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首页> 外文期刊>Earth, planets and space: EPS >Incoherent radar spectra in the auroral ionosphere in the presence of a large electric field: The effect of 0(+)-0(+) Coulomb collisions
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Incoherent radar spectra in the auroral ionosphere in the presence of a large electric field: The effect of 0(+)-0(+) Coulomb collisions

机译：存在大电场的极光电离层中非相干雷达光谱：0（+）-0（+）库仑碰撞的影响

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摘要

We have used Monte Carlo simulations of O+ velocity distributions in the high latitude F- region to improve the calculation of incoherent radar spectra in auroral ionosphere. The Monte Carlo simulation includes ion-neutral, O+-O collisions (resonant charge exchange and polarization interaction) as well as O+-O+ Coulomb self-collisions. At high altitudes, atomic oxygen O and atomic oxygen ion 01 dominate the composition of the auroral ionosphere and consequently, the influence of O+-O+ Coulomb collisions becomes significant. In this study we consider the effect of O+-O+ Coulomb collisions on the incoherent radar spectra in the presence of large electric field (100 m Vm(-1)). As altitude increases (i.e. the ion-to-neutral density ratio increases) the role of O+-O+ Coulomb self-collisions becomes significant, therefore, the one-dimensional, 1-D, O+ ion velocity distribution function becomes more Maxwellian and the features of the radar spectrum corresponding to non-Maxwellian ion velocity distribution (e.g. baby bottle and triple hump shapes) evolve to Maxwellian ion velocity distribution (single and double hump shapes). Therefore, O+-O+ Coulomb self-collisions act to isotropize the 1-D O+ velocity distribution by transferring thermal energy from the perpendicular direction to the parallel direction, however the convection electric field acts to drive the O+ ions away from equilibrium and consequently, non-Maxwellian O+ ion velocity distributions appeared. Therefore, neglecting O+-O+ Coulomb self-collisions overestimates the effect of convection electric field.
机译：我们已使用高纬度F-区域中O +速度分布的蒙特卡罗模拟来改进极光电离层中非相干雷达光谱的计算。蒙特卡洛模拟包括离子中性，O + -O碰撞（共振电荷交换和极化相互作用）以及O + -O +库仑自碰撞。在高海拔，原子氧O和原子氧离子01在极光电离层的组成中占主导地位，因此，O + -O +库仑碰撞的影响变得显着。在这项研究中，我们考虑了在存在大电场（100 m Vm（-1））的情况下O + -O +库仑碰撞对非相干雷达光谱的影响。随着高度的增加（即离子对中性密度比的增加），O + -O +库仑自碰撞的作用变得很明显，因此，一维，一维，O +离子速度分布函数变得更接近麦克斯韦态，并且其特征对应于非麦克斯韦离子速度分布（例如，奶瓶和三峰形状）的雷达频谱的总和演变为麦克斯韦离子速度分布（单峰和双峰形状）。因此，O + -O +库仑自碰撞通过将热能从垂直方向传递到平行方向来使一维O +速度分布各向同性，但是对流电场的作用是使O +离子远离平衡，因此，出现麦克斯韦O +离子速度分布。因此，忽略O + -O +库仑自碰撞会高估对流电场的影响。

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