阅读说明：本技术 一种负氢离子源系统 (Negative hydrogen ion source system ) 是由 高飞 王英杰 王友年 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种负氢离子源系统。该系统包括：等离子体产生装置和负氢离子引出装置；等离子体产生装置的等离子体出射口处设置负氢离子引出装置；负氢离子引出装置包括外壳、过滤磁场产生装置和扩散区；外壳内设置扩散区；外壳包括金属侧壁和金属顶面；金属顶面为静磁屏蔽面；金属顶面开设有等离子体通道；等离子体产生装置产生的等离子体从等离子体通道进入扩散区的顶部,并从扩散区的底部引出负氢离子；过滤磁场产生装置设置在金属侧壁的外部且位于扩散区的底部。本发明能够在冷却扩散区的电子的同时,避免等离子体产生装置内放电源区等离子体密度的降低。(The invention discloses a negative hydrogen ion source system. The system comprises: a plasma generating device and a negative hydrogen ion leading-out device; a negative hydrogen ion leading-out device is arranged at a plasma exit of the plasma generating device; the negative hydrogen ion leading-out device comprises a shell, a filtering magnetic field generating device and a diffusion area; a diffusion area is arranged in the shell; the housing comprises a metal side wall and a metal top surface; the top metal surface is a magnetostatic shielding surface; the top surface of the metal is provided with a plasma channel; the plasma generated by the plasma generating device enters the top of the diffusion area from the plasma channel and negative hydrogen ions are led out from the bottom of the diffusion area; the filtering magnetic field generating device is arranged outside the metal side wall and at the bottom of the diffusion region. The invention can cool the electrons in the diffusion region and simultaneously avoid the reduction of the plasma density in the power supply region in the plasma generating device.)

1. A negative hydrogen ion source system, comprising: a plasma generating device and a negative hydrogen ion leading-out device; the negative hydrogen ion extraction device is arranged at a plasma exit of the plasma generation device;

the negative hydrogen ion leading-out device comprises a shell, a filtering magnetic field generating device and a diffusion area;

the diffusion region is arranged in the shell; the housing comprises a metal side wall and a metal top surface; the metal top surface is a magnetostatic shielding surface; the metal top surface is provided with a plasma channel; the plasma generated by the plasma generating device enters the top of the diffusion area from the plasma channel and negative hydrogen ions are led out from the bottom of the diffusion area; the filtering magnetic field generating device is arranged outside the metal side wall and at the bottom of the diffusion region.

2. A magnetostatic shielding system for a negative hydrogen ion source system as claimed in claim 1, wherein the material of said metallic top surface is a magnetic material having a relative magnetic permeability of not less than 4000.

3. A magnetostatic shielding system for a negative hydrogen ion source system as claimed in claim 1 wherein said metallic top surface comprises a first top surface and a second top surface overlying said first top surface; the material of the first top surface is stainless steel; the material of the second top surface is a magnetic material with the relative magnetic permeability not less than 4000.

4. A magnetostatic shielding system for a negative hydrogen ion source system as claimed in claim 2 wherein the material of the metallic top surface is pure iron.

5. A static magnetic shielding system for a negative hydrogen ion source system according to claim 3, wherein the material of said second top surface is pure iron.

6. A magnetostatic shield system for a negative hydrogen ion source system as claimed in claim 1, wherein said plasma generating means comprises: the device comprises a power discharge area, a quartz barrel, a radio frequency coil, a metal sealing element and a Faraday shield;

the power discharge area is arranged in the quartz barrel; the quartz barrel is of a structure with openings at two ends; the quartz barrel is arranged at the plasma channel; the bottom opening of the quartz barrel is matched with the opening of the plasma channel; the metal sealing element is arranged at the opening at the top of the quartz barrel; the radio frequency coil is wound outside the quartz barrel; the quartz barrel, the radio frequency coil and the metal seal are all positioned in the Faraday shield; the Faraday shield is disposed at a juncture of the metal sidewall and the metal top surface.

7. A magnetostatic shielding system for a negative hydrogen ion source system as claimed in claim 1, wherein said negative hydrogen ion extraction means further comprises: leading out an electrode; the extraction electrode is positioned at the bottom of the diffusion region.

8. A magnetostatic shielding system for a negative hydrogen ion source system as claimed in claim 1, wherein said filtering magnetic field generating means is a magnetostatic iron.

9. A static magnetic shielding system for a negative hydrogen ion source system according to claim 6, characterized in that the metal sealing member is provided with hydrogen gas inlet holes.

10. A magnetostatic shielding system for a negative hydrogen ion source system as claimed in claim 1, wherein the material of the metal sidewall is stainless steel.

