  A concept of a 650 MHz CW magnetron transmitter with fast control in phase
and power, based on two-stage injection-locked CW magnetrons, has been proposed
to drive Superconducting Cavities (SC) for intensity-frontier accelerators. The
concept is based on a theoretical model considering a magnetron as a forced
oscillator and experimentally verified with a 2.5 MW pulsed magnetron. To
fulfill fast control of phase and output power requirements of SC accelerators,
both two-stage injection-locked CW magnetrons are combined with a 3-dB hybrid.
Fast control in output power is achieved by varying the input phase of one of
the magnetrons. For output power up to 250 kW we expect the output/input power
ratio to be about 35 to 40 dB in CW or quasi-CW mode with long pulse duration.
All magnetrons of the transmitter should be based on commercially available
models to decrease the cost of the system. An experimental model using 1 kW,
CW, S-band, injection-locked magnetrons with a 3-dB hybrid combiner has been
developed and built for study. A description of the model, simulations, and
experimental results are presented and discussed in this work.
