An extraction electrode for proton extraction from a 65KeV dual plasma ion source

Abstract

The invention discloses an extraction electrode for proton extraction of a 65KeV dual plasma ion source, belonging to the technical field of ion sources, comprising an anode, a front spacer, a suppression electrode, a rear spacer, a ground electrode and a flange arranged in sequence from front to back; the front spacer and the rear spacer are both ceramic spacers. The invention discloses an extraction electrode for proton extraction of a dual plasma ion source that can suppress the return of secondary electrons to the ion source.

Description

Technical Field

[0001] The invention belongs to the technical field of ion sources, and in particular relates to an extraction electrode used for proton extraction of a 65KeV dual plasma ion source. Background Art

[0002] Currently, commonly used extraction electrodes include flat plate and cone-shaped ones. The existing extraction electrodes easily cause secondary electrons to return to the ion source, resulting in beam instability, which in turn affects the stability of the beam. Summary of the invention

[0003] The object of the present invention is to provide an extraction electrode for proton extraction of a plasma ion source which can suppress the return of secondary electrons to the ion source.

[0004] To achieve the above object, the present invention adopts the following technical scheme: an extraction electrode for proton extraction of a 65KeV dual plasma ion source, comprising an anode, a front spacer, a suppression electrode, a rear spacer, a ground electrode and a flange arranged in sequence from front to back;

[0005] The suppression electrode comprises a first annular portion, a first conical portion and a second conical portion which are connected in sequence from the back to the front, and a through hole is arranged at the front end of the second conical portion;

[0006] The ground electrode comprises a ring portion, a cone portion a and a cone portion b which are connected in sequence from the back to the front, and a through hole is also arranged at the front end of the cone portion b;

[0007] The front end of the conical cylinder part b of the ground electrode extends into the second conical cylinder part of the suppression electrode, the conical cylinder part b is spaced from the second conical cylinder part, and the first conical cylinder part and the conical cylinder part a are both provided with ventilation holes;

[0008] Both the front and rear spacers are ceramic spacers;

[0009] The flange is provided with a central hole, and the central hole of the flange, the inner cavity of the ground electrode, the inner cavity of the rear spacer, the inner cavity of the suppression electrode and the inner cavity of the front spacer are interconnected, and a chamber formed by the five is a vacuum chamber.

[0010] The anode includes an anode mounting plate, and the anode mounting plate, a front spacer, a first annular portion of the suppression electrode, a rear spacer, an annular portion of the ground electrode and a flange are in contact in sequence.

[0011] Sealing rings are arranged between the front spacer and the first annular portion of the suppression electrode, between the first annular portion of the suppression electrode and the rear spacer, between the rear spacer and the annular portion of the ground electrode, and between the annular portion of the ground electrode and the flange.

[0012] The anode is connected to an external 65KV power supply, the suppression electrode is connected to an external -5KV power supply, and the ground electrode is connected to the ground wire.

[0013] The anode mounting plate and the flange are fixedly connected by ceramic bolts.

[0014] The extraction electrode for proton extraction of a 65KeV dual plasma ion source described in the present invention can prevent secondary electrons from returning to the ion source by using a suppression electrode, and the beam is stable. The present invention is applicable to a 65KeV dual plasma ion source and is an extraction electrode with low proton beam emittance and high extraction efficiency. The structure is relatively simple, which is conducive to production, has a high suppression rate for secondary electrons, and has high beam stability. The cone angles of the inner wall surface of the cone cylinder part b and the inner wall surface of the second cone cylinder part are both 90°, which can maximize the suppression of secondary electrons. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic diagram of the structure of the suppression electrode;

[0016] Figure 2 is a stereogram of the suppressor electrode;

[0017] Figure 3 It is a schematic diagram of the structure of the ground electrode;

[0018] Figure 4 yes Figure 3 Right view of;

[0019] Figure 5 It is a schematic diagram of the structure of the present invention;

[0020] FIG6 is a proton beam extraction simulation diagram;

