Crossed-field amplifier

Raytheon engineer William C. Brown's work to adapt magnetron principles to create a new broadband amplifier is generally recognized as the first CFA, which he called an Amplitron.

Their current use is in satellite ground stations and deep space communications networks.

This is the same type of field interaction used in a magnetron; as a result, the two devices share many characteristics (such as high peak power and efficiency), and they have similar physical appearances.

The CFA has the useful property that when power is shut off, the input simply passes to the output with little loss.

This approach with built-in redundancy was used on the S-band downlink transmitter on the Apollo Lunar Module, where high efficiency and reliability were needed.