Technical Field

The invention relates to the field of negative hydrogen ion sources, in particular to a negative hydrogen ion source system.

Background

The energy problem is increasingly paid attention, and magnetic confinement nuclear fusion is considered to be one of the best solutions for solving the energy crisis of human beings in the future. To achieve this goal early, International Thermonuclear Experimental Reactor (ITER) is being built internationally, and china is planning to build Chinese nuclear Fusion Engineering Test Reactor (CFETR). The basic targets of future large fusion devices are to achieve fusion ignition conditions and realize steady-state operation so as to develop experimental research on combustion plasma physics and engineering technology. A neutral beam injection system with high energy (ion energy is in the MeV magnitude) and quasi-steady state (injection time 3600s) is one of the necessary conditions for realizing high-parameter and high-confinement mode operation of a large fusion device. The study of domestic and foreign scholars finds that the development of a high-energy long-pulse neutral beam injection system based on the cylindrical coil radio frequency negative hydrogen ion source technology is a necessary choice for meeting the heating requirement of the plasma of the magnetic confinement nuclear fusion core.

However, the technology of the neutral beam implantation system based on the cylindrical coil radio frequency negative hydrogen ion source is very complicated, and no precedent for successful development exists in the world. Two key issues need to be addressed to achieve this goal: (1) generating high-density plasma in a discharge source region, particularly high-density electrons, high-vibration excited-state hydrogen molecules, hydrogen positive ions and hydrogen atoms; (2) either there is a high density of low energy electrons (less than 2eV) at the bottom of the diffusion region (above the extraction gate) or the wall surface is able to escape large amounts of low energy electrons. In order to solve the two problems, a transverse filtering magnetic field is generally applied to the bottom of the diffusion region of the negative hydrogen ion source of the cylindrical coil, and is used for restraining low-energy electrons and reducing the electron temperature in the region. However, it has been found that the filtering magnetic field not only lowers the electron temperature but also lowers the plasma density in the discharge region. The high-power negative hydrogen ion source ensures that the high plasma density is enough to generate enough negative hydrogen ions for extraction. Therefore, the current negative hydrogen ion source system has the problem that the plasma density is reduced while the magnetic field is filtered to cool electrons.

Disclosure of Invention

Accordingly, embodiments of the present invention provide a negative hydrogen ion source system, which can cool electrons in the diffusion region and simultaneously avoid a decrease in plasma density in the discharge region.

In order to achieve the purpose, the invention provides the following scheme:

a negative hydrogen ion source system comprising: a plasma generating device and a negative hydrogen ion leading-out device; the negative hydrogen ion extraction device is arranged at a plasma exit of the plasma generation device;

the negative hydrogen ion leading-out device comprises a shell, a filtering magnetic field generating device and a diffusion area;

the diffusion region is arranged in the shell; the housing comprises a metal side wall and a metal top surface; the metal top surface is a magnetostatic shielding surface; the metal top surface is provided with a plasma channel; the plasma generated by the plasma generating device enters the top of the diffusion area from the plasma channel and negative hydrogen ions are led out from the bottom of the diffusion area; the filtering magnetic field generating device is arranged outside the metal side wall and at the bottom of the diffusion region.

Optionally, the material of the metal top surface is a magnetic material with a relative permeability not less than 4000.

Optionally, the metal top surface comprises a first top surface and a second top surface covering the first top surface; the material of the first top surface is stainless steel; the material of the second top surface is a magnetic material with the relative magnetic permeability not less than 4000.

Optionally, the material of the metal top surface is pure iron.

Optionally, the material of the second top surface is pure iron.

Optionally, the plasma generation device includes: the device comprises a power discharge area, a quartz barrel, a radio frequency coil, a metal sealing element and a Faraday shield;

the discharge power area, namely a plasma generation area, is arranged in the quartz barrel; the quartz barrel is of a structure with openings at two ends; the quartz barrel is arranged at the plasma channel; the bottom opening of the quartz barrel is matched with the opening of the plasma channel; the metal sealing element is arranged at the opening at the top of the quartz barrel; the radio frequency coil is wound outside the quartz barrel; the quartz barrel, the radio frequency coil and the metal seal are all positioned in the Faraday shield; the Faraday shield is disposed at a juncture of the metal sidewall and the metal top surface.

Optionally, the negative hydrogen ion extraction device further includes: leading out an electrode; the extraction electrode is positioned at the bottom of the diffusion region.

Optionally, the filtering magnetic field generating device is a static magnet.

Optionally, the metal sealing element is provided with a hydrogen access hole.

Optionally, the metal side wall is made of stainless steel.

