KLYSTRONS
How Klystrons Work
Electrons emitted from the cathode are accelerated by the electric field between the cathode and anode and enter a cavity. At this time, depending upon the phase of the microwave field input from a drive circuit, electrons may be accelerated or decelerated (this is known as "velocity modulation").
Accelerated and decelerated electrons become grouped (density modulation) while passing through a uniform electric field in the interaction section, and gradually become bunched. The electron bunches are gradually emphasized by self-induced microwave fields in appropriately located interim cavities.
Finally the bunched electron beam enters the output cavity and induces a large alternating electric field which is output as an amplified microwave through the output window.
