Gridded-Ion Thruster Perveance Testing for Grid Erosion Control
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Solution Overview
Problem
Existing methods for testing gridded ion thrusters aboard spacecraft are insufficient for accurately characterizing wear and aging due to the lack of representative environmental conditions on Earth, particularly affecting the acceleration grid's erosion and lifespan.
Innovation Solution
A perveance test method that adjusts electrical power supply to predetermined thrust operating points, varying positive electrical voltage while monitoring the acceleration grid current to identify minimal erosion states, allowing for in-space thruster management and optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Earth-based tests are conducted to characterize thruster wear and aging, then testing can be performed, but the measurement accuracy is insufficient due to non-representative environmental conditions
Solution Approach 1:
The patent performs in-space tests that replicate the actual operational environment of the thruster during spacecraft missions. By conducting measurements in the real space environment rather than attempting to copy it on Earth, the patent achieves accurate characterization of wear and aging phenomena under genuine operational conditions.
2Force
If the acceleration grid is operated at higher voltages to increase thrust, then thrust force is improved, but erosion of the acceleration grid increases
Solution Approach 1:
The patent systematically varies electrical parameters (voltages applied to grids, power supply levels) during in-space tests to identify optimal operating points. By changing these parameters and monitoring erosion effects, the patent determines the voltage and power settings that maximize thrust while minimizing acceleration grid erosion, enabling extended operational lifespan.
Solution Approach 2:
The patent implements monitoring of acceleration grid current and other parameters during operation to provide feedback on erosion state. This feedback information allows for adjustment of operating parameters to maintain optimal balance between thrust production and grid preservation throughout the thruster's mission.
3Measurement precision
If in-space testing is conducted to accurately characterize wear and aging, then measurement accuracy is improved, but disruption of thrust production may occur
Solution Approach 1:
The patent performs characterization tests during specific periods of the spacecraft mission when thrust requirements allow for temporary adjustments. By scheduling measurements during appropriate mission phases and using periodic testing approaches, the patent obtains accurate wear and aging data while minimizing impact on overall thrust production and mission objectives.
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 accurate, in-space thruster characterization and optimization, reducing erosion and extending lifespan by identifying optimal operating points without disrupting thrust production, providing superior accuracy over Earth-based tests.
Implementation Method 1
a power supply unit, commonly referred to as a PPU for 'Power Processing Unit', is also on board the spacecraft and arranged to, during thruster operation, simultaneously provide at least one positive electrical voltage to the screen grid and one negative electrical voltage to the acceleration grid
Implementation Method 2
positive ions produced in the plasma chamber pass through the screen grid and then the acceleration grid
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
A method of testing a gridded-ion thruster (2) is performed on board a spacecraft (100) while the spacecraft is in thrust in extraterrestrial space. The test method is a perveance-type test which makes it possible to update a thrust operating point of the thruster and to monitor an ageing of said thruster, in particular an aging by erosion of an acceleration grid (25) disposed at the plasma chamber outlet (20).