Self-generated magnetic fields play a crucial role in relativistic laser–plasma interactions. A comprehensive understanding of their microscopic structures and parameter dependencies is of great significance for enhancing the energy gain of inertial confinement fusion, optimizing the efficiency of plasma-based accelerators and radiation sources [1,2], and enabling laboratory astrophysics experiments. Recent work reveals that, in relativistic laser-driven near-critical-density plasma channels, the self-generated magnetic field exhibits a nontrivial island-like structure [3]. This structure originates from the interplay between the global longitudinal current and the transverse current induced by laser ablation at the channel front edge. Their superposition leads to vortex currents distributed alternately above and below the channel axis, thereby generating periodically arranged asymmetric magnetic islands. In this talk, we will discuss the influences of the magnetic island structure on particle accelerations and gamma-ray photon emission [4,5].
[1] Z. Gong et al., Scientific Reports 9 (1), 17181 (2019)
[2] Z. Gong et al., Physical Review E 102 (1), 013206 (2020)
[3] Z. Gong et al., Physical Review Letters 127 (16), 165002 (2021)
[4] D. Cai, Z. Gong et al., Physics of Plasmas 32 (7) (2025)
[5] G. Qiu, …, Z. Gong et al., Ultrafast Science 6, 0126 (2026)

laser plasma interaction,self-excitation magnetic field,photon emission