[0021] In the figure: first annular portion 1, annular groove 2, sealing ring groove 3, central through hole 4, first conical cylinder portion 5, second conical cylinder portion 6, through hole 7, vent hole 8, suppression electrode 9, annular portion 10, conical cylinder portion a11, conical cylinder portion b12, ground electrode 13, flange 14, sealing ring 15, ceramic bolt 16, rear spacer 17, anode hole 18, front spacer 19, anode mounting plate 20, central hole 21, anode 22, proton beam 23. DETAILED DESCRIPTION

[0022] Depend on Figure 1-Figure 5 The extraction electrode shown is used for proton extraction of a 65KeV dual plasma ion source, and includes an anode 22, a front spacer 19, a suppression electrode 9, a rear spacer 17, a ground electrode 13 and a flange 14 arranged in sequence from front to back.

[0023] The anode 22 includes a vertically arranged anode mounting plate 20 . The flange 14 is provided with a central hole 21 . The central axis of the flange 14 extends horizontally frontward and rearward. The anode mounting plate 20 and the flange 14 are fixedly connected by two ceramic bolts 16 .

[0024] The front spacer 19 , the suppression electrode 9 , the rear spacer 17 and the ground electrode 13 are all arranged between the two ceramic bolts 16 .

[0025] The front spacer 19 and the rear spacer 17 are both arranged horizontally front to back and are both ceramic spacers, that is, the material of the front spacer 19 and the rear spacer 17 are both ceramic, and the cross-sections of the front spacer 19 and the rear spacer 17 are both circular.

[0026] The suppression electrode 9 includes a first annular portion 1, a first conical portion 5, and a second conical portion 6 which are fixedly connected in sequence from back to front. The first annular portion 1, the first conical portion 5, and the second conical portion 6 are an integrated structure. The first annular portion 1 is a circular ring body with a central through hole 4. The first conical portion 5 and the second conical portion 6 are both truncated cone-shaped and hollow structures. The first annular portion 1, the first conical portion 5, and the second conical portion 6 are connected in sequence from back to front. The central axes of the three are all arranged horizontally front and back and the central axes of the three coincide (that is, they are coaxially arranged). A through hole 7 is arranged at the front end of the second conical portion 6. The cone angle of the first conical portion 5 is greater than the cone angle of the second conical portion 6. The outer wall surface and the inner wall surface of the second conical portion 6 are both truncated cone surfaces. In this embodiment, the cone angle α of the inner wall surface of the second conical portion 6 is 90°. A plurality of ventilation holes 8 are evenly spaced and arranged on the first conical portion 5 around its central axis.

[0027] The ground electrode 13 includes an annular portion 10, a conical portion a11 and a conical portion b12 which are fixedly connected in sequence from back to front. The annular portion 10, the conical portion a11 and the conical portion b12 are an integrated structure. The annular portion 10 is a circular ring body with a central through hole 4. The conical portion a11 and the conical portion b12 are both truncated cone-shaped and hollow structures. The annular portion 10, the conical portion a11 and the conical portion b12 are connected in sequence from back to front. The central axes of the three are all arranged horizontally front and back and the three are arranged coaxially. A through hole 7a is also arranged at the front end of the conical portion b12. The cone angle of the conical portion a11 is greater than the cone angle of the conical portion b12. The outer wall surface and the inner wall surface of the conical portion b12 are both truncated cone surfaces. In this embodiment, the cone angle β of the inner wall surface of the conical portion b12 is 90°. A plurality of ventilation holes 8 are evenly spaced and arranged on the conical portion a11 around its central axis.

[0028] The cone angle is the angle between the two generatrixes of the axial section of a cone or a frustum (the section passing through the axis of the cone or the frustum).

[0029] The second conical cylinder portion 6 and the first conical cylinder portion 5 of the suppression electrode 9 both extend forward into the front spacer 19 , and the suppression electrode 9 is spaced behind the anode 22 .

