高频微波系统多电子倍增效应的纳秒级时间分辨测量、理论研究及其抑制方法研究

Multipacting phenomena can be observed in various radio freqency(RF) or microwave components,like the RF system of particle accelerators, the RF/microwave payloads of spacecrafts or satellites. The breakdown caused by Multipacting can cause many problems in practical applications. On one hand, it will limit the gradient of the electromagnetic field which consequently limits the compactness of the accelerators or satellites. On the other hand, it will cause the failure of the RF/microwave system, which turns out to be one of the main limitations in the practical use of accelerator driven subcritical(ADS) systems as well as the main limitation of the performance of the new generation of comunication satellites.Our proposal is suppose to perform the first nano-second-time resolved measurement of the Multipacting current in the world, which can provide the experimental data for benchmarking the newly developed Multipacting theory and the particle tracking codes which can be used to optimize the design to obtain the Multipacting free RF/microwave components. The goal of the proposed research also includes fully understanding the Multipacting process, including the saturation stage of the Multipacting process,through experiment,theory and advanced parallel computing capability obtained under the support of our previous Chinese Science Fundation on parallel computing. In the meantime, the proposed research on the subject of Multipacting between the dielectric window and the copper plate and its relation with the surface treatment and surface etching due to breakdown, will be greatly helpful for the commissioning of the RF system of the 100MeV cyclotron and for the devolopments of the suppression strategies of multipacting in RF windows .

多电子倍增（Multipacting）效应广泛存在于粒子加速器高频加速系统、航天器及卫星机载射频微波系统等重要的科研与工程应用领域。由多电子倍增引起的高频/微波元件放电，一方面限制了高频/微波系统的场梯度；另一方面，会使得高频/微波系统失效，制约了加速器驱动次临界堆、核废料处理等需要更高系统稳定性的应用并限制了新一代更高功率的通讯卫星的稳定性表现。因此，本申请拟进行国际上第一次平行板结构多电子倍增过程的具有时间分辨的定量测量，为最新的多电子倍增理论及用于三维复杂元件设计的粒子模拟程序提供比对数据；通过实验、理论及先前我部获自然科学基金项目支持研发的先进并行计算算法与搭建的计算平台，研究掌握平行板结构多电子倍增动力学过程，包括倍增电流的饱和过程；同时，研究介质与金属电极间的多电子倍增效应及其与极板表面特性的关系，找到抑制多电子倍增效应的方法。

二次电子倍增（Multipacting）效应广泛存在于粒子加速器高频加速系统、航天器及卫星机载射频微波系统等重要的科研与工程应用领域。由二次电子倍增引起的高频/微波元件放电，一方面限制了高频/微波系统的场梯度；另一方面，会使得高频/微波系统失效，制约了加速器驱动次临界堆、核废料处理等需要更高系统稳定性的应用并限制了新一代更高功率的通讯卫星的稳定性表现。因此，本项目通过搭建72MHz以及162MHz两个高频实验腔体，国际上第一次在不同的参数条件下分别进行了平行板结构二次电子倍增过程的具有时间分辨的定量测量，为最新的多电子倍增理论及用于三维复杂元件设计的粒子模拟程序提供比对数据；扩展了Non-stationary理论，包含了多种介质、考虑了出射二次电子的散角、考虑了高频腔体的束流负载效应；利用实验数据、理论模型以及先前我部获自然科学基金项目支持研发的先进并行计算算法与搭建的计算平台，研究掌握平行板结构多电子倍增动力学过程，包括倍增电流的饱和过程；同时，研究介质与金属电极间的多电子倍增效应及其与极板表面特性的关系，通过实验验证了抑制多电子倍增效应的方法。