Thermal isolation structure of metal working medium hall thruster
By employing low thermal conductivity materials and a vacuum gap thermal isolation structure in the Hall thruster, the thermal management problem of the metallic working fluid Hall thruster was solved, achieving efficient thermal isolation and magnetic field stability, thus improving the performance and reliability of the thruster.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-04-20
- Publication Date
- 2026-06-05
AI Technical Summary
When using metallic working fluids, existing Hall thrusters have difficulty effectively isolating high-temperature and low-temperature components in terms of thermal management, leading to a decline in the performance and reliability of the magnetic circuit system.
By employing low thermal conductivity materials and mechanically optimized supports, combined with vacuum gaps and radiation shielding components, a thermal isolation structure is constructed between the high-temperature assembly and the low-temperature assembly, ensuring structural rigidity and efficient thermal isolation.
It achieves effective thermal isolation between the high-temperature and low-temperature zones, stabilizes the magnetic field strength, improves thruster performance and service life, and reduces the power consumption of heating components.
Smart Images
Figure CN122148519A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of Hall thrusters. Background Technology
[0002] A Hall effect thruster (HET) is an electric thruster that uses orthogonal electromagnetic fields to ionize and accelerate atomic working fluid, converting electrical energy into ion kinetic energy to achieve a high specific impulse. It features simple structure, high specific impulse, high efficiency, long service life, high power density, and long on-orbit service time. It is suitable for various spacecraft missions including attitude control, orbit correction, orbit transfer, dynamic compensation, position holding, repositioning, deorbiting, space exploration, and interplanetary travel. It is currently the most widely used and mature electric propulsion system internationally.
[0003] The Hall thruster works by using a ring-shaped plasma discharge channel composed of two ceramic sleeves with different radii to confine plasma motion. The combined action of inner and outer excitation coils (or inner and outer permanent magnet rings), magnetic poles, and a magnetic screen generates a magnetic field within the discharge channel. Electrons emitted from the cathode enter the discharge channel and undergo Hall drift motion under the influence of the orthogonal electromagnetic field. Propellant injected from the bottom of the discharge channel collides with the electrons to produce ions. These ions are ionized and accelerated within the discharge channel, generating thrust. Traditional gaseous working fluids such as xenon suffer from high cost, low storage density, and the need for additional pressure reduction and stabilization devices. Solid-state Hall thrusters, with their low ionization energy and low cost, hold promise as a replacement for gaseous working fluids like xenon.
[0004] However, unlike gaseous working fluids, metallic working fluids are solid at room temperature and must be heated to hundreds or even thousands of degrees Celsius by heating components to evaporate or sublimate into a gaseous state before being fed into the discharge channel through the gas distributor. This process introduces severe thermal management challenges: the heating components, gas distributor, gas path, and discharge channel heated by plasma constitute a high-temperature region. Heat from this region is transferred to other parts of the thruster through structural connectors, gases, and thermal radiation, especially the temperature-sensitive magnetic circuit system. The performance of the magnetic circuit system is closely related to its operating temperature. Once the temperature exceeds its Curie temperature or design limit, the magnetic field strength will decrease significantly or even permanently demagnetize, directly leading to reduced thruster ionization efficiency, performance degradation, or even complete failure. On the other hand, temperature dissipation also increases the power consumption of the heating components.
[0005] Existing designs often rely on simple connections made of high-temperature resistant materials, but their thermal insulation effect is limited. This makes it difficult to achieve efficient thermal isolation while maintaining structural rigidity, thus restricting the performance and long-term reliability of metal-based Hall thrusters. Therefore, a specially designed, highly efficient thermal insulation structure is urgently needed to address these issues. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a thermal isolation structure for Hall thrusters with metallic working fluids. This structure can establish an effective thermal barrier between high-temperature components (heaters, gas paths, channels, etc.) and low-temperature components (magnetic circuits) while maintaining the necessary structural rigidity.
[0007] To achieve this objective, the present invention employs the following technical solution:
[0008] A thermal isolation structure suitable for a Hall thruster with a metallic working fluid includes: a high-temperature assembly, a low-temperature assembly, and a thermal isolation structure disposed between the two.
[0009] High-temperature assembly: The high-temperature assembly includes a heating component for evaporating the metal working fluid, a gas distributor for conveying the metal working fluid vapor, and a discharge channel for ionizing and accelerating the working fluid.
