A 150-kW Pulse Solid-State Amplifier for Radio Frequency Quadrupole Application

The development of a four vane 3-MeV radio frequency quadrupole is under progress at Raja Ramanna Centre for Advanced Technology, as part of the Indian facility for spallation source. This quadrupole will be powered by four identical 150-kW solid-state amplifiers, each operating at 325 MHz. This article describes the design details, rigorous testing, and measured results of the first such constructed amplifier and its constituent components. Its output power is 150 kW, with variable pulsewidth from 1 to 5 ms, at 50 Hz of pulse repletion rate. Its pulse amplitude droop measured at 1 ms is 0.46 dB. The phase variation around an average value, measured within a single pulse at 1 ms, is less than 2.7°. Its pulse-to-pulse amplitude stability and phase stability are ±0.1 dB and ±2°, respectively. Its main features are its modular and scalable design architecture, comprising of multiple extended continuous class F 1.5-kW amplifiers, energy-efficient two-tier radial power dividers as well as combiners, compact dual-channel power sensors, and aperture-coupled directional couplers.