Alfvén Number for the Richtmyer–Meshkov Instability in Magnetized Plasmas

Magnetohydrodynamical evolution of the Richtmyer-Meshkov instability (RMI) is investigated by two-dimensional MHD simulations. The RMI suppressed a strong magnetic field, whereas amplifies an ambient field many orders magnitude if seed weak. We have found that suppression and amplification processes can be evaluated continuously along with amplitude Alfv\'en number $R_A$, which defined as ratio linear growth velocity to speed at interface. When less than unity, Lorentz force acting on fluid mitigates unstable motion significantly, interface oscillates stably in this limit. If $R_A \gtrsim 1$, other hand, surface modulation increases due RMI. maximum strength enhanced up factor $R_A$. This critical feature universal independent initial Mach incident shock, Atwood number, corrugation amplitude, even direction field.