X-ray tube cooling by emissive heat transfer

An x-ray tube, comprising:

• an evacuated envelope;
• a cathode assembly disposed in the evacuated envelope, the cathode assembly comprising a cathode shield, a supporting body disposed inside the cathode shield, and an electron source attached to the supporting body and partially enclosed by the cathode shield;
• and
• an anode assembly disposed in the evacuated envelope, the anode assembly comprising a target configured to produce x-rays upon impingement by electrons produced by the electron source;
• a cathode can disposed in the evacuated envelope surrounding the cathode assembly,
• wherein the cathode shield comprises a shield base material, and at least a portion of the cathode shield comprises a first layer converted from the shield base material, the first layer possesses a first emissivity greater than an emissivity of the shield base material;
• and
• wherein the cathode can comprises a can base material, and at least a portion of the cathode can comprises a second layer converted from the can base material, the second layer possesses a second emissivity greater than an emissivity of the can base material.

A cathode assembly, comprising:

• a cathode shield;
• a supporting body disposed inside the cathode shield;
• and
• an electron source attached to the supporting body and partially enclosed by the cathode shield;
• wherein the cathode shield comprises a shield base material, and at least a portion of the cathode shield comprises a layer converted from the shield base material, the layer possesses an emissivity greater than an emissivity of the shield base material.

An x-ray tube, comprising:

• an evacuated envelope;
• a cathode assembly disposed in the evacuated envelope, the cathode assembly comprising a cathode shield, a supporting body disposed inside the cathode shield, and an electron source attached to the supporting body and partially enclosed by the cathode shield;
• and
• an anode assembly disposed in the evacuated envelope, the anode assembly comprising a target configured to produce x-rays upon impingement by electrons produced by the electron source;
• wherein the cathode shield comprises a shield base material and a layer over at least a portion of the base material, the layer comprises an emissivity enhancer having an emissivity greater than an emissivity of the shield base material, wherein the emissivity enhancer comprises titanium nitride or titanium aluminum nitride.