Patent ID: 8804910

Claim:
An x-ray tube comprising: a) an evacuated insulative cylinder; b) an anode disposed at one end of the insulative cylinder including a material configured to produce x-rays in response to impact of electrons; c) a cathode disposed at an opposing end of the insulative cylinder from the anode, the cathode including a filament disposed at an inward face of the cathode, the filament configured to produce electrons accelerated towards the anode in response to an electric field between the anode and the cathode; d) an infrared heat reflector disposed inside the insulative cylinder between the cathode and the anode, and oriented to reflect a substantial portion of infrared heat radiating from the filament back to the filament; e) the reflector having a curved, concave shape facing the cathode; f) an opening in the reflector aligned with an electron path between the filament and the anode; and g) the opening sized to allow a substantial amount of electrons to flow from the filament to the anode.