The key subsystems of a high efficiency material processing gyrotron are designed at an operating frequency of 27.885 GHz. A triode-type electron gun is designed to launch hollow spiraling electron beam. The outer diameter of the gun is kept at 50 mm to lower inside diameter of the magnet. Start oscillation current for TE02 operating as well as competing modes is plotted. The output power and efficiency are predicted to be 18.4 kW and 46%, respectively, based on single mode time-dependent analytical equation. Beam–wave interaction is studied by employing particle-in-cell (PIC) simulation. Electronic efficiency and output power are increased by operating the tube in hard excitation region. An axially slotted cavity is adopted to abridge mode competitions. The output power and electronic efficiency are obtained to be 20.08 kW and 50.2%, respectively, without considering any velocity spread of the electron beam. However, the efficiency is reduced to 45%, when a moderate transverse velocity spread of 5% is considered. The power efficiency is enhanced to 67.07% by introducing a 3-staged depressed collector.

中文翻译：

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Ka波段工业回旋管的设计与效率提升

高效材料加工回旋管的关键子系统设计工作频率为 27.885 GHz。三极管型电子枪设计用于发射空心螺旋电子束。枪的外径保持在 50 毫米，以降低磁铁的内径。绘制了 TE02 操作以及竞争模式的启动振荡电流。根据单模瞬态分析方程，预计输出功率和效率分别为 18.4 kW 和 46%。通过采用细胞内粒子 (PIC) 模拟来研究光束-波相互作用。通过在硬激发区操作电子管来提高电子效率和输出功率。采用轴向开槽的腔体来减少模式比赛。获得的输出功率和电子效率分别为 20.08 kW 和 50.2%，不考虑电子束的任何速度扩展。然而，当考虑 5% 的中等横向速度扩展时，效率降低到 45%。通过引入三级降压集电极，功率效率提高到 67.07%。