CAREER: Experimental Research on the Runaway Breakdown of Air During Thunderstorms

这个CAREER项目包括观察雷暴中的x射线、伽马射线和高能电子，并在实验室实验中研究雷暴条件下空气的失控分解。失控击穿是指高能电子在强电场中产生雪崩，产生x射线、伽马射线和二次电离，并将大量电荷传输到很远的地方的过程。当电子在强电场中加速所获得的能量超过碰撞所损失的能量时，这一过程就会发生。它可能在雷暴中的闪电起始和大规模电荷输运中发挥作用，也可以解释雷暴中的x射线发射和雷暴上方高层大气中的瞬态发光事件（喷流和喷流）。该项目的目标是证明失控击穿是否会在大气中发生，测试目前的机制模型，了解失控击穿在雷暴现象中的重要性，并使实验科学研究成为每个学生正常课程的一部分。为实现上述目标，本项目主要包括以下工作：设计和建造用于x射线和伽马射线发射的敏感探测器，作为高级物理实验课程的一部分。2. 与盖恩斯维尔佛罗里达大学闪电研究实验室合作，观察与触发闪电有关的x射线、伽马射线和高能电子。进行实验室实验，在强电场中加速电子，以研究失控的雪崩；将这项工作整合到本科物理实验室中。该项目将提供空气中失控电子过程重要性的第一个直接证据，有助于理解雷暴，并为学生提供大气物理仪器开发和研究的机会。

This CAREER project consists of observing x-rays, gamma rays, and energetic electrons from thunderstorms and in laboratory experiments to study the runaway breakdown of air in thunderstorm conditions. Runaway breakdown is a process in which an avalanche of high-energy electrons develops in a strong electric field, producing x-rays, gamma rays, and secondary ionization, and transporting large quantities of charge great distances. This process can occur when the energy gained by an electron accelerating in a strong electric field exceeds the energy lost by collisions. It may play a part in lightning initiation and large-scale charge transport in thunderstorms, as well as in explaining x-ray emissions from storms and transient luminous events (sprites and jets) in the high atmosphere above thunderstorms. The goals of the project are to demonstrate whether runaway breakdown occurs in the atmosphere, to test current models of the mechanism, to understand the importance of runaway breakdown in thunderstorm phenomena, and to make experimental scientific research part of every student's normal curriculum. To achieve the goals, the project includes the following work:1. Design and construction of sensitive detectors for x-ray and gamma ray emissions, as part of a senior physics laboratory course. 2. Observing x-rays, gamma rays, and energetic electrons associated with triggered lightning in collaboration with the Lightning Research Laboratory of the University of Florida, Gainesville.3. Conducting laboratory experiments with accelerating electrons in strong electric fields to investigate runaway avalanche; integrating the work into undergraduate physics labs.The project will provide the first direct evidence of the importance of the runaway electron process in air, contribute to the understanding of thunderstorms, and provide students with opportunities for instrument development and research in atmospheric physics.