JPH06101319B2 - High vacuum device and vacuum pump device using the high vacuum device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-vacuum device and a vacuum pump device using the high-vacuum device, and in particular, a high vacuum is generated in the vacuum container by ionizing and sucking gas in the vacuum container. The present invention relates to a high-vacuum device and a vacuum pump device that combines the high-vacuum device with a vacuum pump to release the suction gas into the atmosphere.

[0002]

2. Description of the Related Art FIG. 2 is an explanatory view showing a conventional vacuum exhaust method. In the figure, reference numeral 1 is a container to be evacuated to vacuum (hereinafter referred to as a vacuum container), and this vacuum container 1 is connected to a vacuum pump 2 via an exhaust hole 3. The vacuum pump 2 is composed of, for example, a turbo molecular pump, an oil diffusion pump, an ion pump, or the like.

In the above structure, only the gas molecules in the vacuum container 1 that have jumped into the exhaust hole 3 are discharged to the outside by the vacuum pump 2.

In the above conventional method, the vacuum pump 2 is used.
However, in the case of the turbo molecular pump, there is a problem that hydrogen gas, helium gas, etc., which cannot obtain a large compression ratio, are back-diffused from the turbo molecular pump and return to the vacuum container 1 to lower the degree of vacuum. Further, in the case of the oil diffusion pump, there is a problem that hydrogen and the like are back-diffused into the vacuum container 1 for the same reason, and the vapor of the hydraulic oil is also back-diffused to lower the vacuum degree. In the case of an oil diffusion pump, there is a method of using a cold trap with liquid nitrogen in combination to prevent the back diffusion of this hydraulic oil, but this method is expensive and long-term due to the problem of liquid nitrogen supply. There is a problem that it is difficult to drive on time. Further, in the ion pump, there is a problem that gas molecules absorbed by the titanium wall are desorbed and return to the vacuum container 1 to lower the degree of vacuum.

Therefore, the applicant of the present invention previously filed Japanese Patent Application No. 2-2.
In No. 05224, a high vacuum device and a vacuum pump device using the high vacuum device were proposed. The proposed vacuum pump 100 includes a high vacuum device 50 as shown in FIG.
This high vacuum device 50 is configured by combining it with an arbitrary vacuum pump 31 provided on the back pressure side.

The high vacuum device 50 has a container 25 connecting a vacuum pump 31 and a vacuum container 32, and a hairpin-shaped thermionic emission filament 21 is arranged at the center of the container 25. An electron acceleration grid 22 is provided so as to concentrically surround the filament 21. The cylindrical electrode 23 forming the outer electrode is provided so as to concentrically surround the electron acceleration grid 22, is orthogonal to the axis of the cylindrical electrode 23, and is slightly separated from the cylindrical electrode 23, and the ion acceleration grid 24 is provided. Is provided.

On the other hand, an electromagnet 26 is arranged outside the container 25, and the electromagnet 26 is adapted to generate a DC magnetic field substantially parallel to the axis of the cylindrical electrode 23. Further, three power supplies 28, 29, 30 are provided on the outside of the container 25, and the current and voltage of each power supply 28, 29, 30 are respectively supplied via a current introduction terminal installed in a part of the container 25. It is adapted to be transmitted to the elements 21, 22, 23 and 24.

A power supply 28 is a heating power supply for heating the filament 21, and a DC power supply 29 applies a voltage between the filament 21, the electron acceleration grid 22 and the cylindrical electrode 23 so that the filament 21 becomes negative. The DC power supply 30 applies a voltage between the cylindrical electrode 23 and the ion acceleration grid 24 so that the ion acceleration grid 24 becomes negative.

The operation is as follows. The thermoelectrons emitted from the filament 21 are accelerated toward the electron acceleration grid 22 to obtain sufficient energy and pass through the electron acceleration grid 22. Electron acceleration grid 22 and cylindrical electrode 23
Since a magnetic field is applied to the space in a direction orthogonal to the movement direction of the electrons, the electrons move toward the cylindrical electrode 23 while making a circular motion in a plane perpendicular to the central axis of the cylindrical electrode 23. Since the electrons make a circular motion, the path to reach the cylindrical electrode 23 becomes very long, and during that time, the electrons collide with many gas molecules and produce a large amount of ions. The generated ions are accelerated toward the ion acceleration grid 24, pass through this, and are trapped by the vacuum pump 31 and exhausted.

The gas molecules, which are de-diffused and desorbed from the vacuum pump 31 and cause a decrease in the degree of vacuum, are ionized and accelerated by this pump and are sent back to the vacuum pump 31 again, so that a high vacuum is generated. To be achieved. Further, with the vacuum pump 31 alone, only gas molecules that have jumped into the exhaust hole are exhausted. However, by using a high vacuum device together, the vacuum pump 31 is positively ionized and accelerated to accelerate gas molecules. The exhaust efficiency is improved and a high vacuum is achieved.

