JPH06111741A - Rotating anode x-ray generator - Google Patents

Abstract

PURPOSE:To provide an x-ray generator which can emit intense x-rays with high intensity from individual x-ray output ports even in the case x-rays are taken out of the plural ports by installing a plurality of cathodes against a rotating anode. CONSTITUTION:Electrons emitted from a filament 6 are struck against a rotating anode 2 to generate x-rays out of the rotating anode 2. This x-ray generator has a plurality of cathodes 6 installed in the surrounding of the rotating anode 2 at positions with different angles and these cathodes 6 are located at the different positions with different directions against rotary axial line L of the rotating anode 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray generator which causes electrons generated from a cathode to collide with a rotating anticathode to generate X-rays from the anticathode.

[0002]

2. Description of the Related Art X-ray diffractometers and other devices utilizing X-rays require an X-ray source for generating X-rays. Conventionally, as an X-ray generator used as such an X-ray source,
Some have a rotating cylindrical anticathode and a cathode arranged to face the anticathode. In this X-ray generator, a current is passed through the cathode to generate thermoelectrons, and the thermoelectrons are accelerated by the voltage applied between the cathode and the anticathode to collide with the anticathode. X-rays are generated from the anticathode. It is necessary to cool the anticathode as heat is generated with the X-rays when the thermoelectrons strike the anticathode. For this cooling, a technique is usually used in which the anticathode is rotated at a high speed, and at the same time, cooling water is flown into the anticathode.

Generally, the load applied to the anticathode by the collision of electrons is an electric power due to the product of the voltage applied between the cathode and the anticathode and the current flowing between the cathode and the anticathode, so-called tube current. Expressed as a quantity. The maximum permissible limit of this load is determined solely by the size of the so-called X-ray focus area of the electrons on the anticathode, the cooling capacity of the anticathode. For example, when a general cooling device is used and the X-ray focal spot size is 0.5 mm × 10 mm, 1
8KW, 1.2K when the focus size is 0.1mm x 1mm
It is set like W.

By the way, conventionally, a plurality of cathodes are arranged at different angular positions around one rotating anticathode, and X-rays are simultaneously extracted from different portions on the anticathode.
A line generator has already been proposed by the applicant. According to this X-ray generator, a large number of X-ray utilization apparatuses can be operated by one X-ray source, which is very advantageous.

[0005]

However, in the conventional X-ray generator having a plurality of cathodes, the plurality of cathodes are arranged at the same position in the direction of the rotation axis of the anticathode. Therefore, the plurality of cathodes was supposed to irradiate the same area on the anticathode with electrons. As described above, one rotating anticathode has its own maximum allowable load, and when a plurality of cathodes are provided in the one anticathode, the load that each cathode can bear becomes smaller as the number of cathodes increases. I had to do it. That is, in the conventional X-ray generator having a plurality of cathodes, the load that the anticathode can bear is limited corresponding to each cathode, so that the intensity of X-rays generated from each X-ray extraction point is limited. There was a problem that could not be increased.

The present invention has been made in order to solve the problem, and even when a plurality of cathodes are provided for one rotating anticathode and X-rays are taken out from a plurality of locations, each X-ray is taken out. It is an object of the present invention to provide an X-ray generator capable of extracting strong X-rays from a location.

[0007]

In order to achieve the above object, a rotating anticathode X-ray generator according to the present invention makes an electron generated from a cathode collide with the rotating anticathode to generate X from the anticathode.
An X-ray generator for generating rays, comprising a plurality of cathodes arranged at different angular positions around a rotating anticathode, the cathodes being offset from each other with respect to the rotational axis direction of the rotating anticathode. It is characterized by being placed in a position.

[0008]

Operation: Electrons emitted from a plurality of cathodes installed at positions displaced from each other with respect to the rotation axis direction of the rotating anticathode are
Focusing is made on different positions on the outer peripheral surface of the rotating anticathode in the direction of the rotation axis. In this way, when the electron irradiation areas of the respective cathodes with respect to the anticathode are no longer overlapped with each other, it becomes possible for each cathode to individually impinge the amount of electron flux corresponding to the maximum allowable load of the anticathode on the anticathode. . As a result, X-rays of maximum intensity can be extracted from each X-ray extraction position corresponding to each cathode.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a rotary anticathode X-ray generator according to the present invention when viewed in plan from above.
This X-ray generator has a casing 1 in the shape of a rectangular tube, and a rotating anticathode 2 in the shape of a cylinder centered on an axis L arranged inside the casing 1. The inside of the casing 1 is held in a vacuum state by a vacuum suction device (not shown). The rotating anticathode 2 is made of, for example, copper and is fixed to the side wall 1 a of the casing 1 by the support tube 3. A pulley 4 is fixed to the shaft end of the rotating anticathode 2, and a driving force is transmitted from a drive source (not shown), for example, a motor, through the pulley 4 so that the rotating anticathode 2 is rotated.
Rotates at high speed around the axis L.

Front and rear position of the rotating anticathode 2 (up and down position in the figure)
2 electron guns 5a and 5b, one for each
Are provided in a fixed state. Each electron gun 5a, 5b is
A coil-shaped filament 6 serving as a cathode and a Wehnelt 7 that forms an electric field for controlling the traveling direction of electrons emitted from the filament 6 are provided. A current is supplied to each filament 6 from a current supply circuit 8. Further, a voltage is applied between each filament 6 and the anticathode 2 by a voltage applying circuit 9. The electron guns 5a and 5b are arranged in a horizontal position as shown in FIG.
It has an angle interval of 80 degrees. Further, as shown in FIG. 1, the electron guns 5a and 5b are arranged at positions displaced from each other in the direction of the rotation axis L of the anticathode 2. As a result, the regions where the electrons emitted from the electron guns 5a and 5b collide with the anticathode 2 do not overlap each other.

