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首页> 外文期刊>Astrobiology >Oxidant Enhancement in Martian Dust Devils and Storms: Storm Electric Fields and Electron Dissociative Attachment
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Oxidant Enhancement in Martian Dust Devils and Storms: Storm Electric Fields and Electron Dissociative Attachment

机译：火星尘埃和风暴中氧化剂的增强作用：风暴电场和电子离解性附着

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摘要

Laboratory studies, numerical simulations, and desert field tests indicate that aeolian dust transport can generate atmospheric electricity via contact electrification or "triboelectricity." In convective structures such as dust devils and dust storms, grain stratification leads to macroscopic charge separations and gives rise to an overall electric dipole moment in the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous numerical simulations indicate that these storm electric fields on Mars can approach the ambient breakdown field strength of ～ 25 kV/m. In terrestrial dust phenomena, potentials ranging from ～ 20 to 160 kV/m have been directly measured. The large electrostatic fields predicted in martian dust devils and storms can energize electrons in the low pressure mar-tian atmosphere to values exceeding the electron dissociative attachment energy of both CO_2 and H_2O, which results in the formation of the new chemical products CO/O~- and OH/H~-, respectively. Using a collisional plasma physics model, we present calculations of the CO/O~- and OH/H~- reaction and production rates. We demonstrate that these rates vary geometrically with the ambient electric field, with substantial production of dissociative products when fields approach the breakdown value of ～ 25 kV/m. The dissociation of H_2O into OH/H~- provides a key ingredient for the generation of oxidants; thus electrically charged dust may significantly impact the habitability of Mars.
机译：实验室研究，数值模拟和沙漠野外试验表明，风尘运输可以通过接触带电或“摩擦电”产生大气电力。在对流结构中，例如沙尘暴和沙尘暴，颗粒分层会导致宏观的电荷分离，并在风沙特征中产生整体的电偶极矩，其性质与陆地雷暴中产生的偶极电场相似。先前的数值模拟表明，火星上的这些风暴电场可以达到〜25 kV / m的环境击穿场强。在地面尘埃现象中，已经直接测量了〜20至160 kV / m的电位。火星尘埃和暴风雨中预测到的巨大静电场可以使低压火星大气中的电子激发到超过CO_2和H_2O的电子离解附着能的值，从而导致形成新的化学产物CO / O〜 -和OH / H〜-。利用碰撞等离子体物理模型，我们给出了CO / O〜-和OH / H〜-反应和产率的计算。我们证明了这些速率随环境电场的变化而发生几何变化，当电场接近击穿值约25 kV / m时，会产生大量的离解产物。 H_2O分解成OH / H〜-提供了产生氧化剂的关键成分；因此带电的灰尘可能会严重影响火星的可居住性。

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