Energy recovery linear accelerators (ERLs) rely upon single-axis superconducting radio frequency (SRF) cavities to be an efficient source of relativistic electrons for high energy and nuclear physics. SRF cavities are also considered relevant for next-generation photon factories and radio-isotope production facilities. The ultimate energy recovery capability for the accelerator would be the ability to operate with a sufficiently spent beam and decrease the energy of the beam before the beam dump to a value lower than the beam injection energy. This is especially important for high current accelerators, where the beam injection energy could be as high as several MeV, and systems where partial beam loss can be expected. The efficient operation of energy recovery in linear accelerators is adversely affected by the typical degradation of the beam quality and current loss. This hinders the application of the ERLs in research and industry, and enabling the use of spent (partially lost current), degraded beams should broaden their application. We suggest that the use of the asymmetric operating mode observed in the dual-axis asymmetric cavities will enable such ultimate capabilities. We discuss the advantages of the application of fields of different amplitude along the cavity accelerating and decelerating axes and demonstrate that the fields can be tuned separately in each axis of the dual-axis cavity. The design of such a cavity and ways to optimize the energy recovery of a spent electron beam by tuning the dual-axis asymmetric SRF cavity are discussed.

中文翻译：

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能量回收线性加速器中用过的相对论电子束的最终能量回收

能量回收线性加速器（ERL）依靠单轴超导射频（SRF）腔体作为高能和核物理的相对论电子的有效来源。SRF腔也被认为与下一代光子工厂和放射性同位素生产设施有关。加速器的最终能量回收能力将是使用足够用完的射束进行操作并在射束释放之前将射束能量降低至低于射束注入能量的值的能力。这对于大电流加速器尤其重要，在大电流加速器中，束流注入能量可能高达几个MeV，并且在系统中可能会有部分束流损耗。线性加速器中能量回收的有效运行受到光束质量和电流损耗的典型降低的不利影响。这阻碍了ERL在研究和工业中的应用，并且使得能够使用用过的（部分损失的电流）退化光束来扩大其应用范围。我们建议使用在双轴不对称腔中观察到的不对称操作模式将实现这种最终功能。我们讨论了沿腔体加速和减速轴应用不同振幅场的优势，并证明了可以在双轴腔体的每个轴上分别调整场。讨论了这种腔的设计以及通过调整双轴非对称SRF腔来优化废电子束能量回收的方法。