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

Yoo, Jongsoo ; Byungkeun, Na; Jara-Almonte, Jonathan ; Yamada, Masaaki ; Ji, Hantao ; Roytershteyn, V. ; Argall, M. R. ; Fox, W. ; Chen, Li-Jen
Issue date: 2017
Creative Commons Attribution 4.0 International (CC BY)
Cite as:
Yoo, Jongsoo, Byungkeun, Na, Jara-Almonte, Jonathan, Yamada, Masaaki, Ji, Hantao, Roytershteyn, V., Argall, M. R., Fox, W., & Chen, Li-Jen. (2017). Electron heating and energy inventory during asymmetric reconnection in a laboratory plasma [Data set]. Princeton Plasma Physics Laboratory, Princeton University. https://doi.org/10.11578/1562000
  author      = {Yoo, Jongsoo and
                Byungkeun, Na and
                Jara-Almonte, Jonathan and
                Yamada, Masaaki and
                Ji, Hantao and
                Roytershteyn, V. and
                Argall, M. R. and
                Fox, W. and
                Chen, Li-Jen},
  title       = {{Electron heating and energy inventory du
                ring asymmetric reconnection in a labora
                tory plasma}},
  publisher   = {{Princeton Plasma Physics Laboratory, Pri
                nceton University}},
  year        = 2017,
  url         = {https://doi.org/10.11578/1562000}

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.

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