THE ENERGY SWITCH IN A 20 MeV MULTI-ENERGY

A 20MeV S-band on-axis coupled SW guide with "Energy Switch" has been developed for the high-energy medical accelerator. Since the guide is on-axis coupled and operated in the π/2 mode at 2856MHz, the axial size of the coupling cells is so small that the existing technology of energy switch in side coupled accelerators is difficult to use. Consequently a new type of energy switch is developed to fit the on-axis coupled structure. This paper presents the microwave properties of the energy switch under cold and high power tests. Commissioning test has been completed by the end of year 2000. The beam test results show that the energy switch performs well, meeting the design criteria.