用基于PIC(Particle In...地球同步轨道航天器在地磁亚暴环境下处于向光面和背光面的两侧会产生电位差。本文利用高能电子和高能离子的双麦克斯韦分布拟合同步轨道环境等离子体并加入二次电子和光电子的影响,建立了航天器的三维计算模型,利用基于PIC(Particle In Cell)方法的仿真程序,计算了航天器表面各材料的充电电位及其附近的等离子体的电位分布,以及低能电子、高能电子、二次电子和光电子的密度分布和充电电流分布,最后探讨了航天器不同表面材料电势随时间的变化情况。展开更多
为了考察亲电子效应(包含斥电子效应)对等离子体中尘埃带电的影响,建立了基于粒子网格(particle in cell,PIC)技术的尘埃带电计算方法.在物理上使用表面附加电荷来表征亲电子效应,并在计算方法中增加了相应的数学描述.基于该方法,开展...为了考察亲电子效应(包含斥电子效应)对等离子体中尘埃带电的影响,建立了基于粒子网格(particle in cell,PIC)技术的尘埃带电计算方法.在物理上使用表面附加电荷来表征亲电子效应,并在计算方法中增加了相应的数学描述.基于该方法,开展了多个场景例的计算,结果表明:亲电子效应越强,尘埃平衡电荷量就越大,且其平衡电荷量增幅与表面附加电荷面密度有着近似的正比关系;类似地,斥电子尘埃同样具有这种正比关系,但与亲电子尘埃不同的特点是,斥电子尘埃达到平衡电荷量的用时更长;此外,尘埃的粒径越大,亲电子效应所带来的平衡电荷量提升效果就越显著.该方法实现了对等离子体中亲电子尘埃带电的计算能力.通过该方法的计算表明,亲电子材质对等离子体中尘埃带电可以造成影响,且当亲电子效应足够强时,影响效果将不可忽视.展开更多
Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculation...Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.展开更多
文摘地球同步轨道航天器在地磁亚暴环境下处于向光面和背光面的两侧会产生电位差。本文利用高能电子和高能离子的双麦克斯韦分布拟合同步轨道环境等离子体并加入二次电子和光电子的影响,建立了航天器的三维计算模型,利用基于PIC(Particle In Cell)方法的仿真程序,计算了航天器表面各材料的充电电位及其附近的等离子体的电位分布,以及低能电子、高能电子、二次电子和光电子的密度分布和充电电流分布,最后探讨了航天器不同表面材料电势随时间的变化情况。
文摘为了考察亲电子效应(包含斥电子效应)对等离子体中尘埃带电的影响,建立了基于粒子网格(particle in cell,PIC)技术的尘埃带电计算方法.在物理上使用表面附加电荷来表征亲电子效应,并在计算方法中增加了相应的数学描述.基于该方法,开展了多个场景例的计算,结果表明:亲电子效应越强,尘埃平衡电荷量就越大,且其平衡电荷量增幅与表面附加电荷面密度有着近似的正比关系;类似地,斥电子尘埃同样具有这种正比关系,但与亲电子尘埃不同的特点是,斥电子尘埃达到平衡电荷量的用时更长;此外,尘埃的粒径越大,亲电子效应所带来的平衡电荷量提升效果就越显著.该方法实现了对等离子体中亲电子尘埃带电的计算能力.通过该方法的计算表明,亲电子材质对等离子体中尘埃带电可以造成影响,且当亲电子效应足够强时,影响效果将不可忽视.
基金Project(51004034)supported by the National Natural Science Foundation of ChinaProject(N090302009)supported by the Fundamental Research Funds for the Central Universities,China
文摘Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.