文章基本信息

标题：Plasma frequency demand for mode conversion processes from slow Z-mode to LO-mode waves in an inhomogeneous plasma
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作者：Mohammad Javad Kalaee ; Yuto Katoh
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2020
卷号：72
期号：1
页码：1-7
DOI：10.1186/s40623-020-01226-x
出版社：Springer Verlag
摘要：The mode conversion process responsible for radio wave generation has been studied for several decades; however, the properties of the condition required for an efcient conversion process are still unknown.The aim of this study is to determine the value of plasma frequency required for an efcient mode conversion process from slow Z-mode to left-hand ordinary (LO)-mode waves in the matching cases, where the two branches of the dispersion relation of the two modes are perfectly connected.We derive the dispersion relations for electromagnetic wave propagation in an inhomogeneous plasma considering Snell’s law and investigated them in detail.We quantify the minimum variation of plasma frequency required for the efcient mode conversion process, which we call “the plasma frequency demand.” We show that the condition required for the efcient mode conversion can be satisfed by waves propagating frst toward the high-density region and then returning toward the low-density region before reaching the region where the wave frequency matches the cutof frequency; therefore, a large inhomogeneity is not always required.We show that the angle between the background magnetic feld and the density gradient has a signifcant efect on the plasma frequency demand.
关键词：Inhomogeneity; Mode conversion; Z-mode; LO-mode; Snell’s law