Passive thermal control of x-ray tubes

An imaging system, comprising:

• a system for passive thermal control of an X-ray tube, comprising:
• an X-ray tube having an electron beam target and comprising a rotary bearing assembly supporting the electron beam target in rotation, wherein the rotary bearing assembly comprises:
• a stationary shaft;
• a bearing sleeve configured to rotate with respect to the stationary shaft during operation of the X-ray tube;
• a first coolant flow path extending through a center of the stationary shaft;
• a second coolant flow path disposed through a radially inward portion of the stationary shaft disposed about the center of the stationary shaft;
• and
• a flow control valve configured to passively regulate flow of coolant through the second coolant flow path based on a pressure of the coolant;
• a digital detector configured to receive radiation from the X-ray tube transmitted through a subject of interest;
• and
• an image acquisition circuit configured to control acquisition of image data from the detector.

A system for passive thermal control of an X-ray tube, comprising:

• an X-ray tube having an electron beam target and comprising a rotary bearing assembly supporting the electron beam target in rotation, wherein the rotary bearing assembly comprises:
• a stationary shaft;
• a bearing sleeve configured to rotate with respect to the stationary shaft during operation of the X-ray tube;
• a first coolant flow path extending through a center of the stationary shaft, wherein the stationary shaft comprises a first end having an inlet for the first coolant flow path and a second end disposed opposite the first end having an outlet for the first coolant flow path;
• a second coolant flow path disposed through a radially inward portion of the stationary shaft disposed about the center of the stationary shaft;
• a flow control valve configured to passively regulate flow of coolant through the second coolant flow path based on a pressure of the coolant, wherein the flow control valve comprises a spring disposed adjacent the first end or the second end of the stationary shaft, and the flow control valve is configured when closed to block the coolant from entering the second coolant flow path, and flow control valve is configured when open to allow the coolant to flow into the second coolant flow path.