研究目的
To evaluate the stray millimeter-wave radiation loads on ITER fused silica windows, focusing on the effects from ECRH and CTS systems, and to assess potential damage and necessary qualifications for the windows in hostile environmental conditions.
研究成果
The absorbed microwave power by fused silica windows is generally low, except for specific diagnostics like CTS and LFSR, which may require protective measures such as grating mirrors. Gamma and neutron irradiation effects on dielectric properties are limited based on literature, but further testing is recommended, especially for neutron doses. Overall, window integrity appears manageable with current designs, but detailed analysis is needed as final structures are defined.
研究不足
The study focuses on worst-case scenarios, which may overestimate risks. Assumptions include perfect matching of subsystems to stray radiation and neglect of some background power contributions. Computational resources limited the analysis, leading to conservative estimates. Data on materials like Boron Carbide at relevant frequencies are lacking, and effects of gamma and neutron irradiation on dielectric properties have uncertainties, requiring further tests.
1：Experimental Design and Method Selection:
The study uses numerical simulations and analytical calculations to assess stray radiation loads. CST Microwave Studio and GRASP software are employed for simulations of attenuation in ducts and coupling between stray radiation and diagnostic conduits.
2：Sample Selection and Data Sources:
The diagnostics installed in ITER ports #11 and #12 are considered, including systems like Neutral Particle Analyzer (NPA), Low Field Side Reflectometer (LFSR), Vacuum Ultra Violet (VUV), and H-alpha spectrometers. Data on stray power densities are sourced from previous studies and ITER specifications.
3：List of Experimental Equipment and Materials:
Fused silica windows, absorbing coatings (e.g., Boron Carbide B4C), and materials for simulations (e.g., titania allumina as a substitute in some cases).
4：Experimental Procedures and Operational Workflow:
Simulations are conducted to evaluate attenuation and coupling for worst-case scenarios, considering highest power densities and least attenuated modes. Analytical calculations complement simulations to provide upper limits of stray power loads.
5：Data Analysis Methods:
Results are analyzed to determine absorbed power in windows, with absorption fractions of 1.14% at 60 GHz and 3.23% at 170 GHz. Statistical or comparative analysis is not detailed, but worst-case values are reported.
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