Two‐Dimensional Hybrid Simulations of High‐Speed Jets Downstream of Quasi‐Parallel Shocks

High‐speed jets (HSJs) are frequently observed downstream of a quasi‐parallel bow shock, and they are considered to play important roles in the coupling of the solar wind, the magnetosheath, and the magnetosphere. Using two‐dimensional hybrid simulations, we study the formation of HSJs in quasi‐parallel shocks with different shock angles (θBn). The interaction of the upstream compressive structures that are inhomogeneous in the direction perpendicular to the background magnetic field and the shock front leads to the shock ripples, and then the downstream HSJs. In a parallel shock with the shock angle θBn = 0°, the interaction regions of the upstream compressive structures with the shock front don’t change with time. The shock ripples remain in the same regions of the shock front, and then the HSJs can develop into large‐scale sizes, especially under low plasma β or high Mach number (MA). While in a quasi‐parallel shock with a non‐zero shock angle, the interaction regions of the upstream compressive structures with the shock front move along the shock front. The shock ripples change with time, and the scale size of the downstream HSJs becomes smaller with the increase of the shock angle. Key Points 2‐D hybrid simulations are performed to study the formation of downstream high‐speed jets (HSJs) and ripples in quasi‐parallel shocks due to the interaction between upstream structures and the shock front In a parallel shock, the shock ripples remain in the same regions of the shock front, and large‐scale HSJs can form downstream of the ripples In a quasi‐parallel shock, the shock ripples move along the shock front and the downstream HSJs become smaller as the shock angle increases