| Abstract : | The solar atmosphere shows spectacular set of dynamical phenomena like looping prominences, gently oscillating bright loops, instabilities, and explosive release of energy releases in the form of flares and coronal mass ejections (CMEs)-all controlled by the magnetic field. Various structures
and shapes of magnetically confined plasma are governed by the evolution of different phases of instabilities and wave activities. A well-known fluid dynamical phenomenon is the instability of the interface between two differently moving fluids, called the Kelvin-Helmholtz (KH) instability. The KH instability may play a significant role in plasma heating, particle acceleration, mass and energy transportation, and the development of turbulence in different magnetic structures in the solar atmosphere, which need to be explored in a more detailed manner. Using multi-wavelength imaging data obtained from Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO), we diagnose the different onset criteria for the evolution of K-H instability there such as, (i) the increment in the amplitude and characteristic wavelength of the K-H unstable vortices, (ii) velocity difference between two layers, (ii) larger velocity of K-H unstable vortices than the Alfvèn speed in the second denser layer, (iv) parametric constant is greater than 1. This Kelvin-Helmholtz instability evolves in a fan-spine configuration and is responsible for transferring the mass and cascade of energy at smaller spatial scales. These criteria confirm the dominance of velocity shear and the evolution of the linear phase of K-H instability. The estimated growth rate is found to be useful to diagnose the strength of the localized magnetic field in the Fan-spine topology. The upcoming observations from the Aditya-L1 will be useful to understand such multithermal plasma dynamics in the solar atmosphere using SUIT and VELC data up to the mid-corona. |
