靶材自吸收对皮秒激光驱动X射线源特性的影响研究OA

[Background]The self-absorption effect of target materials plays a crucial role in shaping the performance of laser-driven X-ray sources,directly impacting their energy spectrum and angular distribution,which are critical parameters for applications such as high-resolution backlighting and radiographic diagnostics.[Purpose]This study aims to systematically investigate how key parameters,including the electron source position relative to the wire target end-face,the diameter of the wire target,and the atomic number of the target material,affect the energy spectrum and angular distribution of emitted X rays.[Methods]A series of Geant4-based Monte Carlo simulations were performed using a validated wire target model.Key parameters were varied:electron source offset(50-150 μm),wire diameter,and target material(Cu,Mo,W,Au).The simulation model was benchmarked against experimental data obtained from the Xingguang-Ⅲ laser facility.[Results]The results indicate that varying the electron source position within the studied range has a negligible influence on both the photon energy spectrum and angular distribution.In contrast,increasing the wire diameter leads to enhanced absorption of low-energy photons,resulting in noticeable spectral hardening and a broadening of the angular distribution due to increased multiple scattering.Furthermore,higher-Z target materials(W,Au)significantly enhance the high-energy photon yield but concurrently induce greater angular divergence.[Conclusions]The findings provide quantitative insights into the self-absorption mechanism and its differential impact across parameters.This study offers concrete guidance for optimizing target design:selecting appropriate wire diameter and high-Z materials can tailor the spectral hardness and brightness,while mindful management of angular broadening is necessary for applications requiring high directivity.