Upon interaction, a pair of magnetic flux ropes can merge to form a new pair, each consisting of opposite helicity along their axis. Magnetic helicity along such new structures may annihilate and release the energy of the azimuthal magnetic field. In this study, we model the deformation dynamics of such structures within the solar wind at 1 AU. The perturbation front of deformation propagates along the rope axis at approximately the Alfvén speed. However, the process to annihilate 90% of the azimuthal components is much slower and is affected by the screw pitch of the magnetic field. Such a deformation process causes the plasma in the transition region between the two opposite chiralities to spin about the rope axis, and plasma heating is discussed accordingly. Our results provide insights for estimating the lifetimes of such flux ropes, facilitating observational efforts to identify them. This process may also apply to the behavior of magnetic flux ropes in other space and astronomical plasma environments.

Ideal MHD simulation of the evolution of counter-helical flux ropes interacting in the 1Au solar wind.

BATS-R-Us code is used to simulate this evolution (SWMF, 2024):

SWMF. (2024). University of Michigan space weather modeling framework (SWMF) [Software]. https://clasp.engin.umich.edu/research/theory-computational-methods/swmf-downloadable-software/

The data file is stored on Dryad, with input parameters on Zenodo.

We want to thank the American Astronomical Society (AAS) Data Editor and Dryad editors for their assistance with presenting this submission.