Mechanism of x-ray production

The mechanism of x-ray production is NOT the same in a kV x-ray unit and an accelerator unit!

In a kV machine, the potential difference is V between the cathode and the anode accelerates the filament electrons.

In an accelerator, however the electrons are accelerated to near the velocity of light. They are bunched together and injected into the microwave carrying cavities to be accelerated by the waves in the phase stable position.