Based on the Mars Atmosphere and Volatile EvolutioN (MAVEN) observations, we have analyzed the role of the crustal magnetic field on ion loss driven by the direct interaction of the solar wind with the Mars ionosphere. Crustal magnetic fields significantly attenuate the ion ionospheric motions and raise the flux of returning ions. On the other hand, since the ion densities in the ionosphere with strong crustal field are significantly higher than in the ionosphere with a weak crustal magnetic field, the net escape fluxes from the ionosphere with the crustal sources remain vital. The crustal magnetic field also leads to the expansion of the ionosphere and increase of the area exposed to solar wind. As a result, fluxes from higher altitudes essentially contribute to the flow pattern in Martian tail producing an excess of ion loss rate (∼15%) through the southern part of the tail. Thus, effects of inhibition and enhancement of the escape rate by the crustal magnetic field at Mars operate in competition producing a minor influence on the total ion loss.

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火星地壳磁场对离子逃逸的影响

基于火星大气和挥发性演化（MAVEN）的观测，我们分析了地壳磁场对太阳风与火星电离层直接相互作用驱动的离子损失的作用。地壳磁场会大大削弱离子电离层的运动，并增加返回离子的通量。另一方面，由于具有强地壳场的电离层中的离子密度明显高于具有弱地壳磁场的电离层中的离子密度，因此来自具有地壳源的电离层的净逸出通量仍然至关重要。地壳磁场还导致电离层膨胀，并增加暴露于太阳风的面积。结果，来自更高高度的通量实质上有助于火星尾部的流型，从而导致离子损失率过高（约15％）穿过尾巴的南部。因此，火星上的地壳磁场抑制和提高逃逸速率的效果在竞争中起作用，对总离子流的损失影响很小。