Propeller magnet system with high reliability and low heat leakage

Abstract

The invention relates to the technical field of superconducting magnets, and discloses a high-reliability and low-heat-leakage propeller magnet system which comprises a Dewar, a coil assembly and a plurality of sets of heat insulation supporting structures, the coil assembly is arranged in the Dewar and connected with the Dewar through the heat insulation supporting structures, the coil assembly comprises a coil framework, and the coil framework is arranged in the Dewar and connected with the Dewar through the heat insulation supporting structures. The coil body is wound on the surface of the coil framework, the heat insulation supporting structure comprises a hot ring, a cold ring and a pull rod, the two ends of the pull rod are connected with the hot ring and the cold ring respectively, the hot ring is connected with the Dewar, and the cold ring is connected with the coil framework. Through the integrally designed heat insulation supporting structure, the number of parts of the magnet structure is remarkably reduced, the supporting stability is improved, it is guaranteed that the center line of a magnetic field coincides with the center line of plume of the propeller, and heat leakage of the magnet is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of superconducting magnets, and more particularly to a high-reliability, low-heat-leakage thruster magnet system. Background Art

[0002] In the field of space propulsion, electromagnetic propulsion is a new type of electric propulsion technology that uses electromagnetic force to act on charged particles to generate thrust. It has obvious advantages in specific impulse, thrust, and volume weight, and is internationally recognized as the mainstream development direction of space electric propulsion. Faced with the stringent requirements of space vehicles on volume and weight, electromagnetic propulsion technology that uses additional magnetic fields as the core component of propellant plume confinement and acceleration has become a research hotspot.

[0003] The magnet system for space electromagnetic propulsion generally includes coils, support structures and refrigeration systems. Since a large number of ion beams are ejected when the thruster is working and the temperature of the beam ions is relatively high, a refrigeration system needs to be set up to cool the coils down in a low-temperature environment. The coils are usually cooled by conduction from a refrigerator to a low temperature state and maintained stable. Currently, the coils are mostly connected to the dewar through axial and radial tie rods. To ensure the support strength, a large number of tie rods are required, which increases the risk of heat leakage to a certain extent. At the same time, in order to ensure the reliability of the magnetic field's constraint on the propellant plume, the coils need to be reliably fixed to ensure that they do not undergo excessive displacement or deformation in all directions. Furthermore, during the installation and positioning process, the coils should be strictly coaxial with the thruster so that the center line of the magnetic field coincides with the center line of the propellant plume. The current axial and radial tie rod support structure does not have a good effect of stable overlap under strong vibrations in space. Summary of the invention

[0004] The present invention discloses a high-reliability, low-heat-leakage thruster magnet system, which solves the technical problems in the above-mentioned background technology, and comprises: a dewar, a coil assembly and a plurality of groups of thermal insulation support structures, wherein the coil assembly is arranged inside the dewar, and the coil assembly is connected to the dewar through the thermal insulation support structure;

[0005] The coil assembly comprises a coil frame and a plurality of coil bodies, wherein the coil bodies are wound on the surface of the coil frame;

[0006] The thermal insulation support structure includes a hot ring, a cold ring and a pull rod, two ends of the pull rod are respectively connected to the hot ring and the cold ring, the hot ring is connected to the Dewar, and the cold ring is connected to the coil frame.

[0007] Preferably, the hot ring, cold ring and pull rod are manufactured in one piece.

[0008] Preferably, the thermal ring can be directly fixed to the Dewar by screws.

[0009] Preferably, the center points of the hot ring and the cold ring do not overlap, and the pull rod is arranged in an oblique manner.

[0010] Preferably, the internal space of the Dewar released by the pull rod is used for the arrangement of current leads, control wiring and the like.

[0011] Preferably, the overall thermal conductivity of the thermal insulation support structure does not exceed 1 W / m·°C, and the thermal ring is in close contact with the inner wall of the Dewar.

[0012] Preferably, the coil assembly is arranged concentrically with the Dewar with the central discharge channel of the Dewar as a positioning reference.

[0013] Preferably, both sides of the coil frame are provided with slots adapted to the cold ring.

[0014] Preferably, a cooling structure is provided between adjacent coil bodies, and a coil insulation layer is provided between the cooling structure and the coil body.

[0015] Preferably, the surface of the outer cylinder wall of the Dewar is provided with a plurality of flange structures for installing a refrigerator, and the refrigerator is connected to the cooling structure.

[0016] Preferably, the number of tie rods on each of the thermal insulation support structures is not less than 3.

