Electrodeless Plasma Thruster for CubeSats
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Solution Overview
Problem
Conventional electric propulsion systems, such as Hall thrusters and ion engines, are ineffective when scaled down for small satellites like CubeSATS due to their large size, high mass, and high power requirements, limiting their propulsion capabilities and mission flexibility.
Innovation Solution
The CubeSAT Ambipolar Thruster (CAT) uses a radio frequency (RF) generated plasma expanding through a magnetic nozzle, eliminating internal electrodes and utilizing a helicon plasma source to achieve thrust, designed to be small, low mass, and low power, with a propellant tank, mass flow control, and RF power source, allowing for efficient acceleration of plasma without electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional electric propulsion systems (Hall thrusters and ion engines) are used, then thrust capability is achieved, but size, mass, and power requirements become too large for small satellites
Solution Approach 1:
The patent removes electrodes from the plasma generation chamber, extracting the harmful component that requires high power and creates complexity. The electrodeless design using RF fields to generate plasma directly eliminates the need for electrode-based discharge mechanisms, thereby reducing mass and power requirements while maintaining thrust capability
Solution Approach 2:
The patent replaces the mechanical/electrical electrode-based plasma generation system with an electromagnetic field-based system. RF fields are used to couple energy into the plasma without physical contact, substituting mechanical electrode structures with field-based energy transfer, which reduces mass and simplifies the system
2Force
If conventional electric propulsion systems are used, then thrust is generated, but device size and power consumption exceed CubeSAT constraints
Solution Approach 1:
By removing electrodes from the system, the patent eliminates the high power consumption associated with electrode heating, maintenance arcs, and electrode replacement. The electrodeless RF plasma generation requires significantly less power while achieving the same plasma production efficiency
Solution Approach 2:
The patent changes the operating parameters from low-frequency, high-power electrode-based discharge to high-frequency, low-power RF field coupling. This parameter change enables efficient plasma generation at power levels suitable for CubeSATs (tens of watts rather than kilowatts)
3Quantity of substance
If electrodes are used in plasma generation, then plasma is produced, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent extracts electrodes entirely from the plasma generation chamber, eliminating the complex internal electrode structures, support mechanisms, and replacement systems. This simplifies the device design while maintaining effective plasma production through RF field coupling
Solution Approach 2:
The electrodeless design allows the plasma generation system to operate without consumable parts that require maintenance. The RF field-based plasma generation has no moving parts or consumable electrodes, enabling long-duration operation without intervention, ideal for small satellite missions
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 CAT provides a thrust of 0.5 to 4 mN and ΔV of 1-2 km/s, enabling missions beyond the launch orbit, including highly elliptical and geostationary orbits, with potential for a global satellite network and significant cost savings, while being compact and power-efficient.
Implementation Method 1
Gaseous propellant is fed into the plasma discharge chamber, a dielectric, bottle shaped structure or plasma liner having no internal electrodes, and ionized with RF fields
Implementation Method 2
The plasma is accelerated to the speed of sound (Mach 1) by the converging section of a converging/diverging magnetic nozzle and is further accelerated as the plasma expands in the diverging section
Implementation Method 3
The electromagnetic wave launched by the antenna couples to the electrons, thereby heating them
Implementation Method 4
The high velocity plasma leaving the thruster generates a force that can be used to accelerate a satellite
Data Source
AI summary
A plasma propulsion system with no internal electrodes is described. Gas is flowed into an insulated axisymmetric plasma liner. A radio frequency antenna generates an inductive or helicon plasma discharge within the liner. The plasma is accelerated through a converging/diverging magnetic field out of the liner, generating thrust.