JPH0982227A - Evacuation method and device for x-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a evacuation method and device for X-ray tube capable of shortening a total evacuation time. SOLUTION: A vacuum pump 6 is connected to a X-ray tube 1, which consists of a cathode 3 and an anode target 2 arranged opposing each other in a vacuum container, to evacuate gas in the vacuum container. In such a case, after the vacuum container is evacuated, and the pressure of a vacuum pump system begins to drop, the evacuation of metal parts in the vacuum container is started with high frequency induction heat, and after its pressure begins to drop, the anode target 2 is collided with electrons and evacuated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for exhausting an X-ray tube, and more particularly to shortening exhaust time.

[0002]

2. Description of the Related Art Generally, in a vacuum tube such as an X-ray tube, the gas in the tube is discharged to the outside of the tube by using a vacuum pump or the like in the manufacturing process. This is called an exhaust process. However, at this time, in the pipe, there is a gas adsorbed on the surface of the pipe internal component that cannot be discharged only by the vacuum pump or a gas contained inside the pipe internal component.

When operating an X-ray tube, the maximum number of parts inside the tube is 1000.
If the discharge of gas from the surfaces of these parts or inside is insufficient, gas will be released from the parts inside the pipe that have reached a high temperature during actual use after manufacture, and the degree of vacuum inside the pipe will deteriorate.

In order to prevent this, in the exhausting step, the parts inside the pipe are heated above the actual use conditions, and the gas on the surface of the parts or inside the parts is discharged. The components that actually adsorb and contain a large amount of gas are the tube container, the cathode consisting of the cathode filament and the focusing electrode, and the anode target.

In the conventional exhaust process, the tube container is first heated in a heating furnace such as a gas furnace or an electric furnace and exhausted until a time when the degree of vacuum will be lowered. Next, the cathode is heated by filament energization and high-frequency heating, and is similarly evacuated until the time when the degree of vacuum will be lowered. Finally the anode target is X
The self-heating of the wire tube is used to evacuate until the time when the required vacuum degree will be finally reached.

The exhaust device used in the exhaust method as described above is conventionally constructed as shown in FIG. That is, reference numeral 1 is an unexhausted X-ray tube in which a cathode 3 and an anode target 2 are arranged to face each other in a vacuum container. A vacuum pump 6 is connected to the X-ray tube 1 via an exhaust pipe 4, and a vacuum gauge 5 is installed in the middle of the exhaust pipe 4. Furthermore, the X-ray tube 1 has a structure that can be covered with either a heating furnace 11 having a heat insulating structure for heating the X-ray tube 1 or a high frequency heating coil 9 for high frequency heating the cathode 3 in the tube. High frequency heating coil 9
Is connected to the high-frequency heating device 10, and the heater 12 inside the heating furnace 11 is connected to the furnace power supply 13. A filament power source 14 is connected to the filament inside the cathode 3 of the X-ray tube 1, and a high voltage power source 15 is connected to the anode target 2 so as to be positive with respect to the cathode 3. From the control unit 8, the high frequency heating signal line 16, the furnace control signal line 17, the filament power supply control signal line 18, and the high voltage power supply control signal line 19 are supplied.
Is connected to each device. FIG. 4 shows changes in the degree of vacuum in the exhaust pipe when exhausted by the above-mentioned conventional device.

[0007]

The prior art described above has the following disadvantages. That is, even if the components are evacuated while being heated, it takes a very long time to evacuate until the degree of vacuum measured by the vacuum gauge 5 is completely reduced, and it takes an enormous amount of time to perform it for each in-pipe component. . or,
The amount of gas adsorbed / contained in the pipe parts increases / decreases in the manufacturing process up to that point, but of course the most adsorption / adsorption in the exhaust process.
The exhaust time is determined assuming a large amount of contained gas.

For this reason, even when exhausting the X-ray tube using the in-tube parts with a relatively small amount of adsorbed and contained gas, it has the same exhaust time, resulting in unnecessary production time and production cost. It was one of the causes of increase.

The present invention has been made in view of the above circumstances, and by selecting an appropriate heating means for the pipe internal parts while measuring the degree of vacuum in the exhaust pipe, and adjusting the heating energy,
It is an object of the present invention to provide an X-ray tube exhaust method and an exhaust apparatus that can reduce the total exhaust time.