[0030] The front end of the conical cylinder portion b12 of the ground electrode 13 passes through the inner cavity of the rear spacer 17 and extends into the second conical cylinder portion 6 of the suppression electrode 9 . The conical cylinder portion b12 is spaced apart from the second conical cylinder portion 6 , and the suppression electrode 9 is spaced apart from the ground electrode 13 .

[0031] The center hole 21 of the flange 14, the inner cavity of the ground electrode 13, the inner cavity of the rear spacer 17, the inner cavity of the suppression electrode 9 and the inner cavity of the front spacer 19 are connected to each other. The inner cavity of the ground electrode 13 is composed of the central through hole 4 of the annular portion 10, the inner cavity of the conical cylinder portion a11 and the inner cavity of the conical cylinder portion b12. The inner cavity of the suppression electrode 9 is composed of the central through hole 4 of the first annular portion 1, the inner cavity of the first conical cylinder portion 5 and the inner cavity of the second conical cylinder portion 6. The inner cavity of the suppression electrode 9 is connected to the front spacer through the through hole 7 of the second conical cylinder portion 6. 19, the inner cavity of the ground electrode 13 is connected to the inner cavity of the suppression electrode 9 through the through hole 7a of the conical cylinder portion b12, the central through hole 4 of the first annular portion 1 of the suppression electrode 9 is opposite to and connected with the inner cavity of the rear spacer 17 front and back, the central through hole 4 of the annular portion 10 of the ground electrode 13 is opposite to and connected with the central hole 21 of the flange 14 front and back, and the chamber formed by the central hole 21 of the flange 14, the inner cavity of the ground electrode 13, the inner cavity of the rear spacer 17, the inner cavity of the suppression electrode 9 and the inner cavity of the front spacer 19 is a vacuum chamber.

[0032] Furthermore, the anode mounting plate 20, the front spacer 19, the first annular portion 1 of the suppression electrode 9, the rear spacer 17, the annular portion 10 of the ground electrode 13 and the flange 14 are in contact in sequence, the front end face and the rear end face of the first annular portion 1 are both provided with an annular groove 2, the front end face of the annular portion 10 is also provided with an annular groove 2, the front end face of the flange 14 is provided with an annular slot connected with its center hole 21 corresponding to the rear end of the annular portion 10, the front end face of the front spacer 19 is fitted with the rear end face of the anode mounting plate 20, the anode mounting plate 20 covers the front port of the front spacer 19, the rear end of the front spacer 19 is inserted into the annular groove 2 of the front end face of the first annular portion 1, the front end of the rear spacer 17 is inserted into the annular groove 2 of the rear end face of the first annular portion 1, the rear end of the rear spacer 17 is inserted into the annular groove 2 of the front end face of the annular portion 10, and the rear end of the annular portion 10 is inserted into the slot at the front end of the flange 14. This facilitates assembly and reduces the sliding of ceramics.

[0033] Sealing rings 15 are provided between the anode mounting plate 20 and the front spacer 19, between the front spacer 19 and the first annular portion 1 of the suppression electrode 9, between the first annular portion 1 of the suppression electrode 9 and the rear spacer 17, between the rear spacer 17 and the annular portion 10 of the ground electrode 13, and between the annular portion 10 of the ground electrode 13 and the flange 14. Specifically, a circular sealing ring groove 3 is provided on the bottom surface of each circular groove 2, and a circular sealing ring groove 3 is also provided on the rear end face of the anode mounting plate 20 and the rear end face of the annular portion 10, and a sealing ring 15 is provided in each sealing ring groove 3.

[0034] The front spacer 19, the suppression electrode 9, the rear spacer 17, the ground electrode 13 and the flange 14 are coaxially arranged. The rear side of the flange 14 is butted against a vacuum pipe for beam transmission, which is not shown in the figure.

[0035] The anode 22 is connected to an external 65KV power supply, the suppression electrode 9 is connected to an external -5KV power supply, and the ground electrode 13 is connected to the ground wire.

