| 摘要 |
PURPOSE:To improve the accuracy when employing a X-ray tube depth meter by blocking the irradiation of other than X-ray taken out from a radiation port onto an insulation gas or an insulation oil thereby blocking the dark current and producing the stabilized X-ray output. CONSTITUTION:The dark current (field emission) produced from the surface of a cathode 33 is blocked by a barrier board 29 electrically isolated from a target 36. The beam except the X-ray taken out from a radiation port 31 is blocked by a thick tubular port 30, a casing central section 27a and a barrier member 29 to prevent the irradiation onto the insulator 26 at the outside of the tube or the insulation gas or the insulation oil. While only the target current due to the emission from a filament 35 is detected and fed back to a filament power source 41. |
