2023 Volume 1 Article ID: 30
A high-density emitter array for ionic liquid electrospray thrusters is fabricated using a fabrication process for field emitter arrays. SU-8 photoresist is employed as the inter-electrode material. The distance between the emitter and the extractor electrodes was about 10 µm, enough for about 1-kV application between the electrodes. Adequate thrust and specific impulse can be obtained without an accelerator electrode, resulting in a simple propulsion system. Optimal parameters for the photolithography of SU-8 are determined. The fabricated emitter array had a tip diameter of about 1 µm and an emitter density 200 times higher than conventional emitter arrays. A preliminary experiment for ion emissions showed a negative current of −79 nA at 800 V using a 4 × 4 emitter array in an area of 100 µm square, resulting in approximately twice as much current density as a conventional type.