[0017] Preferably, the Dewar is in the shape of a thin-walled cylinder as a whole.

[0018] The beneficial effects of the present invention are:

[0019] The present invention provides an insulating support structure and an integrated structure of a hot ring-pull rod-cold ring to replace the existing independent support pull rod structure, thereby significantly reducing the number of components of the magnet structure, simplifying the connection design between components, and improving the integrity and support stability. The integrated manufacturing of the insulating support structure ensures the processing accuracy, makes the coil assembly concentric with the dewar assembly, ensures that the center line of the magnetic field coincides with the center line of the thruster plume, and the annular design of the hot ring is conducive to local heat dispersion. In addition, the insulating support structure is made of a material with strong insulating properties, which effectively reduces heat leakage. Furthermore, compared with the independent support pull rod that must occupy the radial installation space inside the dewar, the oblique pull rod setting of the insulating support structure releases this part of the space, which is more conducive to the arrangement of the refrigerator cold head, current leads, control wiring, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0021] Figure 2 It is a cross-sectional view of the present invention for showing the internal structure of the Dewar;

[0022] Figure 3is a schematic diagram of the present invention for illustrating a coil assembly;

[0023] Figure 4 It is a schematic diagram of the present invention for demonstrating the thermal insulation support structure.

[0024] In the figure:

[0025] 1. Dewar; 11. Flange structure;

[0026] 2. Coil assembly; 21. Coil frame; 22. Coil body; 23. Coil insulation layer; 24. Cooling structure;

[0027] 3. Insulation support structure; 31. Cold ring; 32. Tie rod; 33. Hot ring. DETAILED DESCRIPTION

[0028] The subject matter described herein will now be discussed with reference to example implementations. It should be understood that the discussion of these implementations is only to enable those skilled in the art to better understand and implement the subject matter described herein, and the functions and arrangements of the elements discussed may be changed without departing from the scope of protection of the present specification. Various examples may omit, replace, or add various processes or components as needed. In addition, the features described in some examples may also be combined in other examples.

[0029] The present invention discloses a high reliability, low heat leakage thruster magnet system, such as Figure 1 and Figure 2 As shown, it includes a dewar 1, a coil assembly 2 and an insulating support structure 3, wherein a discharge channel is opened in the center of the dewar 1, the coil assembly 2 is installed inside the dewar 1 and surrounds the outer periphery of the discharge channel, the coil assembly 2 includes a coil skeleton 21, and a plurality of annular coil bodies 22, the coil bodies 22 are wound on the surface of the coil skeleton 21, the coil assembly 2 is connected to the dewar 1 through the insulating support structure 3, the interior of the dewar 1 is evacuated during operation to reduce heat leakage of the coil assembly 2, the coil body 22 is connected to an external power supply, specifically, the insulating support structure 3 is used to position and support the coil assembly 2, and the insulating support structure 3 includes a heat Ring 33 and cold ring 31, wherein the hot ring 33 has a larger diameter than the cold ring 31, the hot ring 33 is connected to the dewar 1, the hot ring 33 is arranged on the inner wall surface of the dewar 1, the cold ring 31 is connected to the coil assembly 2, and the cold ring 31 is arranged on the end face of the coil skeleton 21, the hot ring 33 is connected to the cold ring 31 through a plurality of groups of tie rods 32, and the two ends of the tie rods 32 are respectively fixed on the hot ring 33 and the end faces of the cold ring 31. Specifically, the hot ring 33 is arranged on the inner wall of the dewar 1, which is closer to the atmosphere / space environment on the outer surface of the dewar 1, but farther from the coil assembly 2, so it is the hot end, and the cold ring 31 is arranged on the end face of the coil skeleton 21 and needs to keep a low temperature, so it is the cold end.

[0030] like Figure 4 As shown, the insulating support structure 3 is designed and manufactured in an integrated manner, wherein the hot ring 33, the cold ring 31 and the pull rod 32 are all integrated to ensure the structural strength when supporting the coil assembly 2, and the hot ring 33 is adapted to the inner wall of the dewar 1, and the cold ring 31 is adapted to the coil skeleton 21. After fixation, the hot ring 33 is close to the inner wall of the dewar 1, and the cold ring 31 is close to the end face of the coil skeleton 21, and is not easy to deviate. The cold ring 31 is installed concentrically with the coil assembly 2, and the hot ring 33 is installed concentrically with the dewar 1, to ensure the concentricity between the dewar 1 and the coil assembly 2. Compared with the existing support of multiple groups of axial and radial pull rods, the insulating support structure 3 has the advantages of higher integrity and higher support strength, which is beneficial to enhancing the overall stability of the magnet system. The cold ring 31 and the hot ring 33 of the insulating support structure 3 can be directly fixed to the dewar 1 and the coil assembly 2 by screws, and the screws are sealed to avoid affecting the vacuum state inside the dewar 1.

