Magnetochemistry

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24 pages, 770 KiB

Open AccessArticle

Study of Solar Energetic Particle Events with Ulysses, ACE Observations and Numerical Simulations

by Lele Lian, Gang Qin, Yang Wang and Shuwang Cui

Magnetochemistry 2023, 9(4), 96; https://doi.org/10.3390/magnetochemistry9040096 - 30 Mar 2023

Viewed by 1247

Abstract

We study the latitudinal extent of the near-relativistic electron events of 10 June 2000 and 26 December 2001, observed by both Ulysses and ACE. From the observations it is shown that the intensity of ACE was quite different from that of Ulysses. Through [...] Read more.

We study the latitudinal extent of the near-relativistic electron events of 10 June 2000 and 26 December 2001, observed by both Ulysses and ACE. From the observations it is shown that the intensity of ACE was quite different from that of Ulysses. Through the numerical simulations, we obtain the SEPs time-intensity profiles, which generally fit well to the observations. To compare the observations we obtained the best fit parameters for the simulations. We suggest that the transport effects, especially the perpendicular diffusion effect, can cause the difference between the intensity profiles of ACE and Ulysses, which is dominated by particle transport at a large radial distance and high-latitude when a spacecraft has poor magnetic connection to the particle source. Furthermore, we present the particle source from the best fit parameters to show that the start and peak times of the particle sources are between the onset and max times of a flare in all the energy channels. Moreover, we propose models for the peak intensity and half width of the particle source, and the time interval from the flare onset to the particle source peak time. We show that the models generally agree with the best fit parameters. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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17 pages, 767 KiB

Open AccessArticle

Modeling of the Magnetic Turbulence Level and Source Function of Particle Injection from Multiple SEP Events

by Lele Lian, Gang Qin, Shuangshuang Wu, Yang Wang and Shuwang Cui

Magnetochemistry 2023, 9(4), 91; https://doi.org/10.3390/magnetochemistry9040091 - 27 Mar 2023

Cited by 1 | Viewed by 1115

Abstract

Solar energetic particles (SEPs) are produced by solar eruptions and are harmful to spacecraft and astronauts. The four source function parameters of particle injection for SEP events and the magnetic turbulence level can be collectively referred to as key parameters. We reproduce the [...] Read more.

Solar energetic particles (SEPs) are produced by solar eruptions and are harmful to spacecraft and astronauts. The four source function parameters of particle injection for SEP events and the magnetic turbulence level can be collectively referred to as key parameters. We reproduce the electron intensity-time profiles with simulations for five SEP events observed by multispacecraft such as ACE, STEREO-A, and STEREO-B, so we can obtain the five fitted key parameters for each of the events. We analyze the relationship among the five fitted key parameters, and also the relationship between these parameters and the observed event features. Thus, the model of key parameters are established. Next, we simulate another 12 SEP events with the key parameters model. Though the predicted electron intensity-time profiles do not fit the observed ones well, the peak flux and event-integrated fluence can be predicted accurately. Therefore, the model can be used to estimate the radiation hazards. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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11 pages, 2218 KiB

Open AccessArticle

The Relationship between Solar Wind Charge Exchange Soft X-ray Emission and the Tangent Direction of Magnetopause in an XMM–Newton Event

by Yingjie Zhang, Tianran Sun, Jennifer A. Carter, Wenhao Liu, Steve Sembay, Li Ji and Chi Wang

Magnetochemistry 2023, 9(4), 88; https://doi.org/10.3390/magnetochemistry9040088 - 24 Mar 2023

Cited by 2 | Viewed by 1174

Abstract

With the advent of soft X-ray imaging enabling global magnetopause detection, it is critical to use reconstruction techniques to derive the 3-dimensional magnetopause location from 2-dimensional X-ray images. One of the important assumptions adopted by most techniques is that the direction with maximum [...] Read more.

