3D Kinetic Simulations of Driven Reconnection in Merging Flux Tubes

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Hauptverfasser: Granier, Camille, Bacchini, Fabio, Groselj, Daniel, Sironi, Lorenzo
Format: Preprint
Veröffentlicht: 2026
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author Granier, Camille
Bacchini, Fabio
Groselj, Daniel
Sironi, Lorenzo
author_facet Granier, Camille
Bacchini, Fabio
Groselj, Daniel
Sironi, Lorenzo
contents We present 2D and 3D Particle-in-Cell simulations of driven collisionless magnetic reconnection triggered by the compression and merger of two Lundquist-type force-free flux tubes in a strongly magnetized pair plasma, with a focus on magnetic energy dissipation and particle acceleration. We show that 3D effects systematically delay the onset of reconnection in comparison with equivalent 2D runs, an effect further enhanced by a strong guide field, due to reduced linear growth rates and phase decoherence of oblique modes. Increasing the external drive accelerates both tearing and drift-kink instabilities, while a strong guide field suppresses coherent drift-kink activity and has a comparatively mild impact on tearing. Despite these differences in early-time dynamics, all simulations enter a fast-merging phase characterized by a normalized reconnection rate 0.08--0.10, coinciding with a transient reduction of the guide-to-reconnecting field ratio inside the current sheet. The high-energy cutoff of accelerated particles converges to a common asymptotic value, gamma_cut/sigma_in ~ 50, with only a weak dependence on the driving strength. This behavior is consistent with an electric-field-limited acceleration process, in which the maximum energy is set by the reconnection electric field and the duration of the energization phase. The resulting nonthermal particle spectra are similar across all runs, with power-law indices p ~ 1.6--2.0.
format Preprint
id arxiv_https___arxiv_org_abs_2604_10431
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle 3D Kinetic Simulations of Driven Reconnection in Merging Flux Tubes
Granier, Camille
Bacchini, Fabio
Groselj, Daniel
Sironi, Lorenzo
Plasma Physics
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
We present 2D and 3D Particle-in-Cell simulations of driven collisionless magnetic reconnection triggered by the compression and merger of two Lundquist-type force-free flux tubes in a strongly magnetized pair plasma, with a focus on magnetic energy dissipation and particle acceleration. We show that 3D effects systematically delay the onset of reconnection in comparison with equivalent 2D runs, an effect further enhanced by a strong guide field, due to reduced linear growth rates and phase decoherence of oblique modes. Increasing the external drive accelerates both tearing and drift-kink instabilities, while a strong guide field suppresses coherent drift-kink activity and has a comparatively mild impact on tearing. Despite these differences in early-time dynamics, all simulations enter a fast-merging phase characterized by a normalized reconnection rate 0.08--0.10, coinciding with a transient reduction of the guide-to-reconnecting field ratio inside the current sheet. The high-energy cutoff of accelerated particles converges to a common asymptotic value, gamma_cut/sigma_in ~ 50, with only a weak dependence on the driving strength. This behavior is consistent with an electric-field-limited acceleration process, in which the maximum energy is set by the reconnection electric field and the duration of the energization phase. The resulting nonthermal particle spectra are similar across all runs, with power-law indices p ~ 1.6--2.0.
title 3D Kinetic Simulations of Driven Reconnection in Merging Flux Tubes
topic Plasma Physics
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2604.10431