Compared with the prior art, the invention has the beneficial effects that:

the embodiment of the invention provides a negative hydrogen ion source system, wherein a negative hydrogen ion leading-out device is arranged at a plasma exit of a plasma generating device in the system; the negative hydrogen ion leading-out device comprises a shell, a filtering magnetic field generating device and a diffusion area; a diffusion area is arranged in the shell; the metal top surface of the shell is a magnetostatic shielding surface; the top surface of the metal is provided with a plasma channel; the plasma enters the top of the diffusion area from the plasma channel, and negative hydrogen ions are led out from the bottom of the diffusion area; the filtering magnetic field generating device is arranged outside the metal side wall and at the bottom of the diffusion region. According to the invention, the filtering magnetic field generating device is arranged at the bottom of the diffusion region, so that low-energy electrons are restrained, and the electron temperature of the diffusion region is reduced; the static magnetic shielding surface provided with the plasma channel is arranged at the interface between the plasma exit port (the bottom of the discharge power area) and the top of the diffusion area, so that magnetic lines of force are gathered in the static magnetic shielding surface, the penetration of a magnetic field in the discharge power area of the plasma generating device is effectively reduced, and the plasma density of the discharge power area is increased.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is a block diagram of a negative hydrogen ion source system according to an embodiment of the present invention;

FIG. 2 is a graph comparing electron density and electron temperature in plasma before and after magnetic shielding provided by embodiments of the present invention; fig. 2 (a) is an axial distribution comparison graph of electron density in plasma before and after magnetic shielding, and fig. 2 (b) is an axial distribution comparison graph of electron temperature before and after magnetic shielding.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

The electron temperature of the extraction region in the negative hydrogen ion source system is high, and the stripping loss of the high-energy electrons to the negative hydrogen ions is serious, so that the negative ions are not generated. A filtering magnetic field is required to be added for cooling the electron temperature at the downstream of the diffusion region, so that the stripping loss of electrons to negative hydrogen ions is reduced, and the lower electron temperature is more favorable for generating negative ions. However, due to the existence of the filtering magnetic field, the filtering magnetic field permeates into the discharge source region while realizing the lower electron temperature at the downstream of the diffusion region, so that the generation of plasma is influenced, the electron density is reduced, the generation of negative hydrogen ions is not facilitated, and a high-power negative hydrogen ion source is required to ensure higher plasma density, so that enough negative hydrogen ions are generated for leading out.

Therefore, the present embodiment proposes a conceptual design of a magnetostatic shield to suppress penetration of a filtering magnetic field into a discharge source region, achieve high density plasma, and achieve a low electron temperature downstream of a diffusion region.

Fig. 1 is a structural diagram of a negative hydrogen ion source system according to an embodiment of the present invention. Referring to fig. 1, the negative hydrogen ion source system of the present embodiment includes: a plasma generating device and a negative hydrogen ion leading-out device; the negative hydrogen ion extraction device is arranged at the plasma exit of the plasma generating device.

The negative hydrogen ion extraction device comprises a shell, a filtering magnetic field generating device 9 and a diffusion area 8.

A diffusion region 8 is arranged in the shell; the housing comprises a metal side wall 7 and a metal top surface 6; the metal top surface 6 is a magnetostatic shielding surface; the metal top surface 6 is provided with a plasma channel; plasma generated by the plasma generating device enters the top of the diffusion region 8 from the plasma channel, and negative hydrogen ions are led out from the bottom of the diffusion region 8; the filtering magnetic field generating device 9 is arranged outside the metal side wall 7 and at the bottom of the diffusion region 8, the filtering magnetic field generating device 9 is used for generating a transverse filtering magnetic field at the bottom of the diffusion region 8, the purpose of applying the filtering magnetic field in the negative hydrogen ion source is to cool the electron temperature of the diffusion region 8 and the extraction region, the stripping loss of electrons to negative hydrogen ions is reduced, and the lower electron temperature is more beneficial to generating the negative hydrogen ions.

As an alternative embodiment, the material of the metal top surface is a high magnetic permeability material, and the high magnetic permeability material is a magnetic material with a relative magnetic permeability not less than 4000. For example, the metal top surface may be pure iron with a relative permeability of 4000. The magnetic material with the relative permeability not less than 4000 is adopted as the metal top surface, so that the effect of static magnetic shielding can be realized.

As an alternative embodiment, the metal top surface may include a first top surface and a second top surface covering the first top surface; the material of the first top surface is stainless steel; the material of the second top surface is a magnetic material with the relative magnetic permeability not less than 4000. For example, the second top surface may be pure iron having a relative magnetic permeability of 4000. Because the stainless steel material is adopted purely, the magnetic flux leakage phenomenon exists, half of the top surface of the metal is made of normal metal shell material (stainless steel), and half of the top surface of the metal is made of pure iron with the relative magnetic permeability of 4000, and the pure iron covers the stainless steel, so that the effect of magnetostatic shielding can be still achieved.

