Status of the Development of Superconducting Undulators at the Advanced Photon Source
Status of the Development of Superconducting Undulators at the Advanced Photon Source
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先进光子源超导波荡器的发展现状
DOI：
10.1080/08940886.2018.1460172
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发表时间：
2017
影响因子：
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通讯作者：
E. Gluskin
中科院分区：
文献类型：
--
作者：
Y. Ivanyushenkov;J. Fuerst;Q. Hasse;M. Kasa;I. Kesgin;Y. Shiroyanagi;E. Gluskin
超导波荡器是一种利用超导线圈产生磁场的电磁波荡器。磁模拟表明，对于给定的磁隙和周期长度，超导波荡器技术在波荡器峰值场方面优于其他波荡器技术[1，2]。较高的波荡器场导致产生较高的光子通量，尤其是在较高的光子能量下。SCU技术的这一预测优势在先进光子源（APS）上通过第一个超导波荡器SCU 0的运行性能得到了证明。虽然只有0.3 m的磁长度，但在光子能量高于80 keV时，这种16 mm周期的设备产生的光子通量高于2.4 m长、33 mm周期的永磁体混合波荡器[3]。超导波荡器技术已经开发出来，目前正在APS使用[4，5]。建造和运行SCU 0的成功经验为两个1.1米长、18毫米周期的设备SCU 18 -1 [6]和SCU 18 -2铺平了道路。其中第一个波动器自2015年5月以来一直在运行，而第二个在完成连续运行超过3.5年后，于2016年9月取代了SCU 0。APS已经证明了构建具有高质量射野的平面SCU的可能性。例如，SCU 18 -2在设计工作电流下的实测相位误差仅为2度rms。作为LCLS SCU研发计划的一部分，还建造并测试了一个FEL SCU原型-一个1.5 m长，21 mm周期的波动器，该计划旨在证明自由电子激光器SCU技术的可用性[7]。该波荡器成功地达到了LCLS-II波荡器的所有要求，包括5度均方根的相位误差。超导波荡器技术还允许圆偏振器件的制造。最近，一个新的螺旋SCU（HSCU）已建成的APS。该装置于2017年底安装在APS储存环上。此外，一种新的超导偏振电磁场（SCAPE）的概念已经提出，目前正在开发中[8]。到目前为止，APS波荡器是用NbTi低温（LTS）超导导线缠绕的。这种超导体不需要热处理，不像LTS家族中的另一种导体Nb 3Sn，因此允许相对容易的制造技术。同时，一组高温超导体（HTS）可能导致无制冷剂的高场波荡器。最近三年的发展-
Superconducting undulators (SCUs) are electromagnetic undulators that employ superconducting coils for generating magnetic field. Magnetic simulations suggest that superconducting undulator technology outperforms other undulator technologies in terms of undulator peak field for a given magnetic gap and period length [1, 2]. The higher undulator field leads to generation of higher photon fluxes, especially at higher photon energies. This predicted advantage of SCU technology was demonstrated at the Advanced Photon Source (APS) by operational performance of the first superconducting undulator, SCU0. While only having a magnetic length of 0.3 m, this 16-mm-period device generates a higher photon flux than a 2.4-m-long, 33-mm-period permanent magnet hybrid undulator at the photon energies above 80 keV [3]. The technology of superconducting undulators has been developed and is currently in use at the APS [4, 5]. The successful experience of building and operating the SCU0 paved the way for two 1.1-m-long, 18-mm-period devices, SCU18-1 [6] and SCU18-2. The first of those undulators has been in operation since May 2015, while the second one replaced SCU0 in September 2016, after completion of its continuous operation for over 3.5 years. The possibility of building planar SCUs with a high quality field has been demonstrated at the APS. The measured phase errors of SCU18-2 at the design operational current are only 2 degrees rms, for example. An FEL SCU prototype—a 1.5-mlong, 21-mm-period undulator—was also built and tested as part of an LCLS SCU R&D program aimed at demonstration of the availability of SCU technology for free electron lasers [7]. This undulator successfully achieved all LCLS-II undulator requirements, including a phase error of 5 degrees rms.The superconducting undulator technology also allows the fabrication of circular polarizing devices. Recently, a new helical SCU (HSCU) has been built at the APS. This device was installed on the APS storage ring at the end of 2017. In addition, the concept of a novel Superconducting Arbitrarily Polarizing Emitter, or SCAPE, has been suggested and is now under development [8]. So far, the APS undulators are wound with NbTi low-temperature (LTS) superconducting wire. This superconductor does not require heat treatment, unlike another conductor in the LTS family, Nb3Sn, and therefore allows for a relatively easy fabrication technology. At the same time, a group of high-temperature superconductors (HTS) might lead to cryogen-free high-field undulators. A recent three-year develop-