[0010] Cryogenic assembly: The cryogenic assembly includes a magnetic circuit system for generating a radial magnetic field, and optionally includes a radiative heat shield;
[0011] Thermal isolation structure: disposed between the high-temperature assembly and the low-temperature assembly, for providing structural support and thermal isolation between the two;
[0012] The thermal isolation structure includes: at least one mechanical support connecting the high-temperature assembly and the low-temperature assembly, the mechanical support being made of a low thermal conductivity material and having a minimized heat conduction path cross-section; and multiple insulators for the high-temperature assembly.
[0013] The beneficial effects of the metal working fluid Hall thruster thermal isolation structure described in this invention are as follows:
[0014] 1. High-efficiency thermal isolation: By synergistically blocking the two main heat transfer paths of conduction and radiation, high-efficiency thermal isolation between the high-temperature zone and the low-temperature zone is achieved. This can control the operating temperature of the magnetic circuit system within a safe range far below its failure temperature and reduce the power of the heating components.
[0015] 2. Improved thruster performance and efficiency: A stable magnetic field is essential for the efficient operation of a Hall thruster. This structure ensures that the magnetic field strength is unaffected by high temperatures, thereby guaranteeing the thruster's ionization efficiency, thrust performance, and operational stability.
[0016] 3. Extended service life: Effective thermal management reduces the risk of magnet demagnetization and reduces structural thermal stress, thereby significantly extending the on-orbit service life and reliability of the thruster. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the thermal isolation structure described in this invention;
[0018] In the diagram: 1-Ceramic disc substrate; 2-Ceramic insulator; 3-Low temperature assembly; 4-High temperature assembly.
[0019] Figure 2 This is a schematic diagram of the ceramic disc substrate described in this invention (high-temperature assembly side);
[0020] Figure 3 This is a schematic diagram of the ceramic disc substrate described in this invention (low-temperature assembly side); Detailed Implementation
[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0022] like Figure 1 As shown, this embodiment discloses a thermal isolation structure for a Hall thruster suitable for metallic working fluids. The core of the thruster mainly consists of a high-temperature assembly and a low-temperature assembly.
[0023] The high-temperature assembly mainly consists of a centrally located heating and discharge component, a tightly coupled gas distributor, and an annular ceramic discharge channel. The metallic working fluid is heated to approximately 600°C by the heating component and evaporates into a gaseous state, then uniformly injected into the discharge channel through multiple small holes in the gas distributor. During operation, the inner wall of the discharge channel is bombarded by plasma, maintaining a high temperature.
[0024] The cryogenic assembly mainly refers to the magnetic circuit system and corresponding mechanical structure surrounding the discharge channel. The magnetic circuit system consists of permanent magnets, magnetic poles, and coils, and its function is to generate a strong radial magnetic field in the exit region of the discharge channel. To ensure the stability of the magnetic field strength, the temperature of the coils and magnetic poles needs to be controlled, for example, below 300°C. Optionally, a heat radiation shielding component can be installed in the cryogenic assembly to further reduce heat radiation.
[0025] The thermal isolation structure is the core component for achieving thermal isolation between the high-temperature assembly and the low-temperature assembly. In this embodiment, the thermal isolation structure specifically includes:
[0026] 1. Ceramic disc substrate: To fix the high-temperature assembly and the low-temperature assembly, a heat-insulating ceramic 1 is provided. The heat-insulating ceramic 1 is made of zirconia ceramic (an insulating ceramic with low thermal conductivity and easy processing) and is designed as a disc with multiple holes.
[0027] 2. Thermal Insulators: To secure the high-temperature discharge channel and gas distributor and maintain precise coaxiality with the magnetic poles, three ceramic insulators 2 are evenly distributed 120° circumferentially. Each insulator 2 is made of boron nitride ceramic (an insulating ceramic with low thermal conductivity and easy processing) and is designed as a cylindrical shape with through holes.
[0028] 3. Vacuum gaps: Multiple vacuum gaps are installed between the high-temperature assembly and the low-temperature assembly to minimize heat conduction between them.
[0029] The specific connection relationship is as follows:
[0030] 1. Magnetic circuit clamping ceramic: The low temperature assembly 3 "clamps" the ceramic disk substrate 1 on its outer edge, serving as the main structural support platform and the first-level thermal barrier.
