Interaction Structure

(delaying structure), a wave-guide system in superhigh-frequency electronic devices; it is used to decelerate the phase velocity of electromagnetic waves to approximately the speed of movement of the electrons in the device. Because of this effect, an interaction structure creates the conditions necessary for the diversion of energy by waves moving parallel to the electron flow through a decrease in the kinetic energy of the electron flow. An increase in power is possible in cases of long-term interaction between the wave and the electron flow.

Interaction structures are of various designs. Spiral structures are widely used. The waves propagate along the conductor of the spiral with a velocity approaching the speed of light; however, the wave velocity along the spiral itself decreases, depending on the pitch of the spiral. Interaction structures are the basic design elements for traveling-wave and backward-wave tubes.