JPH01204337A - X-ray tubular bulb capable of changing over between point focus and line focus - Google Patents

Abstract

PURPOSE:To make it possible to allow switch-over between point focus and line focus only with an electron gun rotated by 90 deg. by forming the cooling water injection opening of a target into a cross shape, and thereby mounting the electron gun rotatably. CONSTITUTION:The cooling water injection opening 26 of the back side of a target face 28 to which electron beams are struck is formed into a cross shape, and an electron gun is rotatably mounted onto a vacuum container. The target face 25 is sufficiently cooled by the injection opening 26 in the range of the cross shape. Electron beams 34 emitted from a filament 32 are struck against the target face 28 in a form of a line extending to the vertical direction so that X-rays 38 of line focus are obtained. When the electron gun 16 is rotated clockwise by 90 deg., the filament 32 is rotated clockwise by 90 deg. so as to let the election beams 34 emitted form a line extending to the horizontal direction so that X-rays of point focus may be obtained. By this constitution, a X-ray tubular bulb 10 can be obtained, which makes it possible to allow switch-over between point focus and line focus in the same direction in a simple manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an X-ray tube having a water-cooled target, and more particularly to an X-ray tube capable of switching between a point focus and a line focus.

[Prior Art] In an X-ray tube, an electron beam from an electron gun is applied linearly to a target to generate X-rays. Therefore, the portion where X-rays are generated becomes linear. Then, depending on the direction in which this linear X-ray is extracted from the X-ray tube, the
It is used as a radiation source.

In analytical devices that use X-rays, it is necessary to use point focus and line focus depending on the purpose of use.
It would be convenient if the X-ray tube on the stand could be used for different purposes. Conventionally, these are used depending on the direction in which the X-rays are extracted from the X-ray tube.

[Problem to be solved by the invention] If you want to switch between a point focus and a line focus in one specific direction, in an enclosed X-ray tube, you have to rotate the entire tube by 90 degrees. On the other hand, in the case of an open-type X-ray tube, the vacuum must be returned to the atmosphere and the mounting angle of the target and electron gun must be changed. It's also time consuming. In the latter case, in principle, the mounting of the electron gun can be switched simply by changing the angle, but the shape of the cooling water spout on the back of the target is linear in accordance with the area hit by the electrons. Because of this, the angle at which the target is mounted must also be changed.

In view of the above points, an object of the present invention is to provide an X-ray tube that can switch between a point focus and an X-ray focus in the same direction with a very simple operation.

[Means for Solving the Problems] In order to achieve the above object, in the X-ray tube according to the invention of claim 1, the shape of the cooling water spout on the back side of the target surface that is hit by the electron beam is cross-shaped, It is characterized in that the electron gun is rotatably attached to the vacuum vessel.

Further, in the X-ray tube according to the invention of claim 2, the shape of the cooling water spout on the back side of the target surface that is hit by the electron beam is cross-shaped, and the electromagnetic wave that changes the traveling direction of the electron beam from the electron gun toward the target is provided. A lens is provided in a vacuum container, and the polarity of the current flowing through the electromagnetic lens is switchable.

[Function] In the invention of claim 1, when the electron gun is rotated by 90 degrees with respect to the vacuum vessel, the linear electron beam irradiation area on the target surface is rotated by 90 degrees, and the point focus becomes a line focus. Or vice versa, it becomes possible to switch. Since the cooling water spout on the back side of the target is cross-shaped, even if the linear electron beam irradiation area on the target surface rotates 90 degrees, the electron beam irradiation area will always be sufficiently cooled by the cooling water. That will happen. In other words, the target remains fixed.

In the invention of claim 2, instead of rotating the electron gun,
The direction of the electron beam from the electron gun toward the target is changed. In other words, the electron gun can also remain fixed.

By switching the polarity of the current flowing through the electromagnetic lens,
The linear electron beam irradiation area on the target surface is rotated by 90 degrees.

The shape of the cooling water spout on the back surface of the target is the same as that of the first aspect of the invention, and the target is similarly cooled.

Examples] Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partially sectional front view of an embodiment of the invention according to claim 1. This X-ray tube 10 is an open type, and the vacuum container 1
2 includes a target 14 and an electron gun 16. The electron gun 16 is vacuum-sealed by an O-ring 18 and rotatably attached to the vacuum container 12 by a bearing 20.

Note that the O-ring 18 may be replaced with other sealing means, such as a sealing means using magnetic fluid.

As shown in FIG. 2, the target 14 is water-cooled. The cooling water 22 flows through the inner passage 24 of the target 14.
The electron beam passes through and is vigorously ejected from the ejection port 26, cooling the back side of the target surface 28 that is hit by the electron beam. The cooling water is then discharged through the outer passage 30. The jet nozzle 26 is cross-shaped as shown in FIG. 3, and sufficiently cools the target surface 28 within the cross-shaped area.

Next, how to use this X-ray tube will be explained. First, the fourth
Assume that the electron gun is set so that the filament 32 is oriented vertically, as shown in the figure. In this case, the electron beam 34 emitted from the filament 32 becomes a line extending in the vertical direction and hits the target surface 28,
A linear X-ray beam 36 emerges in the front left direction of FIG. That is, X-rays 3B with a line focus are obtained. A broken line drawn on the target surface 28 indicates the position of the cooling water spout 26 on the back surface thereof.

