耦合系数和束流强度对驻波加速器性能的影响和耦合系数的测量

Influence of Coupling Coefficient and Beam Current on Characteristics of Standing Wave Accelerator

根据加速器和微波谐振腔的基本理论,采用微波电路理论,分析和计算了驻波加速器输入波导和加速腔之间的耦合系数和束流强度对能量、束流功率、效率和X射线辐射强度等性能的影响。当耦合系数大于1时,随着耦合系数增加,加速器最大输出能量下降。随着加速器束流强度增加,加速器能量V_s降低。对于给定的束流强度,随着耦合系数增加,加速器输出能量、电子注束流功率和X射线的辐射强度存在最大值。为了使加速器获得最佳性能,确定和测量耦合系数十分重要。论文在大功率速调管输出电路的外观品质因子测试方法的基础上,针对不同耦合系数,推导出了驻波加速管的外观品质因子、固有品质因子与加速管输入端处的群延迟和驻波比的相互关系,建立了相应的测试方法。采用矢量网络分析仪,通过测量加速管输入端的群延迟和驻波比,可测得耦合系数等相关参数,该方法已在实验中获得了验证。

The coupling of microwave-cavity and standing-wave accelerator was mathematically modeled with microwave equivalent circuits,theoretically analyzed in electrodynamics and experimentally evaluated.The influence of the beam current and coupling coefficient on the accelerator＇ s properties,including the output energy,beam power,efficiency and X-ray emission,was investigated.The calculated results show that the coupling coefficient and beam current significantly affect the standing-wave accelerators＇ characteristics.For example,as the coupling coefficient increases in β_c 1 range,the peak output energy V_（ms）decreases;as the beam-current increases,the output energy Vs decreases.At a given beam-current,the output energy,beam power and X-ray emission intensity can be maximized by increasing β_c.In addition,the dependence of the group delay and voltage standing-wave ratio on the coupling coefficient,external and inherent factors was derived and measured with vector network analyzer.The calculated and measured results were found to be in good agreement.