How does an RF linac structure work?
In RF linacs, very high electric and magnetic fields are produced by injecting RF energy from a powerful RF system, similar to a radar transmitter, into a confined region of space (cavity) bounded by conducting materials (usually copper) to keep the energy from radiating away (as in radio, television or radar transmissions). The particles to be accelerated are injected into the linac structure. As the direction of the electric field reverses millions of times per second, the linac structure must be designed to manage the distribution of the electric fields within the structure and the distribution of the particles within the beam so that the particles are exposed to the electric fields when they are in the accelerating direction and shielded from them when they are in the decelerating direction.
