High power tests of first input couplers for cornell erl injector cavities

The first two RF power couplers for the ERL injector, currently under construction at Cornell University, have been fabricated. The couplers were assembled in the liquid nitrogen cryostat, built for their tests. A 15 kW CW IOT transmitter was available for coupler tests. A resonant ring was used for an additional increase of power. The couplers were successfully tested up to the goal power level of 50 kW CW. However, the first pair of couplers showed an excessive temperature rise at some points. Therefore, minor changes in the design have been done to improve cooling.