5. Conclusion

This article gives an overview of high-power electronic tubes: intrinsic and practical performance and limitations.

Klystrons deliver unrivalled peak powers (from MW to several tens of MW) up to around 15 GHz, and are mainly found in circular (LHC) and linear (LINAC) particle gas pedals, where they are indispensable. Crossed-field tubes are hardly ever used as amplifiers any more, due to their very modest gain, but as oscillators they remain the most widely manufactured tubes in the world (magnetrons equip all microwave ovens). Last but not least, gyrotrons are essential power sources for future thermonuclear fusion reactors. Over the last few decades, other concepts have been put forward to produce very high power in the millimeter range, but these are currently used for confidential purposes.