A compact switchable electron-ion gun

Abstract

The application relates to a small switchable electron-ion gun. The small switchable electron-ion gun comprises a knife-edge sealed standard CF flange, a vacuum lead assembly arranged at the non-knife edge side of the CF flange and located at a central position, a support arranged at the other side of the CF flange, and an electron-ion source assembly arranged on the support. The switchable electron-ion gun has the advantages of being clean and pollution-free, reliable in work, and long in service life.

Description

Technical Field

[0001] This invention relates to a small, switchable electron-ion gun for cleaning, activating, and processing material surfaces in a vacuum, particularly for surface cleaning and activation before laser crystal bonding, and belongs to the field of vacuum electronics technology. Background Technology

[0002] Electron guns and ion guns are important electro-vacuum devices. They consist of a main structure operating in a vacuum environment and an external electronic control module. The main structure can extract electron beams, ion beams, or atomic beams in the vacuum environment to achieve specific functions. For example, an electron beam accelerated at tens of kV and then bombarding a metal target can generate X-rays. Electron beams can also generate THz electromagnetic wave emission through external modulation. Ion beams can be used in focused ion beam etching in micro-nano fabrication and ion implantation of semiconductor materials. Ion guns with large beam cross-sections have very wide applications in vacuum coating. The high-speed ejection of an atomic beam after the ion beam is neutralized by electrons is also an important space electric propulsion technology. For the surface treatment of electrically insulating materials, pure electron or ion beam bombardment can cause surface charging, which can prevent subsequent beam bombardment; therefore, ion guns with neutralization capabilities (i.e., atomic beam bombardment) are also needed.

[0003] Low-current electron guns typically employ thermionic emission. Thermionic emission offers advantages such as good stability and reliable operation, but also has significant disadvantages: high power consumption, short filament life, low emitted electron current, requirement for high-temperature resistant components, and long start-up warm-up time. Field emission electron guns have also been extensively studied, offering advantages such as low power consumption, fast start-up, and room-temperature emission, but disadvantages such as poor stability and short emitter life. Hollow cathode electron guns are "cold" electron guns based on the principle of rarefied gas discharge. In recent years, they have been widely studied due to their enormous application potential in the THz field, capable of producing ampere-level currents per square centimeter (A / cm²). 2 While electron guns can produce high-current beams, the complex components required for electrode water cooling and electromagnetic coils result in a complex and large main structure, and the working gas pressure is typically high (several Pa to tens of Pa). To reduce the working pressure, a heated filament is usually needed as a trigger source, which brings about the old problem of short lifespan. In recent years, many industrial and scientific research fields have had an urgent need for electron guns with low current (μA to mA), small structure, fast start-up, high stability, and long lifespan.

[0004] An ion gun works on the principle of rarefied gas discharge in a vacuum. It ionizes the working gas and extracts an ion beam through appropriate extraction and focusing electrodes. If necessary, a thermionic emission electron source is added near the extraction point to neutralize the ions, thus achieving an atomic beam. The gas ionization principle of an ion gun can be categorized into electron collision ionization (EI), magnetron discharge ionization (MI), and electrostatic discharge ionization (SEI). In EI, electrons with energies of 70-100 eV collide inelasticly with gas molecules, causing them to lose their outer electrons and become positive ions. This type of EI ion gun requires a suitable excitation electron source. Industrially, heated filament emission is commonly used as the electron source. In an EI source, the ion current generated by ionization is proportional to the excitation electron current (I0). ion =kI ele Furthermore, the ion current is much smaller than the excitation electron current (typically, the gas ionization coefficient k << 1). Therefore, this type of ion gun is mostly used in situations where only a very weak ion beam current is required (such as in mass spectrometry). Magnetron discharge utilizes a special electromagnetic field structure to confine stray electrons in space to excite initial ionization. The generation of each positive ion is accompanied by the generation of at least one free electron, thus creating an "avalanche" ionization effect. The main function of the magnetic field is to prolong the path of electrons before they reach the electrodes, increasing the probability of ionization by collision with gas molecules. The ion beam current that can be extracted by this MI-type ion gun is generally exponentially related to the gas pressure and ionization voltage (I0). ion =k1P n ;I ion =k1V m Therefore, a larger ion current can generally be achieved by increasing the pressure and ionization voltage of the working gas. To reduce the discharge voltage and increase the ion beam current, industrial applications typically combine EI and MI technologies. This involves using thermal emission to increase the initial number of electrons in space, making discharge easier, and then relying primarily on MI to generate a larger ion beam current. Currently, most commercially available Kaufman and Hall ion guns utilize the combined EI & MI principle. Their ion neutralization is also achieved by adding a thermal emission electron source at the ion beam exit. This approach introduces drawbacks such as short filament life (typically tens to hundreds of hours), complex ion source structure, and large size (some requiring electrode water cooling), which become major limitations in practical applications. To eliminate the bulky magnet (permanent magnet or electromagnetic), in recent years, some international researchers have designed electrostatic ion guns that rely solely on electrostatic fields to confine the movement of free electrons to achieve gas discharge and thus extract the ion beam. These ion guns operate at high pressures, have complex discharge modes, and exhibit random transitions between different modes, resulting in poor ion beam stability.