[0011]

However, in the above-described high vacuum device and the vacuum pump device using the high vacuum device, the electrons that have collided with the gas molecules lose a large amount of kinetic energy, so that the gas is not used. There is a problem that it cannot participate in the ionization of molecules.

The present invention has been made in view of the above circumstances. An object of the present invention is to improve the ionization probability of gas molecules by further accelerating the electrons that have lost energy due to collision, and to further improve the ionization probability. It is to provide a high-vacuum device that achieves the above-mentioned vacuum.

Another object of the present invention is to combine with an optional vacuum pump provided on the back pressure side to act as an auxiliary pump, ionize and accelerate the gas molecules that flow back and desorb from the vacuum pump to produce a vacuum. At the same time as returning to the pump,
It is an object of the present invention to provide a vacuum pump device using a high vacuum device that achieves a high degree of vacuum by ionizing and accelerating gas molecules in a vacuum container and positively sending the gas molecules to the vacuum pump.

[0014]

In order to achieve the above object, a high vacuum device of the present invention comprises a thermoelectron source, an electron acceleration grid surrounding the thermoelectron source, and an outer electrode surrounding the electron acceleration grid. An ion acceleration grid that intersects with the axis of the outer electrode and is separated from the outer electrode,
A container accommodating each of the grids and the electrodes, a magnet arranged outside the container to generate a magnetic field substantially parallel to the axis of the outer electrode, and a power source for a thermoelectron source that supplies a current to the thermoelectron source. A direct current power supply for applying a voltage between the thermoelectron source and the electron acceleration grid and the outer electrode to make the thermoelectron source negative, and an arbitrary range from negative to positive with respect to the electron acceleration grid. A variable direct current power source for applying the voltage to the outer electrode and a direct current power source for applying a voltage between the outer electrode and the ion acceleration grid so that the outer electrode side becomes positive. It is a thing.

The vacuum pump apparatus of the present invention is a combination of the high vacuum apparatus and an arbitrary vacuum pump.

[0016]

According to the high vacuum apparatus of the present invention, by re-accelerating the electrons that have lost energy due to collision with gas molecules, the gas molecules in the vacuum container are efficiently ionized and accelerated, and the electrons are attracted. The gas molecules are evacuated and a high vacuum can be achieved. According to the vacuum pump device of the present invention, it is possible to ionize and accelerate the gas molecules de-diffused and desorbed from the vacuum pump and return them to the vacuum pump, and positively accelerate the gas molecules in the vacuum container by ionization. It can be sent to a vacuum pump, the exhaust efficiency is improved, and a high degree of vacuum can be achieved in the vacuum container.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a high vacuum device according to the present invention and a vacuum pump device using the high vacuum device will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 50 is a high vacuum apparatus of the present invention, and reference numeral 100 is a vacuum pump apparatus of the present invention using the high vacuum apparatus 50. The vacuum pump device 100 is a high vacuum device 50.
And an optional vacuum pump 31 provided on the back pressure side of the high vacuum device 50.

The high vacuum device 50 has a container 25 connecting a vacuum pump 31 and a vacuum container 32, and a hairpin-shaped thermionic emission filament 21 is arranged at the center of the container 25. A cylindrical electrode 23 that concentrically surrounds the filament 21 and forms an outer electrode is provided. Further, an ion acceleration grid 24 is arranged orthogonal to the axis of the cylindrical electrode 23 and slightly separated from the cylindrical electrode 23.

An electromagnet 26 is arranged outside the container 25, and the electromagnet 26 generates a DC magnetic field substantially parallel to the axis of the cylindrical electrode 23. On the other hand, three power sources 28, 29, 30 are provided on the outside of the container 25, and the current and voltage of each power source 28, 29, 30 are respectively supplied via a current introduction terminal installed in a part of the container 25. It is adapted to be transmitted to the elements 21, 22, 23 and 24.

The power source 28 is a heating power source for heating the filament 21, and the DC power source 29 applies a voltage between the filament 21, the electron acceleration grid 22 and the cylindrical electrode 23 so that the filament 21 becomes negative. The DC power supply 30 applies a voltage between the cylindrical electrode 23 and the ion acceleration grid 24 so that the ion acceleration grid 24 becomes negative.

Further, in this embodiment, the cylindrical electrode 2
A variable DC power supply 41 capable of changing the potential of 3 from negative to positive with respect to the electron acceleration grid 22 is provided.

The container 25 has a structure which communicates with the exhaust hole of the vacuum container 32 or a structure which also serves as the exhaust hole.

Next, the operation of the high vacuum apparatus of the present invention constructed as described above and the vacuum pump apparatus using the high vacuum apparatus will be described.

