3.9GHz谐振腔中高阶模的渐近反冲和RMS反冲的计算

Detuning related coupler kick variation of a superconducting nine-cell 1.3 GHz cavity

Superconducting TESLA-type cavities are widely used to accelerate electrons in long bunch trains, such as in high repetition rate free electron lasers. The TESLA cavity is equipped with two higher order mode couplers and a fundamental power coupler (FPC), which break the axial symmetry of the cavity. The passing electrons therefore experience axially asymmetrical coupler kicks, which depend on the transverse beam position at the couplers and the rf phase. The resulting emittance dilution has been studied in detail in the literature. However, the kick induced by the FPC depends explicitly on th…

SHINE注入器的耦合器RF踢及发射度优化

Coupler RF kick and emittance optimization of the SHINE injector

本文针对SHINE注入器中耦合器RF踢导致的发射度增长，提出有损材料结合CST仿真的计算方法，并通过双耦合器腔及多腔角度排列优化使发射度低于设计指标。

Efficient model for low-energy transverse beam dynamics in a nine-cell 1.3 GHz cavity

FLASH and the European XFEL are SASE-FEL user facilities, at which superconducting TESLA cavities are operated in a pulsed mode to accelerate long bunch-trains. Several cavities are powered by one klystron. While the low-level rf system is able to stabilize the vector sum of the accelerating gradient of one rf station sufficiently, the rf parameters of individual cavities vary within the bunch-train. In correlation with misalignments, intrabunch-train trajectory variations are induced. An efficient model is developed to describe the effect at low beam energy, using numerically adjusted transfe…

NLC加速结构中的高偶极带

Higher Dipole Bands in the NLC Accelerating Structure

我们表明，散射矩阵计算的偶极模式之间的23-43 GHz的206细胞失谐结构（DS）是一致的有限元计算和非耦合模型的结果。特别是，这些频带的尾流均方根和与第一偶极子频带的尾流均方根和相当。我们还表明，对于RDDS 1非耦合尾场计算较高的频段是一致的测量。特别是，一个明确的26 GHz的信号，在短距离尾流中被发现在这两个结果。

康奈尔能量回收直线加速器注入器原型的低发射度验证

Demonstration of Low Emittance in the Cornell Energy Recovery Linac Injector Prototype

我们提出了一个详细的研究康奈尔能量恢复直线加速器的光电注入器，高亮度，高重复率（1.3 GHz）的直流光电发射源，旨在驱动硬X射线能量恢复直线加速器（ERL）所产生的电子束的六维相空间。建立了完整的喷油器仿真模型，并进行了试验验证和优化。水平和垂直的二维横向相空间，以及时间分辨（切片）的水平相空间，进行了模拟和直接测量的19 pC和77 pC聚束在大约8 MeV的注射器的末端。选择这些聚束电荷是因为如果以全1.3 GHz重复率操作，则它们对应于25 mA和100 mA的平均电流。对于19（77）pC/聚束，所得到的90%归一化横向发射度在水平平面中分别为0.23 +/-0.02（0.51 +/-0.04）微米，在垂直平面中分别为0.14 +/-0.01（0.29 +/-0.02）微米。这些发射度分别用2.1 +/- 0.1（3.0 +/- 0.2）ps的相应聚束长度测量。在每种情况下，均方根动量扩散被确定为1 e-3的数量级。测量和模拟之间的良好的整体协议已被证明。使用的发射度和聚束长度测量在19 pC/聚束，我们估计在1.3 GHz，5 GeV的硬X射线ERL的电子束质量至少是一个因素的20倍，优于现有的存储环时，每个设备的均方根能量扩展被认为是。这些结果代表了高亮度，高电流光电注入器领域的一个里程碑。

Gigahertz repetition rate thermionic electron gun concept

We present a novel concept for the generation of gigahertz repetition rate high brightness electron bunches. A custom design 100 kV thermionic gun provides a continuous electron beam, with the current determined by the filament size and temperature. A 1 GHz rectangular RF cavity deflects the beam across a knife-edge, creating a pulsed beam. Adding a higher harmonic mode to this cavity results in a flattened magnetic field profile which increases the duty cycle to 30%. Finally, a compression cavity induces a negative longitudinal velocity-time chirp in a bunch, initiating ballistic compression.…