[0005] With the rapid development of functional materials, high-power lasers, MEMS technology, and other fields, many industrial and scientific research sectors have an urgent need for ion guns that are small in size, long in life, and have low beam currents (μA to mA). For example, in the field of high-power laser crystal bonding, it is necessary to perform fine surface treatment of small-sized precision laser crystals using ion beams. Laser crystals are typically small in size, thus requiring a small beam current cross-section; the surface treatment of optical components requires high precision, therefore the ion beam current cannot be too high; and since laser crystals are usually non-conductive, the ion beam needs to be neutralized. In particular, the surface of optical components is most susceptible to contamination, and the thermal filaments typically used to generate neutralizing electrons will rapidly sublimate and produce contaminants. For process stability, it is also desirable for the ion gun to operate stably for a long lifespan. Traditional electron guns can only emit electron beams, and ion guns can only extract ion beams. Therefore, there is an urgent need for a long-life, small ion gun with electron neutralization capabilities that does not require a thermal filament. Summary of the Invention

[0006] Therefore, the present invention provides a small, switchable electron-ion gun, comprising:

[0007] The standard CF flange (1) with knife edge (6) sealing;

[0008] Vacuum lead assembly (3) is located on the non-knife-edge side of the CF flange and at the center.

[0009] Support member (7) is installed on the other side of the CF flange;

[0010] An assembly of an electron-ion source mounted on a support.

[0011] In this invention, the switchable electron-ion gun can emit either an electron beam or an ion beam independently. Switching between the two is very simple, requiring only a switch or relay. In particular, for the charge neutralization requirements of ion bombardment cleaning of insulator surfaces, the ion beam and electron beam can be drawn out separately at different times, alternating back and forth, allowing electrons and ions to automatically neutralize on the insulator surface, thereby eliminating the negative effects caused by surface charging.

[0012] Preferably, the vacuum lead assembly (3) is provided with a plurality of high-voltage resistant vacuum lead terminals (4).

[0013] Preferably, the components of the electron-ion source include: an insulating sleeve magnetic assembly (8, 12, 13, 15) with a hollow structure; and a magnetically conductive electrode (9), an anode cylinder electrode (14), a grid electrode (16), and a focusing cylinder electrode (17) arranged sequentially on the insulating sleeve magnetic assembly (8, 12, 13, 15) in a direction away from the support.

[0014] Preferably, the magnetic electrode (9) is provided with a magnetic ring (10) and a field emission magnetic needle (11) installed in an axially symmetrical manner; preferably, the magnetic electrode (9) is also designed with a gas guide hole to facilitate gas conduction.

[0015] Preferably, the small switchable electron-ion gun also includes a shielding outer cylinder (19) fixed to the support and used to shield the electron-ion source.

[0016] Preferably, a throttling outlet tube (18) is designed in the center of the upper end cover of the shielding outer cylinder (19); more preferably, the throttling outlet tube (18) is connected to the shell through the shielding outer cylinder (19).

[0017] Preferably, one side of the standard CF flange (1) sealed by the knife edge (6) is designed with an air inlet pipe (2).

[0018] Preferably, the air intake pipe is connected to an external valve or gas flow meter to control the entry of the working gas into the discharge chamber where the electron-ion source component is located.

