For FRIB production, SRF cavities will be jacketed with titanium helium vessels. The fabrication process requires mechanical joints to be made between titanium vessel subassemblies and direct connections to the cavity itself.  Special welding techniques are required to complete the welds and ensure mechanical design requirements (vacuum integrity and pressure fluctuations) are met.

Staff from Thomas Jefferson National Accelerator Laboratory (JLab) visited FRIB on January 24 to share the expertise developed by working with titanium vessels during assembly of cavities for the Spallation Neutron Source (SNS) for Oak Ridge National Laboratory. John Hogan (cryomodule engineer), Ken Worland (certified titanium welder), and Joseph Brock (certified titanium welder) of JLab met with the FRIB cavity fabrication team and members of the NSCL welding group to share their experience and knowledge.

The group discussed the engineering requirements of the welds and designed weld interfaces that would allow the appropriate weld penetration to be achieved.  The group also worked on the welding technique used in titanium joining. The JLab welders worked directly with the NSCL welding group in setting welding parameters and training them on the procedures through a series of mock-up assemblies.  The collaboration was very successful and resulted in increased understanding and improvement in the titanium welds.