Study of the effect of loop inductance on the RF transmission line to cavity coupling coefficient.
Study of the effect of loop inductance on the RF transmission line to cavity coupling coefficient.
复制标题
研究射频传输线上的环路电感对腔体耦合系数的影响。
DOI：
10.1063/1.4961578
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
K. K. Pant
中科院分区：
文献类型：
--
作者：
S. Lal;K. K. Pant
射频功率耦合是射频加速结构设计和研制中的一个重要方面。采用耦合环的射频功率耦合具有传输线-腔耦合系数β的可调性。文献中使用法拉第感应定律确定耦合环大小的解析表达式与β在临界耦合(β≤1)以下的实验值相当吻合，但与实验值和较高β值的模拟预测有较大偏差。在实际的加速器应用中，由于束流负载补偿、缩短腔填充时间等原因，许多射频腔需要与β>；1过耦合。本文讨论了一种修正的解析公式，在确定任意期望耦合系数的环路尺寸时考虑了环路电感的影响。该解析公式与三维模拟和实验测量值吻合较好。它已经成功地通过了两个476 MHz预聚束器射频腔的功率耦合环路的设计和开发，并使用这些耦合环路成功地将其调节到额定功率水平。
Coupling of RF power is an important aspect in the design and development of RF accelerating structures. RF power coupling employing coupler loops has the advantage of tunability of β, the transmission line to cavity coupling coefficient. Analytical expressions available in literature for determination of size of the coupler loop using Faraday's law of induction show reasonably good agreement with experimentally measured values of β below critical coupling (β ≤ 1) but show large deviation with experimentally measured values and predictions by simulations for higher values of β. In actual accelerator application, many RF cavities need to be over-coupled with β > 1 for reasons of beam loading compensation, reduction of cavity filling time, etc. This paper discusses a modified analytical formulation by including the effect of loop inductance in the determination of loop size for any desired coupling coefficient. The analytical formulation shows good agreement with 3D simulations and with experimentally measured values. It has been successfully qualified by the design and development of power coupler loops for two 476 MHz pre-buncher RF cavities, which have successfully been conditioned at rated power levels using these coupler loops.