RF average power measurement system at the S-DALINAC

When injecting charged particles into a radio frequency (RF) field at a phase, where the particles are decelerated instead of accelerated, the particles return energy to the RF field. This effect is called energy recovery. The beam-energy recovery efficiency is determined by the measurement of RF forward and reverse powers. At the S-DALINAC, no RF power detection system was available to permanently measure all cavities simultaneously for a full energy recovery characterization. In this paper, the new RF power measurement setup is described regarding design and characterization of this system. With an energy gain measurement, an additional application of the system is presented, which was done for the first time for 20-cell cavities using an RF power measurement.