[0036] The anode 22 is the anode of a 65KeV dual plasma ion source, and is provided with an anode hole 18. The anode hole 18, the through hole of the suppression electrode and the through hole of the ground electrode are arranged in sequence from front to back. The anode 22 emits a proton beam 23 from the anode hole, which passes through the front spacer cavity, the suppression electrode through hole, the suppression electrode cavity, the ground electrode through hole, the ground electrode cavity from front to back, and finally is emitted from the center hole 21 of the flange.

[0037] The extraction electrode for proton extraction of a 65KeV dual plasma ion source of the present invention has a conical design and a suppression electrode that reduces the return of secondary electrons to the ion source, has a high suppression rate for secondary electrons, and has an impact on the stability of the proton beam, achieving very high beam stability. The cone angle of the inner wall of the cone barrel b and the second cone barrel is 90°, which can maximize the suppression of secondary electrons. The vent increases the speed of gas passing through to achieve the effect of quickly emptying the gas in the vacuum chamber of the ion source; the suppression electrode and the ground electrode are both made of high-temperature resistant copper material, which can have good high-temperature resistance and resistance to electron and proton bombardment.

[0038] Figure 6 The figure shows the simulation diagram of the proton beam extraction from the extraction electrode of the 65KeV dual plasma ion source, and specifically Figure 5 The simulation diagram of the proton beam 23 extraction in the A area. The simulation results of the extraction electrode of this 65KeV dual plasma ion source are good, the beam focusing is strong, and the normalized emittance is less than 0.05 Overall, this optimized design of the extraction electrode can not only suppress the electron return, but also has a good focusing effect. Figure 6 where trajectories andequipotentials are proton trajectories and equipotential lines.

Claims

1. An extraction electrode for proton extraction of a 65KeV dual plasma ion source, characterized in that: It comprises an anode (22), a front spacer (19), a suppression electrode (9), a rear spacer (17), a ground electrode (13) and a flange (14) which are arranged in sequence from front to back; The suppression electrode (9) comprises a first annular portion (1), a first conical portion (5) and a second conical portion (6) which are connected in sequence from the back to the front, and a through hole (7) is provided at the front end of the second conical portion (6); The ground electrode (13) comprises an annular portion (10), a conical portion a (11) and a conical portion b (12) which are connected in sequence from the back to the front, and a through hole (7a) is also provided at the front end of the conical portion b (12); The front end of the conical cylinder portion b (12) of the ground electrode (13) extends into the second conical cylinder portion (6) of the suppression electrode (9), the conical cylinder portion b (12) is spaced from the second conical cylinder portion (6), and the first conical cylinder portion (5) and the conical cylinder portion a (11) are both provided with ventilation holes (8); The front spacer (19) and the rear spacer (17) are both ceramic spacers; The flange (14) is provided with a central hole (21); the central hole (21) of the flange (14), the inner cavity of the ground electrode (13), the inner cavity of the rear spacer (17), the inner cavity of the suppression electrode (9) and the inner cavity of the front spacer (19) are interconnected, and a chamber formed by the five is a vacuum chamber; The anode (22) comprises an anode mounting plate (20), wherein the anode mounting plate (20), a front spacer (19), a first annular portion (1) of a suppression electrode (9), a rear spacer (17), an annular portion (10) of a ground electrode (13) and a flange (14) are in contact with each other in sequence; Sealing rings (15) are provided between the front spacer (19) and the first annular portion (1) of the suppression electrode (9), between the first annular portion (1) of the suppression electrode (9) and the rear spacer (17), between the rear spacer (17) and the annular portion (10) of the ground electrode (13), and between the annular portion (10) of the ground electrode (13) and the flange (14); The anode (22) is connected to an external 65KV power supply, the suppression electrode (9) is connected to an external -5KV power supply, and the ground electrode (13) is connected to the ground wire.

2. The extraction electrode for proton extraction of a 65KeV dual plasma ion source according to claim 1, characterized in that: The anode mounting plate (20) and the flange (14) are fixedly connected via ceramic bolts (16).

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