On the left and right side walls of the casing 1, two X-ray extraction windows 10, two for each, are attached in a fixed state. Each window 10 has a disc-shaped X-ray transmission member 11 formed of beryllium inside.

A water supply / drainage port 12 for cooling water is provided at the shaft end of the rotating anticathode 2, and the cooling water sent from a water source (not shown) is supplied to the inside of the anticathode 2 through the water supply / drainage port 12. To be done. The cooling water that has finished flowing through the circulation path (not shown) formed inside the anticathode 2 is discharged from the water supply / drainage port 12 to the outside.

The operation of the X-ray generator having the above structure will be described below.

The thermoelectrons are emitted from the filament 6 which generates heat due to the power supply from the current supply circuit 8, and the thermoelectrons are accelerated by the voltage applied between the filament 6 and the anticathode 2 by the voltage application circuit 9, and the thermoelectrons are accelerated. It collides with the outer peripheral surface of the anticathode 2. For example, 0.
Collisions within an area of 5 mm x 10 mm. This area is the so-called X-ray focus. Due to this collision, 2 of the anticathode 2
X-rays R1 and R2 are generated from the location, and these X-rays are taken out through the window 10. Extracted X-ray R
1 and R2 are so-called point-focused X-rays having a dot-shaped cross section, which are introduced into an X-ray utilizing apparatus such as a known X-ray diffractometer and used for various measurements.

While X-rays are generated from the anticathode 2, the anticathode 2
Is cooled by its own high speed rotation and cooling water circulating inside. By this cooling, the maximum allowable load applied to the anticathode 2, for example, 18 KW is maintained.

By the way, it is assumed that the two electron guns 5a and 5 are
Considering the case where the arrangement positions of b in the direction of the axis L are the same, the electrons emitted from those electron guns are not
The region that collides with is overlapped with the same position of the anticathode 2. Even in this case, since the maximum allowable load of the anticathode 2 held by the high speed rotation of the anticathode 2 and the cooling by the cooling water is 18 KW, the amount of electrons that can be output by each of the electron guns 5a and 5b is half that of 18 KW. You will be limited.
If the sum of the outputs of both electron guns 5a and 5b exceeds 18 kW, the overcathode 2 is damaged due to overload and normal generation of X-rays cannot be continued. With this, each electron gun 5a
And 5b, the intensity of the X-rays R1 and R2 that are generated cannot be maintained high.

On the other hand, in this embodiment, the arrangement positions of the electron guns 5a and 5b in the direction of the axis L are displaced from each other. Therefore, on the anticathode 2, the region that receives electrons from the one electron gun 5a and the region that receives electrons from the other electron gun 5b do not overlap each other. As a result, the maximum allowable load of the anticathode 2 corresponding to each electron gun 5a and 5b is maintained at 18 KW. Therefore, each electron gun 5a
The X-rays R1 and R2 generated corresponding to 5 and 5b can have the maximum intensity corresponding to the maximum allowable load, respectively.

Although the present invention has been described with reference to one embodiment, the present invention is not limited to this embodiment.

For example, the anticathode 2 of the electron gun 5a or 5b
2 can be set at a vertical position, that is, at an angular position 90 degrees away from the horizontal position, as indicated by reference numeral 5c in FIG. Alternatively, in addition to the two electron guns 5a and 5b arranged in the horizontal position, the third electron gun 5
It is also possible to place c in its vertical position. The electrons emitted from the filament in the electron gun 5c arranged at this vertical position form X-ray focal points on the anticathode 2 which are long in the left and right directions as indicated by symbol A in FIG. Therefore, if X-rays are extracted from the front and rear walls 1b or 1c of the casing 1, so-called line-focus X-rays can be extracted.

[0020]

According to the present invention, since the electron flux emitted from a plurality of cathodes, that is, filaments, are focused on different positions of one anticathode and do not overlap with each other, the individual filaments are not overlapped with each other. It is possible to increase the electron output amount of the device to the output amount corresponding to the maximum allowable load of the anticathode. As a result, the output intensity of X-rays generated from different positions of the anticathode can be maximized.

[0021]

[Brief description of drawings]

FIG. 1 is a plan sectional view showing an embodiment of a rotating anticathode X-ray generator according to the present invention.

FIG. 2 is a side sectional view taken along the line II-II in FIG.

[Explanation of symbols]

 1 Casing 2 Rotating anticathode 5a, 5b Electron gun 6 Filament (cathode) L Rotating anticathode rotation axis

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sadayuki Takahashi 3-9-12 Matsubara-cho, Akishima-shi, Tokyo Rigaku Denki Co., Ltd. Haijima factory

Claims (2)

[Claims] 1. An X-ray generator for colliding electrons generated from a cathode with a rotating anticathode to generate X-rays from the anticathode, wherein a plurality of cathodes are arranged at different angular positions around the rotating anticathode. And an X-ray generator for rotating anticathodes, wherein the cathodes are arranged at positions displaced from each other with respect to the rotation axis direction of the rotating anticathode. 2. The rotating anticathode X-ray generator according to claim 1, further comprising at least two cathodes arranged in a horizontal position and a cathode arranged in a vertical direction.