EVALUATION OF FLUX EXPULSION AND FLUX TRAPPING SENSITIVITY OF SRF CAVITIES FABRICATED FROM COLDWORK NB SHEET WITH SUCCESSIVE HEAT TREATMENT

Conference · Sat Jul 01 04:00:00 EDT 2023

DOI:https://doi.org/10.18429/JACoW-SRF2023-MOPMB042· OSTI ID:2202370

Khanal, Bashu; Dhakal, Pashupati

The main source of RF losses leading to lower quality factor of SRF cavities is due to the residual magnetic flux trapped during cooldown. The loss due to flux trapping is more pronounced for cavities subjected to impurities doping. The flux trapping and its sensitivity to rf losses are related to several intrinsic and extrinsic phenomena. To elucidate the effect of recrystallization by high temperature heat treatment on the flux trapping sensitivity, we have fabricated two 1.3 GHz single cell cavities from cold-worked Nb sheets and compared with cavities made from standard fine-grain Nb. Flux expulsion ratio and flux trapping sensitivity were measured after successive high temperature heat treatments as well as after low temperature, 120 0C baking. The cavity made from cold worked Nb showed better performance after 800 0C/3hr heat treatment and similar behavior when heat treated with additional 900 0C and 1000 0C compared to standard fine-grain Nb cavity. In this contribution, we present the summary of flux expulsion, trapping sensitivity and results from RF tests at 2 K.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 2202370
• Report Number(s): JLAB-ACC-23-3923; DOE/OR/23177-7223
• Country of Publication: United States
• Language: English