Magnetron Cavity Dimensioning for Stable Compact Atomic Clocks
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Solution Overview
Problem
Existing hydrogen masers are bulky and heavy, posing challenges for space applications, and current methods for reducing their size and stabilizing frequency-temperature coefficients (FTC) are unpredictable and impractical.
Innovation Solution
A computer-assisted method for dimensioning a magnetron cavity that involves adjusting geometrical parameters and thermal expansion to achieve a predictable and optimized frequency-temperature coefficient (FTC) using Maxwell equations and finite element modeling, without altering materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the size of the cavity is reduced to make the atomic clock compact, then the dimensions of the cavity are improved, but the frequency-temperature coefficient (FTC) becomes unpredictable and the stability deteriorates
Solution Approach 1:
The invention changes the geometrical parameters of the cavity, specifically the radial interstice between the storage bulb and electrodes, to optimize the FTC. By adjusting this parameter, the cavity maintains predictability and stability even at reduced dimensions, resolving the contradiction between compact size and frequency stability.
Solution Approach 2:
The invention performs preliminary computer-assisted calculations and simulations to determine the optimal geometrical parameters before manufacturing. This preliminary action ensures that the cavity design achieves both compact dimensions and predictable FTC, avoiding instability issues that would otherwise arise from size reduction.
2Reliability
If multi-material cavity design is used to reduce FTC, then the frequency-temperature coefficient is improved, but the manufacturing complexity and production time increase
Solution Approach 1:
The invention uses a single-material cavity design (typically copper or aluminum) rather than multi-material construction. The radial interstice geometry alone is used to control the FTC, eliminating the manufacturing complexity, increased production time, and cost associated with multi-material assembly while maintaining frequency stability.
3Volume of moving object
If the radial interstice is reduced to improve compactness, then the cavity dimensions are improved, but the resonance frequency becomes difficult to control
Solution Approach 1:
The invention uses computer-assisted calculations to preliminarily determine the optimal radial interstice value that simultaneously achieves compact dimensions and precise resonance frequency control. This preliminary design phase ensures that the reduced interstice does not compromise frequency accuracy.
Solution Approach 2:
The invention incorporates feedback mechanisms where the actual resonance frequency is measured and compared with the target frequency, and the radial interstice geometry is adjusted accordingly. This feedback loop ensures precise frequency control even when the cavity is compact.
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
Enables the production of compact hydrogen masers with stable frequency performance by controlling FTC between 0 and 60 kHz/°C, preferably 0 and 20 kHz/°C, ensuring high stability and manufacturability.
Implementation Method 1
a computer program intended to determine, using Maxwell equations, the resonance frequency of the cavity
Implementation Method 2
The deformation is due to the thermal expansion of the materials. The deformation comprises the deformation of the geometry of the cavity, of the at least two electrodes and of the storage bulb and is based on the known thermal expansion coefficients of the materials used
Data Source
AI summary
A computer-assisted method for the dimensioning of a magnetron cavity for an atomic clock, in particular for a hydrogen maser, the cavity being substantially cylindrical and including at least two curved electrodes disposed along a circular arc and delimiting a substantially cylindrical space of predetermined radius r, the cavity also including a substantially cylindrical storage bulb of radius rB disposed in said space such that there is a radial interstice ei between the at least two electrodes and the storage bulb.