Miniature ion pump for connecting standard vacuum electrical feedthroughs

Abstract

The present application relates to a kind of micro ion pump for connecting standard vacuum electric feedthrough, belong to ion pump technical field.The micro ion pump for connecting standard vacuum electric feedthrough includes cathode, anode and magnetic ring, the cathode includes cathode column and cathode cone, the anode includes anode cylinder and several gas inlet holes on the side wall of anode cylinder, the tail of the cathode cone and the side wall of anode cylinder form annulus.The present application makes electron rotate around cathode axis by magnetic ring, and form electric field between cathode and anode, and because cathode is located on the side of annulus and presents I-shaped, electron can spiral motion around cathode axis and up and down under the action of electromagnetic field, so that electron can almost infinitely move in very small space, ion pump can continuously and stably extract air ion, and the volume of ion pump is small enough, can be applied in micro vacuum system.

Description

Technical Field

[0001] This invention belongs to the field of ion pump technology, specifically relating to a miniature ion pump for connecting to a standard vacuum power supply. Background Technology

[0002] An ion pump is a vacuum pumping device that utilizes the Penning discharge effect to increase the vacuum level, and is mostly used in ultra-high vacuum systems. Existing ion pumps include a pump body with a built-in honeycomb anode cylinder and cathode plates located on the upper and lower sides of the anode cylinder. A DC high-voltage current is connected to the anode cylinder, causing free electrons in the pump body to move towards the anode cylinder. During this movement, the air inside the anode cylinder is ionized. The gas ions generated by ionization bombard the cathode plates, and titanium atoms sputtered from the cathode plates react with the gas and solidify on the anode cylinder, thus enabling the ion pump to perform its vacuum pumping function.

[0003] Existing ion pumps also have magnets installed on the upper and lower sides of the pump body, thereby creating an orthogonal electromagnetic field within the pump body. Electrons move in a spiral motion within this electromagnetic field, approaching the anode cylinder in a roller-like manner, thus increasing the electron's travel distance and improving ionization efficiency. Commercially available ion pumps are relatively large and are connected to the vacuum chamber via flanges. Although these ion pumps have high pumping speeds and good venting capabilities, they are difficult to apply to micro-vacuum systems and cannot be directly connected to standard vacuum power supplies. Summary of the Invention

[0004] The purpose of this invention is to provide a simple and rationally designed miniature ion pump for connecting to a standard vacuum power supply in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions:

[0006] A miniature ion pump for connection to a standard vacuum power supply includes a cathode, an anode surrounding the cathode, and a magnet. The magnet is used to generate an electromagnetic field with the cathode and anode. The cathode includes a cathode column and a cathode cone with its tail fixed to the end of the cathode column. The anode includes an anode cylinder and several inlet holes on the side wall of the anode cylinder. An annular space is formed between the tail of the cathode cone and the side wall of the anode cylinder. The magnet is a magnetic ring on the anode cylinder corresponding to the annular space. The magnetic ring is used to provide centripetal force for electrons in the annular space. The cathode column and cathode cone are used to axially confine electrons. The cathode is made of titanium. The magnetic ring provides Lorentz force to the free electrons in the annular space, causing the electrons to rotate around the cathode axis. An electric field is formed between the cathode and the anode. Furthermore, because the cathode is located on one side of the annulus in an I-shape, electrons moving to the upper and lower sides of the annulus are repelled by the longitudinal electric field force, causing them to undulate within the annulus. Under the influence of the electromagnetic fields provided by the magnetic ring, cathode, and anode, the electrons within the annulus spiral around the cathode axis and undulate up and down, allowing them to move almost infinitely within a very small annular space. Both the cathode and anode are located inside the vacuum chamber, and the gas in the vacuum chamber enters the annulus through the air inlet. Free electrons ionize the gas, producing gas ions and secondary electrons, which then accumulate within the annulus to form an electron cloud rotating around the cathode axis. This ion pump can continuously and stably extract air ions, and its size is small enough to be applied in micro vacuum systems.

