Spacecraft Propulsion System Switching Electrostatic Thruster and Resistojet

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Solution Overview

Problem

Current space propulsion systems combining electrostatic and cold gas thrusters face challenges with high propellant fluid consumption and complexity due to limited specific impulse of cold gas thrusters and power supply complexity, particularly in achieving both high specific impulse and thrust modes efficiently.

Innovation Solution

A space propulsion system integrating an electrostatic thruster and a resistojet with a shared propellant fluid supply circuit and a simplified electrical power supply circuit, utilizing a switch to alternate electrical supply between the thrusters, allowing for high specific impulse and higher thrust modes with reduced complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If cold gas thrusters are used for high thrust maneuvers, then thrust is increased, but propellant consumption increases significantly due to limited specific impulse

Engineering Contradiction:
ImprovethrustVSAvoidpropellant consumption
Core Design Contradiction:
ForceVSLoss of substance

Solution Approach 1:

The patent changes the physical state and heating parameters of the propellant fluid by using a resistojet heater element that electrically heats the propellant to high temperatures before expansion, transforming it from a cold gas thruster operating at low temperature to a resistojet operating at high temperature, thereby achieving higher specific impulse

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The propulsion system is segmented into two distinct thruster types: cold gas thrusters for low-thrust maneuvers and resistojet thrusters for high-thrust maneuvers, allowing each segment to operate in its optimal performance regime and reducing overall propellant consumption

Inventive Principle:
Principle #1Segmentation

2Loss of substance

If electrostatic thrusters are used for high specific impulse maneuvers, then propellant consumption is reduced, but thrust becomes very low

Engineering Contradiction:
Improvepropellant consumptionVSAvoidthrust
Core Design Contradiction:
Loss of substanceVSForce

Solution Approach 1:

The system dynamically switches between different thruster types based on mission requirements, using electrostatic thrusters when propellant efficiency is critical and resistojet or cold gas thrusters when higher thrust is needed, optimizing performance throughout the mission lifecycle

Inventive Principle:
Principle #15Dynamics

3Reliability

If separate power supply circuits are used for electrostatic thrusters and resistojet, then thruster functionality is maintained, but system complexity increases

Engineering Contradiction:
Improvethruster functionalityVSAvoidpower supply circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A single power supply circuit is designed to perform multiple functions by switching between different load configurations: it can power the resistojet heater element, power the electrostatic thruster discharge, or provide both simultaneously, thereby reducing overall system complexity while maintaining full thruster functionality

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The power supply circuits for the resistojet and electrostatic thruster are merged into a single unified power supply system with switching capability, eliminating redundant components and reducing circuit complexity while preserving the ability to independently control each thruster type

Inventive Principle:
Principle #5Merging (Combining)

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 system achieves efficient propellant use and simplified power supply by enabling high specific impulse and thrust modes, reducing propellant consumption and system complexity while maintaining reliability and flexibility for spacecraft maneuvers.

Implementation Method 1

resistor jets, in which heat is transferred to the propellant fluid by at least one resistor heated by Joule heating

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

electrostatic thrusters, in which the propellant fluid is ionized and directly accelerated by an electric field

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 3

The propellant is then accelerated towards the virtual cathode grid by the electric field between the grid and the anode

Methodology Applied
Scientific EffectElectric field acceleration: Electric Field

Implementation Method 4

electrons emitted by a cathode are captured by a magnetic field generated by coils located around and at the center of an annular discharge channel, thus forming a virtual cathode grid

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 5

Hall effect thrusters. In these thrusters, also known as closed-drift electron plasma engines or stationary plasma engines

Methodology Applied
Scientific EffectHall effect: Hall Effect

Data Source

PatentEP3174795B1Spacecraft propulsion system and method
Publication Date: 2021.12.01 SAFRAN AIRCRAFT ENGINES SAS
  • EP3174795B1 patent drawingFigure 1
  • EP3174795B1 patent drawingFigure 2A
  • EP3174795B1 patent drawingFigure 2B

AI summary

The invention relates to the field of spacecraft propulsion, and more specifically to electrically powered spacecraft propulsion. A spacecraft propulsion system (100) according to the invention includes at least one electrostatic thruster (101) with at least one first electricity consumer, a resistojet (102), a circuit (104) for supplying a propellant fluid, and a circuit (103) for supplying electricity comprising at least one first electricity supply line (131) and a first switch (114-1, 114'-1, 114"-1) making it possible to choose between connecting said first electricity supply line (131) to the resistojet (102) and connecting said first electricity supply line (131) to said first electricity consumer of the electrostatic thruster (101). This system thus allows the application of a spacecraft propulsion method including a switching step for selecting a first propulsion mode, in which the resistojet (102) is activated, or a second propulsion mode, in which the electrostatic thruster (101) is activated.