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Exploring the Kinetic Scale Mechanism of the Dayside Magnetopause Current System /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Exploring the Kinetic Scale Mechanism of the Dayside Magnetopause Current System // Jason Michael Harry Beedle.
Author:	Beedle, Jason Michael Harry,
Description:	1 electronic resource (145 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-06, Section: B.
Contained By:	Dissertations Abstracts International85-06B.
Subject:	Astrophysics. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30694029
ISBN:	9798381164459

Exploring the Kinetic Scale Mechanism of the Dayside Magnetopause Current System /
Beedle, Jason Michael Harry,

Exploring the Kinetic Scale Mechanism of the Dayside Magnetopause Current System /Jason Michael Harry Beedle. - 1 electronic resource (145 pages)

Source: Dissertations Abstracts International, Volume: 85-06, Section: B.

Originating from the Sun's atmosphere, the solar wind fills interplanetary space with a dynamic expanse of plasma and magnetic field lines. As the solar wind moves through the solar system it can encounter obstacles such as the Earth's magnetosphere and its intrinsic magnetic field. Separating the solar wind's plasma from the magnetosphere is a boundary layer called the magnetopause. Across this boundary layer, pressure gradients generate a current sheet named the Chapman-Ferraro (CF) current. Magnetic reconnection can then occur in the current sheet when opposing magnetic field lines in the solar wind and Earth's magnetic field are driven together by plasma flows, break, and then reform, changing the local magnetic topology and releasing previously stored magnetic energy into the surrounding plasma. This process occurs in what are known as diffusion regions. Specifically, there are two such diffusion regions in the standard reconnection process: an ion diffusion region (IDR) and an electron diffusion region (EDR). The process of magnetic reconnection leads to the magnetopause acting as the entry "gate" of the solar wind's energy into the Earth's magnetosphere, providing both the opportunity to view the Northern Lights and potentially harming our increasingly critical orbital infrastructure. Through this process, the magnetopause and its current sheet become essential pieces of the near-Earth space weather system, making its generation, structure, and the impact of magnetic reconnection important areas of research. In this dissertation, I will discuss how my coauthors and I utilize data from NASA's Magnetospheric Multiscale (MMS) Mission to study how the magnetopause current sheet is formed, how the diffusion regions' current system differs from the background magnetopause, and theorize how the magnetopause current sheet itself interacts with the diffusion regions through the following published studies and current research:In Beedle et al. (2022b), I statistically analyzed the diamagnetic current density during 561 flank and dayside magnetopause crossings and found that the Chapman-Ferraro current is com- posed of opposing density and temperature gradient components with the temperature component contributing a significant fraction (up to 37%) of the total ion diamagnetic current density along the magnetopause. I also found that this temperature component generally opposes the classical Chapman-Ferraro current direction, working to reduce the overall diamagnetic current density. The electron diamagnetic current was also studied and found to be significantly, 5-14 times, smaller than its ion counterpart.In Beedle et al. (2023), I studied 225 dayside magnetopause crossings, termed regular crossings, previously identified in Beedle et al. (2022b) and compared these with 26 EDR events from Webster et al. (2018). Through this comparison, I found that EDR crossings show current densities an order of magnitude higher than regular magnetopause crossings, indicating the significantly enhanced current sheet during EDR events. Additionally, I found that EDR crossings contain significant current components parallel to the local magnetic field, especially in the φ or out-of-plane direction. I also found that EDR and regular magnetopause crossings show average ion velocities that are highly correlated with a crossing's location along the magnetopause, indicating the presence of magnetosheath flows in the magnetopause current sheet.In my current work, I explore the enhanced out-of-plane parallel current signatures previously reported in Beedle et al. (2023) by focusing on three specific case studies: the Burch et al. (2016), Norgren et al. (2016), and Phan et al. (2016b) EDR events and comparing these results with an asymmetric, 2.5D PIC (Particle-In-Cell) simulation of the diffusion regions. From this analysis, I found enhanced out-of-plane parallel current signatures represent an additional distinguishing feature of the IDR and separate it from the EDR. This finding is substantiated in both the case studies and PIC results with the simulated results showing significant out-of-plane parallel current dominance as a defining feature of both the IDR and the interaction region between theIDR and EDR.Using these findings as inspiration for a theoretical look into how the large scale CF current may interact with the small-scale, localized diffusion regions, I then theorize that a portion of the background CF current could become diverted around finite M-direction diffusion regions. The current closure of the Hall magnetic field around a finite X-line in the diffusion region would causethe CF current ions to become diverted around the central EDR and into the outer IDR, potentially creating an out-of-plane, parallel current signature in this region, which I call the Diverted Chapman-Ferraro current. This mechanism allows for the current closure of the large-scale ion-dominated CF current around the diffusion regions, while also allowing for the observed dominance of the small-scale electron reconnection currents in the EDR.