[0019] Preferably, the other side of the standard CF flange (1) sealed by the knife edge (6) is provided with screw holes (5) for connecting a small switchable electron-ion gun to a vacuum system.

[0020] Preferably, the magnetic electrode (9) is connected to a negative high voltage -HV as a cathode; preferably, the negative high voltage -HV ranges from -300V to -3000V, and more preferably from -1000V to -2500V.

[0021] Preferably, the anode cylindrical electrode (14) has a hollow cylindrical structure.

[0022] Preferably, the anode cylinder electrode (14) is grounded through resistor R2 and simultaneously connected to positive high voltage +HV through switch K;

[0023] Preferably, the value of resistor R2 is 5MΩ to 10MΩ; and the range of positive high voltage +HV is +300V to +3000V, more preferably +1000V to +3000V.

[0024] Preferably, the switch K is a manual switch or an automatically controlled relay switch.

[0025] Preferably, the grid electrode (16) is grounded through resistor R1; resistor R1 is a sampling resistor with a value of 10KΩ to 1MΩ, and the voltage across resistor R1 can detect the relative magnitude of electron flow or ion flow.

[0026] Preferably, the focusing cylinder electrode (17) is suspended, which plays a self-focusing and self-collimating role for the electron flow and ion flow.

[0027] Preferably, the potential on the anode tube electrode is controlled to achieve the switching of the extracted beam current;

[0028] Preferably, a positive ion beam is drawn out when the anode cylinder electrode is connected to a positive high voltage +HV; an electron beam is drawn out when the anode cylinder electrode is grounded through a resistor.

[0029] More preferably, when the positive high voltage +HV value is in the range of +1000 to +3000V, the electron beam current range is -1μA to -200μA, and the ion beam current range is +1μA to +600μA.

[0030] Beneficial effects:

[0031] This switchable electron-ion gun can emit either an electron beam or an ion beam independently. Switching between the two is very simple, requiring only a switch or relay. Specifically, for the neutralization requirements of ion bombardment cleaning of insulator surfaces, the ion beam and electron beam can be drawn out separately at different times, alternating back and forth, allowing electrons and ions to automatically neutralize on the insulator surface, thus eliminating the negative effects caused by surface charging. The switchable electron-ion gun proposed in this invention has the advantages of being clean and pollution-free, reliable in operation, and having a long lifespan. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the main structure of the low-pressure start-up type small-size switchable electron-ion gun in this invention;

[0033] Figure 2 This is a schematic diagram of the cathode-anode electromagnetic field and electron trajectory in this invention. Curved arrows represent the magnetic field, straight arrows represent the electric field, and spirals represent the electron trajectory.

[0034] Figure 3 These are typical test results. The dots represent ion flow, and the squares represent electron flow. Detailed Implementation

[0035] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0036] In this disclosure, the main structure of the small switchable electron-ion gun is shown below. Figure 1The main structure is mounted on a standard CF flange (1) with a knife-edge (6) seal, which facilitates direct connection of the main structure to the vacuum system via screw holes (5). An inlet pipe (2) is designed on the side of the CF flange (1), allowing the working gas (e.g., Ar gas) to enter the chamber of the electron-ion source via an external valve or gas flow meter. A vacuum lead assembly (3) is designed in the center of the CF flange (1), which has several high-pressure resistant vacuum lead terminals (4). A support (7) is fixed to the vacuum side of the CF flange (1), and the key components of the electron-ion source are sequentially stacked on the support (7).

[0037] The components of the electron-ion source include: an insulating magnetic sleeve assembly (8, 12, 13, 15) with a hollow structure; and a magnetically conductive electrode (9), an anode cylinder electrode (14), a grid electrode (16), and a focusing cylinder electrode (17) arranged sequentially on the insulating magnetic sleeve assembly away from the support. It should be noted that the insulating magnetic sleeve assembly (8, 12, 13, 15) with a hollow structure can be integrally formed or separately distributed between any two adjacent elements of the support (7), the magnetically conductive electrode (9), the anode cylinder electrode (14), the grid electrode (16), and the focusing cylinder electrode (17).

