Mitsubishi Heavy Industries, LTD. (MHI) has been developing manufacturing process of superconducting cavities. 4 topics of our recent activities, QWR, facilities of surface preparation, Superconducting RF electron gun and EBW of 4 cavities in a batch, are introduced in this report.
MHI activities for ILC are reported. MHI had developed several procedure and method of cavity production for stable quality and cost reduction. And we are producing cryomodules too. These activities are reported in detail.
Cavity fabrication method with new forming and laser welding technology are reported. 1.3 GHz 9-cell cavity with laser welding for stiffener and flange joint was achieved 29.5 MV/m at vertical test by KEK. 1.3 GHz 2- cell seamless dumbbell cavity is fabricated at MHI to verify the new fabrication method. These improvements are reported in detail. Some fabrication methods for cost reduction and stable quality are introduced.
MHI has supplied various types of superconducting cavities mainly to KEK in Japan since TRISTAN project started at 1977. We have a lot of experience in the development of superconducting cavities for Japanese projects. And we have the technology to design and fabricate the superconducting cavities. We can present some ideas to improve the quality, cost, and delivery time of the superconducting cavities based on our experience. We designed and fabricated four STF-Baseline superconducting cavities with frequency tuners, helium jackets, according to KEK specifications. To decrease a cavity deformation occurring due to Lorenz force, rigid jacket systems including tuner were designed. By fabricating four cavities, some problems and improvements in the next step are cleared. Some ideas to reduce the fabrication cost are proposed in this paper.
Since 1995, Manufacturing techniques of superconducting Nb cavity have been developed on R&D of Crab Cavity for KEK-B at MHI. Especially the Roll Forming process is applicable to accuracy seamless Nb pipe for Co-axial Coupler. With the parameters optimized in short sample, we produced 850mm-long pipes.
A HOM (Higher Order Mode) coupler for a 600MHz superconducting linac of the JAERI/KEK Joint Project is described. Design of the coupler is based on coaxial line technique. The filter characteristics of the HOM coupler are calculated by using the HFSS code. The test results of the model HOM coupler are reported.
Since 1990, L-band niobium superconducting cavities have been developed with collaboration between MHI and KEK. The test result of the single-cell cavity with a waveguide is presented. The maximum accelerating gradient of 27MV/m was attained with no field emission.