研究目的
To study methods to enhance the infrared emissivity of Molybdenum surfaces for use in ITER optical diagnostics, aiming to improve radiative cooling and maintain alignment under high heat loads.
研究成果
The study demonstrated that Al2O3 coatings provide the highest emissivity (εeff ≈ 0.8-0.9), while V-grooving and drilling offer acceptable enhancements (εeff ≈ 0.25-0.3) without requiring ITER qualification. Effective emissivity shows little variation with temperature in the 200-400°C range. These methods can significantly reduce temperatures in ITER mirror units, supporting passive radiative cooling designs.
研究不足
Method 1 is susceptible to environmental variations (air humidity, CO2) and only applicable at room temperature. Method 2 requires vacuum setup and may have directional biases for structured surfaces. Coatings need qualification for ITER vacuum standards, and there are uncertainties in real surface parameters like roughness and oxidation.
1：Experimental Design and Method Selection:
The study tested various surface treatment methods (V-grooving, detonation spray coating, drilling, electro-erosion) to enhance emissivity, using infrared spectral emissivity measurements with FTIR spectrometry. Theoretical models included Planck's law and energy conservation for emissivity calculation.
2：Sample Selection and Data Sources:
Samples included flat and treated Molybdenum pieces with specific geometries (e.g., V-grooves with angles 10-60°, depths 1-2.5 mm, drilled holes with diameters 1 mm and spacings 1-2 mm), and an Al2O3-coated sample. Data were acquired through spectral measurements.
3：5 mm, drilled holes with diameters 1 mm and spacings 1-2 mm), and an Al2O3-coated sample. Data were acquired through spectral measurements.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Equipment included a Bruker Vertex-70 FTIR spectrometer with integrating sphere and detectors (MCT D316 and DLaTGS D301), vacuum setup for heated samples, and reference samples like graphite. Materials were Molybdenum samples and Al2O3 coatings.
4：Experimental Procedures and Operational Workflow:
For Method 1, total IR reflectivity was measured at room temperature using the integrating sphere. For Method 2, spectral emission power was measured for samples heated to 200-300°C in a vacuum to avoid oxidation, normalized to reference samples.
5：Data Analysis Methods:
Effective emissivity was derived using integration over the IR wavelength range (2-14 μm), with statistical analysis of spectral data to compute average values.
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