English

ISBN: 9798381164459Subjects--Topical Terms:

535904
Astrophysics.
Subjects--Index Terms:

Chapman-Ferraro current

Exploring the Kinetic Scale Mechanism of the Dayside Magnetopause Current System /
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502 $b Ph.D. $c The Catholic University of America $d 2024.
520 $a Originating from the Sun's atmosphere, the solar wind fills interplanetary space with a dynamic expanse of plasma and magnetic field lines. As the solar wind moves through the solar system it can encounter obstacles such as the Earth's magnetosphere and its intrinsic magnetic field. Separating the solar wind's plasma from the magnetosphere is a boundary layer called the magnetopause. Across this boundary layer, pressure gradients generate a current sheet named the Chapman-Ferraro (CF) current. Magnetic reconnection can then occur in the current sheet when opposing magnetic field lines in the solar wind and Earth's magnetic field are driven together by plasma flows, break, and then reform, changing the local magnetic topology and releasing previously stored magnetic energy into the surrounding plasma. This process occurs in what are known as diffusion regions. Specifically, there are two such diffusion regions in the standard reconnection process: an ion diffusion region (IDR) and an electron diffusion region (EDR). The process of magnetic reconnection leads to the magnetopause acting as the entry "gate" of the solar wind's energy into the Earth's magnetosphere, providing both the opportunity to view the Northern Lights and potentially harming our increasingly critical orbital infrastructure. Through this process, the magnetopause and its current sheet become essential pieces of the near-Earth space weather system, making its generation, structure, and the impact of magnetic reconnection important areas of research. In this dissertation, I will discuss how my coauthors and I utilize data from NASA's Magnetospheric Multiscale (MMS) Mission to study how the magnetopause current sheet is formed, how the diffusion regions' current system differs from the background magnetopause, and theorize how the magnetopause current sheet itself interacts with the diffusion regions through the following published studies and current research:In Beedle et al. (2022b), I statistically analyzed the diamagnetic current density during 561 flank and dayside magnetopause crossings and found that the Chapman-Ferraro current is com- posed of opposing density and temperature gradient components with the temperature component contributing a significant fraction (up to 37%) of the total ion diamagnetic current density along the magnetopause. I also found that this temperature component generally opposes the classical Chapman-Ferraro current direction, working to reduce the overall diamagnetic current density. The electron diamagnetic current was also studied and found to be significantly, 5-14 times, smaller than its ion counterpart.In Beedle et al. (2023), I studied 225 dayside magnetopause crossings, termed regular crossings, previously identified in Beedle et al. (2022b) and compared these with 26 EDR events from Webster et al. (2018). Through this comparison, I found that EDR crossings show current densities an order of magnitude higher than regular magnetopause crossings, indicating the significantly enhanced current sheet during EDR events. Additionally, I found that EDR crossings contain significant current components parallel to the local magnetic field, especially in the φ or out-of-plane direction. I also found that EDR and regular magnetopause crossings show average ion velocities that are highly correlated with a crossing's location along the magnetopause, indicating the presence of magnetosheath flows in the magnetopause current sheet.In my current work, I explore the enhanced out-of-plane parallel current signatures previously reported in Beedle et al. (2023) by focusing on three specific case studies: the Burch et al. (2016), Norgren et al. (2016), and Phan et al. (2016b) EDR events and comparing these results with an asymmetric, 2.5D PIC (Particle-In-Cell) simulation of the diffusion regions. From this analysis, I found enhanced out-of-plane parallel current signatures represent an additional distinguishing feature of the IDR and separate it from the EDR. This finding is substantiated in both the case studies and PIC results with the simulated results showing significant out-of-plane parallel current dominance as a defining feature of both the IDR and the interaction region between theIDR and EDR.Using these findings as inspiration for a theoretical look into how the large scale CF current may interact with the small-scale, localized diffusion regions, I then theorize that a portion of the background CF current could become diverted around finite M-direction diffusion regions. The current closure of the Hall magnetic field around a finite X-line in the diffusion region would causethe CF current ions to become diverted around the central EDR and into the outer IDR, potentially creating an out-of-plane, parallel current signature in this region, which I call the Diverted Chapman-Ferraro current. This mechanism allows for the current closure of the large-scale ion-dominated CF current around the diffusion regions, while also allowing for the observed dominance of the small-scale electron reconnection currents in the EDR.
546 $a English
590 $a School code: 0043
650 4 $a Astrophysics. $3 535904
650 4 $a Plasma physics. $3 3175417
650 4 $a Electromagnetics. $3 3173223
653 $a Chapman-Ferraro current
653 $a Magnetic reconnection
653 $a Magnetopause
653 $a Magnetosphere
653 $a Space physics
653 $a Space weather
690 $a 0596
690 $a 0759
690 $a 0607
710 2 $a The Catholic University of America. $b Physics. $e degree granting institution. $3 3770493
720 1 $a Uritsky, Vadim M. $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 85-06B.
790 $a 0043
791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30694029