Dual Propellant Microwave Electrothermal Thruster for High Exhaust Velocity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current rocket propulsion systems, particularly thermal propulsion, are limited by the inability to achieve high exhaust velocities due to material temperature constraints and inefficiencies in heating propellants, such as hydrogen, which restricts their ability to generate sufficient thrust for missions requiring high velocities like those to Mars.
Innovation Solution
A dual propellant electrothermal propulsion system that uses microwaves to heat a mixture of polar and non-polar propellants, specifically hydrogen and water, within a heating chamber, allowing for higher exhaust velocities by mixing and injecting the propellants through an injector and utilizing regenerative cooling to maintain high temperatures, thereby exceeding traditional thermal propulsion limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If chemical thermal propulsion with LH2/LO2 is used, then high thrust levels are achieved, but exhaust velocity is limited to around 15,000 ft/sec due to material temperature constraints
Solution Approach 1:
The patent introduces a microwave heating system as an intermediary energy source that couples electromagnetic energy directly to the propellant molecules through dipole rotation and collision mechanisms. This intermediary approach allows energy transfer without requiring the heating chamber walls to withstand extreme temperatures, thereby achieving higher exhaust velocities while maintaining manageable structural temperature requirements.
Solution Approach 2:
The patent replaces the conventional thermal conduction-based heating system with a microwave electromagnetic field-based heating system. This substitution eliminates the need for direct thermal contact between the heating source and propellant, allowing the propellant to be heated to much higher temperatures without the heating chamber materials being exposed to those extreme temperatures.
2Speed
If arcjet thrusters with hydrogen are used, then exhaust velocity reaches 36,000 ft/sec, but thrust is very limited and energy efficiency is poor
Solution Approach 1:
The patent optimizes multiple parameters including microwave frequency (2.45 GHz), propellant flow rate, chamber pressure, and microwave power coupling efficiency to achieve the optimal balance between exhaust velocity and thrust. By carefully controlling the density and flow characteristics of the hydrogen propellant, the system maximizes both velocity and thrust output simultaneously.
Solution Approach 2:
The patent employs pulsed microwave heating cycles with specific duty cycles to maintain plasma conditions that enhance both exhaust velocity and thrust. The periodic activation and modulation of microwave power allows the system to achieve sustained high-performance operation rather than transient peaks.
3Speed
If solar thermal propulsion is used, then high exhaust velocity is achieved, but the system requires constant positioning of solar concentrator and complex heat exchanger design
Solution Approach 1:
The patent extracts the solar energy conversion function from the propulsion system by using microwave generators powered by solar panels to heat the propellant. This separates the energy collection function (solar panels) from the heating function (microwave generators), eliminating the need for solar concentrators and complex thermal heat exchangers while maintaining high exhaust velocity capability.
Solution Approach 2:
The patent replaces the mechanical solar concentrator positioning system with an electromagnetic microwave heating system. Instead of mechanically tracking and focusing solar rays onto a heat exchanger, the system uses electronically controllable microwave generators that can be precisely directed and modulated, dramatically reducing mechanical complexity.
4Speed
If hydrogen propellant is heated to 6000° R, then maximum exhaust velocity of 36,000 ft/sec is achieved, but no conventional heating method can sustain this temperature
Solution Approach 1:
The patent uses microwave electromagnetic fields as an intermediary heating mechanism that can transfer energy directly to hydrogen molecules without requiring the heating chamber to be constructed from materials that can withstand 6000° R temperatures. The microwave energy penetrates the propellant and heats it internally, allowing the propellant to reach extreme temperatures while the chamber walls remain at manageable temperatures.
Solution Approach 2:
The patent exploits phase transitions and plasma formation in hydrogen at high temperatures to enhance heat absorption and energy coupling. As hydrogen approaches and exceeds its critical point and enters plasma states, it exhibits enhanced electromagnetic absorption characteristics that improve microwave heating efficiency and allow sustained high-temperature operation.
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
This approach enables exhaust velocities exceeding 32,000 ft/sec, potentially reaching up to 36,000 ft/sec, providing a more efficient and practical method for generating thrust compared to arcjet or solar thermal techniques, while using materials like ultra-high temperature ceramics to withstand extreme temperatures.
Implementation Method 1
dual propellant electrothermal propulsion systems that are configured to heat a mixture of polar and non-polar propellants for expulsion from a thruster using microwaves
Implementation Method 2
An electrothermal thruster includes a microwave source operably coupled to a heating chamber. An injector mixes polar and non-polar propellants and a nozzle expands heated mixed propellant that exits the heating chamber to generate thrust.
Implementation Method 3
a nozzle expands heated mixed propellant that exits the heating chamber to generate thrust
Implementation Method 4
using materials like ultra-high temperature ceramics to withstand extreme temperatures
Data Source
AI summary
Dual propellant electrothermal propulsion systems with a polar propellant and a non-polar propellant are disclosed. Such a system may be used for imparting high specific impulse momentum on a spacecraft. A thruster includes a microwave source operably coupled to a heating chamber. An injector mixes polar and non-polar propellants and a nozzle at one end of the heating chamber. The thruster raises the temperature of the mixed propellants that exit the heating chamber to expand in the nozzle to generate thrust.