Ionization and acceleration separation bipolar ion source

Abstract

This invention discloses a bipolar ion source for ionization and acceleration separation, belonging to the field of plasma technology. The bipolar ion source includes an upper inner magnetic ring, a lower inner magnetic ring, an upper outer magnetic ring, a lower outer magnetic ring, a ceramic channel, an anode, and an intermediate electrode. The anode is located in a first zero magnetic field region at the bottom of the ceramic channel cavity, and the intermediate electrode is located in a second zero magnetic field region in the middle of the ceramic channel cavity. The inner and outer magnetic rings are coaxially arranged on the inner and outer sides of the ceramic channel, forming a first magnetic field and a second magnetic field, respectively. The first magnetic field forms a first zero magnetic field region at the bottom of the channel, and the second magnetic field forms a second zero magnetic field region in the middle of the channel, with the peak value of the second magnetic field located in the plume region outside the ceramic channel. This invention, through the combination of the bipolar magnetic field and the intermediate electrode, ensures that the ionization of the working fluid mainly occurs between the anode and the intermediate electrode, and that ion acceleration mainly occurs after the intermediate electrode. This achieves partitioned control and decoupling of the ionization and acceleration processes, reducing electron energy in the ionization region, decreasing electron conduction current, improving ionization and discharge efficiency, and facilitating high-voltage acceleration and increased ion energy, while simultaneously reducing sputtering on the ceramic wall.

Description

Technical Field

[0001] This invention belongs to the field of plasma technology. Background Technology

[0002] The discharge channel of the Hall effect ion source contains orthogonal electric and magnetic fields. The magnetic field confines electrons to collide with the propellant gas and ionizes them. The ionized ions are accelerated out of the discharge channel under the action of the axial electric field, thus generating ions.

[0003] Currently, the common method to increase the energy of ions emitted by ion sources is to increase the discharge voltage. However, under high voltage conditions, the strong coupling between ionization and acceleration processes in the ion source leads to an increase in high-energy electrons in the ionization region. The resulting divalent ionization and sheath saturation increase the electron conduction current, which becomes the main factor restricting the improvement of ion energy. Summary of the Invention

[0004] The purpose of this invention is to address the problem that the strong coupling between ionization and acceleration processes in existing ion sources during high-voltage discharge makes it difficult to further increase ion energy. This invention provides a bipolar ion source with separated ionization and acceleration processes. This bipolar ion source allows for the control of the ionization and acceleration processes by changing the parameter settings of the ionization and acceleration regions, thereby achieving high-voltage acceleration and increasing the ion energy of the ion source.

[0005] The bipolar ion source for ionization and accelerated separation described in this invention includes an upper inner magnetic ring, a lower inner magnetic ring, an upper outer magnetic ring, a lower outer magnetic ring, a ceramic channel, an anode, and an intermediate electrode;

[0006] An anode is provided in the first zero magnetic field region at the bottom of the inner cavity of the ceramic channel, and an intermediate electrode is provided in the second zero magnetic field region in the middle of the inner cavity of the ceramic channel. The upper inner magnetic ring and the lower inner magnetic ring are coaxially arranged with the upper outer magnetic ring and the lower outer magnetic ring on the inner and outer sides of the ceramic channel. The upper inner magnetic ring and the lower inner magnetic ring are arranged from top to bottom on the inner side of the ceramic channel, and the upper outer magnetic ring and the lower outer magnetic ring are arranged from top to bottom on the outer side of the ceramic channel.

[0007] Preferably, the lower inner magnetic ring and the lower outer magnetic ring work together to form a first magnetic field, and the upper inner magnetic ring and the upper outer magnetic ring work together to form a second magnetic field;

[0008] The first magnetic field forms a first zero magnetic field region at the bottom of the inner cavity of the ceramic channel, and the magnetic field peak of the first magnetic field is located between the first zero magnetic field and the second zero magnetic field in the channel.