With the advent of soft X-ray imaging enabling global magnetopause detection, it is critical to use reconstruction techniques to derive the 3-dimensional magnetopause location from 2-dimensional X-ray images. One of the important assumptions adopted by most techniques is that the direction with maximum soft X-ray emission is the tangent direction of the magnetopause, which has not been validated in observation so far. This paper analyzes a magnetospheric solar wind charge exchange (SWCX) soft X-ray event detected by XMM–Newton during relatively stable solar wind and geomagnetic conditions. The tangent direction of the magnetopause is determined by an empirical magnetopause model. Observation results show that the maximum SWCX soft X-ray intensity gradient tends to be the tangent of the magnetopause’s inner boundary, while the maximum SWCX soft X-ray intensity tends to be the tangent of the magnetopause’s outer boundary. Therefore, it is credible to use the assumption that the tangent direction of the magnetopause is the maximum SWCX soft X-ray intensity or its gradient when reconstructing the 3-dimensional magnetopause location. In addition, since these two maxima tend to be the inner and outer boundaries of the magnetopause, the thickness of magnetopause can also be revealed by soft X-ray imaging. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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14 pages, 3043 KiB

Open AccessArticle

The Phase Space Density Evolution of Radiation Belt Electrons under the Action of Solar Wind Dynamic Pressure

by Peng Hu, Haimeng Li, Zhihai Ouyang, Rongxin Tang, Liangjin Song, An Yuan, Bopu Feng, Yangyang Wang and Wenqian Zou

Magnetochemistry 2023, 9(2), 52; https://doi.org/10.3390/magnetochemistry9020052 - 09 Feb 2023

Viewed by 1090

Abstract

Earth’s radiation belt and ring current are donut-shaped regions of energetic and relativistic particles, trapped by the geomagnetic field. The strengthened solar wind dynamic pressure (P_dyn) can alter the structure of the geomagnetic field, which can bring about the dynamic variation [...] Read more.

Earth’s radiation belt and ring current are donut-shaped regions of energetic and relativistic particles, trapped by the geomagnetic field. The strengthened solar wind dynamic pressure (P_dyn) can alter the structure of the geomagnetic field, which can bring about the dynamic variation of radiation belt and ring current. In the study, we firstly utilize group test particle simulations to investigate the phase space density (PSD) under the varying geomagnetic field modeled by the International Geomagnetic Reference Field (IGRF) and T96 magnetic field models from 19 December 2015 to 20 December 2015. Combining the observation of the Van Allen Probe, we find that the PSD of outer radiation belt electrons evolves towards different states under different levels of P_dyn. In the first stage, the P_dyn (~7.94 nPa) results in the obvious rise of electron anisotropy. In the second stage, there is a significant reduction in PSD for energetic electrons at all energy levels and pitch angles under the action of intense P_dyn (~22 nPa), which suggests that the magnetopause shadowing and outward radial diffusion play important roles in the second process. The result of the study can help us further understand the dynamic evolution of the radiation belt and ring current during a period of geomagnetic disturbance. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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10 pages, 6068 KiB

Open AccessArticle

Possible Formation Mechanism of Lunar Hematite

by Yue Fu, Huizi Wang, Jiang Zhang, Jian Chen, Quanqi Shi, Chao Yue, Honglei Lin, Ruilong Guo, Anmin Tian, Chao Xiao and Wensai Shang

Magnetochemistry 2023, 9(2), 43; https://doi.org/10.3390/magnetochemistry9020043 - 28 Jan 2023

Viewed by 1716

Abstract

Hematite, a ferric mineral with diagnostic features in the visible and infrared spectral range, has recently been discovered in the polar regions of the Moon by the Chandrayaan-1 Moon Mineralogy Mapper (M³). The oxygen involving the oxidization process producing lunar hematite [...] Read more.

Hematite, a ferric mineral with diagnostic features in the visible and infrared spectral range, has recently been discovered in the polar regions of the Moon by the Chandrayaan-1 Moon Mineralogy Mapper (M³). The oxygen involving the oxidization process producing lunar hematite is supposed to originate from the Earth’s upper atmosphere, and hematite with different ages may have preserved information on the oxygen evolution of the Earth’s atmosphere in the past billions of years. The discovery of lunar hematite may provide insight into the understanding of the oxidation products on the Moon and other airless bodies. In this work, we analyze hematite abundance distribution in the lunar polar regions, showing that the content of hematite on the lunar surface increases with latitude, and is positively correlated with surface water abundance. We suggest that the latitude dependence of hematite is derived from the latitude dependence of water, which indicates that water may play an essential role in the formation of hematite. The correlation between hematite and the optical maturity parameter (OMAT) was analyzed and a significant positive correlation was observed, which suggests that the hematite in the polar regions is the result of gradual and persistent oxidation reactions. In addition, based on the analysis of oxygen particles in the Earth wind, it was found that O⁺ and O₂⁺ are much more abundant, suggesting that low-energy O⁺ or O₂⁺ ions escaping from the upper atmosphere of the Earth may play a crucial role in the formation of hematite in the lunar polar regions. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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14 pages, 5529 KiB

