Power efficiency enhancement of dielectric assist accelerating structure
Power efficiency enhancement of dielectric assist accelerating structure
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DOI：
10.1016/j.nimb.2019.09.006
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发表时间：
2019-11-15
影响因子：
1.3
通讯作者：
Toyokawa, Hiroyuki
中科院分区：
文献类型：
--
作者：
Satoh, Daisuke;Shibuya, Tatsunori;Toyokawa, Hiroyuki
介质辅助加速（DAA）结构是一种介质加载的加速结构，在室温下具有极高的Q值和分流阻抗。先前的工作集中在使用高纯度氧化镁陶瓷开发原型DAA结构上，表明该结构的无载品质因数（Q（0））为119，314，并且在室温下每单位长度的分流阻抗（Z（sh））为617 M Ω/m。为了实现一个DAA结构具有更高的加速效率比达到与原型，我们研究了一个最佳的介电材料的选择的基础上的分析计算的二维（2D）DAA结构模型和有用的DAA结构在低温下工作。对二维DAA结构的分析计算表明，Ba（Mg 1/3 Ta 2/3）O3中心点Ba（Mg 1/W 2（1/2））O3（BMT-BMW）陶瓷是DAA结构的最佳介电材料，因为它具有最小的射频损耗。采用BMT-BMW陶瓷的五单元C波段（5.712 GHz）DAA结构的模拟表明，在室温下，加速模式的Q（0）超过120，000，Z（sh）超过850 M Ω/m。对于在27 K的低温下操作的DAA结构，由高纯氧化镁陶瓷和无氧高导电性铜组成的DAA结构的Q（0）和Z（sh）通过模拟估计分别大于765，000和3.8 G Ω/m。
Dielectric assist accelerating (DAA) structures, which have extremely high Q-factor and shunt impedance at room temperature, are a type of dielectric loaded accelerating structure. Previous work that focused on developing a prototype DAA structure using high-purity magnesia ceramic showed that the unloaded quality factor (Q(0)) of the structure was 119,314 and the shunt impedance per unit length (Z(sh)) was 617 M Omega/m at room temperature. In order to realise a DAA structure with a higher acceleration efficiency than that attained with the prototype, we investigated the selection of an optimum dielectric material based on the analytical calculations of a two-dimensional (2D) DAA structure model and the usefulness of a DAA structure operating at a cryogenic temperature. The analytical calculations of the 2D-DAA structure showed that the Ba(Mg1/3Ta2/3)O3 center dot Ba(Mg-1/W-2(1/2))O-3 (BMT-BMW) ceramic was the optimum dielectric material for the DAA structure as it had the smallest rf losses. A simulation of a five-cell C-band (5.712 GHz) DAA structure with a BMT-BMW ceramic indicated that Q(0) of the accelerating mode was over 120,000 and Z(sh) exceeded 850 M Omega/m at room temperature. For the DAA structure operating at a cryogenic temperature of 27 K, Q(0) and Z(sh) of the DAA structure, which consisted of high-purity magnesia ceramics and oxygen-free high-conductivity copper, were estimated by simulation to be greater than 765,000 and 3.8 G Omega/m, respectively.