RF properties of a X-band hybrid photoinjector
RF properties of a X-band hybrid photoinjector
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DOI：
10.1016/j.nima.2011.04.057
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发表时间：
2011-11
影响因子：
1.4
通讯作者：
B. Spataro;A. Valloni;D. Alesini;N. Biancacci;L. Faillace;L. Ficcadenti;A. Fukusawa;L. Lancia;M. Migliorati;F. Morelli;A. Mostacci;B. O'Shea;L. Palumbo;J. Rosenzweig;A. Yakub
中科院分区：
文献类型：
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作者：
B. Spataro;A. Valloni;D. Alesini;N. Biancacci;L. Faillace;L. Ficcadenti;A. Fukusawa;L. Lancia;M. Migliorati;F. Morelli;A. Mostacci;B. O'Shea;L. Palumbo;J. Rosenzweig;A. Yakub
INFN-LNF/UCLA/SAPIENZA合作开发x波段混合光注入器。混合光注入器是一种新型的高亮度电子源，它将驻波腔（充当射频枪）直接耦合到多细胞行波结构上。与分离驻波/行波系统相比，这种配置提供了许多优点。最值得注意的是，反射的射频瞬态几乎完全被抑制，从而消除了对环行器的需要和发生在分裂系统漂移部分的束加长效应。这些特性允许将器件缩放到更高的场和频率，这将大大提高光束亮度。驻波段和行波段之间的射频耦合是在波束遇到的第四个单元中完成的，而西南波段则在轴上与之电耦合。这种耦合模式是特别有利的，因为它伴随着加速场的90°相移，在光束上产生强烈的速度聚束效应，从而扭转了标准1.6单元光注入器在枪出口后通常引起的束长。在这种情况下，从光束动力学的角度来看，可以看到装置可以在~ 3.5MeV下产生十倍飞秒的光束，并且即使在存在强压缩的情况下，发射度补偿动力学仍然是可控的。我们在这里提出了器件特性的调查。特别地，我们展示了电磁模拟的结果，与SW和TW部分的温度调谐相关的波束动力学分析，以及使用器件原型的头拉和散射系数测量的RF表征。
An INFN-LNF/UCLA/SAPIENZA collaboration is developing a hybrid photoinjector in X-band. A hybrid photoinjector is a novel high brightness electron source that couples a standing wave cell cavity (acting as an RF gun) directly to a multi-cell travelling-wave structure. This configuration offers a number of advantages over the split standing wave/travelling-wave system. Most notably the reflected RF transient is almost completely suppressed, thus eliminating the need for a circulator and the bunch lengthening effect that occurs in the drift section of the split system. These properties allow scaling of the device to higher field and frequencies, which should dramatically improve beam brightness. The RF coupling between the standing and the traveling wave sections is accomplished in the fourth cell encountered by the beam, with the SW section electrically coupled to it on-axis. This mode of coupling is particularly advantageous, as it is accompanied by a 90° phase shift in the accelerating field, resulting in strong velocity bunching effects on the beam that reverse the usual bunch lengthening induced after the gun exit in standard 1.6 cell photoinjectors. In this scenario, from the beam dynamics point of view, it is seen that device may produce ten's of femtosecond beams at ∼3.5MeV and the emittance compensation dynamics remains manageable even in the presence of strong compression. We present here a survey of the device characteristics. In particular we show the results of the electromagnetic simulations, a beam dynamics analysis related to the temperature tuning of the SW and TW section, and a RF characterization using bead pull and scattering coefficient measurements of a device prototype.