Open AccessArticle

Cluster Observation of Ion Outflow in Middle Altitude LLBL/Cusp from Different Origins

by Bin Li, Huigen Yang, Jicheng Sun, Zejun Hu, Jianjun Liu, Xiangcai Chen, Yongfu Wang, Jie Ren, Chao Yue, C. Philippe Escoubet, Qian Wang and Qiugang Zong

Magnetochemistry 2023, 9(2), 39; https://doi.org/10.3390/magnetochemistry9020039 - 20 Jan 2023

Viewed by 1798

Abstract

The ionosphere is the ionized part of the upper atmosphere that is caused mainly by photoionization by solar extreme ultraviolet (EUV) emission and the atmospheric photochemistry process. The ionospheric ions escape from the ionosphere and populate the Earth’s magnetosphere. In this case study, [...] Read more.

The ionosphere is the ionized part of the upper atmosphere that is caused mainly by photoionization by solar extreme ultraviolet (EUV) emission and the atmospheric photochemistry process. The ionospheric ions escape from the ionosphere and populate the Earth’s magnetosphere. In this case study, ion outflows from two different origins were obtained by spacecraft Cluster C1 in the magnetospheric cusp region. One of the outflows was from the reflection of the dispersed solar wind particles. The other was the ionospheric outflow passing through the low latitude boundary layer of the cusp (LLBL/cusp), which was energized by downward Poynting flux. Similar to the reflected solar wind particles, outflowing ionospheric cold ions could also extend to the high-latitude region with magnetic field line convection, which mixed it up with solar wind particles. Based on the Cluster observation in the cusp region, two different origins of the outflowing particles were determined, and their unique mechanisms of formation were discussed. Results suggest that the strong electric field associated with solar wind particle precipitation may additionally accelerate the cold ionospheric ion flow in the LLBL/cusp. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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11 pages, 2083 KiB

Open AccessFeature PaperArticle

Observations of Time-Domain Structures in the Plasmaspheric Plume by Van Allen Probes

by Shangchun Teng, Huayue Chen, Qiang Zhang and Desheng Han

Magnetochemistry 2023, 9(1), 22; https://doi.org/10.3390/magnetochemistry9010022 - 05 Jan 2023

Viewed by 1272

Abstract

Time-domain structures (TDS), manifested as ≥ 1 ms pulses with significant parallel electric fields, play an important role in accelerating electrons in the field-aligned direction. These precipitated electrons contribute to the formation of aurora. In this study, we present observations of time-domain structures [...] Read more.

Time-domain structures (TDS), manifested as ≥ 1 ms pulses with significant parallel electric fields, play an important role in accelerating electrons in the field-aligned direction. These precipitated electrons contribute to the formation of aurora. In this study, we present observations of time-domain structures that occurred in the plasmaspheric plumes at the post-midnight to dawn sector. The close correlation between TDS and plasmaspheric plumes implies that the generation of TDS might be modulated by plasma density. During the wave occurrence, protons with an energy level below 1 keV show the enhanced field-aligned pitch-angle distributions, and the electron fluxes with the energies ranging from tens to hundreds of eV are also significantly enhanced. The correlation between TDS and scattered particles indicates the importance of including time-domain structures in future studies of radiation belt dynamics. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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9 pages, 301 KiB

Open AccessArticle

Cosmological Phase Transitions—EWPT-QCDPT: Magnetic Field Creation

by Leonard S. Kisslinger

Magnetochemistry 2022, 8(10), 115; https://doi.org/10.3390/magnetochemistry8100115 - 27 Sep 2022

Viewed by 1233

Abstract

We review the cosmic microwave background (CMBR) estimate of ordinary matter, dark matter and dark energy in the universe. Then, we review the cosmological electroweak (EWPT) and quantum chromodynamics (QCDPT) phase transitions. During both the EWPT and QCDPT, bubbles form and collide, producing [...] Read more.

