Quasi-periodic spicule-like cool jets driven by Alfv\'en pulses

We perform a 2.5 dimensional magnetohydrodynamic (MHD) simulation to understand a comprehensive view of the formation of spicule-like cool jets due to initial transverse velocity pulses akin to Alfv\'en pulses in the solar chromosphere. We invoke multiple velocity ($V_{z}$) pulses between 1.5 and 2.0 Mm in the solar atmosphere, which create the initial transverse velocity perturbations. These pulses transfer energy non-linearly to the field aligned perturbations due to the ponderomotive force. This physical process further creates the magnetoacoustic shocks followed by quasi-periodic plasma motions in the solar atmosphere. The field aligned magnetoacoustic shocks move upward which subsequently cause quasi-periodic rise and fall of the chromospheric plasma into the overlying corona as a thin and cool spicule-like jets. The magnitude of the initial applied transverse velocity pulses are taken in the range of 50-90 km $s^{-1}$. These pulses are found to be strong enough to generate the spicule-like jets. We analyze the evolution, kinematics and energetics of these spicule-like jets. We find that the transported mass flux and kinetic energy density are substantial in the localized solar-corona. These mass motions generate $\it in$ $situ$ quasi-periodic oscillations on the scale of $\simeq$ 4.0 min above the transition region.

B. Singh, A.K. Srivastava, K. Sharma, S.K. Mishra, B.N. Dwivedi · 2022