[0038] Specifically, the magnetic electrode (9) is fixed by a ceramic insulator (8). Preferably, a magnetic ring (10) and a field emission magnetic needle (11) are mounted on the magnetic electrode (9) in an axisymmetric manner. The magnetic electrode (9) is also designed with a gas guide hole to facilitate gas conduction.

[0039] Specifically, the pre-welded anode tube electrode (14) is fixed by a ceramic insulator (12). The grid electrode (16) is fixed by a ceramic insulator (13). The focusing tube electrode (17) is fixed by a ceramic insulator (15).

[0040] The shielding outer cylinder (19) is fixed on the support (7). The upper end cap of the shielding outer cylinder (19) is designed with a throttling outlet cylinder (18) in the center. Through it, the electron beam or ion beam can be extracted, and the gas can be throttled, so that the gas pressure in the electron-ion source chamber can be much higher than the pressure of the main vacuum chamber of the vacuum system.

[0041] Figure 1The small illustration on the right shows the basic wiring diagram of each electrode. The magnetic electrode (9) is connected to a negative high voltage (-HV: -300V to -3000V) as the cathode. The anode tube electrode (14) is grounded through resistor R2 (5MΩ to 10MΩ) and also connected to a positive high voltage (+HV: +300V to +3000V) through switch K. Switch K can be a manual switch or an automatic control relay switch. The grid electrode (16) is grounded through resistor R1 (10KΩ to 1MΩ), which serves as a sampling resistor. The voltage across it can be used to detect the relative magnitude of the electron or ion flow. The focusing tube electrode (17) can be suspended, which plays a role in self-focusing and self-collimating the beam. The throttling lead tube (18) is connected to the shell ground through the shielded outer tube (19).

[0042] The key to this invention lies in the specially designed cathode and anode structures. The cathode employs a magnetic ring and magnetic needle structure, while the anode utilizes a hollow cylindrical structure. Figure 2 The left side shows a schematic diagram of its electromagnetic field structure. The curved arrows represent the magnetic field, and the straight arrows represent the electric field. The electric field lines and magnetic field lines have a certain angle, meaning they have both parallel and perpendicular components. After applying a negative high voltage (-HV) to the cathode, the field-emitting magnetic needle (11) emits seed electrons towards the anode cylinder electrode (14). The seed electrons are constrained by the magnetic field and will spiral around the magnetic field lines during their movement towards the anode, while also undergoing Hall precession around the field-emitting magnetic needle (11). In summary, the electrons will undergo involute spiral motion, such as... Figure 2 As shown by the spiral in the right figure, this motion significantly extends the path of seed electrons before reaching the anode, increasing their probability of collisional ionization with gas molecules. Each ionized gas molecule also releases a free electron, which is also constrained by the magnetic field and undergoes the same motion. This creates a chain reaction, triggering an avalanche gas discharge. The advantage of this electrode structure is that it can trigger gas discharge at very low gas pressures (10⁻³ Pa to 1 Pa), while conventional electron guns or ion guns require higher gas pressures (10 Pa to 50 Pa) to trigger gas discharge. To reduce the gas pressure at which the discharge begins, most existing electron and ion sources use heated filament electron sources to generate initial electrons.

[0043] Preferably, the hollow cylindrical structure of the anode cylinder electrode (14) is also crucial. When switch K is turned on, electrons generated by the gas discharge between the cathode and anode will partially reach the anode cylinder electrode and then be conducted to ground through resistor R2. The electron flow through R2 will generate a negative voltage on the anode cylinder electrode, and the greater the electron flow, the higher the negative voltage. This negative voltage has two functions: first, it automatically regulates the gas glow discharge between the cathode and anode to maintain an appropriate steady state, so as not to cause arc discharge. Arc discharge will generate high temperature, which will affect the magnet. Second, when only considering the dual-electrode system composed of the grid electrode (16) and the anode cylinder electrode (14), the anode cylinder electrode (14) becomes the cathode, and the grid electrode (16) becomes the anode because it is close to the ground potential. This local structure constitutes a typical hollow cathode structure, which is conducive to the amplification of electron flow. At this time, some electrons will pass through the grid and be drawn out. Electrons passing through the grid usually have random shooting angles, and some electrons will undoubtedly reach the suspended focusing cylinder electrode (17), making it have a negative voltage, thereby achieving a self-focusing and self-collimating effect on the subsequent electron flow. In fact, the near-ground potential grid electrode (16), the focusing tube electrode (17), and the ground potential throttling tube (18) constitute a typical Enzel lens structure. The self-collimated electron beam can maintain a small divergence angle while moving a long distance in the field-free space.