[0010]

SUMMARY OF THE INVENTION The present invention is an X-ray for exhausting gas in a vacuum container by connecting a vacuum pump to an X-ray tube in which a cathode and an anode target are arranged opposite to each other in the vacuum container. In the tube exhaust method, when gas is discharged from the vacuum container and the pressure of the vacuum pump system starts to decrease, high-frequency induction heating starts gas discharge of the metal parts in the vacuum container. This is a method of exhausting an X-ray tube in which a get is electron-impacted to degas and then exhaust.

Further, the present invention relates to an X-ray tube exhaust device for exhausting gas from an X-ray tube in which a cathode composed of a cathode filament and a focusing electrode and an anode target are arranged to face each other in a vacuum container. A vacuum pump connected to the vacuum container of the X-ray tube via an exhaust pipe, a vacuum gauge provided in the middle of the exhaust pipe, and a high-frequency heating coil arranged so as to cover the outer circumference of the vacuum container of the X-ray tube. A high-frequency heating device having: a heating furnace in which the high-frequency heating coil and the X-ray tube are housed; a filament power source connected to a cathode filament of the X-ray tube;
X-ray tube equipped with a high-voltage power source connected to the anode target of the wire tube, and a computer for reading the measurement result of the vacuum gauge and controlling the high-frequency heating device, heating furnace, filament power source, and high-voltage power source Exhaust system.

[0012]

An embodiment of the present invention will be described below in detail with reference to the drawings. First, the exhaust device used in the method for exhausting an X-ray tube according to the present invention is configured as shown in FIG. 1, and the same parts as those in the conventional example (FIG. 3) are designated by the same reference numerals. That is, reference numeral 1 is an unexhausted X-ray tube in which a cathode 3 and an anode target 2 are arranged to face each other in a vacuum container. A vacuum pump 6 is attached to the X-ray tube 1 via an exhaust pipe 4.
Is connected. A vacuum gauge 5 is installed in the middle of the exhaust pipe 4, and its measurement output 7 is input to the control unit 8. On the other hand, X
The circumference of the wire tube 1 is surrounded by a high frequency heating coil 9 for high frequency heating the anode target 2 and the cathode 3 in the tube, and the circumference is covered with a heating furnace 11 having a heat insulating structure. The high-frequency heating coil 9 is connected to the high-frequency heating device 10, and the heating furnace 11
The internal heater 12 is connected to the furnace power supply 13. Also, X
A filament power supply 14 is connected to the cathode filament in the cathode 3 of the wire tube 1, and a high voltage power supply 15 is connected to the anode target 2 so as to be positive with respect to the cathode 3. The control unit 8 connects the high-frequency heating signal line 16, the furnace control signal line 17, the filament power supply control signal line 18, and the high-voltage power supply control signal line 19 to the respective devices.

Next, the exhaust method of the present invention using the above exhaust device will be described. First, the vacuum pump 6 is operated without heating the in-tube components of the X-ray tube 1 to discharge the gas in the tube. When the measured value of the vacuum gauge 5 falls below the level A shown in FIG. 2, the furnace power supply 13 is operated to heat the X-ray tube 1. Then, the adsorbed gas on the inner wall of the X-ray tube and the contained gas are released, and when this amount exceeds the exhaust capacity of the vacuum pump 6,
Although the measured value of the vacuum gauge 5 temporarily deteriorates, the temperature inside the furnace is controlled by the control unit 8 so that the vacuum degree is slightly better than the level A. Here, the level A is a vacuum level at which oxidation is not caused even if the temperature of the metal parts in the pipe rises. When the amount of gas released from the parts inside the tube starts to fall below the capacity of the vacuum pump 6, the degree of vacuum increases, but the temperature inside the furnace is raised so that the level A is maintained. The maximum temperature that does not have a thermal effect on the X-ray tube 1 is generally about 500 degrees, but if the vacuum level starts to rise above level A even after reaching this temperature, then the anode target 2 and the cathode 3. Perform high frequency heating in 3. Here, the high-frequency output is adjusted so that the degree of vacuum maintains the level A as in the case of controlling the furnace, and the heating output is gradually increased.
The allowable temperature of the cathode 3 is about 800 degrees, but if the degree of vacuum starts to rise above the level B even after reaching this temperature, self-heating of the X-ray tube 1 is started. The level B is the degree of vacuum that does not cause discharge in the tube even when a high voltage is applied to the X-ray tube 1. In the self heating of the X-ray tube 1, the anode target 2 is heated intensively,
Filament power supply 1 so that the vacuum degree maintains level B without exceeding the allowable temperature of the anode target 2 of about 1000 degrees.
4. Control the high voltage power supply 15. Even when the temperature of the anode target 2 reaches the allowable temperature, when the degree of vacuum reaches the final target vacuum degree level C, exhausting is completed.