[0031] 2. Channel Placement: The high-temperature assembly 4 is placed directly or mounted on the low thermal conductivity ceramic substrate, utilizing the low thermal conductivity of the ceramic to block the conduction of heat from the channel to the downward magnetic circuit.
[0032] 3. Distributor Suspended Isolation: The gas distributor is located at the bottom or inside of the discharge channel. The gas distributor has extended fixing posts (such as threaded posts). These fixing posts are screwed onto or through the ceramic disc substrate 1 and are ultimately fixed to the cylindrical ceramic insulator 2.
[0033] The gas distributor body, gas pipeline, and mounting posts do not have direct physical contact with the magnetic circuit components (magnets, yokes, etc.). All mechanical support forces are transmitted through a low thermal conductivity ceramic substrate and cylindrical ceramic insulators. This design results in an extremely small cross-section of the solid-state heat conduction path from the high-temperature assembly to the low-temperature assembly, while the path length is relatively long, thus creating a large thermal resistance.
[0034] With the above structure, heat transfer from the high-temperature assembly (approximately 600-800℃) to the low-temperature assembly (target <300℃) is effectively suppressed:
[0035] • Conductive heat: Solid conductive heat is minimized by using materials with low thermal conductivity and mechanical supports with optimized geometry.
[0036] • Radiant heat: By setting up radiant heat shields and insulation components, radiant heat transfer is greatly reduced.
[0037] • Gas thermal conduction: Since the thruster operates in a vacuum environment, there are almost no gas molecules in the gap, so gas convection and thermal conduction can be ignored.
Claims
1. A thermal isolation structure for a Hall thruster suitable for metallic working fluids, characterized in that, include: • High-temperature assembly, which includes a heating component for evaporating a metal working fluid, a gas distributor for conveying the metal working fluid vapor, and a discharge channel for ionizing and accelerating the working fluid. • Cryogenic assembly, the cryogenic assembly including a magnetic circuit system for generating a radial magnetic field; A thermal insulation structure is disposed between the high-temperature assembly and the low-temperature assembly to provide structural support and thermal insulation between the two. The thermal isolation structure includes: at least one mechanical support connecting the high-temperature assembly and the low-temperature assembly, the mechanical support being made of a low thermal conductivity material and having a minimized heat conduction path cross-section; Multiple insulators used in high-temperature assemblies.
2. The thermal insulation structure according to claim 1, characterized in that, The low thermal conductivity ceramic substrate is located above the inner magnetic circuit base plate, but only contacts the inner magnetic circuit on the outer ring, serving as the main thermal barrier layer between the discharge channel and the magnetic circuit.
3. The thermal insulation structure according to claim 1, characterized in that, The gas distributor is suspended or supported on the side of the low thermal conductivity ceramic substrate away from the discharge channel by the fixed column, and the cylindrical ceramic insulator provides insulation and heat insulation at the end of the fixed column.
4. The thermal insulation structure according to claim 1, characterized in that, The magnetic circuit assembly includes an inner magnetic circuit and an outer magnetic circuit. The low thermal conductivity ceramic substrate is sandwiched between the mechanical structures of the inner and outer magnetic circuits, serving to support the discharge channel and isolate the magnetic circuit from heat conduction.
5. The thermal insulation structure according to claim 1, characterized in that, The heating component is wrapped or covered around the outer wall of the gas distributor and the discharge channel. The heat generated by the heating component is confined to the discharge area by the low thermal conductivity ceramic substrate and the cylindrical ceramic insulator, blocking the transfer to the magnetic circuit component.
6. The thermal insulation structure according to claim 1, characterized in that, The materials of the low thermal conductivity ceramic substrate and the cylindrical ceramic insulator are selected from one or more of boron nitride (BN), alumina, and zirconium oxide.
7. The low thermal conductivity ceramic substrate according to claim 6, characterized in that, The low thermal conductivity ceramic substrate has a recessed area for positioning on the high-temperature assembly side.
8. The low thermal conductivity ceramic substrate according to claim 6, characterized in that, The low thermal conductivity ceramic substrate contains multiple holes for wiring and multiple holes for avoiding the fixing posts.
9. The low thermal conductivity ceramic substrate according to claim 6, characterized in that, The low thermal conductivity ceramic substrate has a recessed area on the low temperature assembly side for the insulator of claim 3.