CN105736273B - A kind of magnetic structure of larger ratio of height to diameter hall thruster - Google Patents

Abstract

A magnetic circuit structure of a Hall thruster with a large aspect ratio, which belongs to the field of aerospace electric propulsion technology and plasma technology. There is the problem that the design of the magnetic circuit structure is not ideal. The invention comprises an upper magnetic pole plate, a lower magnetically conductive bottom plate, an inner iron core, an outer magnetically conductive cover and a magnetic shield; an upper magnetic pole plate with a ring structure is arranged on the upper edge of the outer magnetically conductive cover; the upper surface center of the lower magnetically conductive bottom plate is provided with a The inner iron core of cylindrical structure; the magnetic screen includes the outer magnetic screen, the inner magnetic screen and the magnetic screen base; the outer magnetic screen is a cylindrical structure, the magnetic screen base is a circular flat plate structure, and the inner magnetic screen is downward-opening Horn-shaped structure, there is a gap between the small mouth end of the inner magnetic screen and the side wall of the inner iron core, the large mouth end of the inner magnetic screen is fixed on the inner ring end of the magnetic screen base, and the outer ring end of the magnetic screen base is fixed on the outer guide On the inner side wall of the magnetic cover; the lower edge of the outer magnetic screen is fixed on the ring surface of the magnetic screen base.

Description

Magnetic Circuit Structure of a Hall Thruster with Large Aspect Ratio

technical field

The invention belongs to the fields of aerospace electric propulsion technology and plasma technology.

Background technique

The Hall thruster is an electric thruster that uses orthogonal electromagnetic fields to ionize and accelerate atomic working fluids, and converts electrical energy into ion kinetic energy. It has the advantages of simple structure, high specific impulse, high efficiency, and high reliability. It is suitable for various aerospace applications At present, it is one of the most mature electric propulsion devices in the world.

The design of the magnetic field in the channel of the Hall thruster is an indispensable part of the thruster research, and it is the key to maintaining the thruster's continuous and stable discharge and controlling the divergence of the ion beam. The magnetic field formed by the ideal magnetic circuit structure should be able to ensure the normal discharge operation of the Hall thruster, and the magnetic field gradient along the center line of the channel is large, the position of the maximum magnetic field strength is reasonable, and it has a focusing effect on the ions, so as to reduce the impact of ions on the ceramic wall. sputter corrosion.

The Hall thruster is developing towards the direction of high power and high thrust, so that the spacecraft can obtain a large speed increment in a short time and shorten the mission time. The acceleration mechanism of the Hall thruster determines that its thrust density is constant, so the main means to increase the thrust and power is to increase the flow area. At present, the main measure to increase the flow area is to increase the radial dimension on the basis of maintaining a certain channel height-to-diameter ratio, the ratio of the channel width to the channel diameter. However, this will not only cause the weight of the thruster to increase too much, which is not conducive to the overall quality and cost control of the spacecraft, but will also make it difficult to install the thruster on the spacecraft. In order to avoid the above problems, it is an important direction for the development of high-power and high-thrust Hall thrusters to adopt a design with a large aspect ratio to increase the flow area under the premise of keeping the radial dimension basically unchanged. Compared with thrusters of the same radial size, thrusters with large aspect ratio face two new challenges in magnetic field design: one is that the internal magnetic circuit space is inevitably compressed, making it difficult to ensure efficient excitation structure design, The second is that the magnetic gap between the inner and outer magnetic poles increases, and the magnetic field strength in the channel is difficult to guarantee.

In summary, in the development process of Hall thrusters toward high power and high thrust, the thruster with a large aspect ratio channel configuration has the advantages of large thrust-to-weight ratio and small size; however, the excitation performance under the condition of large aspect ratio and efficiency challenges. A reasonable magnetic circuit structure design is required to satisfy the magnetic field formed by the ideal magnetic circuit structure.

Contents of the invention

The purpose of the present invention is to solve the problem of difficult magnetic field design caused by adopting a channel design with a large aspect ratio in order to increase the area of the discharge channel under the premise that the Hall thruster maintains the radial profile size without increasing, and provides a large The magnetic circuit structure of the high-diameter ratio Hall thruster.

The magnetic circuit structure of a Hall thruster with a large aspect ratio according to the present invention comprises an upper magnetic pole plate, an outer magnetically conductive cover, a lower magnetically conductive bottom plate, an inner iron core and a magnetic shield;

The lower magnetic bottom plate and the outer magnetic cover together form a barrel-shaped structure with an upward opening;

A ring-shaped upper magnetic pole plate is arranged on the upper edge of the outer magnetic permeable cover, and the upper magnetic pole plate is opposite to the lower magnetic permeable bottom plate up and down;

An inner iron core with a cylindrical structure is arranged at the center of the upper surface of the lower magnetically permeable bottom plate;

The magnetic screen includes an outer magnetic screen, an inner magnetic screen and a magnetic screen base; the outer magnetic screen is a cylindrical structure, the magnetic screen base is a circular flat plate structure, the inner magnetic screen is a horn-shaped structure with a downward opening, and the inner magnetic screen There is a gap between the small mouth end of the horn and the side wall of the inner iron core. The big mouth end of the horn of the inner magnetic screen is fixed on the inner ring end of the magnetic screen base, and the outer ring end of the magnetic screen base is fixed on the inner side wall of the outer magnetic shield; The lower edge of the magnetic screen is fixed on the annulus surface of the magnetic screen base;

The gap between the base of the magnetic shield and the lower magnetic bottom plate is used to install the excitation coil; the gap between the outer magnetic shield and the upper part of the outer magnetic shield is used to install the excitation coil.

