Development of an Integrated View of Plasma Instability Processes in the Lower Ionosphere

地球的电离层是中性气体和带电粒子的混合物。电离层通常是分层的，根据最常吸收的辐射的波长来划分。e区从90-150公里延伸，通过x射线和紫外线辐射电离。f区（150-600公里）被极紫外辐射电离。虽然波浪和扰动（“结构”）发生在整个电离层介质（“等离子体”），但研究通常集中在；E层或F层部分由于实验和理论的限制；技术工作。因此，电离层等离子体结构过程的统一观点的发展仍然不完整。这一提议将通过(1)发展一个统一的等离子体不稳定性理论来填补这一空白，该理论适用于广泛的海拔范围，包括以前未探索的E和F区峰之间的过渡谷区；(2)用常规接收来自广泛海拔范围的回波的雷达观测谷区。拟议的研究利用美国国家科学基金会的资产和知识综合，从根本上为等离子体不稳定性和结构理论做出贡献。这些知识与通信和导航行业相关，因此也与社会相关。整合的理论将被纳入UAF等离子体物理课程中，这些课程目前主要依赖于原始期刊出版物，而不是教学模块。该提案还将资助一名新的博士生。提出的研究将解决不稳定因素和稳定因素的什么组合导致等离子体扰动振幅增加并产生电离层结构的基本问题。实际的提案活动由三个相互关联的项目组成：1。发展电离层等离子体不稳定性的统一理论，包括任意高度和传播的热、惯性和梯度效应；2. 任意高度非等温条件下等离子体失稳所需临界梯度长度的确定3. 利用SuperDARN和ISR数据分析以前未勘探的过渡“山谷”区域（~150 km）的小尺度不规则现象。这些测量结果有望为一个理论提供支持，该理论认为，在小尺度上，等离子体在山谷中不稳定需要很强的梯度。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Earth's ionosphere is a mixture of neutral gas and charged particles. The ionosphere is generally broken out by layers, defined according to the wavelengths of the radiation most commonly absorbed. The E-region extends from 90-150 km and is ionized through X-ray and ultraviolet radiation. The F-region (150-600 km) is ionized by extreme ultraviolet radiation. Although waves and disturbances ("structuring") occur throughout the ionospheric medium ("plasma"), studies often focus on; either the E or F layer owing in part to limitations of experimental and theoretical; techniques employed. As a result, development of a unified view of ionospheric plasma structuring processes remains incomplete. This proposal will fill this gap by (1) developing a unified plasma instability theory applicable in the broad range of altitudes including the previously unexplored transitional valley region between the E and F region peaks and (2) observing the valley region with a radar that routinely receives returns from a broad range of altitudes. The proposed research leverages NSF assets and knowledge synthesis to contribute fundamentally to the theory of plasma instability and structuring. This knowledge is relevant to the communication and navigation industries, and therefore to society. The integrated theory will be incorporated into UAF plasma physics classes, that currently rely primarily on original journal publications rather than teaching modules. The proposal will also fund a new Ph.D. student.The proposed research will address the fundamental question of what combination of destabilizing and stabilizing factors results in the plasma perturbations growing in amplitude and producing ionospheric structures. The actual proposal activity consists of three interconnected projects: 1. Development a unified theory of ionospheric plasma instabilities including thermal, inertial, and gradient effects for arbitrary altitude and propagation; 2. Determination of the critical gradient length required to destabilize plasma in the non-isothermal case for arbitrary altitude; 3. Analysis of SuperDARN and ISR data to investigate small-scale irregularity occurrence in the previously unexplored transitional "valley" region (~150 km). These measurements are expected to provide support for a theory that strong gradients are required to make plasma unstable in the valley at small scales.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.