Patent ID: 8761345

Claim:
An X-ray tube, comprising: a cathode to emit electrons; an anode target to emit X-rays by incident electrons emitted from the cathode; a vacuum envelope housing the cathode and the anode target, the vacuum envelope including: a first metal member connected to the anode target and extending in a direction along a tube axis of the x-ray tube, the first metal member having an X-ray radiation window; a second metal member connected to the first metal member, extending in a direction along the tube axis, and having a coefficient of thermal expansion lower than that of the first metal member; and an electrically insulating annular ceramic member connected to the second metal member and the cathode, and projecting from the cathode in a direction perpendicular to the tube axis; and an adapter placed so as to be in contact with the first metal member, and surrounding the second metal member outside the vacuum envelope, and having a thermal conductivity higher than that of the second metal member; a heat-transfer medium placed between the ceramic member and the adapter, outside the vacuum envelope; and a cooling system connected to the first metal member and forming a cooling passage through which coolant flows, wherein heat released from the anode target is conducted to the cooling system directly or indirectly via the first metal member, and heat released from the cathode is conducted to the cooling system indirectly via the ceramic member, the heat-transfer medium, the adapter, and the first metal member.