Multi-source driving radio frequency ion source for improving plasma distribution uniformity

Abstract

The invention discloses a multi-source driving radio frequency ion source for improving plasma distribution uniformity, and belongs to the technical field of plasma generation devices. Comprising an ion diffusion cavity and a plurality of ion sources communicated with the ion diffusion cavity, cylindrical coils are wound around the peripheries of the ion sources, and planar coils are arranged between the adjacent ion sources and located on the outer top wall of the diffusion cavity. The device has the beneficial effects that the design of the auxiliary planar coil is added, active modulation of plasma uniformity is carried out by adjusting the driving current passing through the planar coil, and the distribution uniformity of plasmas in the diffusion cavity is optimized.

Description

Technical Field

[0001] The invention relates to a multi-source driven radio frequency ion source capable of improving plasma distribution uniformity, and belongs to the technical field of plasma generating devices. Background Art

[0002] As an important option for clean energy, nuclear fusion energy faces one of the core challenges of achieving efficient and stable plasma confinement and heating. Neutral beam injection (NBI) is a key auxiliary heating technology in magnetic confinement nuclear fusion, and the radio frequency ion source is the core component of the NBI system. Radio frequency source plasma is generated by a vortex electric field. In a single-driven ion source with a large chamber axis-to-diameter ratio, the plasma density is mainly distributed at the axis of the cylindrical cavity. Therefore, for the parallel discharge of dual-driven sources, electrons mainly diffuse downward from the generation area of ​​the cylindrical coil. Therefore, the electron density near the middle diffusion area of ​​the driven source is relatively low, and the lateral distribution uniformity of the induced plasma density is low at this time.

[0003] Patent CN119833382A uses a multi-electrode drive circuit design to adjust plasma characteristics through a combination of multiple electrodes. However, this method primarily improves uniformity by changing electromagnetic field parameters rather than the physical structure, making it less effective in addressing the problem of insufficient density in the central region of cavities with large axis-to-diameter ratios. Summary of the Invention

[0004] In order to address the defects of the existing technology, the purpose of the present invention is to provide a multi-source driven radio frequency ion source that improves the uniformity of plasma distribution, introduces independently controlled planar drive coils for auxiliary discharge, actively modulates the plasma uniformity, and improves the uniformity of plasma density distribution.

[0005] The technical solution of the present invention is: a multi-source driven radio frequency ion source for improving the uniformity of plasma distribution, including an ion diffusion chamber and several ion sources connected thereto, a cylindrical coil wrapped around the periphery of the ion source, and a planar coil is provided between adjacent ion sources, and the planar coil is located on the outer top wall of the diffusion chamber.

[0006] There are two ion sources.

[0007] The ion source has a height of 200 mm and a diameter of 300 mm, and the distance between the two ion source axes is 600 mm.

[0008] The diffusion chamber is 920 mm long, 400 mm wide and 200 mm high.

[0009] The planar coil is equidistant from the ion sources on both sides.

[0010] The beneficial effects of the present invention are: adding an auxiliary planar coil design, actively modulating the plasma uniformity by adjusting the driving current passing through the planar coil, and optimizing the uniformity of plasma distribution in the diffusion cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A stereoscopic view of the present invention;

[0012] Figure 2 It is the front view of the present invention;

[0013] Figure 3 A top view of the present invention;

[0014] Figure 4 is the electron density cross-section distribution under different input current conditions;

[0015] Figure 5 The electron density distribution along the cross section under different driving current conditions.

[0016] The reference numerals in the figure are as follows: 1. ion source, 2. diffusion chamber, 3. cylindrical coil, 4. planar coil. DETAILED DESCRIPTION

[0017] The following is combined with Figure 1-5 The present invention will be further described:

[0018] Example 1

[0019] A multi-source driven radio frequency ion source for improving plasma distribution uniformity can be divided into a power supply area and a diffusion area. The ion source 1 in the power supply area can be regarded as a cylindrical coil inductively coupled plasma radio frequency source structure. Each radio frequency source is individually controlled by the coupling coil current. This embodiment takes the collaborative drive of two ion sources as an example. Each ion source 1 is 200 mm high and 300 mm in diameter. A cylindrical coil 3 with 6 turns is wound around the periphery. The two ion sources 1 are spaced 600 mm apart from each other. A planar coil 4 is provided between the ion sources 1. The planar coil 4 is located on the outer top wall of a diffusion chamber 2. Two groups are provided, each with 3 turns. The two groups of planar coils 4 are located in the middle of the two ion sources 1. The diffusion chamber 2 is 920 mm long, 400 mm wide, and 200 mm high.

[0020] Example 2

[0021] Figure 4 (a)- Figure 4(c) shows the electron density cross-sectional distribution when the planar coil 4 is unpowered, powered at 20A, and 25A, respectively, when the ion source input current is 5A. The color distribution in the figure clearly shows that the electron density distribution is extremely uneven when the planar coil 4 is unpowered. When the planar coil is powered at 20A, the electron distribution is well-uniform. However, excessively increasing the drive current of the planar coil 4 can cause the plasma density in the central region to exceed that below the ion source, disrupting its uniformity. Therefore, by appropriately driving the planar coil 4 with an appropriate current, plasma density uniformity can be significantly improved.

[0022] Table 1 Comparison of electron density uniformity under different input currents

[0023]

[0024] Table 1 shows the comparison of electron density uniformity under different input currents. In the input current, the left side of "+" is the input current of the planar coil, and the right side is the ion source input current of 5A. As can be seen from the above table, when the planar coil 4 is not energized, that is, under the original driving structure, the electron uniformity is very poor. Adding an auxiliary planar coil can significantly improve the uniformity of the extraction area. The optimal current size is matched through testing.

[0025] Figure 5 The electron density distribution along the cross-section for different drive currents is shown in the figure. The distribution line plot provides a more intuitive view of the changing trend of plasma density uniformity: while the cylindrical coil drive current remains constant, as the planar coil drive current increases, plasma density uniformity initially improves significantly but then decreases. The plasma density uniformity is best when the planar coil current is 20A.

[0026] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-source driven radio frequency ion source for improving plasma distribution uniformity, characterized in that: The invention comprises an ion diffusion chamber (2) and a plurality of ion sources (1) connected thereto. A cylindrical coil (3) is wound around the periphery of the ion source (1). A planar coil (4) is provided between adjacent ion sources (1). The planar coil (4) is located on the outer top wall of the diffusion chamber (2).

2. The multi-source driven radio frequency ion source for improving plasma distribution uniformity according to claim 1, characterized in that: The number of the ion sources (1) is two.

3. The multi-source driven radio frequency ion source for improving plasma distribution uniformity according to claim 2, characterized in that: The ion source (1) has a height of 200 mm and a diameter of 300 mm, and the axial center distance between the two ion sources (1) is 600 mm.

4. The multi-source driven radio frequency ion source for improving plasma distribution uniformity according to claim 2, characterized in that: The diffusion chamber (2) is 920 mm long, 400 mm wide and 200 mm high.

5. The multi-source driven radio frequency ion source for improving plasma distribution uniformity according to claim 1, characterized in that: The planar coil (4) is equidistant from the ion sources (1) on both sides.

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