[0031] Furthermore, the tie rod 32 of the insulating support structure 3 is integrated with the hot ring 33 and the cold ring 31, unlike independent radial and axial insulating support tie rods, each of which needs to be designed with connection structures at both ends, thereby reducing the connection design inside the dewar 1 and between the insulating support structure 3 and the dewar 1 and the coil assembly 2, thereby reducing costs. Correspondingly, due to the excessive number of design points for the existing radial and axial tie rod connections, the strong spatial vibration during the operation of the thruster poses a great challenge to the connection stability of the existing tie rods. When some of the tie rods are loose, it is easy to cause the coil assembly 2 to be misaligned with the center of the propellant plume, thereby reducing the operating stability of the thruster. The integrated design of the insulating support structure 3 effectively reduces the overall offset problem of the coil assembly 2 caused by looseness in some areas, thereby improving the overall reliability of the magnet system.

[0032] Furthermore, the center points of the hot ring 33 and the cold ring 31 do not coincide. Compared with the independent support rods that must occupy the radial installation space inside the dewar 1, the oblique rod setting of the insulating support structure 3 releases this part of the space, which is more conducive to the arrangement of the refrigerator cold head, current leads, control wiring, etc., and the occupied space is significantly reduced, which is beneficial to the internal layout of the dewar 1.

[0033] The heat-insulating support structure 3 is made of a material that is easy to process, has high structural strength, and has good heat insulation, such as glass fiber reinforced epoxy resin material. Generally, the thermal conductivity of the heat-insulating support structure 3 material should not exceed 1W / m·℃, thereby reducing external heat leakage. Specifically, the heat source that the coil assembly 2 needs to prevent from leaking heat is mainly the atmospheric heat and radiation heat outside the Dewar 1. In the prior art, since the Dewar 1 is evacuated inside, the heat conduction and radiation of air to heat is relatively subtle or negligible. Therefore, the external heat source of the Dewar 1 is mostly conducted to the coil assembly 2 through a number of radial and axial tie rods and a central discharge channel, thereby reducing the heat dissipation effect. The heat of several independent radial and axial tie rods in the prior art is concentrated, which will cause adverse effects. When the heat is concentrated, the dissipation effect is poor. If the heat is concentrated at the end of a single tie rod, it is difficult to radiate completely and heat leakage is likely to occur. Compared with the prior art, the hot end of the insulation support structure 3 is an annular heat ring 33, and the heat ring 33 is in close contact with the inner wall of the Dewar 1 to form an annular structure to facilitate the treatment of heat leakage caused by local heat concentration. The local heat can be dissipated annularly through the heat ring 33. Compared with the dispersion of contact points of the existing single-point support of the tie rod, the design of the annular support makes the heat flow path longer, thereby increasing the efficiency of heat insulation and reducing local heat leakage.

[0034] like Figure 3 As shown, the coil assembly 2 is generally annular, with the discharge channel of the inner cylinder of the dewar 1 as the positioning reference, and is arranged concentrically with the dewar 1 to improve the accuracy and stability of the thruster. The coil assembly 2 includes a coil skeleton 21, and a plurality of annular coil bodies 22, a coil insulation layer 23 and a cooling structure 24. The coil body 22 is a circular coil wound by a strip material. The strip material of the coil body 22 is generally a material with high electrical conductivity, such as copper. A cooling structure 24 is arranged between the plurality of coil bodies 22 to participate in the heat exchange and cooling of the coil body 22. If two groups of coil bodies 22 are wound on the surface of the coil assembly 2, the coil body 22 is formed by winding a plurality of coil bodies 22. For coil bodies 22 of 100 mm or larger, installing a cooling structure 24 between adjacent coil bodies 22 is beneficial to reducing the temperature difference between different areas of the coil assembly 2. Furthermore, a coil insulation layer 23 is installed between the coil body 22 and the cooling structure 24. The coil insulation layer 23 is made of high-insulation material. The coil body 22, the cooling structure 24, and the coil insulation layer 23 are stacked together and fixed to the coil skeleton 21, and the coil assembly 2 is formed by pressing the coil skeleton 21. It is worth noting that a coil insulation layer 23 should also be set between the coil skeleton 21 and the coil body 22.