[0044] When switch K is closed, the anode cylinder electrode (14) is directly connected to a positive high voltage (+HV). Similar to the above, more electrons are generated by the gas discharge between the cathode of the field emission magnetic needle (11) and the anode cylinder electrode (14). Some of these electrons are received by the anode cylinder electrode (14) and then conducted to ground through resistor R2 and the +HV power supply. The remaining free electrons pass through the inside of the anode cylinder electrode (14) and collide with gas molecules, causing an avalanche ionization effect. The electrons and ions generated by the gas discharge diffuse freely in the equipotential space of the cylinder. At the upper end of the cylinder, ions are attracted away by the grid electrode (16), and some ions pass through the grid and are drawn out. Electrons are repelled by the grid electrode (16) and return to the inside of the cylinder to continue participating in gas collision ionization. A similar effect occurs at the lower end of the cylinder. In this way, the anode cylinder electrode (14) and the grid electrode (16) constitute a typical hollow anode structure. Similarly, ions passing through the grid typically have random angles of incidence, and some ions will inevitably reach the suspended focusing tube electrode (17), giving it a positive voltage and thus achieving self-focusing and self-collimation for the subsequent ion beam. In fact, the near-ground potential grid electrode (16), the focusing tube electrode (17), and the ground potential throttling tube (18) constitute a typical Enzel lens structure. The self-collimated ion beam can maintain a small divergence angle while traveling a considerable distance in field-free space.

[0045] Therefore, this invention can extract approximately collimated electron and ion beams separately by controlling the opening and closing of switch K. For processing materials with poor conductivity (such as laser crystals), the ion and electron beams can be extracted in a time-sharing manner. By controlling the on / off time of switch K, surface charging of the material can be avoided, achieving overall electrical neutralization. This approach avoids the serious problems of filament sublimation pollution and short lifespan associated with adding a heated filament for neutralization to the ion source outlet, as is commonly done. Because it does not use a heated filament, the switching electron-ion gun proposed in this invention has the advantages of being clean and pollution-free, reliable and robust, and having a long lifespan.

[0046] In other words, this invention allows for one-button switching between extracting an electron beam and an ion beam by controlling a switch or relay on the power supply, without altering the structure of the gun itself or interrupting the gas discharge process. By time-divisionally extracting the positive ion beam and the electron beam, electrical neutralization can be achieved during beam bombardment cleaning of insulating material surfaces.

[0047] In an optional embodiment, a magnetic field emission needle applying a negative high voltage (-HV) is used to provide initial electrons. A special cross-electromagnetic field structure is employed to increase the electron cyclotron path, thereby increasing the probability of collisional ionization with gas molecules. The value of -HV is in the range of -1000 to -2500V. Controlling the potential on the anode electrode allows for convenient switching of the extracted beam. In an optional embodiment, a positive ion beam is extracted when the anode electrode is connected to a positive high voltage (+HV); an electron beam is extracted when the anode electrode is grounded through a resistor. The value of +HV is in the range of +1000 to +3000V. The electron beam range is -1μA to -200μA; the ion beam range is +1μA to +600μA. In an optional embodiment, the invention incorporates a self-focusing electrode to achieve beam self-collimation and self-focusing. In an optional embodiment, the invention incorporates a throttling extraction cylinder, which allows the gas pressure in the discharge chamber to be an order of magnitude higher than that in the main vacuum chamber.

[0048] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0049] Example

[0050] A small-sized switchable electron-ion gun was fabricated based on a standard CF35 flange (knife-edge seal). The CF35 flange has an inlet pipe on its side, connected to a standard CF16 flange. A gas flow meter or fine-tuning valve can be connected via this CF16 flange. In actual testing, an ultra-high vacuum fine-tuning valve was connected to control the gas flow. A standard vacuum lead assembly is installed in the center of the CF35 flange. Different colored leads were soldered to the various terminals on the vacuum side using a soldering iron. The vacuum side of the CF35 flange has six evenly distributed M3 mounting holes for securing the electron-ion gun's electrodes and insulating components.

