X波段高梯度加速技术是常温加速结构的研究热点，在正负电子对撞机、自由电子激光、小型光源和紧凑型医疗装置中有着广泛的应用前景。提升加速梯度可以大大缩小装置的尺寸，降低装置的造价。限制加速结构达到高梯度的重要制约因素是射频击穿现象，该现象会引起束流品质下降、腔间相移改变、加速结构表面损伤等不利影响，研究并抑制射频击穿现象对于实现高梯度加速结构具有重要意义。另一方面X波段加速结构中的尾场效应严重，尾场会对束团产生恶劣影响甚至导致束流崩溃。为了实现装置在多束团模式下的稳定工作，目前人们研制出了多种可以阻尼尾场的加速结构。Choke-mode加速结构是一种可以抑制高阶模式的强阻尼结构，具有加工简单、成本低廉、表面磁场低等优点。经过多年的发展，C波段的Choke-mode加速结构已应用于可在多束团模式下工作的自由电子激光装置中，但其在X波段下的研究仅停留在理论设计阶段。目前，国内外对X波段Choke-mode加速结构的高梯度性能研究鲜见报道，人类对其在高梯度下的射频击穿现象认识很少。本论文首先采用行波多腔加速结构开展了加速结构测试的实验方法研究，通过高梯度实验总结出具有普适性的研究分析方法。该加速结构稳定工作时的加速梯度达到110 MV/m，验证了清华大学加速器实验室的高梯度研制技术。本论文设计并制作两节型Choke-mode单腔加速结构，开展高梯度实验，对choke中的射频击穿现象进行了深入研究。提出利用场致发射电流信号作为choke中射频击穿事件的依据，并在表面形态观察中得到了验证。通过对射频击穿时间分布的研究，发现射频击穿具有脉冲宽度和电场记忆效应，单一微波脉冲内的射频击穿概率不符合经验公式中脉宽5次方和电场30次方的关系。射频击穿概率的研究表明老练过程存在10^7量级的微波脉冲变化常数。研究发现choke内过高的电场和较小的尺寸引发了严重的射频击穿，choke内的射频击穿限制了加速结构梯度的提升。通过降低choke区域的电场和扩大choke区域的尺寸，论文工作设计并研制出高梯度Choke-mode单腔加速结构，实验中最大加速梯度可达130 MV/m。通过比较不同尺寸choke的高梯度实验结果，论文总结出评估Choke-mode加速结构高梯度性能的参量，为将来设计高梯度Choke-mode行波多腔加速结构打下了基础。

X-band high-gradient accelerating technology is a hotspot in the research of room-temperature accelerating structures having wide ranging application prospects in electron-positron linear colliders, X-ray free electron lasers (XFEL), small light sources, and compact medical accelerators. The size and cost of such devices can be reduced by increasing the accelerating gradient. The Radio Frequency (RF) breakdown phenomenon, which will lower beam quality and damage the structure surface, is one of the main limitations to achieving high gradients. In addition the strong wakefield excited by multibunch beam in X-band accelerating structures will cause beam instability or even beam break up. Several kinds of structures with higher-order-mode (HOM) suppression have been researched in the effort to damp the wakefield effect.The Choke-mode accelerating structure is one of these HOM damping structures. It has the advantage of relatively simple fabrication and low surface magnetic field. C-band Choke-mode accelerating structures have been successfully applied in multibunch XFEL. However, the X-band Choke-mode study remains in the theoretical design stage. The breakdown characteristics and high-gradient performance of the choke are still unknown.In the thesis, a universal high-gradient testing and analyzing method was established by conducting high-gradient experiments on a multi-cell traveling-wave structure. This structure reached 110 MV/m which validated Tsinghua high-gradient technology. Based on the same X-band high-gradient technology, several different single-cell Choke-mode accelerating structures were designed, fabricated and high-gradient tested to study the related RF breakdown characteristics. The absence of field emission current flash was proposed to be the sign of breakdowns occurring inside the choke, this was verified by the post-mortem observation. Evaluation of the breakdown rate revealed that there is memory effect with pulse width and electric field. The breakdown rate in a single RF pulse did not have the 5th order pulse width and 30th order electric field dependency predicted by the empirical formula.An RF pulse evolution constant of the order of 10^7 was observed from the conditioning rate of the structure. It was observed that high electric field and small choke dimension caused serious breakdowns in the choke which was the main limitation of the high-gradient performance. The Choke-mode accelerating structures reached 130 MV/m by decreasing the electric field and increasing the choke gap. A new quantity was proposed to give the high-gradient performance limit of Choke-mode accelerating structures due to RF breakdown. The new quantity was obtained from the summary of the high-gradient experiments and could be used to guide high-gradient Choke-mode accelerating structure design.