The inner magnetic screen is designed to be inclined, the outer diameter of the discharge channel remains unchanged, the inner wall of the channel is inclined inward, and the inner iron core is retracted inward. After the structure is optimized, the magnetic field configuration obtained by the magnetic circuit is shown in the figure. The magnetic field strength in the channel will change due to the change of the distance between the inner and outer magnetic screens. It can be adjusted by adjusting the structural size of the outer magnetic screen and the outer magnetic screen, The number of turns of the coil and the excitation current are used to optimize the magnetic field to obtain a suitable magnetic field gradient and a suitable position of the maximum magnetic field intensity.

Advantages of the present invention:

1 The magnetic circuit structure of the Hall thruster of the present invention, by tilting the inner magnetic shield and optimizing the magnetic circuit structure, the aspect ratio of the discharge channel is increased, and the area of the discharge channel is increased to increase the thrust, but not too much Increase the radial structural size of the thruster;

2. The magnetic force lines inside the channel bend into the channel, and the centerline of the magnetic field is basically the same as the centerline of the channel, pointing to the central axis of the thruster. Such a magnetic field can move the ion beam after ionization and acceleration of the working fluid toward the central axis of the thruster, reducing the Sputter erosion of the outer wall surface of the channel exit section by ions.

Description of drawings

Fig. 1 is a structural schematic diagram of the magnetic circuit structure of the Hall thruster with a large aspect ratio according to the present invention;

Fig. 2 is the configuration diagram of the magnetic field in the discharge channel of the high-height-diameter ratio Hall thruster in the present invention, and the straight line in the channel is the channel center line;

Fig. 3 is a distribution diagram of the magnetic field intensity of the central line of the discharge channel of the Hall thruster with a large aspect ratio in the present invention.

Detailed ways

Specific Embodiment 1: The present embodiment will be described below in conjunction with FIGS. 1 to 3. The magnetic circuit structure of a Hall thruster with a large aspect ratio described in this embodiment includes an upper magnetic pole plate 1, an outer magnetic cover 2, The lower magnetic bottom plate 3, the inner iron core 4 and the magnetic screen 5;

The lower magnetic bottom plate 3 and the outer magnetic cover 2 together form a barrel-shaped structure opening upward;

The upper edge of the outer magnetic cover 2 is provided with an upper magnetic pole plate 1 of a ring structure, and the upper magnetic pole plate 1 is opposite to the lower magnetic base plate 3 up and down;

An inner core 4 with a cylindrical structure is provided at the center of the upper surface of the lower magnetically permeable bottom plate 3;

The magnetic screen 5 includes an outer magnetic screen 51, an inner magnetic screen 52 and a magnetic screen base 53; the outer magnetic screen 51 is a cylindrical structure, the magnetic screen base 53 is a circular flat plate structure, and the inner magnetic screen 52 is a horn with a downward opening type structure, there is a gap between the small end of the horn of the inner magnetic screen 52 and the side wall of the inner iron core 4, the large mouth end of the horn of the inner magnetic screen 52 is fixed on the inner ring end of the magnetic screen base 53, and the outer ring of the magnetic screen base 53 The end is fixed on the inner side wall of the outer magnetic shield 2; the lower edge of the outer magnetic shield 51 is fixed on the annulus surface of the magnetic shield base 53;

The gap between the magnetic shield base 53 and the lower magnetic bottom plate 3 is used for installing the exciting coil; the gap between the outer magnetic shield 51 and the upper part of the outer magnetic shield 2 is used for installing the exciting coil.

The inner magnetic screen 52 is designed to be inclined, the outer diameter of the discharge channel remains unchanged, the inner wall of the channel is inclined inwardly, and the inner iron core 4 is retracted inwardly. After the optimization of the structure, the magnetic field configuration obtained by the magnetic circuit is shown in Figure 2. The magnetic field strength in the channel will change due to the distance between the inner and outer magnetic screens. The structure size, the number of turns of the coil and the excitation current are used to optimize the magnetic field to obtain a suitable magnetic field gradient and a suitable position of the maximum magnetic field intensity.

