Normal trace inequalities and decay of solutions to the nonlinear Maxwell system with absorbing boundary
Richard Nutt, Roland Schnaubelt
TL;DR
This work analyzes a quasilinear Maxwell system with a state-dependent absorbing boundary to establish global existence and exponential decay for small data under a nontrapping condition. The authors develop a refined trace theory for the non-autonomous linear Maxwell problem, including a collar-operator-based normal-trace control and a div-curl framework in negative Sobolev spaces, culminating in an observability-type inequality. A key regularity-boost result then enables a bootstrap argument to absorb high-order error terms and derive decay for the nonlinear problem, while an autonomous linear case yields time-uniform trace bounds and exponential stability. Collectively, the results extend decay theory for Maxwell systems with nonlinear boundary damping beyond star-shaped domains, using advanced trace, microlocal, and div-curl techniques.
Abstract
We study the quasilinear Maxwell system with a strictly positive, state dependent boundary conductivity. For small data we show that the solution exists for all times and decays exponentially to $0$. As in related literature we assume a nontrapping condition. Our approach relies on a new trace estimate for the corresponding non-autonomous linear problem, an observability-type estimate, and a detailed regularity analysis. The results are improved in the linear autonomous case, using properties of the Helmholtz decomposition in Sobolev spaces of (small) negative order.
