scholarly journals Effect of high temperature heat treatments on the quality factor of a large-grain superconducting radio-frequency niobium cavity

Author(s):  
P. Dhakal ◽  
G. Ciovati ◽  
G. R. Myneni ◽  
K. E. Gray ◽  
N. Groll ◽  
...  
2022 ◽  
Vol 12 (2) ◽  
pp. 546
Author(s):  
Peng Sha ◽  
Weimin Pan ◽  
Jiyuan Zhai ◽  
Zhenghui Mi ◽  
Song Jin ◽  
...  

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.


1996 ◽  
Vol 458 ◽  
Author(s):  
B. P. Bewlay ◽  
C. L. Briant ◽  
M. L. Murray

ABSTRACTThe effects of Mo contamination on the microstructure of lamp-grade tungsten wire are investigated in this study. Mo is often used as the mandrel material in the coiling of lamp filaments, and when utilized during high temperature heat treatments significant amounts of Mo can diffuse into the W. In this study, W-Mo diffusion couples were prepared and heat treated at temperatures of 2500°C and above to intentionally contaminate the W with Mo. After dissolution of the Mo and additional high temperature heat treatments of the W, equiaxed grains were observed in the W and excessive porosity was also observed. Explanations for these microstructural changes are discussed. Microprobe data were also obtained to quantify interdiffusion between the W and Mo.


1990 ◽  
Vol 120 (1) ◽  
pp. K11-K14 ◽  
Author(s):  
Y. Kamiura ◽  
M. Yoneta ◽  
F. Hashimoto

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