Novel radiative trapping mechanism in ultra-intense laser–plasma interactions

Known mechanisms for radiation-reaction-induced trapping are restricted to transverse confinement or require the standing wave formed by colliding laser pulses. Here, we report a distinct mechanism where radiation reaction drives longitudinal trapping using a single ultra-intense laser pulse. Particle-in-cell simulations and a recently found attractor solution of the Landau–Lifshitz equation reveal that in the superposition of the laser field and the laser-driven electrostatic field, electrons acquire a field-strength-determined drift velocity vd. In regions where the field distribution satisfies dvd/dx < 0, electrons accumulate where vd matches the hole-boring velocity, forming dense and ultra-thin layers with solid densities.