新一代高能量、高流强和高亮度粒子加速器在低温真空系统束窗设计方面所面临的挑战主要是：高真空梯度、高密集度和电子云问题，这些问题亟待解决。本项目拟从理论和实验两个方面对低温真空系统束窗的真空性能优化进行研究。在理论方面，以高能质子束流为例，建立全新的包含光子、离子、电子和气体裂解等因素引起的低温真空不稳定性模型，对束窗模型的工作温度、开口面积等关键参数进行模拟计算，提出新的束窗模型优化方案；在实验方面，结合激光处理表面技术，提出一种更长使用寿命、更低二次电子产额和更好抽氢气特性的新型Ti-Zr-V-Hf/Pd五元合金吸气剂复合薄膜方案，对该新型薄膜的制备工艺、二次电子产额和抽氢气特性进行系统研究，从材料角度提高束窗内真空的稳定性。研究成果将为新一代粒子加速器低温真空系统束窗设计和真空室壁吸气剂材料选择提供新思路，推动新一代加速器真空系统设计及建造技术的进步，具有重要的科学意义和工程实用价值。

High vacuum gradient, electron cloud problem and high intensity are three key challenges for beam screen design of new generation accelerator with high energy, high intensity, high luminosity and long beam lifetime. In order to solve these problems, we will study the beam screen model and the related vacuum stability at low temperature experimentally and theoretically. Theoretically, we will establish synchrotron radiation, cracked molecules, ions and electrons caused vacuum instability model for high-energy proton beam and simulate the key parameters of beam screen model with different opening size, temperature, open area. Experimentally, the applicants put forward a new nonevaporable getter Ti-Zr-V-Hf/Pd film with longer service life, lower two electron yield and better pumping characteristic of H2. Combined with laser treated surface technique, the film preparation process, the secondary electron yield property and H2 absorption characteristic of this film will be studied. The research results will provide new insights into the design of beam screen model and the selection of new nonevaporable getter materials for vacuum accelerator system design of the new generation at low temperature, and promote the progress of new generation of accelerator technology, then improve new generation accelerator research and design level with important scientific significance and practical value.