[0051] Below is an introduction to each component and its installation steps:

[0052] The first step is to connect the support components using three M3×6 copper posts and screws. Four M4×45 ceramic (or nylon) screws are then passed through the holes in the support components.

[0053] The second step is to fix the field emission magnetic needle to the central screw hole of the magnetically conductive electrode using a screw. The field emission magnetic needle is made of a ferromagnetic material with good magnetic permeability and is shaped like an M3 screw. The end of the screw is tapered, and its surface can be coated with metals such as LaB6 or W to further facilitate electron emission.

[0054] The third step involves fixing the magnetically conductive electrode to the center of the support using M3×15 ceramic screws. The screws pass through an 8mm high ceramic tube, electrically isolating the magnetically conductive electrode from the support. Then, the SmCo magnet ring is placed on the magnetically conductive electrode, ensuring it is coaxial with the magnetic field emission needle.

[0055] The fourth step is to thread a 24mm high ceramic tube through four M4×45 ceramic screws, and then thread the anode tube electrode through the four holes at its corners onto these ceramic (or nylon) screws.

[0056] Fifth, thread 12mm high ceramic tubes through four M4×45 ceramic screws, and then thread the grid electrode through the four holes at its corners onto these ceramic screws. Finally, secure the installed component with four 20mm high M4 nylon nuts.

[0057] Step 6: Fix the focusing tube electrode to the ceramic nut using 4 M4×10 ceramic posts;

[0058] Step 7: Fit the outer shielding cylinder, ensuring its inner diameter matches the outer diameter of the support component, and its lower end contacts the CF35 flange face, completely surrounding the air inlet. The throttling outlet cylinder assembly at the upper end of the outer shielding cylinder is connected to the M4×10 ceramic pillar inside the cylinder by four screws, thus securing the outer shielding cylinder.

[0059] Step 8: Connect the leads to each electrode. Mechanical connections are preferred. Since some electrodes will generate heat, avoid using a soldering iron. Finally, the main structure of the switchable electron-ion gun is assembled.

[0060] Next, we will begin the actual operational testing of the switchable electron-ion gun. Prepare one positive high-voltage power supply (+HV) and one negative high-voltage power supply (-HV) for backup. Install the main structure of the switchable electron-ion gun onto a vacuum system with a molecular pump as the primary pump. Place an electrically suspended planar test target directly in front of the throttling outlet of the main structure. Connect the target to the outside of the vacuum chamber via appropriate vacuum leads, and then ground it through a 10KΩ~1MΩ sampling resistor. By monitoring the voltage to ground of the sampling resistor using a digital multimeter, the electron or ion current can be determined. Connect the two high-voltage power supplies to the corresponding electrodes of the main structure according to… Figure 1 The connection is shown in the small illustration on the right. Connect an ultra-high vacuum needle valve to the CF16 flange for the air intake, and then connect it to an Ar gas cylinder.

[0061] After completing the above preparations, begin the vacuum process. When the vacuum level reaches or exceeds 5 × 10⁻⁶... -4 At pressure Pa, disconnect switch K, turn on the negative high-voltage power supply, and adjust it to an appropriate value (e.g., -2500V). Then slowly open the ultra-high vacuum needle valve to allow Ar gas to enter the electron-ion gun. A negative voltage reading will be observed on the multimeter when the pressure in the vacuum system does not rise significantly, indicating that an electron beam has been extracted. At this point, close switch K again and turn on the positive high-voltage (+HV) power supply; a positive voltage reading will be observed on the multimeter, indicating that an ion beam has been extracted. The extraction of the electron and ion beams can be controlled by opening and closing switch K. Optimized electron and ion beams can be obtained by adjusting the gas inlet flow rate and the values ​​of +HV and -HV.

