High-energy radiofrequency (RF) accelerators typically rely on vacuum tubes such as tetrodes and klystrons to drive their final power amplification stage. While well-suited for high-power applications, these vacuum tubes represent a significant running cost as they need to be replaced regularly and come at a high premium. Furthermore, these tubes typically account for the most common cause of downtime and their maintenance requires specific knowledge, fine tuning and trained personnel. The high voltage at which the tubes are operating poses a safety concern and further need for specialized personnel.

Until recently, there were no affordable and practical alternatives to these vacuum tubes. However, promising new developments in the field of solid-state amplifiers (SSA) may very well cause a paradigm shift in the field of RF power for accelerators. These new SSA are based on a plug-and-play modular design, where no component is a single point of failure, making them much more reliable. They do not require any manual tuning, do not contain any short-lived consumable parts and operate at low voltage, facilitating maintenance, reducing costs, and improving safety. Furthermore, they boast superior electrical efficiency which makes them more sustainable and reduces electricity costs.

In this study, we will present the results of the implementation of solid-state technology on a 240 kW Rhodotron accelerator. Numbers from thorough testing at maximum power during several months will be presented, comparing the electrical efficiency measured in practice and the real system uptime to those measured on a Rhodotron equipped with conventional vacuum tubes. A cost analysis will be presented, showing that solid-state amplifiers are already cost-competitive with tube-based amplifiers.