SRF2013 - List of Authors (Nagata, T.)

Paper

Title

Page

Study on Optimum Electron Beam Welding Condition for Superconducting Accelerating Cavities

424

T. Kubo, Y. Ajima, H. Inoue, T. Saeki, K. Umemori, Y. Watanabe, S. Yamaguchi, M. Yamanaka
KEK, Ibaraki, Japan
T. Nagata
ULVAC, Inc., Tsukuba, Japan

Optimizations of electron beam welding conditions might solve the quench problems and improve the accelerating field of the superconducting radio-frequency cavity. As a first step toward optimum conditions, basic properties of weld beads are studied by using niobium test pieces. Effects of a combination of a beam generator position and a welding direction on geometries of weld bead are shown. Good parameter-regions for electron beam welding, which yield full penetration welds without holes or weld spatters, are surveyed. Microscopic structures, such as pits or bumps due to poor welds, have greater influence on cavity performances, which are also our research objects. We introduce a model of the magnetic field enhancement at pits, where a formula for a magnetic field enhancement factor is given as a function of parameters that express a geometry of pit. Comparisons between calculations and vertical test results are also shown.

Slides TUIOC06 [15.958 MB]

Paper	Title	Page
TUIOC06	Study on Optimum Electron Beam Welding Condition for Superconducting Accelerating Cavities	424
	T. Kubo, Y. Ajima, H. Inoue, T. Saeki, K. Umemori, Y. Watanabe, S. Yamaguchi, M. Yamanaka KEK, Ibaraki, Japan T. Nagata ULVAC, Inc., Tsukuba, Japan
	Optimizations of electron beam welding conditions might solve the quench problems and improve the accelerating field of the superconducting radio-frequency cavity. As a first step toward optimum conditions, basic properties of weld beads are studied by using niobium test pieces. Effects of a combination of a beam generator position and a welding direction on geometries of weld bead are shown. Good parameter-regions for electron beam welding, which yield full penetration welds without holes or weld spatters, are surveyed. Microscopic structures, such as pits or bumps due to poor welds, have greater influence on cavity performances, which are also our research objects. We introduce a model of the magnetic field enhancement at pits, where a formula for a magnetic field enhancement factor is given as a function of parameters that express a geometry of pit. Comparisons between calculations and vertical test results are also shown.
	Slides TUIOC06 [15.958 MB]