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Title: Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma

Abstract

Electron heating and the energy inventory during asymmetric reconnection are studied in the laboratory plasma with a density ratio of about 8 across the current sheet. Features of asymmetric reconnection such as the large density gradients near the low-density-side separatrices, asymmetric in-plane electric field, and bipolar out-of-plane magnetic field are observed. Unlike the symmetric case, electrons are also heated near the low-density-side separatrices. The measured parallel electric field may explain the observed electron heating. Although large fluctuations driven by lower-hybrid drift instabilities are also observed near the low-density-side separatrices, laboratory measurements and numerical simulations reported here suggest that they do not play a major role in electron energization. The average electron temperature increase in the exhaust region is proportional to the incoming magnetic energy per an electron/ion pair but exceeds scalings of the previous space observations. This discrepancy is explained by differences in the boundary condition and system size. The profile of electron energy gain from the electric field shows that there is additional electron energy gain associated with the electron diamagnetic current besides a large energy gain near the X-line. This additional energy gain increases electron enthalpy, not the electron temperature. Finally, a quantitative analysis of the energy inventorymore » during asymmetric reconnection is conducted. Unlike the symmetric case where the ion energy gain is about twice more than the electron energy gain, electrons and ions obtain a similar amount of energy during asymmetric reconnection.« less

Creator(s)/Author(s):
; ; ; ; ; ; ; ;
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
U. S. Department of Energy
Keywords:
Energy inventory
OSTI Identifier:
1562000
DOI:
10.11578/1562000

Citation Formats

Yoo, Jongsoo, Na, Byungkeun, Jara-Almonte, Jonathan, Yamada, Maasaki, Ji, Hantao, Roytershteyn, V, Argall, M R, Fox, W, and Chen, Li-Jen. Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma. United States: N. p., 2017. Web. doi:10.11578/1562000.
Yoo, Jongsoo, Na, Byungkeun, Jara-Almonte, Jonathan, Yamada, Maasaki, Ji, Hantao, Roytershteyn, V, Argall, M R, Fox, W, & Chen, Li-Jen. Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma. United States. doi:10.11578/1562000.
Yoo, Jongsoo, Na, Byungkeun, Jara-Almonte, Jonathan, Yamada, Maasaki, Ji, Hantao, Roytershteyn, V, Argall, M R, Fox, W, and Chen, Li-Jen. 2017. "Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma". United States. doi:10.11578/1562000. https://www.osti.gov/servlets/purl/1562000. Pub date:Tue Aug 01 00:00:00 EDT 2017
@article{osti_1562000,
title = {Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma},
author = {Yoo, Jongsoo and Na, Byungkeun and Jara-Almonte, Jonathan and Yamada, Maasaki and Ji, Hantao and Roytershteyn, V and Argall, M R and Fox, W and Chen, Li-Jen},
abstractNote = {Electron heating and the energy inventory during asymmetric reconnection are studied in the laboratory plasma with a density ratio of about 8 across the current sheet. Features of asymmetric reconnection such as the large density gradients near the low-density-side separatrices, asymmetric in-plane electric field, and bipolar out-of-plane magnetic field are observed. Unlike the symmetric case, electrons are also heated near the low-density-side separatrices. The measured parallel electric field may explain the observed electron heating. Although large fluctuations driven by lower-hybrid drift instabilities are also observed near the low-density-side separatrices, laboratory measurements and numerical simulations reported here suggest that they do not play a major role in electron energization. The average electron temperature increase in the exhaust region is proportional to the incoming magnetic energy per an electron/ion pair but exceeds scalings of the previous space observations. This discrepancy is explained by differences in the boundary condition and system size. The profile of electron energy gain from the electric field shows that there is additional electron energy gain associated with the electron diamagnetic current besides a large energy gain near the X-line. This additional energy gain increases electron enthalpy, not the electron temperature. Finally, a quantitative analysis of the energy inventory during asymmetric reconnection is conducted. Unlike the symmetric case where the ion energy gain is about twice more than the electron energy gain, electrons and ions obtain a similar amount of energy during asymmetric reconnection.},
doi = {10.11578/1562000},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {8}
}

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