[0007] As a further optimization of the present invention, the diameter of the tail of the cathode cone is smaller than the diameter of the head, and the diameter of the head of the cathode cone is the same as the diameter of the cathode column.

[0008] As a further optimization of the present invention, the micro ion pump is used to evacuate a vacuum chamber, wherein an electrical feed passage is fixed on the top wall, bottom wall or side wall of the vacuum chamber, and the anode is fixed on one side of the electrical feed passage.

[0009] As a further optimization of the present invention, the end of the cathode column away from the cathode cone has a connecting pipe, the end of the anode cylinder near the annulus has a step, the magnetic ring is disposed on the step, the end of the anode cylinder away from the step has a connecting part, and both the connecting pipe and the connecting part are plugged into each other with the electrical feedthrough.

[0010] As a further optimization of the present invention, the vacuum chamber is equipped with a calibration vacuum gauge and connected to a micro-leakage valve, and the detection end of the vacuum gauge is electrically connected to the cathode.

[0011] The gas ions generated by ionization are bombarded by the cylindrical surface of the titanium cathode cone under the influence of the negative voltage of the cathode. The titanium atoms sputtered from the cathode cone cone react chemically with the gas and solidify on the inner wall of the anode cylinder, thereby absorbing the gas and performing the function of sputtering ion pump. The ionization of gas generates an ion current, the magnitude of which is linearly related to the vacuum level. The vacuum level in the vacuum chamber is characterized by measuring the ion current through a vacuum gauge.

[0012] As a further optimization of the present invention, the vacuum chamber is connected to a vacuum pump unit, which can work with a micro ion pump to evacuate the vacuum chamber.

[0013] As a further optimization of the present invention, insulating gaskets are provided between the cathode cone head and the cathode column end and the anode cylinder sidewall, and the gaskets are made of polyimide resin.

[0014] As a further optimization of the present invention, the number of magnetic rings is two, and both magnetic rings are made of N-neodymium magnets.

[0015] As a further optimization of the present invention, the cathode is connected in series with a high negative bias voltage source, and both the anode and the positive terminal of the voltage source are grounded. The micro ion pump adopts a circuit structure in which the anode is grounded and the cathode is equipped with a high negative bias power supply. This adjustment of the power supply method can completely shield the high voltage inside the anode.

[0016] As a further optimization of the present invention, a ballast resistor is provided on the line between the cathode and the voltage source, and an ammeter is provided on the grounding line of the anode.

[0017] The beneficial effects of this invention are as follows:

[0018] 1) This invention provides Lorentz force to free electrons in the annulus through a magnetic ring, causing the electrons to rotate around the cathode axis. An electric field is formed between the cathode and the anode. Since the cathode is located on one side of the annulus in an I-shape, the electrons can move spirally around the cathode axis and fluctuate up and down under the action of the electromagnetic field, so that the electrons can move almost infinitely in a very small space. The free electrons ionize the gas to produce secondary electrons, forming an electron cloud rotating around the cathode axis in the annulus. The ion pump can continuously and stably extract air ions, and the ion pump is small enough to be applied to a micro vacuum system.

[0019] 2) The gas ions generated by the micro ion pump of the present invention are bombarded by the titanium cathode cone under the influence of the negative voltage of the cathode. The titanium atoms sputtered from the tail of the cathode cone react chemically with the gas and solidify on the inner wall of the anode cylinder, thereby absorbing the gas and performing the function of sputtering ion pump. At the same time, the ionization of gas generates ion current. Since the magnitude of the ion current is linearly related to the vacuum degree, the micro ion pump can also characterize the vacuum degree in the vacuum chamber by measuring the ion current through a vacuum gauge.

