Evaluation of Single-Cell Cavities Made of Forged Ingot Niobium at Jefferson Lab

Conference · Thu Sep 01 04:00:00 EDT 2022

DOI:https://doi.org/10.18429/JACoW-LINAC2022-THPOGE16· OSTI ID:1903597

Dhakal, P. ^[1]; Ciovati, G. ^[2]; Myneni, G. R. ^[3]

---

1. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)
3. Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); BSCE, Yorktown, Virginia, USA

Currently, fine grain niobium (Nb) (grain size ~ 50 um) and large grain Nb (grain size of a few cm) are being used for the fabrication of superconducting radio frequency (SRF) cavities. Medium grain forged ingot with grain size of a few hundred um may be beneficial for cost-effectiveness as well as providing better performance for future SRF-based accelerators. Forged ingot Nb with medium grain size is a novel production method to obtain Nb discs used for the fabrication of superconducting radio frequency cavities. We have fabricated two 1.5 GHz single cell cavities made from forged Nb ingot with a residual resistivity ratio of ~100. The cavities were chemically and mechanically polished and heat-treated in the temperature range of 650-1000 C before the rf test. One of the cavities reached an accelerating gradient of 34 MV/m with a quality factor Q > 1e10, while the second cavity was limited at 14 MV/m, likely due to a weld defect at the equator.

• 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: 1903597
• Report Number(s): JLAB-ACC-22-3708; DOE/OR/23177-5600
• Country of Publication: United States
• Language: English