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Physics of Thermal Cavitons

热空子物理学

基本信息

批准号：
12680482
负责人：
TANAKA Takao
金额：
$ 1.86万
依托单位：
TOKAI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12680482/
关键词：
Thermal Cavitons Ionospheric Plasma Ionospheric Modification Experiment Ohmic Heating of Plasmas Transport Phenomena of Plasmas Plasmas turbulence Strong Ion Turbulence Density Bubbles

项目摘要

Physics of thermal cavitons has been investigated experimentally and theoretically in this research project.The ionosphere can be considered a natural plasma laboratory of great size with no boundaries and an execllent plasma confinement. During ionospheric modification experiments with "long-time, high-power high-frequency (HF) radio wave heating, large-scale (over a few tens of" kilometers) density depletions (nearly 50% density modification) have been observed. Basic processes of this phenomenon can be understood in terms of the Ohmic heating of the plasma "near the HF reflection layer and the subsequent plasma expulsion from this layer. As a result, " these density depletions are dubbed 'thermal cavitons'.The results of recent ionospheric modification experiments performed at Arecibo, Puerto Rico, have revealed that 1)the increase in the electron temperature near the HF reflection layer is "roughly 5 times the initial one, 2) radar observations suggest the existence of strong ion" "turbulence inside thermal cavitons, and 3) thermal cavitons can interact with naturally" generated density bubbles.The size of a thermal caviton sometimes appears too large for the electromagnetic energy "injected into the ionosphere. In order to solve this problem, a new transport model has been" "introduced, in which the self-focusing of the injected em wave due to an initial weak density" cavity in a background plasma is phonomenologically imposed. Numerical analysis of the model equations appear to indicate that we are on the right track.Some laboratory experiments have been performed to investigate the effects of short-time scale plasma turbulence on thermal cavitons.

本研究从实验和理论两个方面对热空穴物理进行了研究，电离层可以看作是一个大尺度的自然等离子体实验室，没有边界，具有良好的等离子体约束。在用“长时间、高功率高频（HF）无线电波加热”的电离层修改实验中，观察到了大规模（超过几十公里）的密度耗尽（近50%的密度修改）。这种现象的基本过程可以理解为高频反射层附近等离子体的欧姆加热以及随后等离子体从该层中排出。最近在波多黎各的阿雷西博进行的电离层修改实验的结果表明，1）HF反射层附近的电子温度增加“大约是初始温度的5倍，2）雷达观测表明热空穴内存在强离子“湍流，热空泡可以与自然产生的密度泡相互作用，有时热空泡的尺寸对于注入电离层的电磁能量来说显得太大。为了解决这一问题，本文引入了一个新的输运模型，该模型从现象学的角度考虑了背景等离子体中初始弱密度腔对注入电磁波的自聚焦作用。对模型方程的数值分析表明，我们的研究方向是正确的。我们在实验室进行了一些实验，研究了短时尺度等离子体湍流对热空穴的影响。