The RF-System of the Flattop-Acceleration Structure in the Sin 590-MeV-Ring-Cyclotron

Ring cyclotron tests with flattop acceleration will be started next year. These tests will be performed with a third harmonic RF-signal, added to the fundamental to flattop the wave form of the accelerating voltage. This reduces the energy spread of the beam and the usable phase spread is increased. The phase error between the fundamental and the third harmonic must not exceed .05° (with respect to 50 MHz) and an amplitude stability ΔU/U of 10-3 is sufficient. The arrangement which produces the third harmonic consists of: one cavity resonator, 60 kW transmitter, preamplifier, phase-and amplitude-regulation loops. A temporary setup of the whole system has been put into operation and tested. It will be installed in the ring cyclotron at the end of 1978.