Ion optical system for leading out extremely-low-energy parallel high-current ion beam

Abstract

The invention discloses an ion optical system for extracting an extremely-low-energy parallel high-current ion beam, which comprises a plasma electrode, an extraction electrode, a suppression electrode, a focusing electrode, a speed reduction electrode I, a speed reduction electrode II and an annular magnet, the plasma electrode, the extraction electrode, the suppression electrode, the focusing electrode, the speed reduction electrode I and the speed reduction electrode II are coaxially mounted in sequence; the annular magnet is positioned between the speed reduction electrode I and the speed reduction electrode II; the plasma electrode is a conical electrode, and a through hole is formed in the center; the extraction electrode is formed by combining a conical electrode and an annular electrode, a through hole is formed in the center of the conical electrode, the conical electrode is located on one side of the plasma electrode, and the annular electrode is located on one side of the suppression electrode; the suppression electrode, the focusing electrode, the deceleration electrode I and the deceleration electrode II are annular electrodes. According to the system, parallel high-current ion beams can be obtained, and a basis can be provided for ground calibration work of a space low-energy particle detector.

Description

Technical Field

[0001] The present invention belongs to the field of low-energy high-intensity ion beams, and relates to an ion optical system, in particular to an ion optical system suitable for extracting extremely low-energy particle beams. Background Art

[0002] In space science research and engineering practice, detecting ions and neutral particles with energies below 100 eV is the core means to analyze the evolution law of the space atmosphere composition and ensure the safe operation of spacecraft in orbit. As the main components of the near-Earth space magnetosphere-ionosphere coupling system and the planetary atmosphere boundary layer, the accurate measurement of the energy spectrum distribution, motion trajectory, and spatial density of such extremely low-energy particles is directly related to basic scientific issues such as solar wind energy input and atmospheric escape mechanism, and is also the key basis for evaluating the corrosion of spacecraft surface materials and the risk of sensor contamination.

[0003] In the development process of space low-energy ion detectors, ground calibration is a key link to verify the energy resolution, direction response characteristics, and sensitivity indicators of the detectors. The core prerequisite is to construct an extremely low-energy high-intensity parallel ion beam calibration source with controllable parameters. However, achieving the efficient extraction of such ion beams faces severe challenges: as the beam energy drops below 100 eV, the Coulomb repulsion caused by the space charge effect increases significantly, making it difficult to maintain the parallelism of the ion beam during transmission. The formed divergent beam has a wide energy distribution characteristic, directly causing an increase in the energy dispersion measurement error during the detector calibration process and seriously affecting the calibration accuracy.

[0004] The mesh-type multi-grid ion beam extraction device proposed in CN116321650A realizes the extraction of high-conductivity low-energy ion beams by regulating the mesh structure of the plasma emission surface; the sputtering coating ion source grid structure proposed in CN119725056A also has application potential in the field of low-energy beam extraction. However, the above technologies have common bottlenecks: firstly, the processing accuracy requirements for micron-level mesh grids are extremely high, the preparation process is complex and the cost is high; secondly, the divergence angles of the extracted wide-beam ion beams are generally greater than 10°, and the energy dispersion index is difficult to meet the high-precision calibration requirement of <10 eV; thirdly, for the small-aperture beam requirements in the detector calibration scenario, the wide-beam design has a significant redundancy in energy utilization. The technical gaps in key indicators such as beam collimation control and energy concentration optimization in the existing technologies urgently need to be broken through by innovative designs of ion optical systems.

[0005] In view of this, there is an urgent need to develop an ion optical system suitable for extracting extremely low-energy particle beams. This system needs to meet the strict technical requirements of small-aperture beam output, energy ≤ 100 eV, and parallel beam transmission (divergence angle ≤ 5°), provide a high-precision controllable ion beam source for the ground calibration of space low-energy particle detectors, and promote the substantial leap of related detection technologies from principle verification to engineering application. Summary of the Invention

[0006] The present invention provides an ion optical system for extracting an extremely low-energy parallel intense ion beam. The system can obtain a parallel intense ion beam with a minimum energy of 40 eV and a current density of about 0.25 mA / cm 2 , which can provide a basis for the ground calibration of space low-energy particle detectors.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] An ion optical system for extracting an extremely low-energy parallel intense ion beam, comprising a plasma electrode, an extraction electrode, a suppression electrode, a focusing electrode, a deceleration electrode I, a deceleration electrode II, and an annular magnet, wherein:

[0009] The plasma electrode, the extraction electrode, the suppression electrode, the focusing electrode, the deceleration electrode I, and the deceleration electrode II are coaxially installed in sequence;

[0010] The annular magnet is located between the deceleration electrode I and the deceleration electrode II;

[0011] The plasma electrode is a conical electrode with a through hole in the center;

[0012] The extraction electrode is composed of a conical electrode and an annular electrode. The conical electrode has a through hole in the center. The conical electrode is located on one side of the plasma electrode, and the annular electrode is located on one side of the suppression electrode;

[0013] The suppression electrode, the focusing electrode, the deceleration electrode I, and the deceleration electrode II are annular electrodes.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. By extracting the beam current through an electric field, a beam current with an energy approximately equal to the sum of the potential of the plasma electrode and the plasma potential is obtained at the outlet of the ion optical system.

[0016] 2. By adjusting the intensity and position of the magnetic field, the low-energy beam current can be constrained, the space charge effect can be suppressed, and the parallel output of the beam current can be ensured. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the ion optical system for extracting an extremely low-energy parallel intense ion beam of the present invention, where 1 - plasma electrode; 2 - extraction electrode; 3 - suppression electrode; 4 - focusing electrode; 5 - deceleration electrode I; 6 - deceleration electrode II; 7 - annular magnet, 8 - grid;

[0018] Figure 2 is the current intensity distribution diagram of the 40 eV ion beam extracted by the ion optical system of the present invention;

[0019] Figure 3 This is the ion energy distribution diagram of the 40 eV ion beam extracted by the ion optical system of the present invention;

[0020] Figure 4 This is the ion current density distribution diagram of the 40 eV ion beam extracted by the ion optical system of the present invention. Detailed implementation manners

[0021] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0022] The present invention provides an ion optical system for extracting an extremely low-energy parallel high-current ion beam, as Figure 1 shown. The ion optical system includes a plasma electrode 1, an extraction electrode 2, a suppression electrode 3, a focusing electrode 4, a deceleration electrode I 5, a deceleration electrode II 6, and an annular magnet 7, where:

[0023] The plasma electrode 1, the extraction electrode 2, the suppression electrode 3, the focusing electrode 4, the deceleration electrode I 5, and the deceleration electrode II 6 are coaxially installed in sequence;

[0024] The annular magnet is located between the deceleration electrode I and the deceleration electrode II;

[0025] The plasma electrode 1 is a conical electrode with a cone angle of 110° to 140°, and a through hole with a diameter of 2 mm to 8 mm is opened in the center;

[0026] The extraction electrode 2 is composed of a conical electrode and an annular electrode. The conical electrode is located on one side of the plasma electrode 1, and the annular electrode is located on one side of the suppression electrode 3. A through hole is opened in the center of the conical electrode, and the diameter and cone angle are equal to those of the plasma electrode. The inner diameter of the annular part is 10 mm to 15 mm, the thickness is 2 mm to 3 mm, and the length is 10 mm to 15 mm;

[0027] The suppression electrode 3, the focusing electrode 4, the deceleration electrode I 5, and the deceleration electrode II 6 are annular electrodes, and the inner diameter and thickness are equal to those of the annular part of the extraction electrode 2;

[0028] The length of the suppression electrode 3 is 10 mm to 15 mm, the length of the focusing electrode 4 is 30 mm to 35 mm, the lengths of the deceleration electrode I and the deceleration electrode II are 1 mm to 3 mm, and the length of the annular magnet 7 is 10 mm to 50 mm, and the inner diameter only needs to be larger than the outer diameter of the annular electrode;

[0029] The distance between the plasma electrode 1 and the extraction electrode 2 is about 20 mm to 30 mm, the distance between the extraction electrode 2 and the suppression electrode 3 is about 15 mm to 20 mm, the distance between the suppression electrode 3 and the focusing electrode 4 is about 15 mm to 20 mm, the distance between the focusing electrode 4 and the deceleration electrode I 5 is about 30 mm to 40 mm, and the distance between the deceleration electrode I 5 and the deceleration electrode II 6 is about 20 mm to 30 mm;

[0030] The voltage ranges applied to the plasma electrode 2 and the focusing electrode 4 are 40 V to 100 V, the voltage range applied to the extraction electrode 2 is -3.5 kV to -6 kV, the voltage range applied to the suppression electrode 3 is -500 V to 0 V, the voltage range applied to the deceleration electrode I 5 is -500 V to -300 V, the deceleration electrode II 6 is grounded, and the magnetic field intensity of the toroidal magnet 7 is 0.2 T to 0.4 T.

