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Particle Heating and Energy Partition in Reconnection with a Guide Field
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Particle Heating and Energy Partition in Reconnection with a Guide Field. |
| 개인저자 | Zhang, Qile. |
| 단체저자명 | University of Maryland, College Park. Physics. |
| 발행사항 | [S.l.]: University of Maryland, College Park., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 113 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-05B. Dissertation Abstract International |
| ISBN | 9781687921345 |
| 학위논문주기 | Thesis (Ph.D.)--University of Maryland, College Park, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-05, Section: B.
Advisor: Drake, James |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | Kinetic Riemann simulations have been completed to explore particle heating during reconnection with a guide field in the low-beta environment of the inner heliosphere and the solar corona. The reconnection exhaust is bounded by two rotational discontinuities (RDs) with two slow shocks (SSs) that form within the exhaust as in magnetohydrodynamic (MHD) models. At the RDs, ions are accelerated by the magnetic field tension to drive the reconnection outflow as well as flows in the out-of-plane direction. The out-of-plane flows stream toward the midplane and meet to drive the SSs. The turbulence at the SSs is weak so the shocks are laminar and produce little dissipation, which differs greatly from the MHD treatment. Downstream of the SSs the counter-streaming ion beams lead to higher density and therefore to a positive potential between the SSs that confines the downstream electrons to maintain charge neutrality. The potential accelerates electrons from upstream of the SSs to downstream and traps a small fraction but only produces modest electron heating. In the low-beta limit the released magnetic energy is split between bulk flow and ion heating with little energy going to electrons. To firmly establish the laminar nature of reconnection exhausts, we explore the role of instabilities and turbulence in the dynamics. Two-dimensional reconnection and Riemann simulations reveal that the exhaust develops large-amplitude striations resulting from electron-beam-driven ion cyclotron waves. The electron beams driving the instability are injected into the exhaust from one of the RDs. However, in 3D Riemann simulations, the additional dimension results in a strong Buneman instability at the RD, which suppresses electron beam formation. The 3D simulation does reveal a weak ion-ion streaming instability within the exhaust. All these instabilities become weaker with higher ion-to-electron mass ratio due to higher electron thermal speed. We also use a kinetic dispersion relation solver to show that the ion-ion instability will become stable in conditions expected under lower upstream beta. The results suggest that in realistic reconnection exhausts, which have three dimensions and real mass ratio, the kinetic-scale turbulence that develops will be too weak to play a significant role in energy conversion. |
| 일반주제명 | Physics. Plasma physics. |
| 언어 | 영어 |
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: 이 자료의 원문은 한국교육학술정보원에서 제공합니다. |
