Electron beam welding of copper-stabilized superconductors for a large bubble chamber magnet

In the European Nuclear Research Center CERN in Geneva, the presently largest hydrogen bubble chamber of the world is due to be put into operation at the end of 1972. The magnetic flux density of 3.5 T necessary for the detection of the high-energy elementary particles is generated by superconducting coils of 4.7 m inner diameter. The fully stabilized conductor for half of these coils was fabricated from component conductors by longitudinal seam welding with the electron beam under vacuum. The conductor design, the design and the method of operation of the electron beam welding installation and the operating and fabricating experience gained by the processing of approximately 60 t of conductor material are discussed. (7 refs).