[0020] 3) Compared with traditional designs, this invention is compatible with standard vacuum power supply, allowing for wider use and modification of existing vacuum chambers. This invention adopts a circuit structure with anode grounded and cathode set with high negative bias power supply. This power supply adjustment can completely shield the high voltage inside the anode, reducing the adverse factors that interfere with the high voltage of the ion pump and reducing the safety hazards when operating the ion pump. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a schematic diagram of the anode structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the cathode structure of the present invention;

[0024] Figure 4 This is a cross-sectional structural schematic diagram of the present invention;

[0025] Figure 5 This is a top view of the anode structure of the present invention;

[0026] Figure 6 This is a schematic diagram of the electronic motion trajectory of the present invention;

[0027] Figure 7 This is a schematic diagram of the micro ion pump test circuit structure of the present invention;

[0028] Figure 8 This is a top-view simulation diagram of the electronic motion trajectory of the present invention;

[0029] Figure 9 This is a front-view simulation diagram of the electronic motion trajectory of the present invention.

[0030] In the diagram: 1. Cathode; 2. Anode; 3. Magnetic ring; 4. Vacuum chamber; 5. Electrical feedthrough; 6. Vacuum gauge; 7. Micro-leakage valve; 8. Vacuum pump unit; 9. Gasket; 11. Cathode column; 12. Cathode cone; 13. Connecting pipe; 21. Anode cylinder; 22. Air inlet; 23. Step; 24. Connecting part; H. Annular space. Detailed Implementation

[0031] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0032] Example

[0033] like Figure 1-4 As shown, a miniature ion pump for connecting to a standard vacuum power supply includes a cathode 1, an anode 2 surrounding the cathode 1, and a magnet for forming an electromagnetic field with the cathode 1 and anode 2. The cathode 1 includes a cathode column 11 and a cathode cone 12 fixed at the end of the cathode column 11. The anode 2 includes an anode cylinder 21 and several air inlets 22 on the side wall of the anode cylinder 21. An annular space H is formed between the tail of the cathode cone 12 and the side wall of the anode cylinder 21. The magnet is a magnetic ring 3 on the anode cylinder 21 corresponding to the annular space H. The magnetic ring 3 is used to provide centripetal force for electrons in the annular space H. The cathode column 11 and cathode cone 12 are used to axially confine electrons. The cathode 1 is made of titanium. Made of stainless steel, the magnetic field lines formed by the magnetic ring 3 run longitudinally through the annular space H. The magnetic ring 3 provides the Lorentz force to the free electrons within the annular space H, which in turn provides the centripetal force, causing the electrons to rotate around the axis of the cathode 1. An electric field is formed between the cathode 1 and the anode 2. Since the cathode 1 is located on one side of the annular space H in an I-shape, electrons moving to the upper or lower sides of the annular space H are repelled by the longitudinal electric field force, causing them to undulate up and down within the annular space H. Under the influence of the electromagnetic fields provided by the magnetic ring 3, cathode 1, and anode 2, the electrons within the annular space H spiral around the axis of the cathode 1 and undulate up and down, allowing the electrons to move almost infinitely within a very small annular space. For the trajectory of the electrons, please refer to [link to relevant documentation]. Figure 6 as well as Figure 8 and Figure 9 , Figure 6 , 8 The spiral in 9 represents the trajectory of electron motion. Both cathode 1 and anode 2 are located inside vacuum chamber 4. The gas in vacuum chamber 4 enters the annulus H through air inlet 22. Free electrons ionize the gas, generating gas ions and secondary electrons, which then accumulate in the annulus H to form an electron cloud rotating around the axis of cathode 1. This ion pump can continuously and stably extract air ions, and the pump is small enough to be used in micro vacuum systems.

