  Phase and power control methods that satisfy the requirements of
superconducting accelerators to magnetron RF sources were considered by a
simplified kinetic model of a magnetron driven by a resonant injected signal.
The model predicting and explaining stable, low noise operation of the tube
below the threshold of self-excitation (the Hatrree voltage in free run mode)
at a highest efficiency, a wide range of power control and a wide-band phase
control was well verified in experiments demonstrating capabilities of the
magnetron transmitters for powering of state of the art superconducting
accelerators. Descriptions of the kinetic model, the experimental verification
and a conceptual scheme of the highly-efficient magnetron RF transmitter for
the accelerators are presented and discussed.
