On the Phase Grouping Mechanism for a Magnetron Coherent Oscillation

TL;DR

This paper explores a phase grouping mechanism in magnetrons, proposing a novel approach to optimize their use as coherent RF sources for superconducting RF cavities, especially under wide bandwidth control conditions.

Contribution

It introduces a new method for controlling magnetron phase coherence, enhancing their suitability for feeding high Q-factor SRF cavities with wide bandwidth phase and power control.

Findings

Magnetrons can operate in regimes suitable for SRF cavities with proper phase control.

The proposed approach enables almost coherent oscillation over wide bandwidths.

Optimized magnetron parameters improve stability and control for accelerator applications.

Abstract

CW magnetrons, developed for industrial heaters, but driven by an injection-locking signal were suggested to power Superconducting RF (SRF) cavities due to higher efficiency and lower cost of generated RF power per Watt than traditionally used RF sources (klystrons, IOTs, solid-state amplifiers). When the magnetrons are intended to feed Room Temperature (RT) cavities, the injected phase or frequency locking signal may provide required phase or frequency stability of the accelerating field. However, when the magnetron RF sources are intended to feed high Q-factor SRF cavities, the sources must be controlled in phase and power in a wide bandwidth to compensate parasitic phase and amplitude modulations caused by microphonics. In dependence on parameters of magnetron and the injection-locking signal one can choose regime most suitable for feeding SRF cavities, enabling magnetron almost coherent oscillation at the wide bandwidth of control. A novel approach considering magnetrons as quasi-coherent or coherent RF generators enables choosing the tube parameters and operation most suitable for various SRF accelerators.