Mean field theory for intense light-matter interactions in high energy density plasmas

We present a generalization of Vlasov-Maxwell kinetic theory that accounts for intense electromagnetic fields. A strongly-radiating, possibly optically-thick plasma is decomposed into fragments, each comprising a charged particle together with its self-generated electromagnetic field. Assuming weak inter-fragment correlations, but strong intra-fragment correlations, a mean-field evolution equation for the single-fragment distribution functional is derived. We also identify the equation's Hamiltonian formulation. By incorporating strong correlations between a charged particle and the field it generates, the new model captures the effects of strong radiation reaction non-perturbatively. The fragment kinetic formalism offers an attractive approach to modeling exotic light-matter interactions such as nonlinear and multiple Compton scattering.