[0031] The working principle of the above ion optical system is as follows: By applying a certain voltage to the plasma electrode and the extraction electrode, the ions in the plasma are accelerated and extracted using the potential difference between the plasma electrode and the extraction electrode. Then, under the action of the voltages of the suppression electrode and the focusing electrode, a parallel beam of a certain size is obtained, and this parallel beam is decelerated by the deceleration electrode. However, in the deceleration region, due to the influence of the space charge effect, the ion beam will diverge, resulting in a decrease in parallelism. Therefore, the beam is constrained by the toroidal magnet to suppress the influence of the space charge effect, and finally a parallel beam can be obtained at the outlet of the deceleration electrode II. The energy of this parallel beam is approximately the sum of the potential of the plasma electrode and the plasma potential (due to the inherent potential of the plasma itself). Therefore, by adjusting the voltage of the plasma electrode, extremely low-energy parallel ion beams with different energies can be obtained.

[0032] In the present invention, a grid or wire can be welded at the downstream outlet position of the focusing electrode, on the deceleration electrode I, and on the deceleration electrode II to homogenize the electric field between the electrodes.

[0033] In the present invention, the toroidal magnet can be a permanent magnet or a helical coil; either a single magnet or a coaxial arrangement of multiple magnets can be adopted to perform targeted beam constraint and collimation.

[0034] In the present invention, the number of deceleration electrodes can be increased based on the deceleration electrode I and the deceleration electrode II, such as adding a deceleration electrode III and a deceleration electrode IV, to forcibly set the change of the electric field in order to obtain better beam quality.

[0035] Embodiment:

[0036] This embodiment provides an ion optical system for extracting extremely low-energy parallel intense ion beams, as Figure 1As shown, the ion optical system mainly consists of a plasma electrode 1, an extraction electrode 2, a suppression electrode 3, a focusing electrode 4, a deceleration electrode I 5, a deceleration electrode II 6, and a toroidal magnet 7, where:

[0037] The plasma electrode 1, extraction electrode 2, suppression electrode 3, focusing electrode 4, deceleration electrode I 5, and deceleration electrode II 6 are coaxially installed in sequence;

[0038] The toroidal magnet 7 is located between the deceleration electrode I 5 and the deceleration electrode II 6;

[0039] The plasma electrode 1 is a conical electrode with a cone angle of 140° and a through hole with a diameter of 4 mm in the center;

[0040] The extraction electrode 2 is a combination of a conical electrode and a toroidal electrode, with the same cone angle as the plasma electrode. The inner diameter of the toroidal part is 15 mm, the thickness is 2 mm, and the length is 10 mm;

[0041] The suppression electrode 3, focusing electrode 4, deceleration electrode I 5, and deceleration electrode II 6 are toroidal electrodes, and the inner diameter and thickness are both equal to those of the toroidal part of the extraction electrode;

[0042] The suppression electrode 3 has a length of 10 mm, the focusing electrode 4 has a length of 35 mm, and the deceleration electrode I 5 and deceleration electrode II 6 have a length of 1 mm;

[0043] Metal rings are welded at the downstream outlet position of the focusing electrode 4, on the deceleration electrode I 5, and on the deceleration electrode II 6. The distance between the metal rings is 1 mm, which is used to equalize the electric field between the electrodes;

[0044] The toroidal magnet 7 is a permanent magnet with a length of 10 mm to 50 mm, and the inner diameter only needs to be larger than the outer diameter of the toroidal electrode;

[0045] The distance between the plasma electrode 1 and the extraction electrode 2 is about 20 mm, the distance between the extraction electrode 2 and the suppression electrode 3 is about 15 mm, the distance between the suppression electrode 3 and the focusing electrode 4 is about 15 mm, the distance between the focusing electrode 4 and the deceleration electrode I 5 is about 30 mm, and the distance between the deceleration electrode I 5 and the deceleration electrode II 6 is about 20 mm;

[0046] A voltage of 40 V is applied to the plasma electrode 1 and the focusing electrode 4, a voltage of -3500 V is applied to the extraction electrode 2, a voltage of -500 V is applied to the suppression electrode 3, a voltage of -500 V is applied to the deceleration electrode I 5, the deceleration electrode II 6 is grounded, and the magnetic field intensity of the toroidal magnet 7 is 0.27 T.

