JPS58128644A - Target for x-ray tube - Google Patents

Abstract

PURPOSE:To increase the long-time average input of a large-capacity X-ray tube by increasing the thermal radiation rate of an X-ray tube target, which is prepared by coating a part of the surface of a graphite base body with W-layer, by blackening the surface of said W-layer. CONSTITUTION:In an X-ray tube target which is prepared by coating a part of a graphite base body 1 with a W-layer 2, the W-layer 2 is blackened A, C so as to increase the thermal radiation rate. As a result, the effect of the W-coat layer 2 used as an intensity reinforcing member, can be increased. Besides, the thermal radiation can be increased at the blackened part, and the long-time average input of a large-capacity X-ray tube can be widely increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphite-based target for an X-ray tube that has significantly improved long-term average input power.

Conventionally, the target of the Tenyo II X-ray tube was made of molybdenum, tungsten, etc., but if such materials were used and the volume was increased to increase the heat capacity, the target would become heavier. For this reason, the substrate is made of graphite, which has a relatively large specific heat and a small specific gravity, and is made of thick granite.
Targets coated with a tungsten layer, which has excellent high-temperature strength, have been developed and are beginning to be put into practical use in order to strengthen mechanical strength and to counter high temperatures caused by large amounts of heat generated by electron beam impact. However, in conventional targets of this kind, the thermal emissivity of the tungsten-coated surface is low, so even though a graphite base is used, the thermal emissivity of the target as a whole is not very high, and the heat dissipation is small, so it is difficult to maintain For example, in the case of a large-capacity XIi tube used in combination with a CT display, there is a problem that the average input cannot be made sufficiently large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an X-ray tube target in which the -S surface of a graphite base is covered with a tungsten layer, which allows a larger average input power than before when used for a long time.

In order to achieve the above object, in the present invention, the surface of the tungsten layer is blackened to increase the thermal emissivity. Some good blackened tungsten surfaces have electrical insulation properties or emit gas when struck by fast electrons. All you need to do is blacken the tungsten surface, excluding the protrusions. In this case, the reduced blackened area is small and does not pose a problem.

Figure 1.2 shows this example, Figure 1 is a front view,
2aa is a cross-sectional view, where l is the wax lead base, 2 is the covering tungsten layer, A and C are the blackened portions, and B is the blackened excluded portion where the electron beam strikes. It is clear that the tungsten covering layer is still effective as a strength reinforcing member, but also significantly improves heat dissipation. Since the heat dissipation ratio of the blackened part could be increased to about 0.8 or more, the heat dissipation of the target could be improved by about twice. Therefore, the long-term average input of the target can be approximately doubled, and the actual
Using a tube, it is possible to significantly increase the number of patients who can be diagnosed.

As explained above, according to the present invention, the long-term average input of a large-capacity X-ray tube can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a front view of an embodiment of the present invention, and FIG. 2 is a cross-sectional view thereof. l...graphite base, 2...overcoated tungsten layer, A. C: Blackened area, B: Deterioration excluded area. 1 , , -・ 1st Figure 22 2nd Figure

Claims (1)

[Scope of Claims] 1. An X-ray tube target comprising a graphite base and a portion of its surface covered with a tungsten layer, characterized in that the surface of the tungsten layer is blackened. 2. A target for an X-ray tube according to ITA, in which the surface of the tungsten layer other than the electron beam impact area is blackened.