Yan Wang, Zhenyu Ma, Kai Xu, Qiang Chang, Zhigang Zhang, Chen Luo, Xuefang Huang, Xiang Zheng, Shenjie Zhao, and Yubin Zhao*
Fig. 1. The model of equivalent circuit for N-cell cavity with beam tubes
Fig. 2. The model of equivalent circuit for N-cell cavity operating in fundamental π-mode with ideal field flatness
Fig. 3. Equivalent transformation of the models of equivalent circuit for end-cell and tube of N-cell cavity
Fig. 4. Field flatness F variation with minor perturbation emid of cell capacity, given different A=B
Fig. 5. Field flatness F variation with A, given B=0.5, for different minor perturbation of mid-cell emid不同中间腔胞微扰
、B=0.5情况下,场平坦度随A的变化规律
Fig. 6. The geometry of a half-cell of an elliptical cavity
Fig. 7. Structure diagram of 1.3 GHz 9-cell superconducting radio-frequency cavities without/with enhancement rings
Types of cavity cell | Re/mm
| Ri/mm
| A/mm
| B/mm
| a/mm
| b/mm
| L/mm
| Middle half-cell | XFEL | 103.3 | 35.0 | 42.0 | 42.0 | 12.0 | 19.0 | 57.7 | TRIUMF | 103.3 | 35.0 | 42.0 | 42.0 | 12.0 | 19.0 | 57.7 | SHINE | 103.3 | 35.0 | 42.0 | 42.0 | 12.0 | 19.0 | 57.7 | Pick-up side
half-cell
| XFEL | 103.3 | 39.0 | 42.0 | 42.0 | 9.0 | 12.8 | 56.7 | TRIUMF | 103.3 | 39.0 | 42.0 | 42.0 | 9.0 | 12.8 | 56.7 | SHINE | 103.3 | 39.0 | 42.0 | 42.0 | 9.0 | 12.8 | 56.7 | Coupler side
half-cell
| XFEL | 103.3 | 39.0 | 40.34 | 40.34 | 10.0 | 13.5 | 55.7 | TRIUMF | 103.3 | 48.0 | 45.0 | 40.5 | 10.0 | 13.5 | 56.0 | SHINE | 103.3 | 55.0 | 48.9 | 36.7 | 9.0 | 12.8 | 58.1 |
|
Table 1. Geometry parameters of three types of 1.3 GHz 9-cell cavities for main LINAC of XFEL, TRIUMF e-Linac, and for injector of SHINE as a candidate
Tuning force/kN (squeezed) | Types of cavity cell | Resonant frequency/MHz | 0-mode | π-mode | 0, undeformed | Middle half-cell | XFEL | 1275.748 | 1300 | TRIUMF | 1275.748 | 1300 | SHINE | 1275.748 | 1300 | Pick-up side half-cell with beam pipe | XFEL | 1287.78 | 1300 | TRIUMF | 1287.78 | 1300 | SHINE | 1287.78 | 1300 | Coupler side half-cell with beam pipe | XFEL | 1287.78 | 1300 | TRIUMF | 1288.136 | 1300 | SHINE | 1288.827 | 1300 | 2, deformed | Middle half-cell | XFEL | 1275.468 | 1299.745 | TRIUMF | 1275.468 | 1299.745 | SHINE | 1275.468 | 1299.745 | Pick-up side half-cell with beam pipe | XFEL | 1287.544 | 1299.78 | TRIUMF | 1287.544 | 1299.78 | SHINE | 1287.544 | 1299.78 | Coupler side half-cell with beam pipe | XFEL | 1287.544 | 1299.78 | TRIUMF | 1287.901 | 1299.781 | SHINE | 1288.653 | 1299.836 | 4, deformed | Middle half-cell | XFEL | 1275.155 | 1299.569 | TRIUMF | 1275.155 | 1299.569 | SHINE | 1275.155 | 1299.569 | Pick-up side half-cell with beam pipe | XFEL | 1287.328 | 1299.574 | TRIUMF | 1287.328 | 1299.574 | SHINE | 1287.328 | 1299.574 | Coupler side half-cell with beam pipe | XFEL | 1287.328 | 1299.574 | TRIUMF | 1287.685 | 1299.574 | SHINE | 1288.492 | 1299.68 |
|
Table 2. Variation of resonant frequency due to different tuning force for XFEL, TRIUMF and SHINE 1.3 GHz 9-cell SRF cavities without enhancement rings
Tuning force/kN (squeezed) | emid/105 | eend1/105 | eend2/105 | 0, undeformed | XFEL | 0 | 0 | 0 | TRIUMF | 0 | 0 | 0 | SHINE | 0 | 0 | 0 | 2, deformed | XFEL | 4.877 | 4.149 | 4.149 | TRIUMF | 4.877 | 4.149 | 4.133 | SHINE | 4.877 | 4.149 | 3.062 | 4, deformed | XFEL | 10.327 | 7.946 | 7.946 | TRIUMF | 10.327 | 7.946 | 7.931 | SHINE | 10.327 | 7.946 | 5.894 |
|
Table 3. Minor perturbations due to different tuning force for XFEL, TRIUMF and SHINE candidate 1.3 GHz 9-cell SRF cavities without enhancement rings
Tuning force/kN (squeezed) | F, (Field flatness)