As an alternative embodiment, the plasma generating apparatus includes: the device comprises a discharge power area 4, a quartz barrel 5, a radio frequency coil 3, a metal sealing element 2 and a Faraday shield 1.

A power supply area 4 is arranged in the quartz barrel 5; the quartz barrel 5 is a structure with two open ends; the quartz barrel 5 is arranged at the plasma channel; the bottom opening of the quartz barrel 5 is matched with the opening of the plasma channel; a metal sealing element 2 is arranged at the opening at the top of the quartz barrel 5; the radio frequency coil 3 is wound outside the quartz barrel 5; the quartz barrel 5, the radio frequency coil 3 and the metal sealing piece 2 are all positioned in the Faraday shield cover 1; the faraday shield 1 is disposed at the intersection of the metal sidewall 7 and the metal top surface 6.

As an optional embodiment, the negative hydrogen ion extraction device further includes: an extraction electrode 10; the extraction electrode 10 is located at the bottom of the diffusion region 8. The outer envelope, the quartz vessel 5, the metal seal 2 and the extraction electrode 10 form a sealed structure in which the diffusion region 8 and the discharge source region 4 are located.

As an alternative embodiment, the filtering magnetic field generating means 9 is a static magnet. As shown in fig. 1, the static magnet includes an N pole and an S pole.

As an alternative embodiment, the metal sealing member 2 is provided with a hydrogen gas inlet hole. The hydrogen access hole is used for introducing hydrogen of 0.1Pa-10Pa into the discharge source region 4.

In an alternative embodiment, the material of the metal side wall 7 is stainless steel.

The working principle of the negative hydrogen ion source system of the embodiment is as follows:

hydrogen or deuterium is introduced into the discharge source region 4, working pressure is set, and after radio frequency power is applied to the radio frequency coil 3, plasma is generated in the discharge source region 4, enters the diffusion region 8 from a plasma channel, negative hydrogen ions are generated in the discharge source region 4 and the diffusion region 8, extraction voltage is applied to the extraction electrode 10, and therefore the negative hydrogen ions are extracted from the bottom of the diffusion region 8. In this embodiment, in order to reduce the adverse effect of the filtering magnetic field generated by the static magnet on the plasma, increase the electron density, without affecting the cooling effect of the electron temperature in the vicinity of the extraction electrode 10, a static magnetic shielding surface provided with a plasma channel is arranged at the interface between the bottom of the discharge source region 4 and the top of the diffusion region 8, so that magnetic lines of force are gathered in the static magnetic shielding surface, the penetration of a magnetic field in the discharge source region 4 is effectively reduced, the density of plasma in the chamber is obviously increased, the lower electron temperature is kept near the lead-out region, for example, a material with high magnetic permeability, such as pure iron, is used as the wall material of the interface of the source region diffusion region 8, the relative magnetic permeability is 4000, magnetic lines of force are gathered in the metal side wall 7 of the pure iron material, the plasma density in the internal power supply region 4 of the plasma generating device is prevented from being lowered while cooling the electrons in the diffusion region 8.

The validity of the present embodiment is verified below.

FIG. 2 is a graph comparing electron density and electron temperature in plasma before and after magnetic shielding provided by embodiments of the present invention; fig. 2 (a) is an axial distribution comparison graph of electron density in plasma before and after magnetic shielding, and fig. 2 (b) is an axial distribution comparison graph of electron temperature before and after magnetic shielding. Referring to fig. 2, the 0 point of the axial position of the part (a) and the part (b) of fig. 2 are both located at the bottom surface of the metal sealing member 2 in fig. 1, where the condition I represents that the metal top surface 6 in the negative hydrogen ion source is a metal surface of a common metal material (such as stainless steel), and the condition II represents that the metal top surface 6 is a magnetostatic shielding surface of a magnetic shielding material, it can be seen intuitively that after the magnetostatic shielding surface is applied, the plasma density rises obviously inside the chamber, and the change of the electron temperature is small, and the low electron temperature is still maintained in the diffusion region 8.

The above experiment shows that by replacing the metal top surface 6 on the top of the diffusion region 8 with a magnetic shielding material (e.g., pure iron, with a relative permeability of 4000) from a common metal material (e.g., stainless steel), the penetration of the magnetic field in the source region is significantly reduced, which helps to increase the plasma density, while the diffusion region 8 maintains a higher magnetic field, ensuring that the electron temperature can be cooled in the diffusion region 8 and the extraction region.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.