Summary of the meeting at CERN on the construction of the buncher cavity, 12 June 2009

place: CERN, Switzerland

present: F. Gerigk, R. Kisiel, J. Kopec, S. Mathot

brazing procedure

• The status of the buncher cavity is shown in a presentation.
• The Soltan institute encountered some difficulties with the brazing of the vacuum flanges onto the copper tubes: in most cases material was leaking out of the brazing area, and also the recommended brazing material could not be bought in small quantities.
• A single wire was used at temperature of around 830 degrees. There was a small uncertainty about the precision of the temperature measurements.
• An example piece was brought to CERN and discussed. The piece was almost perfect, but the brazing did not extend completely to the edges of the braze-area.
• The following recommendations were given by CERN:
  • use tighter tolerances between the pieces to be brazed to avoid spilling out of the brazing fluid,
  • use Nickel electrodeposition on the surfaces, which have to brazed, instead a Cu layer (by evaporation). This should give a better wetting of the surfaces. The Nickel, which is not used (e.g. on the knife of the flanges) has to be removed before brazing.
  • CERN used 2 wires: one in the groove, and one at the inner "edge",
  • 2 metres of the recommended brazing wire were given to the Soltan Institute,
• The CERN brazing shop was visited and further details of the procedure were discussed.
• It is expected that the cavity is delivered to CERN in July.
• The Soltan Institute will notify CERN before the acceptance tests of: i) vacuum, ii) water pressure, iii) RF parameters are made.

-- FrankGerigk - 15 Jun 2009