Abstract:

The design and optimization of a new Hybrid Damped accelerating Structure (HDS) is presented. In the HDS, the transverse long-range wakefields are strongly suppressed both by detuning and damping. Damping is obtained both by 4 waveguides attached to the cell outer wall and by 4 slots in the irises. The damping slots also allow a simple structure assembly made from four quadrants and with no ohmic contacts. The shapes of the iris and the outer wall are optimized to minimize the surface electric and magnetic fields. Structure parameters are optimized to give maximum luminosity and rf-to-beam efficiency given constraints imposed by beam dynamics, rf breakdown and pulsed surface heating. The optimization results in a structure with an accelerating gradient of 150 MV/m and a 26% rf-to-beam efficiency.