Ion Thruster Control Method for Miniaturized Satellites
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Solution Overview
Problem
Existing propulsion technologies for miniaturized satellites, such as chemical thrusters, are not easily adaptable due to limitations in exhaust velocity and the large, heavy fuel tanks and power supply systems required, making them incompatible with small spacecraft.
Innovation Solution
A method for controlling an ion thruster that allows independent control of the speed of ejected ions and thrust, using a conductive liquid on the emission electrode and adjusting the emission current and speed through applied potentials, enabling efficient and prolonged operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If chemical thrusters are used for propulsion, then thrust can be generated, but exhaust velocity is limited by the inherent specific energy released by combustion
Solution Approach 1:
The patent replaces chemical combustion propulsion with electric propulsion using an ion thruster. Instead of relying on chemical energy release, the system uses an electric field to accelerate ions, achieving higher exhaust velocities without being constrained by combustion-specific-energy limits. The emission electrode generates ions through field emission, and an extraction electrode accelerates these ions to high speeds using electric fields alone.
2Weight of moving object
If chemical thrusters are used, then propulsion can be provided, but fuel tanks and power supply systems are large and heavy
Solution Approach 1:
The patent extracts and eliminates the heavy fuel tank and large power supply system components associated with chemical thrusters. The ion thruster uses a compact emission electrode with porous tips that can be directly filled with ionic liquid propellant, removing the need for large external fuel tanks. The electric field generation requires significantly less power than chemical combustion systems, reducing the overall power supply system mass.
Solution Approach 2:
The patent changes the fundamental operating parameters from chemical combustion to electric field-based ion acceleration. This parameter change enables the use of ionic liquid propellants with higher specific impulse and eliminates the need for bulky fuel storage systems. The electric field can be generated more efficiently with lower power consumption compared to chemical systems.
3Productivity
If ion thrusters are used with ionic liquid propellant, then thrust can be generated with higher efficiency, but the ionic liquid is depleted and counterions build up over time
Solution Approach 1:
The patent implements periodic reversal of the electric field polarity to alternately emit positive and negative ions. By switching the polarity of the emission and extraction electrodes, the system prevents depletion of a single ionic species and avoids counterion buildup. This periodic action allows the thruster to operate continuously by cycling through different ion emission modes, effectively extending the operational duration.
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
The method allows for precise control of ion thruster performance, enabling efficient propulsion for miniaturized satellites by independently adjusting emission current and speed, thus extending the thruster's operational life and reducing the weight and volume of the conductive liquid required.
Implementation Method 1
A potential difference of the order of 1-10 kV is applied to generate a strong local electric field at the tip of the emitter. This electric field deforms the liquid-propellant film into a conical structure referred to as a Taylor cone, located at the tip of the emitter, and extracts charged particles at the apex of the cone.
Implementation Method 2
Electrospray technology is a type of electric propulsion that generates thrust from an ionic liquid by ejecting and accelerating ions in an electrostatic field of the order of a billion volts per metre.
Implementation Method 3
The charged particles are then accelerated at high speeds of the order of several tens of kilometres per second by the applied electric field.
Data Source
AI summary
A method for controlling an ion thruster including an emission electrode, an extraction electrode and a conductive liquid which is deposited on the emission electrode, the ion thruster configured for emitting an ion beam when an electric field is applied to the conductive liquid, the ion beam providing thrust to the thruster, the thrust depending on an emission current Iem and an ion emission speed, the method including the following steps: adjusting the emission current to a setpoint value Ic by applying a threshold emission potential Vthresh to the emission electrode by means of a current generator; and when the setpoint value Ic of the emission current is reached, adjusting the emission speed by applying an extraction potential Vext to the extraction electrode by means of a voltage generator in order to bring the emission potential Vem to a predetermined value Vempr=Vthresh+Vext.