[0034] Furthermore, such as Figure 2 and Figure 4As shown, the diameter of the tail of the cathode cone 12 is smaller than the diameter of the head, and the diameter of the head of the cathode cone 12 is the same as the diameter of the cathode column 11. The head of the cathode cone 12 and the end of the cathode column 11 connected to the cathode cone 12 provide longitudinal constraint for electrons in the annular space H, and the columnar tail of the cathode cone 12 forms a radial repulsive force on the electrons, thereby causing the electrons to move spirally in the annular region away from the axis of the cathode 1. This increases the trajectory of the electrons in a narrow region, ensuring that the pump has sufficient pumping speed while reducing the size of the micro ion pump. An electric feed passage 5 is fixed on the top wall of the vacuum chamber 4, and the anode 2 is fixed on one side of the electric feed passage 5. Alternatively, the electric feed passage 5 can also be located on the bottom wall or side wall of the vacuum chamber 4. Specifically, the cathode column 11 has a connecting pipe 13 at the end away from the cathode cone 12, and the anode cylinder 21 has an annular step 23 at the end near the annulus H. A magnetic ring 3 is set on the step 23, and the outer edge of the magnetic ring 3 is aligned with the outer edge of the step 23. The anode cylinder 21 has a connecting part 24 at the end away from the step 23. Multiple air inlets 22 are evenly distributed around the anode cylinder 21 on the side away from the step 23. The connecting pipe 13 and the connecting part 24 are both provided with slots. The electrical feeder 5 is provided with inserts corresponding to the slots, so that the connecting pipe 13 and the connecting part 24 can be plugged into the electrical feeder 5. The ion pump is compatible with standard vacuum electrical feeders, allowing for wider use and modification of existing vacuum chambers.

[0035] Furthermore, such as Figure 5 As shown, insulating gaskets 9 are provided between the head of the cathode cone 12 and the end of the cathode column 11 and the side wall of the anode cylinder 21. The gaskets 9 serve to position the cathode 1. The gaskets 9 are preferably made of polyimide resin. The gaskets 9 consist of a washer fixedly fitted on the outside of the cathode 1 and protrusions evenly distributed on the outer periphery of the washer and abutting against the inner wall of the anode 2. There are two magnetic rings 3 on the outside of the end of the anode cylinder 21. The two magnetic rings 3 attract each other and are stacked on the step 23. In addition, the magnetic rings 3 are preferably made of N42 neodymium magnets.

[0036] like Figure 7 As shown, a calibration vacuum gauge 6 is installed on the vacuum chamber 4, and a micro-leak valve 7 is connected to the vacuum chamber 4. The detection end of the vacuum gauge 6 is electrically connected to the cathode 1. The vacuum chamber 4 is interconnected with the vacuum pump unit 8, which can work with the micro ion pump to evacuate the vacuum chamber 4. The gas ions formed by ionization in the annulus H are affected by the negative voltage of the cathode 1 and bombard the cylindrical surface of the tail of the cathode cone 12 of the titanium cathode 1. The titanium atoms sputtered from the tail of the cathode cone 12 react chemically with the gas and solidify on the inner wall of the anode cylinder 21, thereby absorbing the gas and performing the function of the sputtering ion pump. The ionization of the gas generates an ion current, the magnitude of which is linearly related to the vacuum degree. The vacuum degree in the vacuum chamber 4 is characterized by measuring the ion current through the vacuum gauge 6. The micro-leak valve 7 is used to control the vacuum degree of the system in which the vacuum chamber 4 is located, ensuring that the micro ion pump can obtain a current curve with a complete vacuum degree range.

[0037] Specifically, cathode 1 is connected in series with a high negative bias voltage source, and the titanium cathode 1 carries a negative voltage of -1000 to -2500V. Anode 2 and the positive terminal of the voltage source are both grounded. A ballast resistor with a resistance of 10MΩ is installed on the line between cathode 1 and the voltage source. An ammeter of model Keithley-2400 is installed on the grounding line of anode 2. Compared with the traditional design, this invention adopts a circuit structure with anode grounded and cathode equipped with a high negative bias power supply. This power supply adjustment can completely shield the high voltage inside the anode, reduce the adverse factors that interfere with the high voltage of the ion pump, and reduce the safety hazards when operating the ion pump.

