论文标题
在传导冷却超导射频腔的实验，带有场发射阴极
Experiments On A Conduction Cooled Superconducting Radio Frequency Cavity With Field Emission Cathode
论文作者
论文摘要
为了实现安培级电子束加速器，脉冲输送速率需要高于几千摩尔茨的典型照片喷射器重复率。我们在这里提出了一个注射器，原则上可以以与操作RF频率相同的速率生成电子束。在CW模式下运行的传导冷却超导射频（SRF）腔，并在其高轴向电场区域内容纳场发射元件，这是产生高重复速率电子束的可行方法。在本文中，我们报告了具有用于野外发射极支持的niobium杆的传导冷却NB3SN腔的开发和实验。最初的实验表明0.4 mV/m的平均加速梯度相当于峰值梯度为3.2 mV/m。测得的RF腔质量因子比我们的目标略高于1.4 x 108。所达到的现场梯度受到相对较低的输入RF功率以及外部电源和RF腔之间的耦合不佳的限制。通过理想耦合，场梯度的高度可能高达0.6 mV/m，仍然低于我们的目标约为1 mV/m。
To achieve Ampere-class electron beam accelerators the pulse delivery rate need to be much higher than the typical photo injector repetition rate of the order of a few kilohertz. We propose here an injector which can, in principle, generate electron bunches at the same rate as the operating RF frequency. A conduction-cooled superconducting radio frequency (SRF) cavity operating in the CW mode and housing a field emission element at its region of high axial electric field can be a viable method of generating high repetition-rate electron bunches. In this paper, we report the development and experiments on a conduction-cooled Nb3Sn cavity with a niobium rod intended as a field emitter support. The initial experiments demonstrate 0.4 MV/m average accelerating gradient, which is equivalent of peak gradient of 3.2 MV/m. The measured RF cavity quality factor is 1.4 x 108 slightly above our goal. The achieved field gradient is limited by the relatively low input RF power and by the poor coupling between the external power supply and the RF cavity. With ideal coupling the field gradient can be as high as 0.6 MV/m still below our goal of about 1 MV/m.
