• M.L. Langlois, M. Cornelis, D. Einfeld, F. Peréz
  CELLS-ALBA Synchrotron, Cerdanyola del Vallès

The Dampy cavity, operating at 500 MHz and up to 160 kW, normal conducting HOM damped, will be used in the ALBA storage ring. The pre-series has shown two problems. First, the HOM damping is very efficient but for one mode. The longitudinal impedance of the E011 mode was found to be around 11 kΩ, slightly above ALBA stability threshold. Second, overheating close to the dampers flanges induces a vacuum leak after several thermal cyclings. The maximum achieved operational dissipated power is 40 kW, if power is further increased a leak opens at one of the dampers flanges. In order to alleviate this latter drawback, two modifications have been implemented in two different cavities. The pre-series has been provided with short-circuits bridging waveguide ridges and cavity body. These are supposed to decrease the current in the area of the flanges. The first production cavity features a reduced thermal impedance between the water cooling channels and the area of overheating by replacing stainless steel by copper in the critical area. Both these cavities are currently under test and this paper will show the results.