Collaborative Research: Laboratory Measurements of O and N2 Ultraviolet (UV) Cross Sections by Particle Impact for Remote Sensing of Thermosphere O/N2 Variation

该奖项将通过瞄准实验室目标来提高紫外线遥感的能力，实验室目标的中心是确定遥感观测地球日光所需的紫外线发射截面(QEM)。在白天，来自卫星紫外线观测的O/N2密度比的一个独特特征来自于测量OI(135.6 nm(3P2-5SO2))和N2Lyman-Birge-Hopfield(LBH)波段(125250 Nm)发射的强度比。O/N_2密度比是理解在所有地磁条件下全球范围内电离层和热层组成变化的关键。然而，这两组光谱跃迁的总发射截面还没有测量到。这两个总发射截面中的每一个都是一个直接激发发射截面和一个级联截面之和。叶栅截面约占总截面的30%-50%。由于柱密度比O/N_2在空间天气研究中起着关键作用，对O_I和LBH排放的QEM的精确绝对测量对于解释热层组成(O/N_2)变化的大小和时间演变都是至关重要的。同样，极光遥感所需的高能质子(H+)和氢原子撞击QEM的实验室测量也不充分。这件事的主要关注点有两个。获奖项目的第一个目标将是利用该团队位于加州理工/喷气推进实验室的实验设备，测量从电子碰撞发射阈值到500eV，到50keV的绝对直接电子、H+和H影响量子电荷量，从125250 nm到250 nm之间的LBH波段和135.6 nm处的OI(3P2-5SO2)。该研究小组还将在科罗拉多大学测量来自这些上州的级联过程。中佛罗里达大学(UCF)和计算物理公司(CPI)的宇航员将使用对美国太空任务至关重要的两个经典粒子传输代码：Auric和Glow对遥感数据进行建模。

This award would advance the capabilities for UV remote sensing by targeting a laboratory goal, which is centered on the determination of the UV emission cross sections (Qem) needed for remote sensing observations of the Earth's dayglow. In the dayglow a unique signature of the O/N2 density ratio, from satellite-based UV observations, comes from measuring the intensity ratio of the OI (135.6 nm (3P2- 5So2)) and N2 Lyman-Birge-Hopfield (LBH) band (125-250 nm) emissions. This O/N2 density ratio is a key to understanding the ionosphere and thermosphere composition changes on a global scale under all geomagnetic conditions. However, the total emission cross sections of these two sets of spectral transitions have not been measured. Each of these two total emission cross sections is a sum of a direct excitation emission cross section and a cascade cross section. The cascade cross sections are about 30-50% of the total cross section. As the column density ratio O/N2 plays a key role in Space Weather studies, accurate absolute measurements of Qem for both OI and LBH emissions are vital for explaining both the magnitude and temporal evolution of thermosphere composition (O/N2) changes. Similarly, the energetic proton (H+) and H atom impact laboratory measurements of Qem needed for auroral remote sensing are inadequate. The main focus of this is two-fold. One graduate student (UCF) and one undergraduate student would be supported in this effort.The first goal of the award project would be to measure the absolute direct electron, H+, and H impact Qem for both the LBH band between 125 nm to 250 nm and OI (3P2--5So2) at 135.6 nm from their emission thresholds to 500 eV by electron-impact, to 50 keV by H+ and H atom impact, using the team's experimental facilities located at Caltech/JPL. The team would also measure at the University of Colorado the cascade processes from these upper states. Aeronomers at the University of Central Florida (UCF) and Computational Physics Inc. (CPI) would model the remote sensing data using two classic particle transport codes that are paramount to the US space mission: AURIC and GLOW.