太赫兹矩形折叠波导慢波结构铜叠片电铸厚度均匀性研究

Study on the Thickness Uniformity of Electroformed Cu Laminated Arrays for Terahertz Rectangular Folded Waveguide

矩形折叠波导慢波结构是太赫兹波段宽带大功率行波管中最具有应用前景的慢波结构,其矩形金属栅的厚度均匀性直接影响电子注与电磁波的同步,从而造成慢波系统的传输损耗。为提高矩形折叠波导慢波结构UV-LIGA叠层制造工艺中电铸矩形金属栅铜叠片阵列的厚度均匀性,提出一种利用辅助阴极和反向脉冲电流相组合的精密电铸方法。在试验和仿真的基础上,系统研究了辅助阴极和反向脉冲电流密度对叠片厚度均匀性的影响,确定了最优工艺参数。试验和仿真结果一致表明,使用辅助阴极和反向脉冲电流能有效地保证阴极各处电流密度分布的均匀一致性,从而提高沉积厚度均匀性。最佳工艺下,整体和单个叠片的厚度不均匀性系数分别从原先的74.85%和30.88%修正到13.6%和11.6%。

Rectangular folded waveguide is the most promising slow wave structure in terahertz broad-band high-power traveling wave tube.The thickness uniformity of rectangular metal grating directly af-fects the synchronization of electron beam and electromagnetic wave,resulting in the transmission loss of slow wave system.In order to improve the thickness uniformity of electroformed rectangular metal grating Cu laminated arrays in UV-LIGA process,an electroforming process combining auxiliary cathode and re-verse pulse current was proposed.The effects of auxiliary cathode and reverse pulse current density on the thickness uniformity of electroformed Cu laminated arrays are systematically studied based on simulations and experiments.The simulations and experimental results consistently agree that the combination of the two methods can effectively adjust the electric field and induce uniform current density distribution.With the best process condition,the thickness nonuniformity coefficients of overall laminated arrays and of indi-vidual one decrease dramatically from 74.85%to 13.6%and from 30.88%to 11.6%,respectively.