Plasmoid-Trapped Condensation Associated with a Transient Thermal-Instability-Like Process in Chromospheric Magnetic Reconnection
Abstract
We perform high-resolution 2.5D single-fluid magnetohydrodynamic (MHD) simulations to explore the development of cool-dense structures within plasmoids during chromospheric magnetic reconnection. The model incorporates temperature-dependent ionization degrees of hydrogen and helium, resulting in improved diffusivities and viscosity, as well as adequate radiative cooling. The numerical results show that plasma is significantly hot with temperatures reaching several tens of thousands of Kelvin in newly developed plasmoids in the low initial plasma-β cases, β0 = 0.05. Later, the localized accumulation of plasma and decreasing temperature result in an explosive much stronger radiative cooling process. Radiative cooling peaks over the temperature range 8000 K−20,000 K. The co-spatial density enhancement, substantial radiative cooling, shorter radiative cooling timescales, and a significant temperature decrease support the existence of thermal-instability-like condensation within the plasmoids. Similar cool-dense structures are identified in all low-β0 cases at different chromospheric altitudes, suggesting that this occurrence is not limited to a single chromospheric layer. In contrast, in the high initial plasma-β, β0 = 0.5 case, the maximum temperature inside the dense plasmoids is only about 8000 K. Therefore, the radiative cooling has never entered into the explosive increasing stage and the thermal-instability-like condensation does not happen. These findings reveal that plasmoid-trapped condensation may develop in chromospheric reconnection once radiative losses become self-amplifying under low-β0 conditions.
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BibTeX
@misc{zafar2026plasmoidtrapped,
title = {{Plasmoid-Trapped Condensation Associated with a Transient Thermal-Instability-Like Process in Chromospheric Magnetic Reconnection}},
author = {Abdullah Zafar and Lei Ni and Samrat Sen and Yuhao Chen and Mohamed Sedik and Mehdi Yousefzadeh and Jun Lin},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.12699},
eprint = {2609.12699},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.12699},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Plasmoid-Trapped Condensation Associated with a Transient Thermal-Instability-Like Process in Chromospheric Magnetic Reconnection
AU - Abdullah Zafar
AU - Lei Ni
AU - Samrat Sen
AU - Yuhao Chen
AU - Mohamed Sedik
AU - Mehdi Yousefzadeh
AU - Jun Lin
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2609.12699
UR - https://arxiv.org/abs/2609.12699
AB - We perform high-resolution 2.5D single-fluid magnetohydrodynamic (MHD) simulations to explore the development of cool-dense structures within plasmoids during chromospheric magnetic reconnection. The model incorporates temperature-dependent ionization degrees of hydrogen and helium, resulting in improved diffusivities and viscosity, as well as adequate radiative cooling. The numerical results show that plasma is significantly hot with temperatures reaching several tens of thousands of Kelvin in newly developed plasmoids in the low initial plasma-β cases, β_0 = 0.05. Later, the localized accumulation of plasma and decreasing temperature result in an explosive much stronger radiative cooling process. Radiative cooling peaks over the temperature range 8000 K−20,000 K. The co-spatial density enhancement, substantial radiative cooling, shorter radiative cooling timescales, and a significant temperature decrease support the existence of thermal-instability-like condensation within the plasmoids. Similar cool-dense structures are identified in all low-β_0 cases at different chromospheric altitudes, suggesting that this occurrence is not limited to a single chromospheric layer. In contrast, in the high initial plasma-β, β_0 = 0.5 case, the maximum temperature inside the dense plasmoids is only about 8000 K. Therefore, the radiative cooling has never entered into the explosive increasing stage and the thermal-instability-like condensation does not happen. These findings reveal that plasmoid-trapped condensation may develop in chromospheric reconnection once radiative losses become self-amplifying under low-β_0 conditions.
ER -