Low-Cost Two-Stage Magnetron with Power Control for Project X

State of the art high intensity proton accelerators require the development of low cost, reliable RF sources with phase stability of less than 1 degree and amplitude control of +/- 15%. These power sources feed superconducting RF cavities for linacs capable of accelerating protons and ions up to several GeV. A two-stage phase-locked magnetron RF source based on the principle of reflection amplifiers will be developed to feed individual superconducting cavities. The 30-40 db gain of the system will be controlled by a single power supply driving the two magnetrons in parallel, to cancel the variation of the output power due to power supply ripple. The power source for the amplifier chain will feed both magnetrons to enable rapid time-to-lock so the system feedback loop will adjust the gain to the SRF cavity fast enough to damp instabilities caused by microphonics. The development of experimental tests using two magnetrons in parallel off the same power supply with control of the complex impedance of the magnetron loads will test the principle of ripple cancellation which is one of the keys to the low cost design of the power supply. A local oscillator will be fed to both magnetrons and measurements made of the time-to-lock. Commercial Applications and Other Benefits: If this project is successful, SRF linacs will have an option for low cost, highly-efficient RF sources. Other related SRF linac applications such as accelerator-driven subcritical reactors for power generation and the burning of nuclear waste will also be more affordable. In addition, if the time-to-lock and power supply ripple issues are addressed, the magnetron amplifier chain may have important radar applications.