探索性试验了多种微加工技术加工设计频率0.22 THz的折叠波导慢波结构，最终选择了微铣削工艺进行加工，并测试了微铣削工艺加工的WR4标准直波导的损耗特性，得到了0.22 THz电磁波在无氧铜中传播时材料的相对电导率约为3.2×107 S/m。以此为基础设计和制得了国内第一支0.22 THz折叠波导行波管，经过测试和标定得到输出功率大于100 mW，带宽3.5 GHz的初步实验结果。

Several micro-machinings were used to manufacture 0.22 THz folded waveguide slow wave structure. In these micro-machinings, micro-milling was most suitable for manufacturing 0.22 THz folded waveguide slow wave structure now. And the loss of WR4 waveguide manufactured by micro-milling was tested. The relative conductivity of 3.2×107 S/m was obtained when electromagnetic wave of 0.22 THz propagated in oxygen-free copper waveguide. Finally, a 0.22 THz folded waveguide TWT was developed and experimented with output power greater than 100 mW and 3 dB bandwidth of 3.5 GHz.