Laser-driven relativistic intense electron beams are in high demand for applications in inertial confinement fusion, material detection, and laser-driven nuclear physics. Currently, the charge of laser-driven electron sources is typically on the order of nC/sr, which is significantly lower than the fundamental charge requirement of 1μC/sr for the aforementioned applications, thus becoming a critical issue that constrains their development. The interaction of high-power picosecond lasers with near-critical density foams is an extremely effective approach to obtaining ultra-high charge electron beams. On the XGIII laser facility, we have conducted multiple rounds of experimental research on the interaction between lasers and subcritical density foam targets. A nanosecond laser was used to strike a gold cavity target to produce X-rays, which indirectly ablated the foam to generate a stable and controllable subcritical density plasma. Utilizing the interaction of picosecond lasers with this plasma, high-energy, high-charge electron beams with charge exceeding 1μC/sr were experimentally produced. Compared to electron beams produced by laser-solid target interactions, these beams exhibit an order of magnitude higher in charge and similarly, the secondary gamma radiation dose is also an order or two higher. The experiments demonstrate excellent repeatability, preliminarily proving the superiority of subcritical density foam plasma in laser-driven electron acceleration.

near-critical Density Foam,Laser Direct Acceleration