Abstract Details

Name: Arghya Mukherjee
Affiliation: Center of Excellence in Space Sciences India, IISER Kolkata
Conference ID: ASI2021_165
Title : Plasma heating and generation of Kelvin-Helmholtz vortex via the phase mixing of nonlinear shear Alfvén waves
Authors and Co-Authors : Arghya Mukherjee (Center of Excellence in Space Sciences India, IISER Kolkata, Mohanpur, West Bengal, 741246), Dibyendu Nandy (Department of Physical Sciences, IISER Kolkata; CESSI, IISER Kolkata)
Abstract Type : Poster
Abstract Category : Sun and the Solar System
Abstract : Our nearest star Sun remains a source of many scientific mysteries and an assortment of challenging physics problems. To identify the physics behind the coronal heating mechanism is one of the unresolved issues in solar physics and is primarily concerned with how the energy is transported up into the corona and finally converted into heat? The phase mixing of Alfvén waves serves as one of these promising mechanisms thought to be responsible for the coronal plasma heating. We present 2.5-D numerical simulations of the physical processes occur when a nonlinear shear Alfvén wave propagates through a medium, comprising a density gradient along the transverse direction of the applied magnetic field - which ultimately leads to the phase mixing. By performing MHD simulations it is found that due to the gradient in local Alfvén speed, the neighbouring perturbations gradually become out of phase and the wave loses its coherence. As a result higher and higher order modes are generated. Studies have been further extended by injecting test particles into the simulation domain. It is shown that the higher Fourier modes interact with the wave and get accelerated to higher energy. As a result, after a certain time period, the initial wave energy gets converted to the thermal energy of the particles and the plasma reaches a state of higher temperature. The effect of applied magnetic field on the final temperature, attained by the plasma, has been shown. Moreover it is found that the motion of the test particles and their phase space evolution exhibit the development of Kelvin-Helmholtz vortices, which are generated at the velocity antinodes of the wave, due to the local velocity shear.