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Main Authors: Granier, Camille, Groselj, Daniel, Comisso, Luca, Bacchini, Fabio
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2506.06059
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author Granier, Camille
Groselj, Daniel
Comisso, Luca
Bacchini, Fabio
author_facet Granier, Camille
Groselj, Daniel
Comisso, Luca
Bacchini, Fabio
contents We investigate the onset of driven collisionless reconnection and plasmoid formation in a magnetically dominated pair plasma, using 2D Particle-in-Cell simulations. Two force-free flux tubes of radius $R$ are initially pushed together with a prescribed velocity, forming a current sheet whose width shrinks until reconnection sets in. % Even in our largest simulation with $R\approx 1600$ plasma skin depths, the sheet thickness at reconnection onset is comparable to the skin depth. Plasmoid chains develop when the sheet length-to-width aspect ratio $A\gtrsim30$. In the strongly magnetized limit, the onset of reconnection occurs in roughly 2--6 light-crossing times, depending on the imposed driving timescale, which controls the duration of the thinning phase. In the subsequent nonlinear merging phase, the evolution becomes effectively independent of the initially imposed velocity, leading to magnetic-energy dissipation consistent with a normalized reconnection rate $\sim 0.1$. Our results have important implications for explosive release of magnetic energy in magnetospheres of astrophysical compact objects and their surroundings.
format Preprint
id arxiv_https___arxiv_org_abs_2506_06059
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Driven Collisionless Reconnection of Force-free Flux Tubes: From Onset to Coalescence
Granier, Camille
Groselj, Daniel
Comisso, Luca
Bacchini, Fabio
Plasma Physics
High Energy Physics - Theory
We investigate the onset of driven collisionless reconnection and plasmoid formation in a magnetically dominated pair plasma, using 2D Particle-in-Cell simulations. Two force-free flux tubes of radius $R$ are initially pushed together with a prescribed velocity, forming a current sheet whose width shrinks until reconnection sets in. % Even in our largest simulation with $R\approx 1600$ plasma skin depths, the sheet thickness at reconnection onset is comparable to the skin depth. Plasmoid chains develop when the sheet length-to-width aspect ratio $A\gtrsim30$. In the strongly magnetized limit, the onset of reconnection occurs in roughly 2--6 light-crossing times, depending on the imposed driving timescale, which controls the duration of the thinning phase. In the subsequent nonlinear merging phase, the evolution becomes effectively independent of the initially imposed velocity, leading to magnetic-energy dissipation consistent with a normalized reconnection rate $\sim 0.1$. Our results have important implications for explosive release of magnetic energy in magnetospheres of astrophysical compact objects and their surroundings.
title Driven Collisionless Reconnection of Force-free Flux Tubes: From Onset to Coalescence
topic Plasma Physics
High Energy Physics - Theory
url https://arxiv.org/abs/2506.06059