Tunable Emissivity Resonator for Spacecraft Thermal Control
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Solution Overview
Problem
Existing materials have static emissivity properties, making it difficult to achieve desired emissivity in specific radiation frequency ranges, which is crucial for temperature control in spacecraft exposed to varying radiation environments.
Innovation Solution
A tunable emissivity apparatus comprising an impedance layer with resonators and a resistive material that can change its resistivity in response to an electric field, allowing for adjustment of emissivity by altering the absorption and destructive interference of radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static emissivity materials are used, then the material structure is simple, but the emissivity cannot be adjusted for different radiation frequency ranges
Solution Approach 1:
The patent applies dynamics by making the emissivity property adjustable rather than fixed. The resonators' electrical characteristics can be dynamically tuned by changing the resistivity of the resistive material through electric field application, allowing the emissivity to adapt to different radiation frequency ranges and thermal control requirements.
Solution Approach 2:
The patent changes the resistivity parameter of the resistive material to tune the emissivity. By applying an electric field, the resistivity of the resistive material is modified, which directly changes the resonators' electrical characteristics and thus adjusts the emissivity in the long wavelength infrared frequency range.
2Temperature
If emissivity is increased to improve cooling, then radiation emission is enhanced, but temperature control precision decreases due to inability to tune
Solution Approach 1:
The patent implements feedback control for temperature management. The tunable emissivity allows the system to respond to thermal conditions by adjusting the resistivity of the resistive material, thereby controlling the resonators' emission characteristics. This enables precise temperature control by feedback-adjusting the radiative cooling rate.
Solution Approach 2:
The patent uses parameter changes in the resistive material's resistivity to precisely control emissivity. By varying the electric field applied to the resistive material, the emissivity can be tuned to achieve desired temperature control precision, allowing optimization of radiative heating or cooling rates.
3Adaptability or versatility
If resonators are added to create tunable emissivity, then emissivity control is achieved, but the device complexity increases
Solution Approach 1:
The patent extracts the emissivity control function into separate tunable resonator elements that can be independently adjusted. By isolating the emissivity control mechanism into discrete resonators with adjustable resistive materials, the system achieves tunability while maintaining a modular structure that manages complexity.
Solution Approach 2:
The patent uses composite material structures combining dielectric materials with resistive materials in the resonators. This composite approach integrates multiple functions (structural support, electromagnetic resonance, and resistivity tuning) into a unified apparatus, achieving emissivity control without proportionally increasing overall complexity.
4Measurement precision
If the resistive material resistivity is changed to tune emissivity, then emissivity precision is improved, but energy consumption increases
Solution Approach 1:
The patent may employ periodic or pulsed electric fields to adjust the resistive material's resistivity rather than continuous application. This allows emissivity tuning to be achieved with intermittent energy input, reducing overall energy consumption while maintaining the ability to precisely control emissivity when needed.
Solution Approach 2:
The patent optimizes the resistivity parameter changes to achieve the required emissivity precision with minimal energy input. By carefully selecting the magnitude and duration of electric field applications, the system achieves precise emissivity control while minimizing the energy consumed in the resistive material adjustment process.
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 precise control of emissivity, maintaining a constant temperature in spacecraft regardless of orientation and reducing temperature swings by optimizing energy reflection, absorption, and emission.
Implementation Method 1
the plurality of resonators are positioned a distance from the electrically reflective ground plane such that energy reflected from the resonators experience destructive interference with energy reflected from the ground plane
Implementation Method 2
The resistive material exhibits electron migration in response to an electric field
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
Apparatus and methods to provide a surface having a tunable emissivity are disclosed. An example apparatus includes an impedance layer (104) comprising a layer of dielectric material (108) to be attached to an electrically reflective ground plane (106), and a plurality of resonators (110) arranged within the impedance layer (104), wherein an emissivity of the apparatus is based on a characteristic of the resonators (110).