麦克风效应对CiADS超导腔稳定性影响的仿真分析

加速器驱动嬗变研究装置(CiADS)对质子超导直线加速器提出了高稳定性要求，在工程设计阶段需对直线加速器的各种不稳定因素，特别是对超导腔的麦克风效应的影响进行评估。基于谐振系统的冲击响应模型，发展了一种离散化的电压迭代求解方法，并利用该方法构建了高频系统仿真程序，用于分析麦克风效应作用下超导腔的时变状态。通过仿真，研究了麦克风效应对腔体幅相稳定性的影响及与超导腔的谐振频率、Q值和带宽等参数的关系。结果表明，麦克风效应主要影响超导腔的相位稳定，其影响程度取决于麦克风振荡频率与腔的谐振频率、频率偏移量与腔体半带宽的比值。给出了满足CiADS直线加速器超导腔幅相稳定性指标(0.1%和0.1°)的麦克风振荡强度限值。

Simulation and Analysis of Microphonics Instability of CiADS Superconducting Cavity

To satisfy the high stability requirements of the proton linac for China initiative Accelerator Driven System (CiADS), the influence factors including microphonics for linac stability need to be evaluated at the stage of design. Based on the impulse response model of the resonant system, the discretized iterative algorithm of cavity voltage and corresponsive simulation program were developed in order to analyze the time-varying dynamical process of superconductive cavity under the microphonics. The effect of microphonics on the cavity phase stability, and the relationship between microphonics with cavity parameters, such as resonant frequency, Q value and bandwidth, were simulated. The results show that microphonics mainly effect phase stability of superconducting cavity, and the effect depends on the ratio of the oscillation frequency of microphonics to the resonant frequency of the cavity and the ratio of the frequency shift of microphonics to the half bandwidth of the cavity. The microphonics intensity tolerated by the cavity phase stability requirements (amplitude and phase with 0.1% and 0.1° respectively) of CiADS linac was given.