A Priori Estimates of Plasma-Vacuum Interface Problem for 2D Incompressible Ideal MHD
摘要
This paper establishes a priori estimates for the free boundary problem of two-dimensional ideal incompressible magnetohydrodynamics (MHD) involving a plasma-vacuum interface. The system consists of a plasma region governed by the ideal MHD equations and a vacuum region described by pre-Maxwell dynamics, separated by a freely evolving interface where total pressure continuity and magnetic field tangency conditions hold. By adopting a geometric Lagrangian framework, we reformulate the free boundary problem into a fixed domain using trajectory maps and fictitious velocity extensions. Our main contribution lies in deriving higher-order energy norms that combine boundary geometry and interior dynamics, enabling control over the solution’s regularity. For the vacuum magnetic field, we prove that its covariant derivatives in