Hall Thruster Magnetic Plasma Confinement

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Solution Overview

Problem

Ceramic walls in Hall thrusters increase cost, complexity, and mass, and occupy valuable space, as they are no longer necessary for plasma confinement with proper magnetic field application, especially in miniature thrusters where space is critical.

Innovation Solution

Eliminating the discharge chamber walls and using a magnetic shielding configuration with conductive coatings on the magnetic screens to direct propellant ions away from the plasma-facing surfaces, allowing for the use of cheaper materials like graphite and reducing erosion, thereby simplifying the design and reducing mass and cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ceramic walls are used in the discharge chamber, then plasma confinement is improved, but mass, cost, and complexity increase

Engineering Contradiction:

Improveplasma confinementVSAvoiddischarge chamber mass

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent replaces the mechanical ceramic wall structure with a magnetic field-based confinement system. Magnetic poles generate a magnetic field that confines plasma without requiring physical ceramic barriers, thereby reducing mass while maintaining plasma confinement effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention extracts and eliminates the ceramic wall component from the discharge chamber design. By removing the ceramic confinement structure and relying solely on magnetic field generation through magnetic poles, the system achieves plasma confinement without the associated mass, cost, and complexity of ceramic materials.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If ceramic walls are used in the discharge chamber, then plasma confinement is improved, but device complexity increases

Engineering Contradiction:

Improveplasma confinementVSAvoiddischarge chamber structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the complex ceramic wall structure from the discharge chamber. The simplified design uses only magnetic poles and conductive screens, eliminating the need for ceramic materials and their associated manufacturing, assembly, and maintenance complexities.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention substitutes the mechanical ceramic confinement system with an electromagnetic field-based system. Magnetic poles generate the confining field, replacing the need for physical ceramic barriers and reducing overall device structural complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Weight of stationary object

If magnetic field is applied for plasma confinement, then ceramic walls are no longer necessary, but charged particles may collide with conductive coating

Engineering Contradiction:

Improvedischarge chamber massVSAvoidparticle collision erosion

Core Design Contradiction:

Weight of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent introduces magnetic field lines as an intermediary between the plasma and the conductive coating. The magnetic field acts as a protective barrier that guides charged particles along field lines, preventing direct collisions with the conductive coating on the magnetic screens while maintaining the benefits of a wall-less design.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design reduces thruster mass and complexity, lowers costs, and optimizes the volume available for plasma and magnetic fields, enhancing the operational efficiency of Hall thrusters by eliminating the need for expensive ceramic materials and separate electrodes.

Implementation Method 1

an anode adjacent to the rear surface of the annular discharge chamber; a cathode adjacent to the front aperture of the annular discharge chamber, the anode and cathode configured to generate an electric field within the annular discharge chamber

Methodology Applied

Scientific EffectElectric field generation: Electric Field

Implementation Method 2

magnetic poles configured to generate magnetic field in the annular discharge chamber, the magnetic field configured to substantially avoid collisions of charged particles against the conductive coating

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 3

a conductive coating deposited on the inner and outer annular screens; magnetic poles configured to generate magnetic field in the annular discharge chamber, the magnetic field configured to substantially avoid collisions of charged particles against the conductive coating

Methodology Applied

Scientific EffectElectromagnetic interaction: Lorentz Force

Data Source

PatentUS10082133B2Hall thruster with magnetic discharge chamber and conductive coating

Publication Date: 2018.09.25 CALIFORNIA INST OF TECH

AI summary

Hall thrusters with conductive coatings are disclosed. A Hall thruster comprises magnetic shielding in order to avoid collisions with the inner walls of its discharge chamber. By removing the source of erosion, the walls of the chamber can be removed reducing mass, cost and complexity of the thruster. A conductive coating, such as an aluminum coating, is deposited on inner screens between the discharge chamber and the magnetic poles of the thruster. The magnetic field within the chamber shields the conductive coating deposited on the inner and outer screens of the chamber.