[0047] Based on the ion optical system structure and voltage configuration given in this embodiment, low-energy He was simulated +During the extraction process of the beam, the axial current density distribution of the He+ beam is as follows Figure 2 As shown, it can be seen that the ion beam has good parallelism when entering the deceleration region. In addition, the energy and radial current density distribution of the He+ beam were diagnosed downstream of the deceleration electrode II6, and the results are respectively as follows Figure 3 and Figure 4 As shown. It can be seen that under the configuration of this embodiment, a low-energy parallel high-current He+ beam with an energy of about 45 eV (full width at half maximum of the energy distribution <5 eV) and a current density of about 2.5 A / m 2 can be obtained.

Claims

1. An ion optical system for extracting an extremely low-energy parallel high-current ion beam, characterized in that The ion optical system includes a plasma electrode, an extraction electrode, a suppression electrode, a focusing electrode, a deceleration electrode I, a deceleration electrode II, and an annular magnet, where: The plasma electrode, extraction electrode, suppression electrode, focusing electrode, deceleration electrode I, and deceleration electrode II are coaxially installed in sequence; The annular magnet is located between the deceleration electrode I and the deceleration electrode II; The plasma electrode is a conical electrode with a through hole in the center; The extraction electrode is composed of a conical electrode and an annular electrode. The conical electrode has a through hole in the center. The conical electrode is on one side of the plasma electrode, and the annular electrode is on one side of the suppression electrode; The suppression electrode, focusing electrode, deceleration electrode I, and deceleration electrode II are annular electrodes.

2. The ion optical system for extracting an extremely low-energy parallel intense ion beam according to claim 1, characterized in that In the plasma electrode, the cone angle of the conical electrode is 110° - 140°, and the diameter of the through hole is 2 mm - 8 mm.

3. The ion optical system for extracting an extremely low-energy parallel intense ion beam according to claim 1, characterized in that In the extraction electrode, the cone angle of the conical electrode is 110° - 140°, the diameter of the through hole is 2 mm - 8 mm, the inner diameter of the annular electrode is 10 mm - 15 mm, the thickness is 2 mm - 3 mm, and the length is 10 mm - 15 mm.

4. The ion optical system for extracting an extremely low-energy parallel high-current ion beam according to claim 1, characterized in that In the suppression electrode, focusing electrode, deceleration electrode I, and deceleration electrode II, the inner diameter of the annular electrode is 10 mm - 15 mm, the thickness is 2 mm - 3 mm, and the length is 10 mm - 15 mm.

5. The ion optical system for extracting an extremely low-energy parallel high-current ion beam according to claim 1, wherein The length of the suppression electrode is 10 mm - 15 mm, the length of the focusing electrode is 30 mm - 35 mm, the lengths of the deceleration electrode I and the deceleration electrode II are 1 mm - 3 mm, the length of the annular magnet is 10 mm - 50 mm, and the inner diameter is larger than the outer diameter of the annular electrode.

6. The ion optical system for extracting an extremely low-energy parallel high-current ion beam according to claim 1, characterized in that The distance between the plasma electrode and the extraction electrode is 20 mm - 30 mm, the distance between the extraction electrode and the suppression electrode is 15 mm - 20 mm, the distance between the suppression electrode and the focusing electrode is 15 mm - 20 mm, the distance between the focusing electrode and the deceleration electrode I is 30 mm - 40 mm, and the distance between the deceleration electrode I and the deceleration electrode II is 20 mm - 30 mm.

7. The ion optical system for extracting an extremely low-energy parallel high-current ion beam according to claim 1, characterized in that The voltage ranges applied to the plasma electrode and the focusing electrode are 40 V - 100 V, the voltage range applied to the extraction electrode is -3.5 kV - -6 kV, the voltage range applied to the suppression electrode is -500 V - 0 V, the voltage range applied to the deceleration electrode I is -500 V - -300 V, the deceleration electrode II is grounded, and the magnetic field intensity of the annular magnet is 0.2 T - 0.4 T.

8. The ion optical system for extracting an extremely low-energy parallel intense ion beam according to claim 1, characterized in that A grid or wire is welded at the downstream outlet position of the focusing electrode, on the deceleration electrode I, and on the deceleration electrode II.

9. The ion optical system for extracting an extremely low-energy parallel intense ion beam according to claim 1, characterized in that The annular magnet is a permanent magnet or a helical coil.

10. The ion optical system for extracting an extremely low-energy parallel high-current ion beam according to claim 1 or 9, characterized in that The annular magnet adopts a single magnet or a coaxial arrangement of multiple magnets.

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