Abstract
Fragmentation of an elongated current sheet into many reconnection X-points, and therefore multiple plasmoids, occurs frequently in the solar corona. This speeds up the release of solar magnetic energy in the form of thermal and kinetic energy. Moreover, due to the presence of multiple reconnection X-points, the particle acceleration is more efficient in terms of the number of accelerated particles. This type of instability called “plasmoid instability” is accompanied with the excitation of some electrostatic/electromagnetic waves. We carried out 2D particle-in-cell simulations of this instability in the collisionless regime, with the presence of non-uniform magnetic guide field to investigate the nature of excited waves. It is shown that the nature and properties of waves excited inside and outside the current sheet are different. While the outside perturbations are transient, the inside ones are long-lived, and are directly affected by the plasmoid instability process.
Highlights
Magnetic reconnection is a fundamental phenomenon in highly conductive magnetized plasmas such as space and astrophysical plasmas in which the magnetic energy is abruptly released and converted to the heating and kinetic energies as well as the acceleration of particles
2D PIC simulation was carried out to investigate the spatial and temporal variation of electric field generated during the collisionless magnetic reconnection which later transits into the plasmoid instability
The input parameters are applicable for the solar corona, in the region where ωpe > ωce is justified
Summary
Magnetic reconnection is a fundamental phenomenon in highly conductive magnetized plasmas such as space and astrophysical plasmas in which the magnetic energy is abruptly released and converted to the heating and kinetic energies as well as the acceleration of particles. In large systems such as those found in solar flares, the formation of highly elongated current sheets in coronal magnetic fields would result in extremely low reconnection rates, which fail to account for the observed fast energy release rates Such current sheets are stressed by complex photospheric motions and/or eruptive motion of magnetic structures such as flux ropes (external perturbations), and are naturally subject to a violent plasma instability leading to the breakup, fragmentation and formation of multiple current sheets (secondary islands or plasmoids) instead of just one monolithic current layer with reconnection occurring at multiple X-points (Loureiro et al, 2007; Cargill et al, 2012).
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