RF system of VEPP-4M electron-positron collider

RF system of the VEPP-4M collider consists of six 181 MHz copper cavities fed from a single RF power source. The cavity has a Q of 50,000 and a shunt impedance of 15 MOhm. The cavities are connected to a waveguide distributing system with the aid of coaxial lines. The distance between cavity connections is equal to one wave length. Dimensions of the rectangular waveguide are chosen in such a way that the guide wave length is equal to two free-space wave length. Power distribution along the cavity chain is proportional to the distribution of cavity shunt impedances due to a proper design of the coax-to-waveguide transitions. The two-tube tetrode amplifier presently has an output RF power of 300 kW. After upgrading of the RF system its power will increase to 1.2 MW.