COOLING DEVICE USED IN X-RAY TUBE

PROBLEM TO BE SOLVED: To provide a cooling device for a target substrate which eliminates thermal damages occurring in a target substrate of an X-ray tube. SOLUTION: This cooling device used in an X-ray tube, equipped with a target plate cools a reverse side 3 of the target 1 subjected to incidence of an electron beam 9 by cooling water 7 wherein a cooling water channel 6 is formed along the reverse side 3 and a separator 4 is installed over the reverse side 3 of the target 1 and is equipped with a vaporized jet intake 5 which opens above the reverse side 3 of the target area is made incident with the electron beam 9, so that a bubble 8 produced by the vaporized jet is discharged together with the cooling water 7 supplied through the cooling channel 6 out of the vaporized jet intake 5 into the inside of the separator 4.