FIG. 2 shows the transition of the degree of vacuum in the exhaust pipe when exhausted by the exhaust device of the present invention. Each heating device is controlled so as to maintain the worst degree of vacuum that should always be allowed. . However, the area shown in FIG. 2 represents the amount of gas discharged from the X-ray tube 1. In other words, the most efficient exhaust method has been executed.

Further, in the case of the X-ray tube 1 in which a part having a small amount of adsorbed / containing gas is used, the time required to reach the above levels A, B, C is short, and the exhaust completion time is inevitably short. As a result of the above, according to this one embodiment, it is possible to most efficiently adsorb the gas adsorbed and contained in the pipe parts outside the pipe,
As a result, the total exhaust time can be shortened and the manufacturing cost of the X-ray tube can be reduced. Further, the exhaust data can be shared between different devices having different structures, and the utility value thereof is great.

[0016]

As described above, according to the present invention,
When gas is discharged from the vacuum container and the pressure of the vacuum pump system begins to drop, high-frequency induction heating begins to gas out the metal parts in the vacuum container, and when the pressure begins to drop, the anode target is bombarded with electrons. Since the gas is discharged and exhausted, the gas adsorbed by the components inside the pipe and contained gas can be most efficiently discharged outside the pipe. As a result, the total exhaust time is shortened and the manufacturing cost of the X-ray tube is reduced. Further, the exhaust data can be shared between different devices having different structures, and its utility value is great.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an exhaust device for an X-ray tube according to an embodiment of the present invention.

FIG. 2 is a characteristic curve diagram showing changes in the degree of vacuum of the exhaust pipe when the X-ray tube is exhausted by the X-ray tube exhaust method according to the embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a conventional X-ray tube exhaust device.

FIG. 4 is a characteristic curve diagram showing a change in the degree of vacuum of the exhaust pipe when the X-ray tube is exhausted by the conventional X-ray tube exhaust method.

[Explanation of symbols]

1 ... X-ray tube, 2 ... Anode target, 3 ... Cathode, 4 ... Exhaust tube, 5 ... Vacuum gauge, 6 ... Vacuum pump, 7 ... Measurement output, 8 ...
Control part, 9 ... High frequency heating coil, 10 ... High frequency heating device, 11 ... Heating furnace, 12 ... Heater, 13 ... Furnace power source, 1
4 ... Filament power supply ... 15 ... High voltage power supply, 16 ... High frequency heating signal line, 17 ... Furnace control signal line, 18 ... Filament power supply control signal line, 19 ... High voltage power supply control signal line.

Claims (2)

[Claims] 1. A method of exhausting an X-ray tube, wherein a vacuum pump is connected to an X-ray tube in which a cathode and an anode target are opposed to each other in a vacuum container, and gas in the vacuum container is exhausted. When gas is discharged from the vacuum container and the pressure of the vacuum pump system starts to drop, high-frequency induction heating starts gas discharge of the metal parts in the vacuum container, and when the pressure starts to drop, the anode target is electron-impacted. A method of exhausting an X-ray tube, characterized in that the gas is discharged and then exhausted. 2. An X-ray tube exhaust device for exhausting gas from an X-ray tube, in which a cathode composed of a cathode filament and a focusing electrode and an anode target are arranged to face each other in a vacuum container. A vacuum pump connected to the vacuum container via an exhaust pipe, a vacuum gauge provided in the middle of the exhaust pipe, and a high-frequency heating coil arranged to cover the outer circumference of the vacuum container of the X-ray tube. A high-frequency heating device having the same; a heating furnace accommodating the high-frequency heating coil and the X-ray tube;
The filament power source connected to the cathode filament of the X-ray tube, the high voltage power source connected to the anode target of the X-ray tube, the measurement result of the vacuum gauge, and the high-frequency heating device, the heating furnace, the above An X-ray tube exhaust device comprising a filament power supply and a computer for controlling the high voltage power supply.