束流诊断系统为实现和提升加速器性能提供重要测量信息，随着加速器装置的快速发展，对束流参数诊断的要求日益提高。基于腔式探头的束测方法有着分辨率高，动态范围大，包含丰富的束流信息等优点，且属于非阻拦式测量，已在自由电子激光等装置上广泛应用。本论文的工作围绕腔式探头束流诊断系统展开，对基于腔式探头的束团横向位置，到达时间，束团长度以及束流能量等多个参数的高精度诊断进行了深入研究。论文分析了基于腔式探头的束流参数诊断方法的基本原理。从束流负载效应及谐振腔的电磁场分布出发，推导了谐振腔的本征模式与束流参数之间的关系。理论分析表明，TM010 模与 TM110 模可用于束流位置，到达时间等多个参数的测量。腔式束流位置探测器（Beam Position Monitor, BPM）是加速器中高分辨率束流位置监测的关键设备，本论文深入开展了低 ? 型腔式 BPM 的研制。探头部分设计为重入式谐振腔，工作频率为 4760 MHz。针对低 ? 谐振腔，微波信号处理部分设计为 IQ 正交解调方案。在西安高亮源注入器搭建了腔式 BPM 系统，通过束流实验评估得到系统的位置分辨率为 0.73 μm(x),0.92 μm(y)。在此基础上进行了进一步的优化，新研制的腔式 BPM 的 ?/𝑄、隔离度等关键参数都得到了明显的提升。论文面对 FEL、超快电子衍射等装置中泵浦探测实验的需求，设计了用于低电荷量的腔式束流到达时间监测器（Beam Arrival Time Monitor，BAM）。工作的重点在于高灵敏度探头的研制，利用仿真软件对探头进行参数扫描提高 ?/𝑄 值。优化后谐振腔的 ?/𝑄 为 292 Ω，灵敏度为 131.2 mV/pC。论文中对腔式 BAM 的信号处理部分进行了优化，为系统提供了低相噪的参考信号。在实验室的 THz 束线上评估了系统的分辨率，束流实验结果表明到达时间分辨率为 35 fs@0.5 pC，实现了低电荷量下的高分辨率束流到达时间诊断。论文对基于腔式探头的束长及束流能量测量方法进行了深入的理论分析和仿真工作，给出了两个参数测量的基本原理，理论分辨率以及谐振腔的设计原则。同时还考虑了束流横向位置、束团纵向分布等因素可能带来的误差以及束长、束流能量对探头幅度的耦合影响。论文中利用 BAM 探头在 TTX 测试束线上验证了不同束流能量下探头的灵敏度变化，与仿真一致。在以上研究的基础上，设计了由三个谐振腔组成的紧凑系统，能够同时用于束流多个关键参数的实时非阻拦诊断。

Beam diagnostics systems play a crucial role in particle accelerators, serving as essential components. As accelerator facilities continue to advance, the demand for high-precision beam diagnosis is rapidly escalating. The beam monitors based on resonant cavity are effective tools for noninvasive beam characterization. This technique has the advantages of high signal-to-noise ratio, compact structure and is related to multiple parameters compared with other methods. The cavity beam position monitor and cavity beam arrival time monitor have been widely adopted across many accelerators. This paper focuses on beam diagnostics based on the resonant cavity, exploring the application of this approach in achieving high-resolution measurements for multiple parameters, including beam position, arrival time, bunch length, and beam energy.This paper analyzes the fundamental principles of beam parameter diagnostics using resonant cavities. By examining the beam loading effect and the electromagnetic field distribution within the resonant cavity, the relationship between the excited eigenmodes in the cavity and the beam parameters is derived. The theoretical analysis demonstrates that the TM010 and TM110 modes can be utilized for measuring multiple parameters, including beam position, arrival time, etc. The cavity beam position monitor is a critical equipment for high-resolution beam position monitoring in accelerators. In this paper, we have developed a low-? Cavity BPM system. Both the reference cavity and the position cavity are designed as reentrant structures, operating at the working frequency of 4760 MHz. For the low-? resonant cavities, the RF signal processing section adopts an IQ quadrature demodulation scheme. To evaluate the system‘s performance, the cavity-based BPM was implemented at the injector of the Xian gamma-ray light source. The resolution was measured as 0.73 μm (x) and 0.92 μm (y) through beam experiments. Based on the experiment results, further optimization was performed on the pickup of the Cavity BPM, resulting in noticeable enhancements in key parameters such as ?/𝑄 and X-Y isolation, as demonstrated by the ? simulation and cold test results. For the needs of pump-probe experiments in accelerators such as FELs and UEDs, this paper presents the design and implementation of a high-resolution cavity beam arrival time monitor for charges less than 1 pC. The main focus of this work lies in developing a highly sensitive pickup. To improve the ?/𝑄 value, the simulation using CST software was conducted by performing parameter scanning on the cavity length and radius of the resonant cavity. The optimized cavity achieved an ?/𝑄 value of 292 Ω and a sensitivity of 131.2 mV/pC. Furthermore, the paper optimized the readout electronic by providing a reference signal with low phase noise for the BAM system. Following the completion of system fabrication and testing, the resolution of the BAM system was evaluated on the laboratory’s THz beamline. The experimental results revealed an arrival time resolution of 35 fs@0.5 pC, achieving high-resolution diagnostics of beam arrival time for charges less than 1 pC.For the measurement of the bunch length and beam energy based on the resonant cavity, a comprehensive theoretical analysis and simulation are conducted in this paper. The basic principles, theoretical resolution, and design principles of the resonant cavity were elucidated. We also carefully considered the potential errors caused by factors like transverse beam position and longitudinal beam distribution. The sensitivity variation of the TM010 mode with different beam energies was experimentally verified using the BAM pickup on the TTX test beamline, consistent with the simulation analysis. Based on the above research, a compact diagnostics system composed of three resonant cavities was designed for non-intrusive diagnostics of multiple key parameters simultaneously.