The filament 21 is heated by the heating power source 28 to emit thermoelectrons. The emitted thermoelectrons are accelerated toward the electron acceleration grid 22 and obtain sufficient energy to pass through the electron acceleration grid 22. Since a magnetic field is applied to the space between the electron accelerating grid 22 and the cylindrical electrode 23 at right angles to the electron movement direction, the electrons move to the cylindrical electrode 23 while making circular motion in a plane perpendicular to the central axis of the cylindrical electrode 23. Move towards. Since the electrons make a circular motion, the path to reach the cylindrical electrode 23 becomes very long, and during that time, the electrons collide with many gas molecules and produce a large amount of ions. The generated ions are accelerated toward the ion acceleration grid 24, pass through this, and are trapped by the existing vacuum pump 31 and exhausted. The operation up to this point is the same as in the case of FIG. However, the electron loses a large amount of kinetic energy due to collision with the gas molecule, and the electron cannot ionize the gas molecule thereafter. Therefore, as in this embodiment, if a voltage is applied by the power supply 41 so that the cylindrical electrode 23 has a positive potential with respect to the electron acceleration grid 22, the electrons gain energy again and a large number of gas molecules are obtained. Will be ionized, and the exhaust efficiency of the pump will be improved.

When the kinetic energy of the electrons passing through the electron acceleration grid 22 is too large, the collision cross section between the electrons and the gas molecules is reduced and the ion generation efficiency is deteriorated, so that the exhaust efficiency is reduced. descend. In this case, the power supply 41 applies a voltage so that the cylindrical electrode 23 has a negative potential with respect to the electron acceleration grid 22. As a result, the electrons decrease their kinetic energy as they approach the cylindrical electrode 23, so that the collision cross section with gas molecules increases, and the pumping efficiency of the pump improves. In the above-described operation, whether the improvement of the pump exhaust efficiency is due to the compensation of the energy loss of electrons or the increase of the collision cross-sectional area depends on the type of gas to be exhausted and the electron acceleration grid 22.
It depends on the kinetic energy of the electron when passing through. Therefore, the power source 41 is set to a variable power source, the potential of the cylindrical electrode 23 is changed from negative to positive with respect to the electron acceleration grid 22, and the point where the exhaust efficiency of the pump is maximized is searched for. Thus a high degree of vacuum is achieved.

[0027]

As is apparent from the above description, according to the high vacuum apparatus of the present invention, the ionization probability of the gas molecule in the vacuum container is re-accelerated by accelerating the electron that has lost energy due to the collision with the gas molecule. And a high vacuum can be achieved in the vacuum container. Further, according to the vacuum pump device of the present invention, it is possible to ionize and accelerate the gas molecules de-diffused and desorbed from the vacuum pump and return them to the vacuum pump. It can be sent to a vacuum pump, the exhaust efficiency is improved, and a high degree of vacuum can be achieved in the vacuum container. Further, when an oil diffusion pump is used as the vacuum pump, it is not necessary to use a cold trap with liquid nitrogen at the same time, so that the cost can be reduced, and since there is no problem of liquid nitrogen supply, it can be operated for a long time.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a high vacuum device of the present invention and a vacuum pump device using the high vacuum device.

FIG. 2 is an explanatory diagram of a conventional vacuum exhaust method.

FIG. 3 is an explanatory view of a high vacuum device described in Japanese Patent Application No. 2-205224 and a vacuum pump device using the high vacuum device.

[Explanation of symbols]

 1 Vacuum Container 2 Vacuum Pump 3 Exhaust Hole 21 Filament 22 Electron Acceleration Grid 23 Cylindrical Electrode 24 Ion Acceleration Grid 25 Container 26 Electromagnet 28 Heating Power Supply 29 DC Power Supply 30 DC Power Supply 31 Vacuum Pump 32 Vacuum Container 41 Cylindrical Electrode

Claims (2)

[Claims] 1. A thermoelectron source, an electron acceleration grid that surrounds the thermoelectron source, an outer electrode that surrounds the electron acceleration grid, and an axis that intersects the axis of the outer electrode and is spaced apart from the outer electrode. An ion acceleration grid, a container accommodating each of the grids and the electrodes, a magnet arranged outside the container to generate a magnetic field substantially parallel to the axis of the outer electrode, and a current supplied to the thermionic source. A power source for a thermoelectron source, a direct current power source for applying a voltage so that the thermoelectron source side becomes negative between the electron acceleration grid and the outer electrode and the thermoelectron source, and with respect to the electron acceleration grid A variable DC power supply for applying an arbitrary voltage ranging from negative to positive to the outer electrode, and a DC power supply for applying a voltage between the outer electrode and the ion acceleration grid so that the outer electrode side becomes positive. High vacuum and wherein the. 2. A high vacuum device according to claim 1 is installed between an arbitrary vacuum pump and a container to be evacuated to a vacuum.