US Patent 7428298 Magnetic head for X-ray source

An X-ray source includes a magnetic appliance to provide electron beam focusing. The magnetic appliance can provide variably focused and non-focused configurations. The magnetic appliance can include one or more electromagnets and/or permanent magnets. An electric potential difference is applied to an anode and a cathode that are disposed on opposite sides of an evacuated tube. The cathode includes a cathode element to produce electrons that are accelerated towards the anode in response to the electric field between the anode and the cathode. The anode includes a target material to produce x-rays in response to impact of electrons.