【摘要】 为满足长脉冲大功率回旋管研制需求，采用直流电弧等离子体喷射化学气相沉积法合成大尺寸低损耗金刚石厚膜窗片；通过表面金属化和钎焊工艺进行微波窗口的封接。采用法布里-玻罗（Fabry-Perot）开放激励腔、激光导热仪、三维轮廓仪、激光干涉仪等对金刚石窗片介电损耗、热导率、表面平坦度、粗糙度等性能参数进行了表征；采用氦质谱检漏仪、高功率长脉冲微波测试平台测试了窗口气密性和微波吸收特性。实验结果表明，抛光厚度1.36 mm的金刚石窗片具有高尺寸精度，热导率达到17.9～18.7 W·cm^-1·K^-1;波导窗片介电损耗tanδ=1.76×10^-4,回旋管窗片tanδ=2.6×10^-4。计算结果表明，在1 MW微波输入功率下波导窗损耗功率约2.34 kW,窗片中心热应力在安全数值内，相同损耗功率条件下回旋管窗口可承受至少680 kW的输出功率。更多还原

【Abstract】 Large-sized low loss diamond disks for long pulse high-power gyrotron are developed by DC arc plasma jet chemical vapor deposition. The diamond disks are welded through surface metallization and brazing process. Key performance parameters such as dielectric loss, thermal conductivity, surface flatness, and roughness are characterized by Fabry Perot open excitation cavity, laser thermal conductivity meter, 3D profilometer, laser interferometer, etc. The vacuum sealability and microwave absorption property of the windows are tested by helium mass spectrometer leak detector and high-power long pulse microwave testing platform, respectively. The results show that the diamond disks with polished thickness of 1.36 mm have high dimensional accuracy with thermal conductivity of 17.9-18.7 W·cm^-1·K^-1. The dielectric loss tanδ of waveguide window is 1.76×10^-4, and the dielectric loss tanδ of gyrotron window is 2.6×10^-4. The calculation results indicate that with a microwave input power of 1MW, the waveguide window loss power is about 2.34 kW, and the thermal stress at the center of the window is within the safe range. Under this power loss conditions, the gyrotron window can withstand an output power of at least 680 kW.更多还原