Hall Effect Thruster with Movable Wall for Variable Cross-Section
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Solution Overview
Problem
Hall effect thrusters are typically optimized for either high specific impulse or high thrust modes, making them inefficient for rapid maneuvers and increasing spacecraft complexity due to the need for additional chemical thrusters.
Innovation Solution
A Hall effect thruster design with a movable inner or outer wall, actuated by a piezoelectric or ultrasonic motor, allows for adjustable plasma density by varying the cross-section of the annular channel, enabling operation in both high thrust and high specific impulse modes without compromising plasma stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Hall effect thruster is optimized for high specific impulse mode, then specific impulse is improved, but thrust is reduced
Solution Approach 1:
The annular channel cross-section is made variable through movable walls (inner or outer wall) that can be actuated by piezoelectric or ultrasonic motors. This dynamic adjustment allows the thruster to change its operating characteristics in real-time, transitioning between high specific impulse mode (narrower cross-section) and high thrust mode (wider cross-section) as needed, resolving the contradiction between these two performance parameters.
Solution Approach 2:
The invention changes the geometric parameter of the annular channel cross-section by moving the inner or outer wall axially. This parameter change directly affects plasma density and flow characteristics, enabling the thruster to operate in different modes (high specific impulse or high thrust) by adjusting the cross-sectional area, thereby resolving the performance contradiction.
2Force
If Hall effect thruster is optimized for high thrust mode, then thrust is improved, but specific impulse is reduced
Solution Approach 1:
The movable wall mechanism enables dynamic reconfiguration of the annular channel cross-section. For high thrust operations, the wall is positioned to create a wider cross-section, maximizing plasma flow and thrust. For high specific impulse operations, the wall is repositioned to create a narrower cross-section, increasing exhaust velocity. This dynamic adaptability resolves the contradiction between thrust and specific impulse.
Solution Approach 2:
By axially displacing the inner or outer wall, the invention changes the cross-sectional area parameter of the annular channel. This parameter change allows optimization for different operating modes: larger cross-section for high thrust, smaller cross-section for high specific impulse, thereby resolving the performance trade-off.
3Force
If Hall effect thruster operates in high thrust mode with high flow rate, then thrust is improved, but plasma density stability is compromised
Solution Approach 1:
The control unit monitors plasma density and actuator position, using feedback control to maintain optimal operating conditions. When operating in high thrust mode with high flow rates, the system adjusts the movable wall position and propellant flow rate to maintain stable plasma density, preventing the instability that would otherwise occur at high flow rates.
Solution Approach 2:
The invention dynamically adjusts multiple parameters including the annular channel cross-section (by moving the inner or outer wall) and propellant flow rate. This coordinated parameter change allows the system to maintain stable plasma density even at high flow rates by optimizing the balance between mass flow and plasma generation, thereby resolving the stability contradiction.
4Use of energy by moving object
If Hall effect thruster operates in high specific impulse mode with high voltage, then specific impulse is improved, but thrust is reduced
Solution Approach 1:
The movable wall actuator enables dynamic adjustment of the annular channel cross-section to complement the electrical voltage adjustment. When operating in high specific impulse mode with high voltage, the system narrows the cross-section to maintain plasma density and optimize exhaust velocity, while the actuator ensures the geometric configuration supports the high voltage operation, thereby resolving the thrust reduction contradiction.
Solution Approach 2:
The invention coordinates changes in electrical voltage with geometric parameter changes (movable wall position). By simultaneously adjusting both electrical and geometric parameters, the system achieves high specific impulse through optimized plasma density and exhaust velocity, while the geometric adjustment ensures compatibility with the high voltage operation, resolving the thrust-performance contradiction.
5Ease of manufacture
If Hall effect thruster uses fixed annular channel, then manufacturing is simplified, but operational flexibility is reduced
Solution Approach 1:
The invention introduces movable inner or outer walls that can be actuated by piezoelectric or ultrasonic motors, transforming the fixed annular channel into a dynamic structure. This adds operational flexibility, allowing the thruster to adapt to different operating modes (high thrust, high specific impulse) by changing the cross-sectional area, while maintaining relatively simple manufacturing by using standard actuator mechanisms.
Solution Approach 2:
The movable wall mechanism enables the single annular channel structure to serve multiple functions: optimizing for high thrust, optimizing for high specific impulse, and maintaining plasma stability across different operating conditions. This multi-functionality is achieved through a relatively simple add-on actuator system, resolving the contradiction between manufacturing simplicity and operational flexibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables adaptable operation between high thrust and high specific impulse modes by maintaining constant plasma density, reducing spacecraft complexity and increasing operational flexibility.
Implementation Method 1
The magnetic circuit is capable of generating a magnetic field at the downstream end of the annular channel. Electrons emitted from the cathode and attracted to the anode at the bottom of the annular channel are trapped by the magnetic field in spiral paths between the two walls, thus forming a virtual cathode grid
Implementation Method 2
The positive ions of the plasma are accelerated by the electric field prevailing between the anode and the virtual cathode grid formed by the cloud of electrons trapped by the magnetic field at the open end of the annular channel
Implementation Method 3
A Hall effect thruster design with a movable inner or outer wall, actuated by a piezoelectric or ultrasonic motor, allows for adjustable plasma density by varying the cross-section of the annular channel
Data Source
Figure 1A~1B
Figure 2A~2B
AI summary
The invention relates to the field of Hall effect thrusters, and in particular to a thruster (1), the downstream end of the annular channel (2) of which has a variable cross-section so as to be capable of varying the thrust and specific impulse.