NMR Atomic Clock Physics Package for Stable Frequency Reference

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Solution Overview

Problem

Current atomic clocks, such as Rubidium Atomic Frequency Sources, face challenges including high inner temperatures, sensitivity to magnetic and vibration influences, complex handling, and aging due to Rubidium leakage, making them unsuitable for advanced applications like in-orbit use.

Innovation Solution

A Nuclear Magnetic Resonance (NMR) based oscillator with a Physics Package featuring permanent magnets, RF coils, and a DC coil, arranged to create a controlled static magnetic field, using non-hazardous materials like H2O and Y2O3, and housed in an iron cask to minimize external influences and temperature effects, operating at lower frequencies for improved stability and ease of handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Rubidium Atomic Frequency Source is used, then frequency reference stability is improved, but device complexity and handling difficulty increase due to complex glass container filling and metallic Rubidium handling

Engineering Contradiction:
Improvefrequency reference stabilityVSAvoidhandling complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex, expensive, and difficult-to-handle metallic Rubidium system with a simpler, non-hazardous liquid alternative (water or water mixture) that can be easily filled and handled. The solution uses a disposable-like approach where the liquid medium can be readily replaced or refilled without complex procedures, eliminating the need for precision filling of metallic Rubidium into glass containers.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent fundamentally changes the physical state and chemical composition parameters of the frequency reference medium. Instead of using metallic Rubidium requiring high temperatures and vacuum sealing, the invention uses liquid water or water mixtures that can operate at ambient temperatures, are non-hazardous, and can be handled in simple glass containers without complex filling procedures.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If high inner temperatures are used in Rubidium Atomic Frequency Source, then frequency reference operation is enabled, but aging increases due to Rubidium movement into glass walls

Engineering Contradiction:
Improvefrequency reference operationVSAvoidlifespan
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the operating temperature parameter from high temperatures (required for metallic Rubidium) to ambient or lower temperatures. The liquid water-based medium operates effectively at room temperature, eliminating thermal stress on glass containers and preventing the migration of Rubidium into glass walls that causes aging. This parameter change extends the operational lifespan of the frequency reference.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

By using non-hazardous liquid water or water mixtures instead of metallic Rubidium, the patent creates a system where the medium can be easily replaced if needed without complex procedures. The simple glass containers used with liquid media have no aging issues from metal migration, effectively extending system lifespan.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If metallic Rubidium is used in glass containers, then frequency reference function is achieved, but sensitivity to magnetic influences and micro vibrations increases

Engineering Contradiction:
Improvefrequency reference functionVSAvoidmagnetic and vibration sensitivity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material composition parameter from metallic Rubidium to liquid water or water mixtures. This fundamental material substitution reduces sensitivity to magnetic influences and micro vibrations, as liquid media are less susceptible to these external perturbations compared to metallic atoms in vapor phase or condensed state within glass containers.

Inventive Principle:
Principle #35Parameter changes

4Measurement precision

If complex handling procedures are used for Rubidium filling, then frequency reference precision is achieved, but ease of operation decreases

Engineering Contradiction:
Improvefrequency reference precisionVSAvoidhandling ease
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent adopts a simplified, disposable-like approach using liquid water or water mixtures in simple glass containers. The medium can be easily filled, sealed, and handled without complex procedures. If precision is compromised, the entire unit can be readily replaced or refilled without intricate adjustment procedures, significantly improving ease of operation while maintaining adequate frequency reference precision.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

By changing from metallic Rubidium to liquid water-based media, the patent transforms the system from requiring precision filling and complex handling to allowing simple filling and handling. The liquid medium's properties enable easy manipulation while maintaining the frequency reference function, dramatically improving operational ease.

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

The NMR-based oscillator reduces sensitivity to external influences, suppresses aging, simplifies handling, and lowers operational temperatures, resulting in a more reliable and cost-effective frequency reference with extended lifespan, suitable for in-orbit applications and reduced complexity.

Implementation Method 1

The first and second permanent magnets are adapted to generate a static magnetic field inside the space. The predetermined magnitude corresponds to a nuclear magnetic resonance condition for continuous wave operation.

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

The first RF coil is adapted to introduce an RF pulse into the space. This results in a precession of atomic cores of the NMR sample

Methodology Applied
Scientific EffectNuclear magnetic resonance: Resonance

Implementation Method 3

The second RF coil is adapted to measure the precession of the atomic cores of the NRM sample by receiving electromagnetic signal

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3745216B1NMR atomic clock
Publication Date: 2021.09.15 AIRBUS DEFENCE & SPACE GMBH
  • EP3745216B1 patent drawingFigure 1
  • EP3745216B1 patent drawingFigure 2
  • EP3745216B1 patent drawingFigure 3

AI summary

A Physics Package for an Oscillator is provided. The Physics Package comprises first and second permanent magnets. The first and second permanent magnets are arranged to form a space between each other. The first and second permanent magnets are adapted to generate a static magnetic field inside the space. The magnetic field has a direction from the first permanent magnet to the second permanent magnet. The Physics Package further comprises a Nuclear Magnetic Resonance, NMR, sample. The NMR sample is arranged inside the space. The Physics Package further comprises first and second radio frequency, RF, coils. The first and second RF coils are arranged at different sides of the space in an angle of 90° to each other. The first RF coil is adapted to introduce an RF pulse into the space. This results in a precession of atomic cores of the NMR sample. The second RF coil is adapted to measure the precession of the atomic cores of the NRM sample. Further, an oscillator with the Physics Package is provided.