[0009] The second magnetic field forms a second zero magnetic field region in the middle of the inner cavity of the ceramic channel. The magnetic field peak of the second magnetic field is located in the plume region outside the ceramic channel, and the magnetic field at the outlet section is about 90% of the peak value of the second magnetic field.

[0010] Advantages of this invention:

[0011] 1. The present invention forms a double-peak magnetic field and two zero magnetic field regions in the ceramic channel. The peak values ​​of the double-peak magnetic field can be adjusted independently, making the magnetic field adjustment more flexible and the adjustment range wider.

[0012] 2. In this invention, the anode is positioned in the first zero-magnetic-field region at the bottom of the channel, which reduces acceleration voltage loss near the anode. Simultaneously, it facilitates increased diffusion time of the propellant gas, improving gas homogenization and ion source efficiency.

[0013] 3. The intermediate electrode of the present invention is located in the second zero magnetic field region in the middle of the channel. The magnetic field lines are basically parallel to the intermediate electrode. The reasonable configuration of magnetic field strength and electrode potential allows high-energy electrons to pass through the axial magnetic field lines and be absorbed by the intermediate electrode, while low-energy electrons cross the radial magnetic field lines and enter the ionization gas in the ionization stage. This achieves separation and control of high and low energy electrons, reduces the electron energy in the ionization region, and improves the ionization efficiency.

[0014] 4. In the bipolar ion source described in this invention, the ionization of the working fluid and the acceleration of ions occur in different regions of the discharge channel. The main ionization region is located between the anode and the intermediate electrode, and the acceleration region is located after the intermediate electrode. This decouples ionization and acceleration, enabling high-voltage acceleration and increasing ion energy.

[0015] 5. The magnetic field in the acceleration zone of the magnetic circuit structure described in this invention still has a magnetic focusing magnetic field configuration, and the second magnetic field peak is located outside the channel outlet, which reduces the ion sputtering rate on the ceramic wall and effectively improves the ion flux. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the bipolar ion source structure for ionization and accelerated separation described in this invention. This diagram only shows half of the ion source structure. The dashed line in the diagram is the axial center line of the ion source. The overall structure is mirror-oriented with this center line as the reference.

[0017] Figure 2 This is a schematic diagram of the magnetic field configuration within the ceramic channel of the present invention;

[0018] Figure 3 This is a schematic diagram of the magnetic field strength in the ceramic channel of the present invention. Detailed Implementation

[0019] Specific Implementation Method 1: The following is combined with... Figures 1-3 This embodiment describes a bipolar ion source for ionization and accelerated separation, comprising an upper inner magnetic ring 1, a lower inner magnetic ring 2, an upper outer magnetic ring 3, a lower outer magnetic ring 4, a ceramic channel 5, an anode 6, and an intermediate electrode 7.

[0020] An anode 6 is provided in the first zero magnetic field region at the bottom of the inner cavity of the ceramic channel 5, and an intermediate electrode 7 is provided in the second zero magnetic field region in the middle of the inner cavity of the ceramic channel 5. The upper inner magnetic ring 1 and the lower inner magnetic ring 2 are coaxially arranged with the upper outer magnetic ring 3 and the lower outer magnetic ring 4 on the inner and outer sides of the ceramic channel 5. The upper inner magnetic ring 1 and the lower inner magnetic ring 2 are arranged from top to bottom on the inner side of the ceramic channel 5, and the upper outer magnetic ring 3 and the lower outer magnetic ring 4 are arranged from top to bottom on the outer side of the ceramic channel 5.

[0021] The lower inner magnetic ring 2 and the lower outer magnetic ring 4 work together to form the first magnetic field, and the upper inner magnetic ring 1 and the upper outer magnetic ring 3 work together to form the second magnetic field.

[0022] The first magnetic field forms a first zero magnetic field region at the bottom of the inner cavity of the ceramic channel 5, and the magnetic field peak of the first magnetic field is located between the first zero magnetic field and the second zero magnetic field in the channel.

