Generating opposing magnetic fields in a cavity using a four-petal target in laser-plasma interactions

Abstract

High-intensity laser-solid interactions provide a platform for generating strong magnetic fields, but controlling their topology remains a challenge. In this work, we introduce a flower-shaped solid target with a central cavity, designed to produce spatially separated magnetic fields of opposite polarity under irradiation by two relativistic laser pulses incident from opposite directions. Using two-dimensional particle-in-cell simulations with the EPOCH code, we examine the resulting plasma dynamics, current distributions, and magnetic field evolution. The simulations show two distinct current loops forming within the cavity, each sustaining oppositely directed magnetic fields. Compared to the no-target case, all configurations significantly enhance magnetic field confinement. These results demonstrate that target geometry governs both field topology and the trade-off between peak field strength and temporal stability.