JPH04253147A - X-ray generator - Google Patents

Abstract

PURPOSE:To prevent a cooling liquid for cooling a target from infiltrating into a target unit integrated with the target to adversely affect various apparatuses in the target unit. CONSTITUTION:A target unit 3 is fixed to an X-ray tube 1 in the inclined state, and an inflow port and a discharge port of a cooling liquid for cooling a target 2 are arranged at positions lower than a drive motor 11 and other apparatuses in the target unit 3. The cooling liquid is most likely to leak at the inflow port and the discharge port. Even if the cooling liquid is leaked, the leaked liquid drops according to the inclination of the target unit 3 and does not infiltrate into the target unit 3.

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 for generating X-rays used in an X-ray apparatus such as an X-ray diffraction apparatus. In particular, the present invention relates to an X-ray generating apparatus in which a cooling liquid, such as water, is passed through a target.

0002

[Prior Art] Generally, an X-ray generator has a cylindrical X-ray tube, and inside the X-ray tube there is a cathode formed of a coiled filament, etc., and a copper (Cu) , an anticathode made of molybdenum (Mo) or the like and called a target. In this X-ray generator, a cathode is heated to a high temperature to emit thermoelectrons from the cathode, and a high voltage applied between the cathode and anticathode accelerates the thermoelectrons and causes them to collide with the anticathode. When electrons collide with the anticathode, X-rays are generated from the anticathode, and some of these X-rays are emitted to the outside through an X-ray extraction window pre-installed on the side wall of the X-ray tube. be done.

[0003] In the above-mentioned X-ray generator, the anticathode generates heat due to the collision of thermoelectrons and becomes extremely high temperature. Therefore,
In order for the target to continuously emit X-rays, the target must be cooled. Conventionally, known methods for cooling a target include rotating the target to prevent electrons from colliding with only one location on the target, and flowing a cooling liquid, such as water, inside the target. There is. Only one of these methods is used, or both methods are used in combination.

[0004] When the target is rotated and the coolant is allowed to flow inside the target, a rotation drive device for rotating the target and a coolant passage for flowing the coolant into the target are attached to the target. There must be. Generally they are integrally formed as a whole as a target unit. In conventional X-ray generators, this target unit is attached to the X-ray tube in a horizontal state, and the target at the tip thereof is placed inside the X-ray tube.

[0005]

[Problems to be Solved by the Invention] In the conventional X-ray generator, the target unit is arranged horizontally as described above. Therefore, all of the coolant that would normally have to flow into the coolant passage through the coolant inlet and be discharged to the outside of the target unit through the coolant outlet is A phenomenon has occurred in which the coolant leaks to the outside near the discharge port, and the leaked coolant flows back into the target unit. Inside the target unit, various devices are installed, such as a target rotation drive device and bearings for rotatably supporting the target.If the cooling liquid flows back into the target as described above, these various devices There was a risk that the equipment would not function properly. The present invention has been made in view of the above-mentioned problems in conventional X-ray generators, and prevents the backflow of cooling liquid into the target to maintain normal operation of various devices in the target unit for a long period of time. An object of the present invention is to provide an X-ray generating device that can be operated in the following manner.

[0006]

[Means for Solving the Problems] An X-ray generator according to the present invention includes a cylindrical X-ray tube (1) and a target unit (3) fixed to the X-ray tube. . The target unit includes a target (2) arranged in an X-ray tube, a target rotation drive device (drive motor 11) that rotationally drives the target, and a cooling liquid that causes a cooling liquid (cooling water) to flow through the target. It has a passage (the gap between the target rotating shaft 14 and the water pipe 23, the inner peripheral surface of the target 2, and the water pipe 23). The target unit is fixed to the X-ray tube in an inclined state from the bottom to the top, and has a coolant inlet (target rotating shaft 14 and water pipe 23) to the coolant passage circulating inside the target unit. (inlet to the gap between the
3) is characterized by being disposed at a lower position than the bearing position (bearing 13) that rotatably supports the target and the target rotation drive device described above. In this case, it is preferable that the outer peripheral surface of the target, that is, the surface on which the electrons emitted from the filament collide, is inclined in a conical shape.

[0007]

[Operation] The coolant that has flowed into the coolant passage through the coolant inlet circulates inside the target (2) and other equipment in the target unit (3), and then flows through the coolant outlet. Ejected to the outside of the target unit. The target unit is attached to the X-ray tube in an inclined state rather than in a horizontal state, and the liquid inlet and liquid outlet are arranged below the target bearing position and the target rotation drive device. Therefore, even if the coolant leaks from the coolant inlet and the coolant outlet, the leaked liquid flows down to the outside according to the inclination of the target, and does not flow back into the target.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a side sectional view showing an embodiment of an X-ray generator according to the present invention. This X-ray generator consists of an X-ray tube 1 which is a prismatic airtight container, a target unit 3 having a rotor target 2, and a vacuum decompression device 4 disposed below the X-ray tube 1. It is configured. The inside of the X-ray tube 1 is kept in a vacuum state by exhausting air by a vacuum decompression device 4. As the vacuum decompression device 4, any configuration can be used, but in the case of the embodiment,
The rotary pump 5 performs rough evacuation, and the turbo molecular pump 6 performs final and complete evacuation, so that a highly accurate vacuum can be obtained.

