Effect of an applied magnetic field on Kelvin-Helmholtz instability driven by a laser under multi-mode disturbance

Kelvin-Helmholtz instability (KHI), as a fundamental physical process of fluids and plasmas, widely exists in astrophysics and physical phenomena of high energy density. In this paper, through radiation magnetohydrodynamic code, KHI is generated by the interaction between laser pulses and modulation targets in two-dimensional numerical simulations. Here, the evolution process of KHI vortices under different initial disturbance modes and with or without a horizontal external flow-direction magnetic field is investigated and compared from the perspectives of vorticity, magnetic pressure, magnetic tension, and longitudinal maximum kinetic energy. The simulation demonstrates that the external magnetic field in the horizontal flow direction inhibits the evolution of single-mode KHI vortices and the merging of multi-mode KHI vortices. The research results can provide theoretical guidance for KHI experiments using a high-energy-density laser device under a robust magnetic environment. They are also of significance to frontier research related to inertial confinement fusion.