Ion density, temperature, and composition of the Venus nightside ionosphere during a period of moderate solar activity: Implications for maintaining the central nightside
Ion density, temperature, and composition of the Venus nightside ionosphere during a period of moderate solar activity: Implications for maintaining the central nightside
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中等太阳活动期间金星夜间电离层的离子密度、温度和成分：对维持中央夜间电离层的影响
DOI：
10.1029/95ja01470
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发表时间：
1995
影响因子：
--
通讯作者：
W. Lotze
中科院分区：
文献类型：
--
作者：
K. Spenner;W. C. Knudsen;W. Lotze
给出了在太阳活动中金星夜侧电离层主要成分的离子密度、温度和部分密度。这些数据是在1992年任务的进入阶段由先锋金星轨道器的延迟电位分析仪测量的。相对于高太阳活动时测量到的等离子体密度，高度变化的等离子体密度平均明显降低。一个显著的黎明-黄昏不对称，黎明时H +和黄昏时O +的过剩，发生在后终结区。在中央夜侧扇区，超过150°太阳天顶角，电离层被强烈耗尽。离子温度分布与太阳活动高时的测量值相似，但数值略小。测量结果表明，在太阳活动高时，离子通量作为夜间电离层的主要维持源，随着太阳活动的减弱而减小。在中等太阳活动时，我们发现等离子体输运和粒子沉淀对中心扇区电离的贡献大致相等。
Ion density, temperature, and the partial densities of the main constituents of the Venusian nightside ionosphere during moderate solar activity are presented. The data were measured by the retarding potential analyzer of the Pioneer Venus Orbiter during the entry phase of the mission in 1992. The highly variable plasma density is, on average, clearly reduced relative to that measured at high solar activity. A significant dawn-dusk asymmetry, an excess of H + at dawn and O + at dusk, occurs in the postterminator sector. In the central nightside sector, beyond 150° solar zenith angle, the ionosphere is strongly depleted. The ion temperature distribution is similar to that measured during high solar activity, but the values are slightly smaller. The measurements indicate that the ion flux across the terminator, which is the dominant maintenance source for the nightside ionosphere at high solar activity, decreases with decreasing solar activity. At moderate solar activity we find that plasma transport and particle precipitation contribute approximately equally to the ionization of the central sector.