[0035] The end surface of the coil skeleton 21 may be provided with a slot adapted to the cold ring 31 , so as to improve the stable connection state between the coil skeleton 21 and the cold ring 31 .

[0036] A plurality of flange structures 11 are arranged on the outer wall surface of the Dewar 1. In addition, a plurality of neck tubes are arranged on the outer wall surface. The flange structure 11 and the neck tube are used to install a refrigerator, current leads and temperature control components, etc. The refrigerator is used to be connected to the cooling structure 24 to dissipate heat and cool the coil body 22 through the conductive coolant, while the current leads, temperature control components, etc. enter the interior of the Dewar 1 or are connected to the coil assembly 2 inside the Dewar 1 through the flange structure 11 or the neck tube.

[0037] The tie rods 32 of the insulating support structure 3 are evenly spaced apart from each other. The number of tie rods 32 on each insulating support structure 3 is generally not less than 3. The actual number and cross-sectional dimensions need to be calculated through thermal-structural coupling analysis to ensure the structural strength margin and heat leakage margin of the tie rods 32.

[0038] The whole of Dewar 1 is in the shape of a thin-walled cylinder. The anode and cathode of the thruster are installed in the center of Dewar 1. The anode and cathode of the thruster are located on both sides of the discharge channel respectively. Considering the problems such as plume sputtering, the end face of Dewar 1 is kept flat, and no or as few interfaces as possible between the magnet and other components are set. The interfaces are mostly set on the outer cylinder wall of Dewar 1. The inner wall of Dewar 1 is a thin-walled structure, and its wall thickness should ensure the following conditions: convenient welding without large welding deformation; no large deformation when vacuuming in ground tests; able to withstand the stress brought by the insulation support structure 3.

[0039] The above describes an embodiment of the present invention, but this embodiment is not limited to the above-mentioned specific implementation mode. The above-mentioned specific implementation mode is merely illustrative and not restrictive. Under the guidance of this embodiment, ordinary technicians in this field can also make more forms of equivalent embodiments, all of which are protected by this embodiment.

Claims

1. A thruster magnet system, characterized in that: It comprises a dewar (1), a coil assembly (2) and a plurality of groups of heat-insulating support structures (3), wherein the coil assembly (2) is arranged inside the dewar (1), and the coil assembly (2) is connected to the dewar (1) via the heat-insulating support structure (3); The coil assembly (2) comprises a coil frame (21) and a plurality of coil bodies (22), wherein the coil bodies (22) are wound on the surface of the coil frame (21); The thermal insulation support structure (3) comprises a hot ring (31), a cold ring (33) and a pull rod (32), wherein two ends of the pull rod (32) are respectively connected to the hot ring (31) and the cold ring (33), the hot ring (31) is connected to the Dewar (1), and the cold ring (33) is connected to the coil frame (21).

2. A thruster magnet system according to claim 1, characterized in that: The hot ring (31), the cold ring (33) and the pull rod (32) are manufactured in an integrated manner.

3. A thruster magnet system according to claim 1, characterized in that: The center points of the hot ring (31) and the cold ring (33) do not coincide, and the pull rod (32) is arranged in an oblique manner.

4. A thruster magnet system according to claim 1, characterized in that: The overall thermal conductivity of the heat-insulating support structure (3) does not exceed 1 W / m·°C, and the thermal ring (31) is in close contact with the inner wall of the Dewar (1).

5. A thruster magnet system according to claim 1, characterized in that: The coil assembly (2) is arranged concentrically with the dewar (1) using the central discharge channel of the dewar (1) as a positioning reference.

6. A thruster magnet system according to claim 1, characterized in that: Both sides of the coil frame (21) are provided with slots adapted to the cooling ring (33).

7. A thruster magnet system according to claim 1, characterized in that: A cooling structure (24) is provided between adjacent coil bodies (22), and a coil insulation layer (23) is provided between the cooling structure (24) and the coil body (22).

8. A thruster magnet system according to claim 7, characterized in that: The outer wall surface of the Dewar (1) is provided with a plurality of flange structures (11) for installing a refrigerator, and the refrigerator is connected to a cooling structure (24).

9. A thruster magnet system according to claim 1, characterized in that: The number of the pull rods (32) on each of the thermal insulation support structures (3) is not less than 3.

10. A thruster magnet system according to claim 1, characterized in that: The Dewar (1) is in the shape of a thin-walled cylinder as a whole.

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