A magnetic filter plasma source device for simulating the ionospheric environment

Abstract

The present invention relates to a magnetic filter plasma source device for simulating the ionospheric environment. The device includes a vacuum chamber, and a filament support electrode, a magnetic field array and a metal baffle arranged in the vacuum chamber; the filament support electrode is used for installing a hot filament; the metal baffle is arranged at the middle position near the outlet of the vacuum chamber in the vacuum chamber; the magnetic field array includes multiple groups, one of which is installed on the metal baffle to form a magnetic filter configuration, and the remaining groups form a multipole magnetic field configuration. Through this device, a plasma with a uniform distribution down to 10 5 cm ‑3 and a thickness of up to 20 cm can be achieved, and the energies of plasma electrons and ions are very close to the real ionospheric environment, which is of great significance for realizing the ground calibration of space ionospheric payloads and the ground simulation research of ionospheric physics.

Description

Technical Field

[0001] The field of the present invention belongs to the field of plasma discharge and regulation technology, and particularly relates to a magnetic filter plasma source device for simulating the ionospheric environment. Background Art

[0002] The ground simulation of the space plasma environment is of great significance for both satellite calibration applications and the study of basic physical processes in space physics. Ionospheric plasma has characteristics such as low density, similar oxygen component and electron temperature. The plasma generated by traditional plasma discharge methods such as hot cathode, helicon wave, radio frequency, and electron cyclotron resonance has a relatively high electron density, generally around 10 10 cm -3 or even higher; far higher than the electron density of 10 4 -10 6 cm -3 in the ionospheric environment. In the early stage, some people adopted the density gradient natural diffusion scheme, which could achieve a low-density ionospheric environment in the area far from the plasma source. However, in this case, the plasma distribution becomes extremely uneven, and the ion temperature is relatively low, showing a significant difference from the real ionosphere; it is difficult to meet the application requirements such as satellite payload calibration. Summary of the Invention

[0003] Based on the magnetic field filtering principle, the present invention designs and develops a magnetic filter plasma source device for simulating the ionospheric environment, and successfully manufactures a plasma with a density as low as 10 5 cm -3 and a uniformly distributed plasma, with similar electron and ion energies, realizing the ground simulation of the Earth's space ionospheric environment, thus providing a new means for ionospheric electron density detection payloads and ground experimental simulations of ionospheric physics.

[0004] The technical solution provided by the present invention is as follows:

[0005] A magnetic filter plasma source device for simulating the ionospheric environment, the device comprising a vacuum chamber, and a filament support electrode, a magnetic field array, and a metal baffle disposed in the vacuum chamber;

[0006] The filament support electrode is used for mounting a hot filament;

[0007] The metal baffle is disposed in the middle of the vacuum chamber near the vacuum chamber outlet;

[0008] The magnetic field array includes multiple groups, one of which is mounted on the metal baffle to form a magnetic filter configuration, and the remaining groups form a multipole magnetic field configuration.

[0009] Further, the remaining group of magnetic field arrays includes 3 groups and are respectively configured as magnetic ring structures. Among them, the first group is installed on the front flange of the vacuum chamber; the second group is installed on the axial center plane of the device and on the inner wall of the vacuum chamber; the third group is installed near the outlet of the vacuum chamber, and its radius is the same as that of the second group.

[0010] Further, the metal baffle is a disc structure, and the magnetic field array installed thereon forms a magnetic ring structure, and the outer diameter of the magnetic ring structure is the same as the outer diameter of the metal baffle.

[0011] Further, the magnetic field array is composed of permanent magnets.

[0012] The beneficial effects that the present invention can bring:

[0013] Through this device, a plasma with a uniform distribution with a low density of up to 10 5 cm -3 and a thickness of 20 cm can be achieved, and the energies of plasma electrons and ions are very close to the real ionospheric environment. This is of great significance for realizing the ground calibration of space ionospheric payloads and the ground simulation research of ionospheric physics. Description of the Drawings

[0014] Figure 1 Schematic diagram of the magnetic filter plasma source device for simulating the ionospheric environment of the present invention;

[0015] Figure 2 Schematic diagram of the internal magnetic field configuration of the magnetic filter source;

[0016] Figure 3 Yellow characteristic spectrogram emitted by oxygen discharge;

[0017] Figure 4 Graph of electron density varying with oxygen mass flow rate;

[0018] Figure 5 Graph of electron and ion energies varying with mass flow rate;

[0019] Figure 6 Distribution profile of electron density. Detailed Embodiments

[0020] The following describes the specific embodiments of the present invention with reference to the drawings.