[0062] Figure 3 These are typical test results. Test conditions: +HV=+2000V, -HV=-1500V. Main vacuum chamber pressure variation range: 1×10⁻⁶. -4 Pa~2×10 -2 Based on the flow conductance calculation of the throttling tube and the effective pumping speed of the molecular pump, it can be estimated that the gas pressure inside the electron-ion source is approximately 100 times the pressure of the main vacuum chamber, i.e., 1 × 10⁻⁶ Pa. -2 Pa ~ 2Pa. Dots represent ion flow, and squares represent electron flow. As can be seen from the graph, under the same pressure, the electron beam current and ion beam current are very close. It can also be seen that the logarithm of the gas pressure (horizontal axis) is basically linear with the logarithm of the beam current (vertical axis), indicating that the discharge satisfies I = k1P. n The pattern.

Claims

1. A small, switchable electron-ion gun, characterized in that, include: Standard CF flange with knife-edge seal; A vacuum lead assembly located on the non-knife-edge side of the CF flange and at its center. Support components are installed on the other side of the CF flange; An assembly of an electron-ion source mounted on a support member, the assembly of the electron-ion source comprising: an insulating sleeve magnetic assembly having a hollow structure; And a magnetically conductive electrode, an anode cylinder electrode, a grid electrode, and a focusing cylinder electrode are sequentially arranged in the direction away from the support of the insulating sleeve magnetic assembly; The magnetically conductive electrode is provided with a magnetic ring and a field emission magnetic needle installed in an axisymmetric manner; The magnetically conductive electrode is designed with a gas guide hole to facilitate gas conduction, and the magnetically conductive electrode is connected to a negative high voltage -HV as a cathode; the anode cylinder electrode has a hollow cylindrical structure, is grounded through resistor R2, and is connected to a positive high voltage +HV through switch K; by controlling the opening and closing of switch K, electron beam and positive ion beam are respectively led out.

2. The small switchable electron-ion gun according to claim 1, characterized in that, The vacuum lead assembly is provided with multiple high-voltage resistant vacuum lead terminals.

3. The small switchable electron-ion gun according to claim 1, characterized in that, The small switchable electron-ion gun also includes a shielded outer cylinder that is fixed to the support and is used to shield the electron-ion source.

4. The small switchable electron-ion gun according to claim 3, characterized in that, The upper end cap of the shielding outer cylinder is designed with a throttling outlet cylinder in the center.

5. The small switchable electron-ion gun according to claim 4, characterized in that, The throttling outlet tube is connected to the shell via a shielded outer tube.

6. The small switchable electron-ion gun according to claim 1, characterized in that, The standard CF flange with knife-edge seal has an air inlet pipe designed on one side.

7. The small switchable electron-ion gun according to claim 6, characterized in that, The intake pipe is connected to an external valve or gas flow meter to control the entry of the working gas into the discharge chamber where the electron-ion source component is located.

8. The small switchable electron-ion gun according to any one of claims 1-7, characterized in that, The other side of the standard CF flange with knife-edge seal is provided with screw holes for connecting a small switchable electron-ion gun to the vacuum system.

9. The small switchable electron-ion gun according to claim 1, characterized in that, The range of the negative high voltage -HV is -300V to -3000V.

10. The small switchable electron-ion gun according to claim 9, characterized in that, The range of the negative high voltage -HV is -1000 to -2500V.

11. The small switchable electron-ion gun according to claim 1, characterized in that, The value of resistor R2 is 5MΩ to 10MΩ, and the positive high voltage +HV ranges from +300V to +3000V.

12. The small switchable electron-ion gun according to claim 11, characterized in that, The positive high voltage +HV range is +1000 to +3000V.

13. The small switchable electron-ion gun according to claim 1, characterized in that, The switch K is a manual switch or an automatic control relay switch.

14. The small switchable electron-ion gun according to claim 1, characterized in that, The grid electrode is grounded through resistor R1; resistor R1 is a sampling resistor with a value of 10KΩ to 1MΩ, and the voltage across resistor R1 can detect the relative magnitude of the electron beam or positive ion beam.

15. The small switchable electron-ion gun according to claim 1, characterized in that, The focusing cylinder electrode is suspended, which enables it to self-focus and self-collimate the electron beam and positive ion beam.

16. The small switchable electron-ion gun according to claim 12, characterized in that, When the positive high voltage (+HV) is in the range of +1000 to +3000V, the electron beam current range is -1μA to -200μA, and the positive ion beam current range is +1μA to +600μA.

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