Tethered Ion Blocker Layout to Prevent Ion Self-Impingement

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Solution Overview

Problem

Current spacecraft propulsion systems for Low Earth Orbit (LEO) require high propellant mass and costly electric power systems, with ion propulsion systems facing issues of low specific impulse and ion self-impingement, which increases thrust loss and physical damage.

Innovation Solution

The implementation of a tethered ion blocker that captures additional momentum from ions emitted by an ion propulsion system, using a conductive or metallized surface to deflect or accumulate ions, thereby increasing the specific impulse and reducing power requirements while minimizing ion self-impingement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If ion propulsion systems are used to reduce propellant mass, then specific impulse increases, but ion self-impingement causes thrust loss and physical damage

Engineering Contradiction:
Improvepropellant massVSAvoidion self-impingement
Core Design Contradiction:
Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a blocker as an intermediary component positioned between the ion source and the spacecraft body. This blocker intercepts ions that would otherwise self-iminge on the spacecraft, converting the harmful direct impact into a controlled interaction where ions first strike the blocker surface. The blocker serves as a mediator that manages ion trajectories and distributes impact forces, thereby reducing thrust loss and physical damage to the spacecraft while maintaining the high specific impulse benefits of ion propulsion.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Force

If chemical rockets are used for orbit-raising maneuvers, then impulse is produced, but large propellant mass is required with high launch costs

Engineering Contradiction:
ImproveimpulseVSAvoidpropellant mass
Core Design Contradiction:
ForceVSQuantity of substance

Solution Approach 1:

The patent replaces the chemical propulsion mechanism with an ion propulsion system that uses electromagnetic fields to accelerate ions. Instead of relying on chemical combustion to generate thrust, the system uses electric fields to accelerate ionized propellant, achieving much higher specific impulse. The blocker component works in conjunction with this electromagnetic propulsion system to manage ion trajectories, enabling efficient orbit-raising maneuvers with significantly reduced propellant mass compared to chemical rockets.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If ion propulsion systems are used, then specific impulse increases, but costly and heavy electric power systems are required

Engineering Contradiction:
Improvepropellant massVSAvoidelectric power system mass
Core Design Contradiction:
Quantity of substanceVSWeight of stationary object

Solution Approach 1:

The patent employs a blocker that utilizes the kinetic energy and momentum of the ion stream itself to generate additional thrust through ion impact. This self-service mechanism converts the energy already present in the ion propellant into useful work, supplementing the primary ion engine thrust without requiring additional power input. The blocker essentially harvests energy from the ion flow, reducing the overall power system requirements and associated mass while maintaining high propellant efficiency.

Inventive Principle:
Principle #25Self-service

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 doubles or triples the specific impulse of the spacecraft, reducing propellant mass and operational costs, while preventing performance losses and physical damage from ion self-impingement, and avoids the use of reactive chemicals.

Implementation Method 1

a first propulsive force is generated by emission of ions from an ion propulsion system of the spacecraft

Methodology Applied
Scientific EffectElectromagnetic acceleration: Electromagnetic Propulsion

Implementation Method 2

a trajectory of the ion stream is curved by a magnetic field of a planet

Methodology Applied
Scientific EffectMagnetic force on moving charges: Lorentz Force

Implementation Method 3

The surface of the ion blocker may be configured to accumulate an electrical charge from ions contacting the ion blocker such that at least a portion of subsequent ions are deflected before contacting the surface of the ion blocker

Methodology Applied
Scientific EffectElectrical charge accumulation: Electrostatic Induction

Implementation Method 4

The ion blocker may block ions within the ion stream by contacting the ions or deflecting the ions to generate the second propulsive force on the ion blocker

Methodology Applied
Scientific EffectElectrostatic repulsion: Ion Repulsion/Attraction

Data Source

PatentEP3786073B1Enhanced thrust from ion-propelled spacecraft via tethered ion blocker
Publication Date: 2022.03.30 THE BOEING CO
  • EP3786073B1 patent drawingFigure 1
  • EP3786073B1 patent drawingFigure 2
  • EP3786073B1 patent drawingFigure 3

AI summary

Provided are various spacecraft propulsion systems, and associated methods of operation. A spacecraft comprises an ion propulsion system and an ion blocker suspended from the spacecraft via one or more electrically insulated tethers. The ion propulsion system is configured to generate a first propulsive force by emitting a charged ion beam in a direction with an ion velocity vector comprising an ion vector component that is perpendicular to a magnetic field of a planet, such as Earth. The magnetic field causes the ion beam to curve toward the ion blocker at a trajectory such that ions within the ion beam are blocked by the ion blocker to generate a second propulsive force on the ion blocker. The ion blocker blocks the ions by contacting or deflecting the ions. The ion blocker is positioned approximately twice the gyroradius of the ion beam trajectory.