[0021] The core content of this solution is to construct a plasma that can achieve low density, uniformity, and oxygen component. The technological innovation is to design a magnetic field configuration for controlling the plasma density and temperature. The magnetic filter plasma source device for simulating the ionospheric environment involved in the configuration designed by the present invention is as Figure 1As shown. The device includes a vacuum chamber 1, a filament support electrode 2, a magnetic field array 3, and a metal baffle 4 disposed in the vacuum chamber. The vacuum chamber 1 preferably has an inner diameter of 22 cm and a length of 23 cm, and the size of the vacuum chamber can be designed according to experimental requirements, which is not unique. The filament support electrode 2 is used to install a hot filament to achieve plasma discharge and generate initial plasma. The metal baffle 4 is disposed in the middle of the vacuum chamber near the vacuum chamber outlet. The magnetic field array 3 is a magnetic field array composed of permanent magnets to achieve a magnetic filter structure, and the metal baffle 4 is used to block high-energy electrons of the plasma from directly entering the experimental area. In order to use the magnetic filter structure in the present invention, preferably, the entire magnetic filter system is composed of 4 groups of magnets (the number is not unique and can be adjusted according to the parameters of the vacuum chamber 1), forming a magnetic field configuration as shown in Figure 2 As shown. The first group of magnetic field arrays is installed on the front-end face flange of the vacuum chamber to form a magnetic ring with a diameter of 6 cm. The second group of magnetic field arrays is installed at the axial center of the device and on the inner wall of the vacuum chamber. The third group is installed near the outlet position, and the radius of the magnetic ring is the same as that of the second group. The fourth group is installed on the metal baffle, and the size is the same as that of the baffle. Among them, the first to third groups of magnetic field arrays form a multipole magnetic field configuration to limit electrons from contacting the inner wall of the vacuum chamber, increase the collision probability between electrons and neutral components, and reduce the electron energy. A magnetic filter configuration is formed between the third and fourth groups of magnetic field arrays to block most of the plasma from diffusing out of the vacuum chamber, and only a very small number of plasmas can escape from the source area, thereby realizing the realization of low-density and low-energy plasmas. At the same time, oxygen is selected as the working substance during the experiment to make the composition also close to the real ionospheric environment, as shown in Figure 3 As shown.

[0022] Through verification, it is shown that the present invention can successfully simulate the experimental space ionospheric plasma environment on the ground.

[0023] 1) Distribution of plasma density

[0024] Figure 4 It is a graph showing the relationship between plasma density and the mass flow rate of the working substance. The discharge current is fixed at 0.2 A. Ionospheric plasmas can be simulated based on the magnetic filter source. Figure 4 It shows that the change in electron density with the mass flow rate of oxygen increases from 1.3×10 5 cm -3 to 4.9×10 6 cm -3 as the mass flow rate increases from 0.6 sccm to 4 sccm. The electron density in the actual ionosphere is between 10 4 cm -3 and 10 6 cm -3Within this range, the electron density range of the ionospheric plasma in the F region and E region can be simulated in the laboratory. In addition, the ion energy of the ionospheric plasma is usually in the range of a few tenths of an electron volt to a few electron volts. In the experiment, the ion and electron energies measured by the ion energy analyzer are as Figure 5 shown. As the mass flow rate increases, the ion energy decreases from 8 eV to 0.8 eV, and the electron energy shows a similar trend to that of the ions, decreasing from 4 eV to 1 eV. It is worth pointing out that at a large mass flow rate of 2 - 4 sccm, the electron energy is almost the same as that of the ions, which is a characteristic of the actual ionosphere.

[0025] 2) Distribution of plasma density

[0026] In addition, the plasma density is uniformly distributed radially. Figure 6 shows the radial distribution of the electron density at different mass flow rates. The plasma is uniformly distributed within a diameter of 20 cm (0 cm refers to the center, and 10 cm is the radius of the plasma column). For example, the black line represents the plasma density when the mass flow rate is maintained at 0.6 sccm. The plasma density is in the range of 1×10 5 cm -3 to 1.5×10 5 cm -3 . In summary, it can be concluded that the ionosphere-like plasma generated by the magnetic filter source is suitable for laboratory simulation research on ionospheric physics.

[0027] In summary, through the present invention, we can achieve the ground simulation of the space ionospheric plasma environment by using a magnetic filter structure. The relevant research scheme can be applied to the laboratory simulation of space plasma and the calibration of space exploration payloads.

Claims

1. A magnetic filter plasma source device for simulating the ionospheric environment, characterized in that: The device includes a vacuum chamber, and a filament support electrode, a magnetic field array and a metal baffle arranged in the vacuum chamber; The filament support electrode is used to mount a hot filament; The metal baffle is arranged at the middle position near the outlet of the vacuum chamber in the vacuum chamber; The magnetic field array includes multiple groups, one of which is installed on the metal baffle to form a magnetic filter configuration, and the remaining groups form a multipole magnetic field configuration; The remaining groups of the magnetic field array include 3 groups and are respectively configured as magnetic ring structures. Among them, the first group is installed on the front flange of the vacuum chamber; the second group is installed on the axial center plane of the device and on the inner wall of the vacuum chamber; the third group is installed near the outlet of the vacuum chamber, and its radius is the same as that of the second group.

2. The magnetic filter plasma source device for simulating the ionospheric environment according to claim 1, characterized in that: The metal baffle is a disc structure, and the magnetic field array installed on it forms a magnetic ring structure, and the outer diameter of the magnetic ring structure is the same as the outer diameter of the metal baffle.

3. The magnetic filter plasma source device for simulating the ionospheric environment according to claim 1, characterized in that: The magnetic field array is composed of permanent magnets.

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