[0038] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A micro ion pump for connecting to a standard vacuum power supply, comprising a cathode (1), an anode (2) surrounding the cathode (1), and a magnet, the magnet being used to cooperate with the cathode (1) and the anode (2) to form an electromagnetic field, characterized in that: The cathode (1) includes a cathode column (11) and a cathode cone (12) whose tail is fixed to the end of the cathode column (11). The anode (2) includes an anode cylinder (21) and a plurality of air inlets (22) provided on the side wall of the anode cylinder (21). An annular space (H) is formed between the tail of the cathode cone (12) and the side wall of the anode cylinder (21). The magnet is a magnetic ring (3) on the anode cylinder (21) corresponding to the annular space (H). The magnetic ring (3) is used to provide centripetal force for electrons in the annular space (H). The cathode column (11) and the cathode cone (12) are used to axially confine electrons. The micro ion pump is used to evacuate the vacuum chamber (4). An electric feeder (5) is fixed on the top wall, bottom wall or side wall of the vacuum chamber (4). The anode (2) is fixed on one side of the electric feeder (5). The cathode (1) is made of titanium. The cathode (1) and the anode (2) are both located inside the vacuum chamber (4). The gas in the vacuum chamber (4) enters the annulus (H) through the air inlet (22). Free electrons ionize the gas, generating gas ions and secondary electrons, which then accumulate in the annulus (H) to form an electron cloud that rotates around the axis of the cathode (1). The cathode (1) is located on one side of the annulus (H) in an I-shape. Under the action of the electromagnetic field provided by the magnetic ring (3) and the cathode (1) and the anode (2), the electrons in the annulus (H) spiral around the axis of the cathode (1) and undulate up and down. The gas ions formed by ionization in the annulus (H) are affected by the negative voltage of the cathode (1) and bombard the cylindrical surface of the tail of the cathode cone (12) of the titanium cathode (1). The titanium atoms sputtered from the tail of the cathode cone (12) react chemically with the gas and solidify on the inner wall of the anode cylinder (21), thereby absorbing the gas.

2. The micro ion pump according to claim 1, characterized in that: The tail diameter of the cathode cone (12) is smaller than the head diameter, and the head diameter of the cathode cone (12) is the same as the diameter of the cathode column (11).

3. The micro ion pump according to claim 1, characterized in that: The cathode column (11) has a connecting pipe (13) at the end away from the cathode cone (12), the anode cylinder (21) has a step (23) at the end near the annulus (H), the magnetic ring (3) is set on the step (23), the anode cylinder (21) has a connecting part (24) at the end away from the step (23), and the connecting pipe (13) and the connecting part (24) are both plugged into the electric feed (5).

4. The micro ion pump according to claim 1, characterized in that: The vacuum chamber (4) is equipped with a calibration vacuum gauge (6) and connected to a micro-leak valve (7). The detection end of the vacuum gauge (6) is electrically connected to the cathode (1).

5. The micro ion pump according to claim 1, characterized in that: The vacuum chamber (4) is connected to the vacuum pump unit (8).

6. The micro ion pump according to claim 1, characterized in that: Insulating gaskets (9) are provided between the head of the cathode cone (12) and the end of the cathode column (11) and the side wall of the anode cylinder (21).

7. The micro ion pump according to claim 1, characterized in that: The number of magnetic rings (3) is two, and the material of both magnetic rings (3) is N42 neodymium magnet.

8. The micro ion pump according to claim 1, characterized in that: The cathode (1) is connected in series with a high negative bias voltage source, and the anode (2) and the positive terminal of the voltage source are both grounded.

9. The micro ion pump according to claim 8, characterized in that: A ballast resistor is provided on the line between the cathode (1) and the voltage source, and an ammeter is provided on the grounding line of the anode (2).

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