Measurements of copper and cesium telluride cathodes in a radio-frequency photoinjector
Measurements of copper and cesium telluride cathodes in a radio-frequency photoinjector
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DOI：
10.1103/physrevstab.18.043401
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发表时间：
2015-04
影响因子：
--
通讯作者：
E. Prat;S. Bettoni;H. Braun;R. Ganter;T. Schietinger
中科院分区：
文献类型：
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作者：
E. Prat;S. Bettoni;H. Braun;R. Ganter;T. Schietinger
射频（rf）光注入器通常用于产生强烈明亮的电子束，用于广泛的应用，最著名的是作为x射线自由电子激光器的驱动器。光电阴极安装在射频枪内，由合适的激光照射，因此作为电子源起着至关重要的作用。光电阴极表面材料的性质决定了电子源的本征发射率和量子效率。我们在相同的射频光注入器中测量了铜和碲化铯阴极的本征发射度和量子效率，从而首次比较了相同条件下金属和半导体阴极的性能。我们的结果与理论预期一致，并且表明考虑到加速器的应用，两种材料的本征发射度差异并不显著。我们得出结论，碲化铯光电阴极提供了一个高得多的量子效率，基本上可以忽略掉光束发射度的退化。
Radio-frequency (rf) photoinjectors are commonly used to generate intense bright electron beams for a wide range of applications, most notably as drivers for X-ray Free-Electron Lasers. The photocathode, mounted inside an rf gun and illuminated by a suitable laser, thereby plays a crucial role as the source of the electrons. The intrinsic emittance and the quantum efficiency of the electron source are determined by the properties of the photocathode ’ s surface material. We present measurements of the intrinsic emittance and the quantum efficiency performed with copper and cesium telluride cathodes in the same rf photoinjector, thus comparing, for the first time, the performance of metal and semiconductor cathodes under the same conditions. Our results are consistent with theoretical expectations and show that the difference in intrinsic emittance for the two types of material is not significant in view of accelerator applications. We conclude that cesium telluride photocathodes provide a much higher quantum efficiency at essentially negligible degradation in beam emittance.