Development of a compact Local Power Distribution System for the ILC

The Local Power Distribution System (LPDS) of the International Linear Collider (ILC) transmits RF power from a 10 MW klystron to 39 cavities. A variable hybrid and variable phase shifter are adopted in the LPDS to have been adopted in the LPDS to achieve the efficient beam acceleration in the ILC. As it is difficult to construct the LPDS in an accelerator tunnel, the LPDS can be assembled on a cryomodule on the ground. Then, the cryomodule integrated with the LPDS can be installed in the tunnel. Furthermore, production cost can be decreased by utilizing identical variable hybrids and variable phase shifters. In this study, a compact LPDS was developed to satisfy these two requirements. A compact variable hybrid and variable phase shifter were designed for a compact LPDS. The power transmitted to a cavity was adjusted by the variable hybrid to achieve the maximal accelerating field, which exhibited a variation of +/- 20% depending on cavity performance. The variable phase shifter compensated the phase shift of the variable hybrid. Fixed phase shifters were designed to adjust the phase difference between adjacent cavities for beam acceleration. These RF components were manufactured, and the S parameters and power handling capability of the components were tested. An L-band resonant ring was constructed at the Super-conducing RF Test Facility (STF) at KEK. The power handling capability of these RF components were tested using a power of 5.2 MW with a pulse width of 200 is and a power of 2.0 MW with a pulse width of 2 ms. The S parameters and power handling capability satisfied the requirements of the compact LPDS. The compact LPDS will be constructed using these RF components and demonstrated at the STF.