A filament 7 is provided on the inside upper surface of the X-ray tube tube 1 . A high voltage is applied between the filament 7 and the rotary target 2 by a high voltage power source (not shown), and a current is passed through the filament 7 by a current source (not shown). The filament 7 generates heat when a current is passed therethrough, and electrons are emitted from the filament 7. The emitted electrons are accelerated by the potential difference between the filament 7 and the target 2 and collide with the target 2, from which X-rays are emitted. The emitted X-rays are taken out to the outside through an X-ray extraction window 8 provided in advance on the upper left side wall of the X-ray tube 1.

When this X-ray generator is used, for example, as an X-ray source for an X-ray diffraction device, a sample (not shown) is irradiated with X-rays taken out from the X-ray extraction window 8.

As shown in FIG. 2, the target unit 3 includes a cylindrical housing 10 hermetically fixed to a flange 9 fixed to the X-ray tube 1, and a drive motor fixed to the right side of the housing 10. 11, and a water supply and drainage connector 12 fixed to the right side of the drive motor 11. Two bearings 13 are fitted inside the housing 10 on the right side, and the rotating shaft 14 of the target 2 is supported by these bearings. A magnetic fluid shaft sealing device 15 is hermetically fitted inside the housing 10 on the left side. This shaft sealing device 15 maintains the pressure difference between the inside and outside of the X-ray tube tube 1. That is, intrusion of air from the atmospheric pressure P side into the X-ray tube tube 1 which is in a vacuum state is reliably prevented.

The magnetic fluid shaft sealing device 15 itself is already well known, so a detailed explanation will be omitted, but for example, a structure shown in FIG. 3 is known. This magnetic fluid shaft sealing device 1
5 includes a substantially cylindrical case 16, a plurality of annular magnets 17 arranged parallel to each other in the case 16, and an annular magnetic member 18 disposed between each of the magnets 17.
It has The rotating shaft sealed by the magnetic fluid shaft sealing device 15, that is, the target rotating shaft 14 extends in the left-right direction in the figure, passing through each magnet 17 and each magnetic member 18. A magnetic fluid 19 is placed between each magnetic member 18 and the target rotating shaft 14 . The magnetic fluid 19 is a fluid formed by colloidally dispersing magnetic metal fine particles in a non-magnetic fluid medium. For example, a fluid in which ferrite or other magnetic powder is dispersed in a fluid such as hydrocarbon, fluorocarbon, or fatty acid can be used.

The magnets 17 are arranged so that the same N and S poles are adjacent to each other, and the lines of magnetic flux coming from the N pole of each magnet 17 are directed toward the magnetic member as shown by the arrows in the figure. 18, a magnetic fluid 19, and a circulation path passing through the target rotating shaft 14 and reaching the S pole of each magnet 17. These lines of magnetic flux cause the magnetic fluid 19 to move toward the target rotating shaft 14.
and the magnetic member 18 by magnetic force, and thereby the target rotating shaft 14 is sealed between the atmospheric pressure P and the vacuum Q, that is, the pressure is cut off. Therefore, while the target rotating shaft 14 rotates, the magnetic fluid 19 prevents air at the atmospheric pressure P side from entering the vacuum side, that is, into the X-ray tube tube 1 .

If this magnetic fluid shaft sealing device 15 is used,
The vacuum inside the wire tube 1 can be reliably maintained for a long period of time, and wear on the target rotating shaft 14 can be suppressed to an extremely low level.

Returning to FIG. 2, the drive motor 11 includes a case 20 fixed to the housing 10, a stator coil 21 fixed to the case 20, and a target rotating shaft 1.
The rotor 22 is fixed to the outer peripheral surface of the rotor 4. When a current is passed through the stator coil 21, a rotating magnetic field is formed around the rotor 22, and the rotor 22 rotates. When the rotor 22 rotates, the target rotating shaft 14 fixed thereto also rotates, and as a result,
The rotor target 2 attached to the left end of the target rotating shaft 14 rotates.

