R3B-Glad Magnet Cold Mass Manufacture: Coils and Casings Fabrication and Integration

The R3B-Glad magnet is part of a large acceptance spectrometer devoted to the physics of exotic nuclei, under construction at CEA Saclay (France) for the present GSI and the future Fair facilities (Darmstadt, Germany). In this paper is presented the fabrication of the cold mass (22 t), divided into three batches (coil manufacture, machining of coil casings, and integration of the coils inside their casings). The work began in January 2009 and ended in December 2010. A real size prototype coil, was developed to validate the winding process, with double pancakes assembled in a stacking tool, and the procedure for impregnating coils, inserted into a mold. After impregnation of the prototype and the first coil, a failing (short circuit between turns) was detected in both coils by electrical testing. The repair of various defects has been a success. Insulation reinforcements were performed on the following coils to avoid any further electrical default. The whole set of coils was wound and impregnated in 2010 (6 coils, about 3 meter long each). The casings are made of aluminum alloy 5083 (with the exception of a few pins, screws and bolts made of stainless steel) and machined from single blocks without welding. All parts were machined in two stages. The first step was a premachining to perform a blank assembly of the whole cold mass (performed in February 2010). The final machining was performed according to the actual dimensions of the manufactured coils, in order to get a perfect fit of the coils within their casings. The integration of the coils inside their casings (including shims setting, adjusting of pushing systems, bonding of drains and thermal sensors) occurred in autumn 2010. The set of coils in their casings was delivered to Saclay in December 2010.