scholarly journals Quality Factor Enhancement of 650 MHz Superconducting Radio-Frequency Cavity for CEPC

2022 ◽  
Vol 12 (2) ◽  
pp. 546
Author(s):  
Peng Sha ◽  
Weimin Pan ◽  
Jiyuan Zhai ◽  
Zhenghui Mi ◽  
Song Jin ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Quality Factor ◽  
Microwave Surface Resistance ◽  
Medium Temperature ◽  
Residual Resistance ◽  
Electron Positron ◽  
Superconducting Radio Frequency ◽  
Unloaded Quality Factor ◽  
Srf Cavity ◽  
Vertical Test

Medium-temperature (mid-T) furnace baking was conducted at 650 MHz superconducting radio-frequency (SRF) cavity for circular electron positron collider (CEPC), which enhanced the cavity unloaded quality factor (Q0) significantly. In the vertical test (2.0 K), Q0 of 650 MHz cavity reached 6.4 × 1010 at 30 MV/m, which is remarkably high at this unexplored frequency. Additionally, the cavity quenched at 31.2 MV/m finally. There was no anti-Q-slope behavior after mid-T furnace baking, which is characteristic of 1.3 GHz cavities. The microwave surface resistance (RS) was also studied, which indicated both very low Bardeen–Cooper–Schrieffer (BCS) and residual resistance. The recipe of cavity process in this paper is simplified and easy to duplicate, which may benefit the SRF community.

Surface studies of niobium chemically polished under conditions for superconducting radio frequency (SRF) cavity production

2006 ◽  
Vol 253 (3) ◽  
pp. 1236-1242 ◽  
Author(s):  
Hui Tian ◽  
Charles E. Reece ◽  
Michael J. Kelley ◽  
Shancai Wang ◽  
Lukasz Plucinski ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Surface Studies ◽  
Superconducting Radio Frequency ◽  
Srf Cavity

Medium-temperature baking of 1.3 GHz superconducting radio frequency single-cell cavity

2020 ◽  
Vol 4 (4) ◽  
pp. 507-512
Author(s):  
Quan Zhou ◽  
Fei-Si He ◽  
Weimin Pan ◽  
Peng Sha ◽  
Zhenghui Mi ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Single Cell ◽  
Medium Temperature ◽  
Superconducting Radio Frequency ◽  
Cell Cavity

Superconducting Radio-Frequency Fundamentals for Particle Accelerators

2012 ◽  
Vol 05 ◽  
pp. 119-146 ◽  
Author(s):  
Alex Gurevich
Keyword(s):  
Radio Frequency ◽  
Quality Factor ◽  
Electromagnetic Fields ◽  
Surface Resistance ◽  
Particle Accelerators ◽  
Superconducting Radio Frequency ◽  
Srf Cavities

An overview of fundamentals of superconductors under radio-frequency electromagnetic fields in particle accelerators is given, with emphasis on intrinsic physics and materials mechanisms which limit the performance of the superconducting radio-frequency (SRF) resonator cavities. Multiscale mechanisms which control the surface resistance and the quality factor of the SRF cavities at low and high rf fields are discussed. We also discuss possible ways of pushing the limit of the SRF performance by materials impurities and multilayer nanostructuring which may open up opportunities of using materials other than Nb to significantly increase the maximum accelerating fields and improve the performance of the SRF cavities operating at 4.2 K.

scholarly journals Development and Vertical Tests of CEPC 650-MHz Single-Cell Cavities with High Gradient

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7654
Author(s):  
Song Jin ◽  
Peng Sha ◽  
Weimin Pan ◽  
Jiyuan Zhai ◽  
Zhenghui Mi ◽  
...  
Keyword(s):  
Single Cell ◽  
Quality Factor ◽  
State Of The Art ◽  
Test Results ◽  
Fine Grain ◽  
Electron Positron ◽  
Superconducting Cavities ◽  
Intrinsic Quality ◽  
Quality Factor Q ◽  
Vertical Test

A circular electron positron collider (CEPC) will adopt hundreds of 650-MHz superconducting cavities with high quality factor (Q) and accelerating gradient (Eacc). Two 650-MHz single-cell cavities made of fine-grain niobium were first treated via buffered chemical polishing (BCP), which was easy and convenient. However, the vertical test results could not meet the specification of the CEPC (4 × 1010 at 22 MV/m). Therefore, electro-polishing (EP) of 650-MHz single-cell cavities was conducted, which was complicated but remarkably effective. Both 650-MHz single-cell cavities achieved state-of-the-art gradients of 35 MV/m after the EP process, which is extremely high for large elliptical cavities (frequency < 1 GHz). One cavity achieved an intrinsic quality factor (Q0) of 4.5 × 1010 at 22.0 MV/m, which was higher than the CEPC spec. The other cavity obtained a lower Q0 of 3.4 × 1010 at 22.0 MV/m, which may have resulted from the cancellation of high-temperature annealing.

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