The target rotating shaft 14 is hollow, and a water pipe 23 is inserted therein with a predetermined gap. This water pipe 23 itself is also hollow. The right end of the target rotation axis 14 is the packing 2
It is rotatably connected to the water supply and drainage connector 12 via 4. A water passage 25 is formed inside the water supply and drainage connector 12, and the right end of the target rotating shaft 14 and the water supply pipe 26 communicate with each other via the water passage 25. On the other hand, the water pipe 23 passes through the center of the water supply and drainage connector 12 and is connected to a drain pipe 27. The water supply pipe 26 is connected to a water supply source (not shown), and cooling water is supplied from the water supply source. The supplied cooling water passes through the water passage 25 in the water supply and drainage connector 12, and further advances to the left in the figure through the gap between the target rotating shaft 14 and the water pipe 23, and reaches the inner wall surface of the target 2. , flows along its inner wall surface. As a result, the target 2 is cooled. The cooling water that has cooled the target 2 from the inside then returns to the right side of the figure through the hollow part in the water pipe 23 and is finally discharged to the outside via the drain pipe 27.

In FIG. 1, a target 2 collided with electrons emitted from a filament 7 generates heat and reaches a high temperature state. As described above, the reason why the target 2 is rotated by the drive motor 11 and the cooling water is allowed to flow inside the target 2 is to prevent the target 2 from becoming abnormally high temperature.

As is clear from FIG. 1, in this embodiment, the target unit 3 is fixedly attached to the X-ray tube 1 in a tilted state from diagonally downward to upward. Therefore, as is clear from FIG. 2, the right end of the gap between the target rotating shaft 14, which is the inflow side cooling water passage, and the water passage pipe 23, that is, the cooling water inlet and the water passage, which is the discharge side cooling water passage. The right end of the pipe 23, that is, the cooling water outlet, is both connected to the bearing 13 that supports the magnetic fluid shaft sealing device 15 and the target rotating shaft 14.
It is located further below than the drive motor 11. In general, the cooling water inlet and cooling water outlet are most likely to experience water leakage. Therefore, a water leak prevention member such as packing 24 is provided in that area. However, in reality, even if such a water leak prevention member is attached, it is difficult to completely prevent water leakage from the cooling water inlet or the cooling water outlet. In contrast, in this embodiment, the cooling water inlet and the cooling water outlet are arranged at the lowest position of the target unit 3 as described above, so even if water leaks from them, the leaked water will all fall downward and do not enter the inside of the target unit 3. Therefore, cooling water is prevented from entering the magnetic fluid shaft sealing device 15, the bearing 13, and the drive motor 11, and these devices can be operated normally for a long period of time.

As shown in FIGS. 1 and 2, the outer peripheral surface of the target 2, that is, the surface to which electrons are irradiated, is inclined in a conical shape. As can be understood by looking at FIG. 1, this ensures that the electron irradiation surface of the target 2 is parallel to the filament 7 even when the target unit 3 is attached to the X-ray tube 1 in an inclined state. It's for a reason.

Although the present invention has been described above with reference to one embodiment, the present invention is not limited to that embodiment. for example,
In the above embodiment, the pipe 26 connected to the gap between the target rotating shaft 14 and the water pipe 23 (inflow side cooling water passage) via the water passage 25 in the water supply and drainage connector 12 is used as the water supply pipe, and on the other hand, A pipe 27 connected to the water pipe 23 (discharge side cooling water passage) was used as a drain pipe. However, on the contrary, the cooling water flow system can also be constructed by using the pipe 27 as a water supply pipe and the pipe 26 as a drain pipe.

[0021]

[Effects of the Invention] According to the present invention, the target unit (
3) is arranged in an inclined state, and the coolant inlet and coolant outlet, where leakage of coolant (cooling water) is most likely to occur, are placed at the lowest position of the target unit (3). , even if a coolant leak occurs, the leaked liquid will fall directly to the outside and touch the target unit (3).
will not penetrate inside. Therefore, the drive motor (11) and other devices in the target unit (3) can be operated normally for a long period of time.

[Brief explanation of the drawing]

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

FIG. 2 is a side sectional view showing an example of a target unit that is a main component of the X-ray generator shown in FIG. 1;

3 is a side cross-sectional view showing an example of a magnetic fluid shaft sealing device, which is one of the members constituting the target unit shown in FIG. 2. FIG.

[Explanation of symbols]

1 X-ray tube tube 2
Target 3 Target unit
11 Target drive motor 12 Water supply and drainage connector 14
Target rotation axis

Claims (2)

[Claims] 1. An X-ray generator comprising a cylindrical X-ray tube and a target unit fixed to the X-ray tube, the target unit being a target disposed within the X-ray tube. , an X-ray generator having a target rotation drive device that rotationally drives the target and a coolant passage that allows a coolant to flow through the target, in which the target unit is tilted from below to above and is connected to an X-ray tube tube. The coolant inlet to the coolant passage and the coolant outlet from the coolant passage are located below the bearing position that rotatably supports the target and the target rotation drive device. An X-ray generator characterized by: 2. The X-ray generator according to claim 1, wherein the outer peripheral surface of the target is inclined conically.