Two cavities of different sizes with a photonic crystal structure have been developed for axion searches. In the cavities, the dispersion relation in the photonic crystal is utilized, and so they are called “DRiPC cavities”. The size of the smaller cavity is $100 \times 100 \times 10$ mm, where 16 cylindrical metal poles with a diameter of 4 mm are introduced in a $4\times4$ grid at 20 mm intervals. In this study, the grid interval in the $x$ direction in the smaller cavity, $L_x$, was changed to investigate the resonance frequency, $Q$-value, and the electric field profile at each $L_x$. The lowest three frequencies have been compared with those simulated by the finite element method and have been found to be in excellent agreement. The lowest-frequency mode could be tuned from 5.10 GHz ($L_x = 25.0$ mm) to 6.72 GHz (13.9 mm), centered on 5.87 GHz at $L_x = 20$ mm. This wide tunability range, 27.7$\%$, was suitable for a search with a modest $Q$-value. By examining the electric field distributions with the bead-pull method, the lowest-frequency modes at $L_x=16.0$–25.0 mm were ${\rm TM_{010}}$-like. This mode was also obtained in a larger cavity ($180 \times 180 \times 20\,\text{mm} \times 2$) with the same photonic crystal structure. These results led us to conclude that a DRiPC cavity has features suitable for future axion search experiments.

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用于轴子搜索的具有光子晶体结构的腔的开发

已经开发了两个具有光子晶体结构的不同尺寸的腔用于轴子搜索。在腔体中，利用了光子晶体中的色散关系，因此被称为“DRiPC腔体”。较小的空腔尺寸为$100×100×10$mm，其中16个直径为4mm的圆柱形金属杆以20mm的间隔在$4×4$的网格中引入。在这项研究中，改变了较小腔中 $x$ 方向上的网格间隔 $L_x$，以研究每个 $L_x$ 处的共振频率、$Q$ 值和电场分布。最低的三个频率已与有限元方法模拟的频率进行了比较，发现它们非常吻合。最低频率模式可以从 5.10 GHz ($L_x = 25.0$ mm) 调谐到 6.72 GHz (13.9 mm)，以 5 为中心。$L_x = 20$ mm 时为 87 GHz。27.7$\%$ 这个宽的可调范围适用于具有适度 $Q$ 值的搜索。通过珠拉法检查电场分布，$L_x=16.0$–25.0 mm 处的最低频率模式为${\rm TM_{010}}$-like。这种模式也是在具有相同光子晶体结构的更大腔体（$180\times 180\times 20\,\text{mm}\times 2$）中获得的。这些结果使我们得出结论，DRiPC 腔具有适合未来轴子搜索实验的特征。\text{mm} \times 2$) 具有相同的光子晶体结构。这些结果使我们得出结论，DRiPC 腔具有适合未来轴子搜索实验的特征。\text{mm} \times 2$) 具有相同的光子晶体结构。这些结果使我们得出结论，DRiPC 腔具有适合未来轴子搜索实验的特征。