2-cell超导腔的高阶模分析

 阐述了2-cell Telsa腔的设计。用3维程序HFSS分析了其高阶模的特点，给出了高阶模的主要参数频率、品质因数、分路阻抗以及模式的电场分布，并且π模的电场分布与Superfish的模拟结果相比较，两者是一致的。最后，简要分析了各高阶模对电子加速的影响，分析表明高阶模降低了电子加速效率和束流的稳定性。     

储存环部分填充情况下的纵向耦合不稳定性

通过解析的方法分析了储存环在部分填充情况下的纵向耦合不稳定性,给出了不稳定性增长率和同步振荡频移的表达式.得到了一个有趣的结果:虚部阻抗对不稳定性的增长率也有贡献.这一点和均匀填充情况是不一样的.     

RF characters study of a pick-up parallel-setting HOM coupler

A pick-up parallel-setting high order mode coupler(pps-HOM coupler)has been fabricated at Peking University.It has been tested on a coaxial transmission line and a 2-cell TESLA-shape copper cavity.The test result of the 2-cell TESLA cavity shows that the coupler can cut off the fundamental mode TM010 and absorb HOMs electively.As its RF properties are insensitive to the probe dip length,there is no need to adjust the probe repeatedly during practical operation.     

A waveguide overloaded cavity kicker for the HLS Ⅱlongitudinal feedback system

In the upgrade project of Hefei Light Source(HLSⅡ),a new digital longitudinal bunch-by-bunch feedback system will be developed to suppress the coupled bunch instabilities in the storage ring effectively.We design a new waveguide overloaded cavity longitudinal feedback kicker as the feedback actuator.The beam pipe of the kicker is a racetrack shape so as to avoid a transition part to the octagonal vacuum chamber.The central frequency and the bandwidth of the kicker have been simulated and optimized to achieve design goals by the HFSS code.A higher shunt impedance can be obtained by using a nose cone to reduce the feedback power requirement.Before the kicker cavity was installed in the storage ring,a variety of measurements were carried out to check its performance.All these results of simulation and measurement are presented.     

Study on the HOMs coupler design of spoke cavity

The superconducting spoke cavity has been proposed to accelerate the proton in the low energy section of high power proton linac for an Accelerator Driven Sub-critical System (ADS). Considering that the High Order Modes (HOMs) in the superconducting cavity have far reaching influence on power dissipation and beam stability, the analysis of HOMs of the spoke cavity is needed. In this paper, we put emphasis on the analysis of HOMs of the spoke cavity and the HOMs coupler design.     

Development of a 500 MHz high power RF test stand

A flexible high power RF test stand has been designed and constructed at IHEP to test a variety of 500 MHz superconducting RF components for the upgrade project of the Beijing Electron Positron Collider (BEPCⅡ), such as the input coupler, the higher order modes (HOMs) absorber and so on. A high power input coupler has been conditioned and tested with the RF power up to 250 kW in continuous wave (CW), traveling wave (TW) mode and 150 kW CW in standing wave (SW) mode. A prototype of the HOMs absorber has been tested to absorb power of 4.4 kW. An introduction of the test stand design, construction and high power tests is presented in this paper.     

Study of medium beta elliptical cavities for CADS

The China Accelerator-Driven Sub-critical System(CADS) is a high intensity proton facility to dispose of nuclear waste and generate electric power.CADS is based on a 1.5 GeV,10 mA CW superconducting(SC) linac as a driver.The high energy section of the linac is composed of two families of SC elliptical cavities which are designed with geometrical beta 0.63 and 0.82.In this paper,the 650 MHz β=0.63 SC elliptical cavity is studied,including cavity optimization,multipacting,high order modes(HOMs) and generator RF power calculation.     

RF characters study of a pick-up parallel-setting HOM coupler

A pick-up parallel-setting high order mode coupler （pps-HOM coupler） has been fabricated at Peking University. It has been tested on a coaxial transmission line and a 2-cell TESLA-shape copper cavity. The test result of the 2-cell TESLA cavity shows that the coupler can cut off the fundamental mode TM010 and absorb HOMs electively. As its RF properties are insensitive to the probe dip length, there is no need to adjust the probe repeatedly during practical operation.     

Study on the HOMs coupler design of spoke cavity

The superconducting spoke cavity has been proposed to accelerate the proton in the low energy section of high power proton linac for an Accelerator Driven Sub-critical System (ADS).Considering that the High Order Modes (HOMs)in the superconducting cavity have far reaching influence on power dissipation and beam stability,the analysis of HOMs of the spoke cavity is needed.In this paper,we put emphasis on the analysis of HOMs of the spoke cavity and the HOMs coupler design.     

深度抑制的超导高频腔研究

参照KEKB 509MHz超导腔,同时考虑到许多方面因素的影响,为北京正负电子对撞机改造工程改频设计了一个500MHz超导腔,并且对腔的一些性能进行了模拟计算,同时利用铝模型腔对一些主要参数进行了测量和校核.