A High-power 650 MHz CW Magnetron Transmitter for Intensity Frontier Superconducting Accelerators

TL;DR

This paper proposes a novel 650 MHz CW magnetron transmitter with fast phase and power control for superconducting accelerators, verified through experiments with a 2.5 MW pulsed magnetron and a 1 kW CW prototype.

Contribution

It introduces a two-stage injection-locked magnetron system with hybrid combining for fast control, based on theoretical modeling and experimental validation.

Findings

Achieved fast power control by input phase variation.

Demonstrated a 1 kW CW magnetron prototype with hybrid combiner.

Projected high efficiency with 35-40 dB power ratio in CW mode.

Abstract

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.