Hall-effect thruster cathode temperature regulation circuit

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Solution Overview

Problem

Hall effect motors experience unnecessary overheating and reduced lifespan due to prolonged preheating times, which are required to ensure engine starting under varying external conditions, leading to cathode damage and inefficient fuel usage.

Innovation Solution

Incorporating a temperature measurement system and regulation circuit to optimize preheating by heating the cathode only until a threshold temperature is reached and ceasing heating once a critical discharge current is achieved, ensuring the engine starts without excessive overheating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed preheating time is chosen to ensure engine starting under all conditions, then the engine can start under unfavorable external conditions, but the cathode is unnecessarily overheated and damaged, reducing motor life

Engineering Contradiction:
Improveengine starting reliabilityVSAvoidcathode lifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent implements a feedback control system that continuously monitors the cathode temperature and adjusts the heating power accordingly. When the cathode temperature reaches a predetermined threshold, the system automatically reduces or stops heating, preventing unnecessary overheating while ensuring the cathode reaches the required temperature for engine starting under all external conditions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent transforms the static fixed preheating time approach into a dynamic control system. The heating duration and power are no longer fixed but are continuously adjusted based on real-time cathode temperature measurements, allowing the system to adapt to varying external conditions and prevent both insufficient heating and excessive overheating.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a fixed preheating time is used to ensure starting under unfavorable conditions, then all starting scenarios are covered, but the preheating time is too long for favorable conditions, causing unnecessary overheating

Engineering Contradiction:
Improvestarting condition adaptabilityVSAvoidpreheating time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The feedback control system monitors cathode temperature in real-time and adjusts heating based on actual thermal state rather than using a fixed time schedule. This allows the system to adapt to different external conditions dynamically, stopping heating as soon as the cathode reaches the required temperature threshold, thus eliminating unnecessary preheating time in favorable conditions while maintaining reliability in unfavorable conditions.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the control parameter from fixed time to dynamic temperature-based control. By monitoring cathode temperature and adjusting heating power based on thermal state, the system optimizes preheating duration for each specific operating condition, reducing time loss in favorable conditions while ensuring adequate heating in unfavorable conditions.

Inventive Principle:
Principle #35Parameter changes

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 minimizes cathode damage and extends the motor's lifespan by heating the cathode only for the necessary time to initiate the engine, regardless of operating conditions, thereby improving efficiency and durability.

Implementation Method 1

a heating device capable of heating the cathode... The starting of the engine requires the preheating of the cathode 100 by a heating device 60

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

the preheating of the cathode 100 by a heating device 60 up to a threshold temperature which allows the emission by the cathode of the quantity of electrons necessary

Methodology Applied
Scientific EffectThermionic emission: Thermionic Emission

Implementation Method 3

The central magnetic coil 12 and the peripheral magnetic coils 14 are used to generate a radial magnetic field B... they find themselves partly trapped by the magnetic field B... These electrons are thus led to describe circumferential trajectories

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 4

these electrons create an axial electric field E, which accelerates these ions from the anode (injection system 30 at the bottom of the channel 80) towards the downstream opening 52, so that these ions are ejected at high speed

Methodology Applied
Scientific EffectElectric field: Electric Field

Implementation Method 5

These electrons then ionize via shocks the neutral gas atoms (generally xenon Xe) circulating from the upstream towards downstream in the discharge channel 50, thereby creating ions

Methodology Applied
Scientific EffectIonization: Ionisation

Data Source

PatentEP2564064B1Hall-effect thruster with regulation of the cathode heater temperature
Publication Date: 2019.12.18 SAFRAN AIRCRAFT ENGINES SAS
  • EP2564064B1 patent drawingFigure 1
  • EP2564064B1 patent drawingFigure 2
  • EP2564064B1 patent drawing

AI summary

The invention relates to a Hall-effect motor (1) comprising: a discharge channel (50), the downstream end (52) of which is open; a cathode (100) located outside the discharge channel (50); an injection system (30) capable of injecting gas atoms into the discharge channel (50), said injection system (30) being located at the upstream end of the discharge channel (50) and also forming an anode; and a heating device (60) capable of heating the cathode (100). The motor (1) also includes a means (70) for measuring the temperature (Td) of the heating device (60), and a circuit (80) for controlling said temperature (Td) such that the heating device (60) heats the cathode as long as the temperature (Td) of the device is below a threshold temperature (Ts) at or above which the motor can start, and the heating device stops heating shortly after the threshold temperature (Ts) has been reached.