Next, when the electron gun 16 is rotated 90 degrees clockwise when viewed from the right side in FIG. 1, the filament 32 in FIG.
is rotated 90 degrees clockwise, resulting in the state shown in Figure 5. In this state, the electron beam 34 emitted from the filament 32
becomes a line extending in the horizontal direction, and as a result, a point focused X-ray 40 is obtained in the front left direction in FIG.

FIG. 6 is a partially sectional front view of an embodiment of the invention according to claim 2. This X-ray tube 50 includes a target 14 and an electron gun 16 inside a vacuum vessel 12.

This tube has no mechanically moving parts and may be of the enclosed or open type. The electron gun 16 is fixed to the vacuum container 12. As shown in FIG. 7, the filament 32 of the electron gun 16 is fixed at an angle of 45 degrees from the vertical direction.

Returning to FIG. 6, an electromagnetic lens 52 is provided on the outside of the vacuum container 12. The electromagnetic lens 52 is formed by a coil 56 surrounded by a ferromagnetic material 54 such as iron. A part of the ferromagnetic material 54 is open, and a magnetic field 5B is formed in the vicinity thereof. This magnetic field 58 will affect the electron beam.

The coil 56 of the electromagnetic lens 52 is connected to a power source 60,
The polarity of the current flowing through the coil 56 is switched by a changeover switch 62. That is, the polarity of the current can be switched by tilting the two-pole, double-throw changeover switch 62 to the right or left side in FIG. 6.

The target 14 of this X-ray tube 50 has the same cooling structure as shown in FIGS. 2 and 3.

Next, how to use this X-ray tube 50 will be explained.

First, assume that the changeover switch 62 is tilted to the left in FIG. In this case, in FIG. 7, the electron beam 34 emitted from the filament 32 of the electron gun 16 initially travels in a line inclined at 45 degrees with respect to the vertical direction, but due to the influence of the magnetic field of the electromagnetic lens, The whole body rotates in the direction 64, and when it hits the target surface 28, it is in a vertical state. Therefore, at this time, an X-ray 38 with a line focus in the front left direction in FIG. 7 is obtained.

Next, when the changeover switch 62 in FIG. 6 is turned to the right, the polarity of the current flowing through the coil 56 of the electromagnetic lens 52 is switched, and the magnetic field 58 is reversed. Then, in FIG. 8, the electron beam 34 is now rotated a total of 45 degrees in the direction of the arrow 64 and hits the target surface 28. As a result, point focused X-rays 40 are obtained.

In both cases of FIG. 7 and FIG. 8, the target surface 28 is sufficiently cooled by the cooling water jetted from the cross-shaped spout 26.

The rotation angle of the electron beam from the electron gun to the target is determined by the distance from the electromagnetic lens to the target surface, the strength of the magnetic field by the electromagnetic lens, and the electron acceleration voltage. can be rotated by 45°. In this example, the distance from the center of the magnetic field by the electromagnetic lens to the target surface is 130 mm, the inner diameter of the electromagnetic lens is 34 mm, the ampere turns of the electromagnetic lens are 920 to 950 ampere turns, and the voltage applied to the X-ray tube is 50 kV. When , the electron beam is rotated by 45°.

[Effects of the Invention] According to the invention of claim 1, the cooling water spout of the target is made into a cross shape, and the electron gun is rotatably attached, so that by simply rotating the electron gun 90 degrees, a point focus and a line can be created. It has the effect of being able to switch focus.

According to the second aspect of the invention, the cooling water spout of the target is shaped like a cross, and the polarity of the current flowing through the electromagnetic lens is switchable, so that the electric circuit of the electromagnetic lens can be changed without moving the target or the electron gun. The effect is that you can switch between a point focus and a line focus simply by operating the switch.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional front view of an embodiment of the invention of claim 1, Fig. 2 is a vertical sectional view of the target, Fig. 3 is a transverse sectional view taken along the line ■-■ in Fig. 2, and Fig. The figure is a perspective view showing the trajectory of electron beams and X-rays, FIG. 5 is a perspective view similar to FIG. 4 showing another operating state, and FIG. 6 is a partial cross section of an embodiment of the invention of claim 2. The front view, FIGS. 7 and 8 are perspective views similar to FIGS. 4 and 5. 10...X-ray tube 12...Vacuum vessel 14...Target 16...Electron gun 20...Bearing 26...Cooling water spout 38...X-ray focal point 40...・Point focused X-ray 52...Electromagnetic lens 62...Switch switch

Claims (2)

[Claims] (1) In an X-ray tube that includes an electron gun and a water-cooled target inside a vacuum vessel, the shape of the cooling water spout on the back side of the target surface that is hit by the electron beam is cross-shaped, and the electron gun is An X-ray tube capable of switching between a point focus and a line focus, characterized in that it is rotatably attached to a container. (2) In an X-ray tube that includes an electron gun and a water-cooled target inside a vacuum vessel, the shape of the cooling water spout on the back side of the target surface that is hit by the electron beam is cross-shaped, and the An X-ray tube capable of switching between a point focus and a line focus, characterized in that an electromagnetic lens for changing the traveling direction of the electron beam toward the vacuum vessel is provided, and the polarity of the current flowing through the electromagnetic lens can be switched. .