High RF power tests of the first 1.3 GHz fundamental power coupler prototypes for the SHINE project

Abstract

The Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE) project will use 600 1.3 GHz fundamental power couplers, which are modified based on TTF-III power couplers, for continuous-wave operation with input power up to approximately 7 kW. The first batch of 20 sets of 1.3 GHz coupler prototypes was fabricated from three domestic manufacturers for the SHINE project. To better characterize the radio frequency conditioning phenomena for validating the performance of power couplers, a room temperature test stand was designed, constructed, and commissioned for the SHINE 1.3 GHz power couplers. In addition, a horizontal test cryostat was built to test the 1.3 GHz superconducting cavities, fundamental power couplers, tuners, and other components as a set. The results of these tests indicate that the 1.3 GHz couplers are capable of handling up to 14 kW continuous waves. Herein, the main aspects of the radio frequency design and construction of the test stand, along with the test results of the high-power conditioning of the 1.3 GHz couplers, are described.

Coupler RF kick and emittance optimization of the SHINE injector

“…To meet the needs of the SHINE project, the fundamental power coupler was modified and optimized based on the TTF-III FPC design, in which the antenna of the cold part was shortened by 8.5 mm in order to obtain a higher external quality factor 𝑄 ext with a value of 4.12 × 10 7 [15], under the following working conditions: the average linac electron bunch current is 0.3 mA, the nominal accelerating gradient 𝐸 acc of the 1.3 GHz superconducting cavity is 16.0 MV/m, the cavity intrinsic quality factor 𝑄 0 is 2.7 × 10 10 , and the frequency detuning 𝛿 𝑓 caused by the peak microphonics effect is 10 Hz [26].…”

“…The acceleration unit in SHINE injector is a 1.3 GHz 9-cell TESLA superconducting cavity [11,12] installed in the cryomodule, which is usually equipped with two higher-order-mode couplers (HOMC) [13] to couple out the higher-order-mode [14] in the cavity and a fundamental-power coupler (FPC) [15] to feed the cavity with the RF acceleration field. However, these coupler structures break the axisymmetric structure of the cavity, giving rise to relevant transverse multipole field components of the axial electromagnetic field in the coupler region.…”

The MING proposal at SHINE: megahertz cavity enhanced X-ray generation

“…Considering the rapid progress in the development of XFEL around the world and in response to growing demands from the Chinese science community, a new high repetition rate XFEL, SHINE, is currently under construction and is one of the major research infrastructure projects in China [9,[57][58][59]. The SHINE facility consists of a low emittance continuous-wave (CW) injector, a high-performance superconducting radio-frequency (SCRF) linac that can accelerate electrons to 8 GeV with 1 MHz repetition rate, three undulator lines to cover 0.4-25 keV photon energies, and ten end stations.…”

Electromagnetic Design Study of a 12-mm-Period Bulk High-Temperature Superconducting Undulator

“…With this novel BHTSU technology physicists can think about building a compact FEL with much shorter linear accelerators (LINACs) for lasing at the desired photon wavelength [4,5]. This novel HTS undulator is considered as an alternative technology for the future upgrade of the Shanghai HIgh repetitioN rate XFEL and Extreme light facility (SHINE) [6,7]. BHTSU can also be installed in a diffraction-limited storage ring (DLSR).…”