When designing the magnetic field configuration as shown in Figure 2, the present invention has mainly carried out following design:

1 The design of the magnetic circuit structure of the Hall thruster with a large aspect ratio in the present invention is mainly through shrinking the inner iron core 4 and inclining the inner magnetic shield 52 inwardly so that the magnetic force lines of the magnetic field are bent into the channel, and the magnetic force lines The centerline of the channel points to the central axis of the thruster along the channel centerline. In this way, the design of the discharge channel can be conveniently designed as a structure in which the inner wall is inclined and retracted to obtain a large aspect ratio, and the discharge channel flow of the Hall thruster can be increased without increasing the radial size of the thruster. area;

2. Since the inner wall of the discharge channel in the present invention is inclined towards the central axis of the thruster and the axial length is shortened, the center line of the magnetic force line and the center line of the channel obtained by the magnetic circuit design point to the central axis of the thruster. During the working process of the thruster, The ion beam will converge towards the central axis, which will reduce the sputter corrosion of the ion on the wall;

3. For the reduction of the magnetic field strength in the discharge channel caused by the increase of the distance between the inner and outer magnetic screens due to the inward bending of the inner magnetic screen 52, the number of turns of the excitation coil and the magnitude of the excitation current will be changed, and the upper magnetic pole plate and the lower magnetic pole plate will be adjusted. The thickness of the magnetic bottom plate and the length of the inner and outer magnetic shields are used to optimize the magnetic field to obtain a suitable magnetic field strength to increase the ionization efficiency. The obtained magnetic field strength changes are shown in Figure 3, and the maximum value of the magnetic field strength exceeds 280Gauss; and, through appropriate The design and optimization of the obtained magnetic field strength can reach a greater value;

4. At the exit of the channel, by trimming the inner circle of the upper magnetic pole plate, the bending degree of the magnetic field lines close to the outer wall surface at the exit of the channel is increased to surround the outlet section of the outer wall of the ceramic.

In summary, the above are only examples of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Embodiment 2: This embodiment further describes Embodiment 1. The height of the inner iron core 4 is lower than the height of the outer magnetically permeable cover 2 .

Specific embodiment three: This embodiment will further explain the first embodiment. The outer magnetic cover 2 includes an upper outer magnetic cover 21 and a lower outer magnetic cover 22. Between the upper outer magnetic cover 21 and the lower outer magnetic cover 22 Clamp the outer ring end of the magnetic shield base 53 .

Embodiment 4: In this embodiment, Embodiment 1 is further described. The materials of upper magnetic pole plate 1 , outer magnetically conductive cover 2 , lower magnetically conductive bottom plate 3 , inner iron core 4 and magnetic shield 5 are all DT4C.

Embodiment 5: In this embodiment, Embodiment 1 is further described. The top end of the inner iron core 4 is an arc surface structure. In this embodiment, the top end of the inner iron core 4 is rounded to make the structure smoother and the configuration of the magnetic lines of force more optimized.

The top of the inner iron core 4 can also be processed in other shapes according to actual needs.

Claims (5)

1. A magnetic circuit structure of a Hall thruster with a large aspect ratio, which includes an upper magnetic pole plate (1), an outer magnetic cover (2), a lower magnetic base plate (3), an inner iron core (4) and a magnetic screen(5); The lower magnetically permeable bottom plate (3) and the outer magnetically permeable cover (2) together form an upwardly open barrel-shaped structure; The upper edge of the outer magnetic cover (2) is provided with a ring-shaped upper magnetic pole plate (1), and the upper magnetic pole plate (1) is opposite to the lower magnetic base plate (3) up and down; An inner iron core (4) with a cylindrical structure is arranged at the center of the upper surface of the lower magnetically permeable bottom plate (3); The magnetic screen (5) comprises an outer magnetic screen (51), an inner magnetic screen (52) and a magnetic screen base (53); It is characterized in that the outer magnetic screen (51) is a cylindrical structure, the magnetic screen base (53) is a circular flat plate structure, the inner magnetic screen (52) is a horn-shaped structure with a downward opening, and the inner magnetic screen (52) There is a gap between the small mouth end of the horn and the side wall of the inner iron core (4), and the big mouth end of the horn of the inner magnetic screen (52) is fixed on the inner ring end of the magnetic screen base (53), and the outer ring end of the magnetic screen base (53) The ring end is fixed on the inner side wall of the outer magnetic shield (2); the lower edge of the outer magnetic shield (51) is fixed on the annulus surface of the magnetic shield base (53); The gap between the magnetic shield base (53) and the lower magnetic base plate (3) is used to install the exciting coil; the gap between the outer magnetic shield (51) and the upper part of the outer magnetic shield (2) is used to install the exciting coil. 2. The magnetic circuit structure of a Hall thruster with a large aspect ratio according to claim 1, characterized in that the height of the inner iron core (4) is lower than the height of the outer magnetic shield (2). 3. The magnetic circuit structure of a Hall thruster with a large aspect ratio according to claim 1, wherein the outer magnetically permeable cover (2) comprises an upper outer magnetically permeable cover (21) and a lower outer magnetically permeable cover ( 22), the outer ring end of the magnetic shield base (53) is clamped between the upper outer magnetic shield (21) and the lower outer magnetic shield (22). 4. The magnetic circuit structure of a Hall thruster with a large aspect ratio according to claim 1, characterized in that the upper magnetic pole plate (1), the outer magnetic cover (2), the lower magnetic bottom plate (3), The materials of the inner iron core (4) and the magnetic shield (5) are both DT4C. 5. The magnetic circuit structure of a Hall thruster with a large aspect ratio according to claim 1, characterized in that the top end of the inner iron core (4) is an arc surface structure.