Further Measurements of Thermal Energy Charge Transfer in Support of Ground-Based Astronomy

支持地面天文学的热能电荷转移的进一步测量

• 批准号: 0606960
• 负责人: Daniel Wolf Savin
• 金额: $ 39.57万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0606960&HistoricalAwards=false
• 关键词: Further; Measurements; Thermal; Energy; Charge

AWARD NO: AST-0606960PI: Daniel SavinINSTITUTION: Columbia UniversityTITLE: Further Measurements of Thermal Energy ChargeTransfer in Support of Ground-Based AstronomyABSTRACTThis research is a continuation of an ongoing laboratory study of thermal energycharge transfer among atoms and ions of astrophysical interest. It has long been knownthat thermal energy charge transfer plays an important role in determining the ionizationstructure, thermal structure, emission spectrum and absorption spectrum for a range ofcosmic plasmas. These include photoionized gas found in planetary nebulae, H II regions,Wolf-Rayet nebulae, luminous blue variable nebulae, Lyman alpha clouds, and theintergalactic medium; shocks in supernova remnants and Herbig-Haro objects; andprimordial gas clouds during the epoch of protogalaxy and first star formation.Unfortunately, many theoretical calculations carried out during the past 25 years inresponse to the demand for reliable thermal energy charge transfer data are reliable toonly a factor of 3-10. And while the latest state-of-the-art calculations are expected to bemore reliable, such efforts are less common and can still be off by a factor of 3 when notbenchmarked against experiments. However, few laboratory measurements exist despitethe demand from the community.To address this need, an ongoing series of laboratory measurements of thermal energycharge transfer will be continued using the Oak Ridge National Laboratory ion-atommerged-beams apparatus. Here, measurements will be made of the thermal energy chargetransfer of C2+, O+, O2+, Se3+, and Kr2+. Reliable charge transfer data for thecosmically abundant C2+, O+, and O2+ are needed for modeling planetary nebulae and HII regions as well as shocks in supernovae remnants and Herbig-Harrow objects. Data forSe3+ and Kr2+ are needed to analyze planetary nebula spectra in order to study bothnucleosynthesis via the slow neutron capture process and convective dredge-up in theplanetary nebula progenitor stars. These results will be used to produce rate coefficientswith an estimated accuracy of * 20% and will provide fits for plasma modeling. Moderncharge transfer theory will also be benchmarked against these results. Finally, thelaboratory apparatus will be modified so that the metastable fraction in the ion beams canbe measured and controlled. For beams with a significant metastable fraction, this willallow the extraction of absolute cross sections for both the ground state and metastableions in the beam. This new capability will further increase the uniqueness of the OakRidge National Laboratory ion-atom merged-beams apparatus.The training and professional preparation of a graduate student will be supported. Thisstudent will carry out a large portion of the project in partial fulfillment of therequirements for the degree of Doctor of Philosophy. The results of this research will bepresented via seminars and colloquia to colleagues in academia, government, andindustry. Reports at national and international conferences will be given and published inthe appropriate journals. In addition, this work will further enhance the Columbia/OakRidge National Laboratory infrastructure for research and education. Prof. Gary Ferlandat the University of Kentucky will input the new rate coefficients into CLOUDY which isone of the most commonly used codes for modeling photoionized gas.

奖项编号：AST-0606960PI：丹尼尔·萨文机构：哥伦比亚大学标题：支持地面天文学的热能电荷转移的进一步测量摘要这项研究是正在进行的天体物理原子和离子之间热能电荷转移实验室研究的延续。人们早就知道热能电荷转移在确定一系列宇宙等离子体的电离结构、热结构、发射光谱和吸收光谱方面起着重要作用。这些包括在行星状星云、H II 区、沃尔夫-拉叶星云、发光蓝变星云、莱曼阿尔法云和星系间介质中发现的光电离气体；超新星遗迹和赫比格-哈罗天体的冲击；不幸的是，过去25年中为满足可靠热能电荷转移数据的需求而进行的许多理论计算的可靠性只有3-10倍。虽然最新的最先进的计算预计会更加可靠，但这种努力并不常见，并且在不进行实验基准测试时仍然可能会出现 3 倍的偏差。然而，尽管社区有需求，但实验室测量却很少。为了满足这一需求，将使用橡树岭国家实验室离子雾化束设备继续进行一系列正在进行的热能电荷转移实验室测量。此处，将测量 C2+、O+、O2+、Se3+ 和 Kr2+ 的热能电荷转移。行星状星云和 HII 区域以及超新星遗迹和赫比格-哈罗天体的激波建模需要宇宙中丰富的 C2+、O+ 和 O2+ 的可靠电荷转移数据。需要 Se3+ 和 Kr2+ 的数据来分析行星状星云光谱，以便研究通过慢中子捕获过程进行的核合成和行星状星云祖星中的对流挖掘。这些结果将用于生成估计精度为 * 20% 的速率系数，并将为等离子体建模提供拟合。现代电荷转移理论也将以这些结果为基准。最后，将对实验室设备进行修改，以便可以测量和控制离子束中的亚稳态部分。对于具有显着亚稳态分数的梁，这将允许提取梁中基态和亚稳态的绝对横截面。这一新功能将进一步增强橡树岭国家实验室离子原子合并束装置的独特性。研究生的培训和专业准备将得到支持。该学生将完成该项目的大部分内容，部分满足哲学博士学位的要求。这项研究的结果将通过研讨会和座谈会的形式向学术界、政府和工业界的同事展示。国内和国际会议上的报告将在适当的期刊上发表并发表。此外，这项工作将进一步加强哥伦比亚/橡树岭国家实验室的研究和教育基础设施。肯塔基大学的 Gary Ferlandat 教授将把新的速率系数输入到 CLOUDY 中，CLOUDY 是光离子化气体建模最常用的代码之一。