Higher-order mode analysis for SOLEIL-type superconducting cavity

SOLEIL型超导腔的高次模分析研究

A 499.8 MHz SOLEIL-type superconducting cavity was simulated and designed for the first time in this paper.The higher-order mode(HOM)properties of the cavity were investigated.Two kinds of coaxial HOM couplers were designed.Using 4 L-type and 4 T-type HOM couplers,the longitudinal impedance and the transverse impedances were suppressed to below 3 kΩand 30 kΩ/m,respectivly.The HOM damping requirements of Hefei Advanced Light Facility(HALF)were satisfied.This paper conducted an in-depth study on the radio frequency(RF)design,multipacting optimization,and thermal analysis of these coaxial couplers.Simulation results indicated that under operating acceleration voltage,the optimized couplers does not exhibit multiplicating or thermal breakdown phenomena.The cavity has the potential to reach a higher acceleration gradient.

本文首次仿真设计了一种499.8 MHz SOLEIL型超导腔。着重研究了其高次模性能并为之设计了两种同轴型高次模耦合器。在使用了4只L型和4只T型高次模耦合器后,其纵向和横向阻抗分别被抑制在3 kΩ和30 kΩ/m以下。这充分满足了合肥先进光源HALF的高次模性能需求。本文深入地开展了同轴型耦合器的微波性能设计、二次电子倍增性能优化以及热分析。最终仿真结果表明,在正常运行腔压下优化后的设计不会出现二次电子倍增效应和热失超现象。该超导腔具有达到更高加速梯度的潜力。