Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere

The electron population in the solar wind plasma can be described with three different components: a core, a halo, and a magnetic field aligned strahl. The electron quasi-thermal noise (QTN) is investigated by using an electron population model consisting of a core with a Maxwellian distribution and...

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Main Authors: Yi-Lun Li, Ling Chen, De-Jin Wu
Format: Article
Language:English
Published: IOP Publishing 2024-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/ad85d6
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author Yi-Lun Li
Ling Chen
De-Jin Wu
author_facet Yi-Lun Li
Ling Chen
De-Jin Wu
author_sort Yi-Lun Li
collection DOAJ
description The electron population in the solar wind plasma can be described with three different components: a core, a halo, and a magnetic field aligned strahl. The electron quasi-thermal noise (QTN) is investigated by using an electron population model consisting of a core with a Maxwellian distribution and a halo with a kappa distribution, based on the empirical equations for electron density and temperature and the index for the kappa halo. The power spectra of the electron QTN are calculated at different heliocentric radial distances from 10 to 200 R _s . The dependence of the QTN spectrum and effective Debye length on model parameters, including the ratio of the halo to the core for the density and temperature, the kappa index, and the antenna length, is further discussed. The results show that the electron QTN spectrum consists of a plateau in the low-frequency band f < f _pt , a peak at the total plasma frequency f _pt , and a rapidly decreasing part in the high-frequency band f > f _pt . The QTN peak and plateau level continuously decrease as the radial distance increases, with the peak’s shape changing due to the variation of the kappa index. Although the model parameters are variable, the QTN plateau level presents less than an order of change with these parameters changing greatly, and only a monotonic change of the plateau is shown when the parameters are close to the practical situation. The results can provide a reference for future deep-space exploration in the inner heliosphere, and also for the design of detectors.
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spelling doaj-art-5f52d08ec76244a3b7e94bf7689aaae42024-11-22T07:24:01ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01976219210.3847/1538-4357/ad85d6Radial Distribution of Electron Quasi-thermal Noise in the Inner HeliosphereYi-Lun Li0https://orcid.org/0009-0002-5942-752XLing Chen1https://orcid.org/0000-0001-8058-2765De-Jin Wu2https://orcid.org/0000-0003-2418-5508Key Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences , Nanjing 210023, People's Republic of China ; clvslc214@pmo.ac.cn; School of Astronomy and Space Science, University of Science and Technology of China , Hefei 230026, People's Republic of China; State Key Laboratory of Space Weather, Chinese Academy of Sciences , Beijing 100190, People's Republic of ChinaKey Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences , Nanjing 210023, People's Republic of China ; clvslc214@pmo.ac.cn; State Key Laboratory of Space Weather, Chinese Academy of Sciences , Beijing 100190, People's Republic of China; CAS Center for Excellence in Comparative Planetology , Hefei 230026, People’s Republic of ChinaKey Laboratory of Planetary Sciences, Purple Mountain Observatory, Chinese Academy of Sciences , Nanjing 210023, People's Republic of China ; clvslc214@pmo.ac.cn; CAS Center for Excellence in Comparative Planetology , Hefei 230026, People’s Republic of ChinaThe electron population in the solar wind plasma can be described with three different components: a core, a halo, and a magnetic field aligned strahl. The electron quasi-thermal noise (QTN) is investigated by using an electron population model consisting of a core with a Maxwellian distribution and a halo with a kappa distribution, based on the empirical equations for electron density and temperature and the index for the kappa halo. The power spectra of the electron QTN are calculated at different heliocentric radial distances from 10 to 200 R _s . The dependence of the QTN spectrum and effective Debye length on model parameters, including the ratio of the halo to the core for the density and temperature, the kappa index, and the antenna length, is further discussed. The results show that the electron QTN spectrum consists of a plateau in the low-frequency band f < f _pt , a peak at the total plasma frequency f _pt , and a rapidly decreasing part in the high-frequency band f > f _pt . The QTN peak and plateau level continuously decrease as the radial distance increases, with the peak’s shape changing due to the variation of the kappa index. Although the model parameters are variable, the QTN plateau level presents less than an order of change with these parameters changing greatly, and only a monotonic change of the plateau is shown when the parameters are close to the practical situation. The results can provide a reference for future deep-space exploration in the inner heliosphere, and also for the design of detectors.https://doi.org/10.3847/1538-4357/ad85d6Solar windInterplanetary physicsSpace plasmas
spellingShingle Yi-Lun Li
Ling Chen
De-Jin Wu
Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
The Astrophysical Journal
Solar wind
Interplanetary physics
Space plasmas
title Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
title_full Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
title_fullStr Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
title_full_unstemmed Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
title_short Radial Distribution of Electron Quasi-thermal Noise in the Inner Heliosphere
title_sort radial distribution of electron quasi thermal noise in the inner heliosphere
topic Solar wind
Interplanetary physics
Space plasmas
url https://doi.org/10.3847/1538-4357/ad85d6
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AT dejinwu radialdistributionofelectronquasithermalnoiseintheinnerheliosphere