CEDAR: Evaluating Ion Temperature Anisotropy in the Weakly Collisional F-region Ionosphere

CEDAR：评估弱碰撞 F 区电离层中的离子温度各向异性

• 批准号: 2330254
• 负责人: Lindsay Goodwin
• 金额: $ 39.93万
• 依托单位: New Jersey Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-12-15 至 2026-11-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2330254&HistoricalAwards=false
• 关键词: CEDAR; Evaluating; Ion; Temperature; Anisotropy

The Earth’s ionosphere is the part of the upper atmosphere that has ions, electrons, and neutrals, and is mainly formed by the absorption of the incident solar radiation. The motion of these particles results in collisions and the inverse of the rate at which ions and neutrals collide is often referred to as ion-neutral collision frequency, a widely used parameter in ionospheric physics. This important parameter plays a crucial role in the development of models and simulations critical to space weather and national defense. The direct observations of this collision frequency are lacking due to complexities involved in such measurements, and most of the estimations are based on assumptions. Thus, there is a need to develop methodologies to determine realistic values of ion-neutral frequency. The proposal seeks to use existing high frequency incoherent scatter radars (ISRs) that can probe the upper ionosphere. Development of educational materials and websites for popularizing radio science topics is also envisioned, which will contribute to the training of the next generation in STEM aeras facilitating workforce development. The research team consists of diverse groups with representation from minorities and early-career scientists.At ionospheric altitudes, ion velocity is usually approximated by an isotropic Maxwellian distribution. However, in the presence of moderate to strong electric fields the ion velocity distribution in the weakly-ionized, magnetized F-region ionosphere distorts from a Maxwellian. This is the result of ion-neutral collisions and Resonant Charge Exchange (RCE) between O+ and O, which is the dominant ion-neutral collision type in this region. A consequence of the distortion of the ion velocity distribution is that the ion temperature becomes anisotropic, leading to larger ion temperatures perpendicular to the magnetic field than parallel. To obtain accurate ion temperatures, there is a strong need to develop techniques that provide accurate O+ and O collision cross section. The proposal seeks to address following science questions: (i) what is the O+-O REC collision cross-section, (ii) How do radar measurements of ion temperatures using the resolved O+-O cross-section compare to prior measurements that assume Maxwellian ion velocity distributions, (iii) How does the O+-O RCE collision cross-section and resulting ion temperature anisotropy in the F-region impact higher altitudes through upflows? These science questions will be answered using a Monte-Carlo simulation to compute the ion velocity distributions for a wide range of collisional and plasma parameters. Additionally, data from high-latitude advanced modular incoherent scatter radars will be used.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.

地球的电离层是具有离子，电子和中性物质的高层大气层的一部分，并且主要由入射太阳辐射的抽象形成。这些颗粒的运动导致碰撞和离子和中性碰撞的速率的倒数，通常称为离子中性碰撞频率，这是电离层物理学中广泛使用的参数。这个重要的参数在模型和模拟的开发中起着至关重要的作用，对太空天气和国防至关重要。由于此类测量中涉及的复杂性，缺乏对这种碰撞频率的直接观察，并且大多数估计是基于假设。这是需要开发方法来确定离子中性频率的现实值的方法。该提案试图使用可以探测上部电离层的现有高频散射雷达（ISR）。还设想了开发用于普及无线电科学主题的网站的开发，这将有助于培训支持劳动力发展的STEM AERAS中的下一代。研究小组由潜水员组成，这些群体来自少数民族和早期科学家的代表。在电离层高度，离子速度通常通过各向同性的麦克斯韦分布近似。但是，在存在中度至强场的情况下，弱离子化的，磁化的F区电离层与麦克斯韦层扭曲的离子速度分布。这是O+和O之间的离子中性碰撞和共振电荷交换（RCE）的结果，这是该区域中主要的离子中性碰撞类型。离子速度分布失真的结果是离子温度变为各向异性，导致垂直于磁场的离子温度较大，而不是平行。为了获得准确的离子温度，非常需要开发提供准确的O+和O碰撞横截面的技术。 The proposal seeks to address following science questions: (i) what is the O+-O REC collision cross-section, (ii) How do radar measurements of ion temperatures using the resolved O+-O cross-section compare to prior measurements that assume Maxwellian ion velocity distributions, (iii) How does the O+-O RCE collision cross-section and resulting ion temperature anisotropy in the F-region Impact higher altitudes通过上流？这些科学问题将使用蒙特卡洛模拟回答，以计算各种碰撞和等离子体参数的离子速度分布。此外，将使用来自高纬度高级模块化不一致的散射雷达的数据。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响评估标准，被视为通过评估而被视为珍贵的支持。