We demonstrate practical accelerating gradients on a superconducting radiofrequency (SRF) accelerator cavity with cryocooler conduction cooling, a cooling technique that does not involve the complexities of the conventional liquid helium bath. A design is first presented that enables conduction cooling an elliptical-cell SRF cavity. Implementing this design, a single cell 650 MHz Nb3Sn cavity coupled using high purity aluminum thermal links to a 4 K pulse tube cryocooler generated accelerating gradients up to 6.6 MV/m at 100% duty cycle. The experiments were carried out with the cavity-cryocooler assembly in a simple vacuum vessel, completely free of circulating liquid cryogens. We anticipate that this cryocooling technique will make the SRF technology accessible to interested accelerator researchers who lack access to full-stack helium cryogenic systems. Furthermore, the technique can lead to SRF based compact sources of high average power electron beams for environmental protection and industrial applications. A concept of such an SRF compact accelerator is presented.

中文翻译：

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在实际连续波加速梯度下运行的低温冷却器传导冷却超导射频腔的首次演示

我们在具有低温冷却器传导冷却的超导射频 (SRF) 加速器腔上展示了实用的加速梯度，这种冷却技术不涉及传统液氦浴的复杂性。首先提出了一种设计，该设计能够传导冷却椭圆形电池 SRF 腔。实施此设计时，单电池 650 MHz Nb3Sn 腔使用高纯度铝热链接与 4 K 脉冲管低温冷却器耦合，在 100% 占空比下产生高达 6.6 MV/m 的加速梯度。实验是在一个简单的真空容器中用空腔-低温冷却器组件进行的，完全没有循环液体冷冻剂。我们预计这种低温冷却技术将使 SRF 技术可供感兴趣的加速器研究人员使用，他们无法使用全栈氦低温系统。此外，该技术可以产生基于 SRF 的紧凑型高平均功率电子束源，用于环境保护和工业应用。介绍了这种 SRF 紧凑型加速器的概念。