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

合作研究：通过粒子撞击对 O 和 N2 紫外线 (UV) 截面进行实验室测量，以遥感热层 O/N2 变化

• 批准号: 1658813
• 负责人: Joseph Evans
• 金额: $ 9万
• 依托单位: Computational Physics Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1658813&HistoricalAwards=false
• 关键词: Collaborative; Research; Laboratory; Measurements; N2

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.

该奖项将通过瞄准实验室目标来提高紫外线遥感的能力，该目标的重点是确定地球日光遥感观测所需的紫外线发射截面（Qem）。在日光中，O/N2 密度比的独特特征来自卫星紫外线观测，来自测量 OI (135.6 nm (3P2-5So2)) 和 N2 Lyman-Birge-Hopfield (LBH) 波段的强度比(125-250 nm) 发射。 O/N2 密度比是了解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尚未测量。这两个总发射截面中的每一个都是直接激发发射截面和级联截面的总和。级联截面约占总截面的30-50%。由于柱密度比 O/N2 在空间天气研究中起着关键作用，因此 OI 和 LBH 排放的 Qem 的准确绝对测量对于解释热层成分 (O/N2) 变化的幅度和时间演化至关重要。同样，极光遥感所需的高能质子 (H+) 和 H 原子撞击 Qem 实验室测量也是不够的。其主要焦点有两个。这项工作将支持一名研究生 (UCF) 和一名本科生。该奖励项目的第一个目标是测量 125 nm 至 250 nm 之间 LBH 波段的绝对直接电子、H+ 和 H 碰撞 Qem和 OI (3P2--5So2) 在 135.6 nm 处，通过电子撞击将其发射阈值提高到 500 eV，通过 H+ 和 H 原子撞击将其发射阈值提高到 50 keV，使用团队的实验设施位于加州理工学院/喷气推进实验室。 该团队还将在科罗拉多大学测量来自这些上游州的级联过程。 中佛罗里达大学 (UCF) 和计算物理公司 (CPI) 的航空学家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。

项目成果

The UV Spectrum of the Lyman‐Birge‐Hopfield Band System of N 2 Induced by Cascading from Electron Impact

电子撞击级联引起的N 2 Lyman-Birge-Hopfield能带系统的紫外光谱

• DOI: 10.1029/2019ja027546
• 发表时间: 2020-03
• 期刊: Journal of Geophysical Research: Space Physics
• 作者: Ajello, Joseph M.;Evans, J. Scott;Veibell, Victoir;Malone, Charles P.;Holsclaw, Greg M.;Hoskins, Alan C.;Lee, Rena A.;McClintock, William E.;Aryal, Saurav;Eastes, Richard W.;et al
• 通讯作者: et al