Spacecraft Propulsion Electron Control for Voltage Spike Mitigation
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Solution Overview
Problem
Rapid switching of electron sources in spacecraft thrusters leads to rapid charging of the spacecraft, causing potential differences that can damage sensitive electronic components, particularly antennas and other components mounted at remote locations.
Innovation Solution
Control the electron source to ramp up and down gradually from an OFF state to an ON state, and vice versa, using a control signal to constrain the rate of electron emission, and optionally use an auxiliary electron source to maintain a positive potential on the spacecraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the electron source is switched on rapidly, then the thruster can start producing thrust quickly, but the spacecraft experiences rapid charging that can damage sensitive electronic components
Solution Approach 1:
The electron source is activated in a preliminary phase before the ion source is fully activated. This preliminary electron emission builds up a protective electron cloud around the spacecraft, which prevents rapid charging when the full thruster power is engaged, thereby avoiding voltage spikes to sensitive components while still enabling relatively quick thrust startup.
Solution Approach 2:
A protective electron cloud is created beforehand by activating the electron source prior to full ion source operation. This electron cloud acts as a cushion that absorbs and redistributes charge, preventing harmful voltage spikes from reaching sensitive electronic components when the thruster reaches full power.
2Object-affected harmful factors
If the electron source is ramped up gradually, then voltage spikes to components are reduced, but the thruster startup time increases
Solution Approach 1:
The electron source is activated in advance at a controlled rate before the ion source reaches full power. This preliminary activation gradually builds the protective electron cloud, reducing voltage spikes to components while minimizing the time penalty by overlapping the electron source ramp-up with the ion source activation sequence.
Solution Approach 2:
The electron source is operated in periodic or staged increments rather than continuous ramping. This allows the system to build up the protective electron cloud in controlled stages, reducing voltage spikes while maintaining a relatively efficient startup timeline by activating different electron source stages in coordination with ion source power levels.
3Reliability
If electrons are injected into the plasma before ion stream creation, then the spacecraft potential is maintained positive, but the complexity of the control system increases
Solution Approach 1:
The electron source control is merged with the existing ion source control system. The same control unit that manages ion source activation and power levels also manages the electron source activation sequence, eliminating the need for a separate control system and reducing overall system complexity while maintaining reliable spacecraft potential control.
Solution Approach 2:
The control system is designed to perform multiple functions: it controls both the ion source and electron source activation sequences, manages thrust level adjustments, and monitors spacecraft potential. This multi-functional approach reduces the need for dedicated separate control systems, thereby reducing complexity while maintaining reliable potential stability.
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
Reduces the risk of damage to spacecraft components by mitigating voltage spikes and maintaining a stable potential, thereby extending the operational lifespan and reliability of the spacecraft.
Implementation Method 1
an electron source for emitting electrons
Implementation Method 2
a neutral gas is ionised by extracting electrons from it to create a stream of positive ions
Implementation Method 3
The extracted electrons are then injected into the ion stream so that the gas becomes neutral again
Data Source
AI summary
A method of operating a spacecraft propulsion system comprises injecting electrons into the plasma surrounding the spacecraft prior to creating the stream of ions, and after commencing creation of the ion stream, continuing the injection of electrons in an amount sufficient to maintain the spacecraft at a positive potential. This method may be implemented in a single thruster. In spacecraft with multiple thrusters the same method may be implemented in each thruster.Where the propulsion system comprises a plurality of thrusters, the method may comprise: operating at least one of the thrusters as a drive thruster, and operating at least one of the thrusters as an auxiliary or “reserve” thruster. The electron source of the at least one auxiliary thruster may be operated before creation of the ion stream to inject the electrons into the plasma surrounding the spacecraft.