摘要
针对GaAs光阴极像增强器在ns级选通成像中的时空特性,通过引入传输线阻抗完善了光阴极径向RLC传输模型,更准确地描述了选通过程中光快门的变化趋势,实验证实去除防离子反馈膜有利于改善光快门,使得光快门与电快门更为一致,在驱动电脉冲宽度为17.7 ns时,光快门宽度与电快门宽度的差异仅为1.1 ns;基于蒙特卡罗模拟方法,建立了光电子在分段线性快门脉冲电压驱动下经过第一近贴后的空间弥散模型,模拟结果表明:GaAs光阴极相较于S20光阴极在选通成像中的空间分辨下降更小。在20 lp/mm时,GaAs的动态空间分辨是静态空间分辨的80%,而S20光阴极不足70%,理论模拟与实验结果相一致,所建立的模型可用来分析和优化像增强器结构参数,为优化选通成像性能提供理论依据。
Considering the spacetime characteristics of the GaAs photocathode image intensifier in ns-level gated imaging,this study undertakes a theoretical simulation and experimental validation.For theoretical simulation,the radial RLC transmission model of the photocathode is enhanced by incorporating transmis⁃sion line impedance.This refinement enables a more accurate description of the optical shutter's behavior during the gating process.Experimental evidence confirms that removing the anti-ion feedback film en⁃hances the optical shutter,aligning it closely with the electric shutter.Specifically,when the driving elec⁃tric pulse width is 17.7 ns,the difference between the optical shutter width and the electric shutter width is merely 1.1 ns.For experimental validation,a spatial dispersion model of photoelectrons,driven by a seg⁃mented linear shutter pulse voltage after the first close attachment,is established using the Monte Carlo simulation method.Simulation outcomes indicate that the spatial resolution degradation of the GaAs photo⁃cathode in gating imaging is inferior to that of the S20 photocathode.At a spatial resolution of 20-line pairs per millimeter(lp/mm),GaAs maintains 80%of its static spatial resolution,whereas the corresponding figure for the S20 photocathode is less than 70%.Notably,the theoretical simulation aligns seamlessly with the experimental results,affirming the applicability of the model for analyzing and optimizing image intensifier structural parameters.This model serves as a foundational framework for enhancing gating im⁃aging performance.
作者
李冬
杨凯翔
盛亮
李阳
段宝军
张美
LI Dong;YANG Kaixiang;SHENG Liang;LI Yang;DUAN Baojun;ZHANG Mei(State Key Laboratory of Intense Pulsed Radiation Simulation and Effect(NorthwestInstitute of Nuclear Technology),Xi’an 710024,China)
出处
《光学精密工程》
EI
CAS
CSCD
北大核心
2023年第17期2505-2514,共10页
Optics and Precision Engineering
基金
卓越青年基金资助项目(No.JQZQ021901)
国家自然科学基金资助项目(No.12175183)。
关键词
GaAs光阴极
选通特性
动态空间分辨
像增强器
GaAs photocathode
gating characteristics
dynamic spatial resolution
image intensifier
