Ionic liquid ion source (ILIS) is a promising ion source, which can be applied to space propulsion, microfabrication, and surface modification. Fabrication of high-quality ILIS emitters is one of the key technologies for the application of ILIS. A new method is proposed for the fabrication of porous emitters with a designed shape. This method uses wire electrical discharge machining (WEDM) combined with electrochemical etching, and the porous emitter is fabricated by two steps. First, the porous metal is machined by WEDM to get the external geometry of the emitter. Then, electrochemical etching is employed to remove the recast layer. A series of experiments has been conducted to find the appropriate machining parameters. Experiments reveal that sharp porous emitter tips for the ILIS can be fabricated by WEDM combined with electrochemical etching at 5 V etching voltage. Moreover, the apex curvature radius of the emitter is controllable by adjusting the etching time. It is found that the apex curvature radius varies from 4.5 μm to 18.4 μm when increasing etching time from 40 s to 120 s at 5 V etching voltage. Those emitters have been applied to ILIS tests, and their I-V characteristics are investigated. Furthermore, this method has been used to machine dense fields of emitters. A 1 cm2 emitter array chip integrated with 676 emitters has been successfully machined, and the I-V characteristic curve of the emitter array chip is also achieved.

中文翻译：

---

线放电加工结合电化学蚀刻制备离子液体离子源多孔发射体

离子液体离子源（ILIS）是一种很有前景的离子源，可应用于空间推进、微制造和表面改性。制造高质量的ILIS发射器是ILIS应用的关键技术之一。提出了一种制造具有设计形状的多孔发射器的新方法。该方法采用线材电火花加工（WEDM）结合电化学蚀刻，通过两步制造多孔发射器。首先，多孔金属通过线切割加工获得发射器的外部几何形状。然后，采用电化学蚀刻去除重铸层。已经进行了一系列实验来寻找合适的加工参数。实验表明，可以通过 WEDM 结合电化学蚀刻在 5 V 蚀刻电压下制造用于 ILIS 的尖锐多孔发射器尖端。此外，发射器的顶点曲率半径可通过调整蚀刻时间来控制。发现在 5 V 蚀刻电压下，当蚀刻时间从 40 s 增加到 120 s 时，顶点曲率半径从 4.5 μm 变化到 18.4 μm。这些发射器已应用于 ILIS 测试，并研究了它们的 IV 特性。此外，这种方法已被用于加工密集的发射器场。成功加工出集成676个发射器的1 cm2发射器阵列芯片，并获得了发射器阵列芯片的IV特性曲线。发现在 5 V 蚀刻电压下，当蚀刻时间从 40 s 增加到 120 s 时，顶点曲率半径从 4.5 μm 变化到 18.4 μm。这些发射器已应用于 ILIS 测试，并研究了它们的 IV 特性。此外，这种方法已被用于加工密集的发射器场。成功加工出集成676个发射器的1 cm2发射器阵列芯片，并获得了发射器阵列芯片的IV特性曲线。发现在 5 V 蚀刻电压下，当蚀刻时间从 40 s 增加到 120 s 时，顶点曲率半径从 4.5 μm 变化到 18.4 μm。这些发射器已应用于 ILIS 测试，并研究了它们的 IV 特性。此外，这种方法已被用于加工密集的发射器场。成功加工出集成676个发射器的1 cm2发射器阵列芯片，并获得了发射器阵列芯片的IV特性曲线。