We review the cosmic microwave background (CMBR) estimate of ordinary matter, dark matter and dark energy in the universe. Then, we review the cosmological electroweak (EWPT) and quantum chromodynamics (QCDPT) phase transitions. During both the EWPT and QCDPT, bubbles form and collide, producing magnetic fields. We review dark matter produced during the EWPT and the estimate of dark matter via galaxy rotation. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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11 pages, 3422 KiB

Open AccessArticle

Plasma Temperatures in the Martian Subsolar Magnetosheath: MAVEN Observations

by Nian Ren, Chao Shen and Yong Ji

Magnetochemistry 2022, 8(8), 88; https://doi.org/10.3390/magnetochemistry8080088 - 09 Aug 2022

Viewed by 1452

Abstract

We studied the thermal features of magnetized plasmas in the Martian subsolar magnetosheath using MAVEN’s observations from 2014 to 2019. Statistical analyses show that the average ion and electron temperature in the Martian subsolar magnetosheath are 210 and 31 eV, respectively, which are [...] Read more.

We studied the thermal features of magnetized plasmas in the Martian subsolar magnetosheath using MAVEN’s observations from 2014 to 2019. Statistical analyses show that the average ion and electron temperature in the Martian subsolar magnetosheath are 210 and 31 eV, respectively, which are significantly lower than their counterparts in the subsolar magnetosheaths of Earth and Saturn which both have an inherent magnetosphere. However, the ratio

{\bar{T}}_{i} / {\bar{T}}_{e}

in the Martian subsolar magnetosheath is about 6.8, which is very close to that of Earth and Saturn. We further investigated the relationship between

T_{i} / T_{e}

and the bulk ion flow velocity

V_{i}

, as well as the relationship between the total plasma beta

β

and

V_{i}

. Results show that the average value of

T_{i} / T_{e}

when

V_{i} < 300 km / s

is considerably higher than when

V_{i} > 300 km / s

. A value of

V_{i}

closer to 250–300 km/s leads to a higher average value of the total plasma beta

β

. These results confirm the prediction of previous researchers, that there is not enough room for solar wind thermalization as the distance between the Martian bow shock and the so-called obstacle is of the order of a solar wind proton gyroradius. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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Review

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14 pages, 2021 KiB

Open AccessReview

Energetic Neutral Atom Imaging of the Earth’s Ring Current and Some Results from the Chinese Double Star Program

by Zhiqing Chen, Chao Shen, Qiong Wu, Li Lu, Xianguo Zhang and Qinglong Yu

Magnetochemistry 2023, 9(1), 29; https://doi.org/10.3390/magnetochemistry9010029 - 12 Jan 2023

Viewed by 1417

Abstract

The ring current region in the Earth’s magnetosphere contains energetic charged particles, which are injected from the magnetotail, get trapped in the inner magnetosphere, and finally drift around the Earth. The current, essentially carried by ions, is caused by the differences between the [...] Read more.

The ring current region in the Earth’s magnetosphere contains energetic charged particles, which are injected from the magnetotail, get trapped in the inner magnetosphere, and finally drift around the Earth. The current, essentially carried by ions, is caused by the differences between the drift of the positively charged ions and that of negatively charged electrons. The charge exchange that occurs between ring current ions and geocoronal atoms determines the distribution and evolution of the ring current and lays the basis for remote detection techniques. By measuring the energetic neutral atoms produced by the charge-exchange process, the ring current can be remotely detected via energetic neutral atom imaging. The Chinese Double Star Program operated the NeUtral Atom Detector Unit (NUADU) onboard one of its two satellites for more than four years. A variety of studies were conducted using multiple methods applied to observations, such as intuitive image inspection, forward modeling, and inversion. Energetic neutral atom imaging was established as a promising technique for future imaging projects. Full article

(This article belongs to the Special Issue Magnetodynamics of Space Plasmas)

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