| Theoretical calculation value | Simulation calculation value | 0, undeformed | XFEL | 100% | 99.95% | TRIUMF | 100% | 99.94% | SHINE | 100% | 99.92% | 2, deformed | XFEL | 98.79% | 97.7% | TRIUMF | 98.74% | 97.6% | SHINE | 95.35% | 93.9% | 4, deformed | XFEL | 96.03% | 96.8% | TRIUMF | 95.99% | 96.7% | SHINE | 89.86% | 89.0% |
|
Table 4. Results comparison of field flatness between theoretical and simulation calculations for XFEL, TRIUMF and SHINE 1.3 GHz 9-cell SRF cavities without enhancement rings
Tuning force/kN (squeezed) | Types of cavity cell | Resonant frequency/MHz | 0-mode | π-mode | 0, undeformed | Middle half-cell | XFEL | 1275.748 | 1300 | TRIUMF | 1275.748 | 1300 | SHINE | 1275.748 | 1300 | Pick-up side half-cell with beam pipe | XFEL | 1287.78 | 1300 | TRIUMF | 1287.78 | 1300 | SHINE | 1287.78 | 1300 | Coupler side half-cell with beam pipe | XFEL | 1287.78 | 1300 | TRIUMF | 1288.136 | 1300 | SHINE | 1288.827 | 1300 | 2, deformed | Middle half-cell | XFEL | 1275.603 | 1299.857 | TRIUMF | 1275.603 | 1299.857 | SHINE | 1275.603 | 1299.857 | Pick-up side half-cell with beam pipe | XFEL | 1287.631 | 1299.855 | TRIUMF | 1287.631 | 1299.855 | SHINE | 1287.631 | 1299.855 | Coupler side half-cell with beam pipe | XFEL | 1287.631 | 1299.855 | TRIUMF | 1287.977 | 1299.848 | SHINE | 1288.638 | 1299.865 | 4, deformed | Middle half-cell | XFEL | 1275.449 | 1299.708 | TRIUMF | 1275.449 | 1299.708 | SHINE | 1275.449 | 1299.708 | Pick-up side half-cell with beam pipe | XFEL | 1287.468 | 1299.695 | TRIUMF | 1287.468 | 1299.695 | SHINE | 1287.468 | 1299.695 | Coupler side half-cell with beam pipe | XFEL | 1287.468 | 1299.695 | TRIUMF | 1287.817 | 1299.688 | SHINE | 1288.448 | 1299.733 | 6, deformed | Middle half-cell | XFEL | 1275.299 | 1299.558 | TRIUMF | 1275.299 | 1299.558 | SHINE | 1275.299 | 1299.558 | Pick-up side half-cell with beam pipe | XFEL | 1287.306 | 1299.534 | TRIUMF | 1287.306 | 1299.534 | SHINE | 1287.306 | 1299.534 | Coupler side half-cell with beam pipe | XFEL | 1287.306 | 1299.534 | TRIUMF | 1287.656 | 1299.529 | SHINE | 1288.257 | 1299.600 |
|
Table 5. Variation of resonant frequency due to different tuning force for XFEL, TRIUMF and SHINE 1.3 GHz 9-cell SRF cavities with enhancement rings
Tuning force/kN (squeezed) | emid/105 | eend1/105 | eend2/105 | 0, undeformed | XFEL | 0 | 0 | 0 | TRIUMF | 0 | 0 | 0 | SHINE | 0 | 0 | 0 | 2, deformed | XFEL | 2.526 | 2.620 | 2.620 | TRIUMF | 2.526 | 2.620 | 2.796 | SHINE | 2.526 | 2.620 | 3.326 | 4, deformed | XFEL | 5.208 | 5.485 | 5.485 | TRIUMF | 5.208 | 5.485 | 5.610 | SHINE | 5.208 | 5.485 | 6.668 | 6, deformed | XFEL | 7.820 | 8.333 | 8.333 | TRIUMF | 7.820 | 8.333 | 8.441 | SHINE | 7.820 | 8.333 | 10.028 |
|
Table 6. Minor perturbations due to different tuning force for XFEL, TRIUMF and SHINE candidate 1.3 GHz 9-cell SRF cavities with enhancement rings
Tuning force/kN (squeezed) | F, (Field flatness)
| Theoretical calculation value | Simulation calculation value | 0, undeformed | XFEL | 100% | 99.95% | TRIUMF | 100% | 99.94% | SHINE | 100% | 99.92% | 2, deformed | XFEL | 99.84% | 99.16% | TRIUMF | 99.27% | 98.77% | SHINE | 97.35% | 98.48% | 4, deformed | XFEL | 99.54% | 98.85% | TRIUMF | 99.17% | 98.26% | SHINE | 95.48% | 96.66% | 6, deformed | XFEL | 99.14% | 98.32% | TRIUMF | 98.85% | 97.56% | SHINE | 93.44% | 94.27% |
|
Table 7. Results comparison of field flatness between theoretical and simulation calculations for XFEL, TRIUMF and SHINE candidate 1.3 GHz 9-cell SRF cavities with enhancement rings