[0023] The second magnetic field forms a second zero magnetic field region in the middle of the inner cavity of the ceramic channel 5. The magnetic field peak of the second magnetic field is located in the plume region outside the ceramic channel 5, and the magnetic field at the outlet section is about 90% of the peak value of the second magnetic field.

[0024] Finite element method (FEM) software was used to optimize the axial and radial dimensions and positions of the four permanent magnet rings to form the optimal magnetic field configuration. This magnetic field is symmetrical about the channel's mid-diameter, exhibiting two magnetic field peaks and two zero-magnetic-field regions. Anode 6 is positioned at the bottom of the channel in the first zero-magnetic-field region, which reduces acceleration voltage loss near the anode and improves voltage utilization.

[0025] The ionization of neutral gas and the acceleration of ions occur in different regions of the discharge channel. The main ionization region is located between the anode and the intermediate electrode, and the acceleration region is located after the intermediate electrode, thus achieving decoupling of the ionization and acceleration processes in the ion source.

[0026] The intermediate electrode 7 is arranged in the second zero magnetic field region in the middle of the ceramic channel 5. The reasonable configuration of the axial magnetic field and electrode potential near the intermediate electrode allows high-energy electrons to pass through the axial magnetic field lines and be absorbed by the intermediate electrode, while low-energy electrons cross the radial magnetic field lines and enter the ionization gas of the ionization stage. This reduces the electron energy in the ionization region, realizes the separation and control of high and low energy electrons, reduces the electron current, and thus improves the discharge efficiency.

[0027] Depend on Figure 2 It is known that the second magnetic field peak of this invention is located outside the channel outlet, reducing the ion sputtering rate on the ceramic wall surface. Figure 3 It can be seen that the peak value of the first magnetic field is about 1.8 times that of the peak value of the second magnetic field. Ionization mainly occurs between the anode and the peak value of the first magnetic field. The acceleration region is located after the intermediate electrode, thus achieving decoupling of the ionization and acceleration processes.

Claims

1. A bipolar ion source for ionization and accelerated separation, characterized in that, It includes an upper inner magnetic ring (1), a lower inner magnetic ring (2), an upper outer magnetic ring (3), a lower outer magnetic ring (4), a ceramic channel (5), an anode (6), and an intermediate electrode (7); An anode (6) is provided in the first zero magnetic field region at the bottom of the inner cavity of the ceramic channel (5), and an intermediate electrode (7) is provided in the second zero magnetic field region in the middle of the inner cavity of the ceramic channel (5). The upper inner magnetic ring (1), the lower inner magnetic ring (2), the upper outer magnetic ring (3), and the lower outer magnetic ring (4) are coaxially arranged on the inner and outer sides of the ceramic channel (5). The upper inner magnetic ring (1) and the lower inner magnetic ring (2) are arranged from top to bottom on the inner side of the ceramic channel (5), and the upper outer magnetic ring (3) and the lower outer magnetic ring (4) are arranged from top to bottom on the outer side of the ceramic channel (5).

2. The bipolar ion source for ionization and accelerated separation according to claim 1, characterized in that, The lower inner magnetic ring (2) and the lower outer magnetic ring (4) work together to form the first magnetic field, and the upper inner magnetic ring (1) and the upper outer magnetic ring (3) work together to form the second magnetic field; The first magnetic field forms a first zero magnetic field region at the bottom of the inner cavity of the ceramic channel (5), and the magnetic field peak of the first magnetic field is located between the first zero magnetic field and the second zero magnetic field in the channel. The second magnetic field forms a second zero magnetic field region in the middle of the inner cavity of the ceramic channel (5). The magnetic field peak of the second magnetic field is located in the plume region outside the ceramic channel (5), and the magnetic field of the outlet section is about 90% of the peak value of the second magnetic field.

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