• S. Barbanotti, M.H. Foley, I.G. Gonin, J. Grimm, T.N. Khabiboulline, L. Ristori, N. Solyak, V.P. Yakovlev
  Fermilab, Batavia

Project X is a proposed high-intensity proton accelerator complex that could provide beam to create a high-intensity neutrino beam, feed protons to kaon- and muon-based precision experiments, and for other applications still under investigation. The present configuration of the proton accelerator foresees a section with 650 MHz beta = 0.6 and beta = 0.9 elliptical cavities. Prototypes of single-cell 650 MHz cavities and five-cell beta = 0.9 650 MHz cavities are being designed and fabricated at Fermilab in the R&D process for Project X. This paper summarizes the design status of the beta = 0.6 and beta = 0.9 single-cell prototype cavities, and also addresses the design effort focused on the five-cell beta = 0.9 cavities.

• N. Dhanaraj, S. Barbanotti, J.S. Brandt, H. Carter, M.H. Foley, J. Grimm, T.N. Khabiboulline, R. Wands
  Fermilab, Batavia

Fermilab is currently focusing its efforts toward the development of Stainless Steel (SS) helium vessels for its 1.3 GHz SRF cavities. The objective is to transition towards the concept of using SS helium vessels to dress the bare SRF cavities, thereby paving way for significant cost reduction and efficient production techniques for future accelerators. The biggest challenge has been to design a reliable interface between the niobium cavity end group and the stainless steel end flange that encloses the helium vessel. Fermilab has been pursuing a brazed joint design to allow this transition. Additional design challenges associated with this transition are ensuring proper cooling of the cavity, compensating for the difference in thermal contraction between the SS helium vessel and niobium cavities, and also modification of the tuning procedure and ensuring the safety and reliability of the blade and piezo tuners. Current efforts on the qualification of the niobium-SS braze joint, finite element simulations of the thermal design aspects, bench testing of actual cavity displacements, and study of the effects on the tuners will be presented.