Research progress on laser beam–target coupling for fusion energy

Since 2022, the U.S. National Ignition Facility has achieved controlled thermonuclear fusion ignition eleven times, confirming the scientific feasibility of laser inertial fusion energy (IFE). This has spurred global efforts toward high-repetition-rate, high-gain fusion. Efficient laser-target coupling is critical but faces three challenges: high-gain target fusion physics design, dynamic beam-target coupling technology, and the environmental impact of high-repetition-rate energy release in the target chamber. This paper systematically reviews worldwide research progress focused on efficient beam-target coupling for commercial fusion energy. First, it discusses direct-drive target optimization, broadband laser technologies and laser-plasma instability suppression to raise fusion energy gain close to the hundredfold threshold required for power generation. Second, it summarizes international engineering demonstrations of flying pellet injection, high-speed optical tracking and closed-loop laser steering, comparing milestone achievements from the U.S., Japan, and emerging non-contact superconducting target delivery schemes. Third, it analyzes how repeated neutron, X-ray and ion radiation deteriorates the first wall and generates aerosol/gas disturbances that disrupt laser propagation and cryogenic target survival, evaluating dry-wall, buffer gas, wetted wall, and thick liquid wall mitigation strategies. Future directions include integrated multiphysics modeling, machine-learning-enhanced control, novel injection methods, and experimental studies on aerosol-laser interactions and chamber recovery. These challenges are expected to be resolved within 5-10 years, paving the way to commercial IFE.