{"title":"太阳大气中氢的电离","authors":"J. Chae","doi":"10.5140/JASS.2021.38.2.83","DOIUrl":null,"url":null,"abstract":"The ionization degree of hydrogen is crucial in the physics of the plasma in the\n solar chromosphere. It specifically limits the range of plasma temperatures that can be\n determined from the Hα line. Given that the chromosphere greatly deviates from the local\n thermodynamic equilibrium (LTE) condition, precise determinations of hydrogen ionization\n require the solving of the full set of non-LTE radiative transfer equations throughout\n the atmosphere, which is usually a formidable task. In many cases, it is still necessary\n to obtain a quick estimate of hydrogen ionization without having to solve for the\n non-LTE radiative transfer. Here, we present a simple method to meet this need. We adopt\n the assumption that the photoionizing radiation field changes little over time, even if\n physical conditions change locally. With this assumption, the photoionization rate can\n be obtained from a published atmosphere model and can be used to determine the degree of\n hydrogen ionization when the temperature and electron density are specified. The\n application of our method indicates that in the chromospheric environment, plasma\n features contain more than 10% neutral hydrogen at temperatures lower than 17,000 K but\n less than 1% neutral hydrogen at temperatures higher than 23,000 K, implying that the\n hydrogen temperature determined from the Hα line is physically plausible if it is lower\n than 20,000 K, but may not be real, if it is higher than 25,000 K. We conclude that our\n method can be readily exploited to obtain a quick estimate of hydrogen ionization in\n plasma features in the solar chromosphere.","PeriodicalId":44366,"journal":{"name":"Journal of Astronomy and Space Sciences","volume":"27 1","pages":""},"PeriodicalIF":0.6000,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":"{\"title\":\"Ionization of Hydrogen in the Solar Atmosphere\",\"authors\":\"J. Chae\",\"doi\":\"10.5140/JASS.2021.38.2.83\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"The ionization degree of hydrogen is crucial in the physics of the plasma in the\\n solar chromosphere. It specifically limits the range of plasma temperatures that can be\\n determined from the Hα line. Given that the chromosphere greatly deviates from the local\\n thermodynamic equilibrium (LTE) condition, precise determinations of hydrogen ionization\\n require the solving of the full set of non-LTE radiative transfer equations throughout\\n the atmosphere, which is usually a formidable task. In many cases, it is still necessary\\n to obtain a quick estimate of hydrogen ionization without having to solve for the\\n non-LTE radiative transfer. Here, we present a simple method to meet this need. We adopt\\n the assumption that the photoionizing radiation field changes little over time, even if\\n physical conditions change locally. With this assumption, the photoionization rate can\\n be obtained from a published atmosphere model and can be used to determine the degree of\\n hydrogen ionization when the temperature and electron density are specified. The\\n application of our method indicates that in the chromospheric environment, plasma\\n features contain more than 10% neutral hydrogen at temperatures lower than 17,000 K but\\n less than 1% neutral hydrogen at temperatures higher than 23,000 K, implying that the\\n hydrogen temperature determined from the Hα line is physically plausible if it is lower\\n than 20,000 K, but may not be real, if it is higher than 25,000 K. We conclude that our\\n method can be readily exploited to obtain a quick estimate of hydrogen ionization in\\n plasma features in the solar chromosphere.\",\"PeriodicalId\":44366,\"journal\":{\"name\":\"Journal of Astronomy and Space Sciences\",\"volume\":\"27 1\",\"pages\":\"\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2021-06-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Astronomy and Space Sciences\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.5140/JASS.2021.38.2.83\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q4\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Astronomy and Space Sciences","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.5140/JASS.2021.38.2.83","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
The ionization degree of hydrogen is crucial in the physics of the plasma in the
solar chromosphere. It specifically limits the range of plasma temperatures that can be
determined from the Hα line. Given that the chromosphere greatly deviates from the local
thermodynamic equilibrium (LTE) condition, precise determinations of hydrogen ionization
require the solving of the full set of non-LTE radiative transfer equations throughout
the atmosphere, which is usually a formidable task. In many cases, it is still necessary
to obtain a quick estimate of hydrogen ionization without having to solve for the
non-LTE radiative transfer. Here, we present a simple method to meet this need. We adopt
the assumption that the photoionizing radiation field changes little over time, even if
physical conditions change locally. With this assumption, the photoionization rate can
be obtained from a published atmosphere model and can be used to determine the degree of
hydrogen ionization when the temperature and electron density are specified. The
application of our method indicates that in the chromospheric environment, plasma
features contain more than 10% neutral hydrogen at temperatures lower than 17,000 K but
less than 1% neutral hydrogen at temperatures higher than 23,000 K, implying that the
hydrogen temperature determined from the Hα line is physically plausible if it is lower
than 20,000 K, but may not be real, if it is higher than 25,000 K. We conclude that our
method can be readily exploited to obtain a quick estimate of hydrogen ionization in
plasma features in the solar chromosphere.
期刊介绍:
JASS aims for the promotion of global awareness and understanding of space science and related applications. Unlike other journals that focus either on space science or on space technologies, it intends to bridge the two communities of space science and technologies, by providing opportunities to exchange ideas and viewpoints in a single journal. Topics suitable for publication in JASS include researches in the following fields: space astronomy, solar physics, magnetospheric and ionospheric physics, cosmic ray, space weather, and planetary sciences; space instrumentation, satellite dynamics, geodesy, spacecraft control, and spacecraft navigation. However, the topics covered by JASS are not restricted to those mentioned above as the journal also encourages submission of research results in all other branches related to space science and technologies. Even though JASS was established on the heritage and achievements of the Korean space science community, it is now open to the worldwide community, while maintaining a high standard as a leading international journal. Hence, it solicits papers from the international community with a vision of global collaboration in the fields of space science and technologies.