Stable vacuum electronic devices for aerospace and environment-hard applications

Stable vacuum electronic devices have been fabricated by the Transfer Mold fabrication method to realize electric propulsion engines in harsh environments such as strong radical atmospheres in space for aerospace and environment-hard applications. The Transfer Mold field emitter arrays (FEAs) are extremely sharpened to 6.8 nm of tip radii and extremely uniform. The turn-on fields of low work function Transfer Mold FEAs at the short distance of 10 μm between anode and emitter are as low as 15.4 V/μm. The emission fluctuation rates without resistive layer, were as low as ±1.7%, which is one of the lowest value ever reported, compared with 5-several hundred % of the conventional FEAs. Moreover, sharp and uniform Transfer Mold FEAs having not only low work function but also environment-hard characteristics, exhibit the extremely stable fluctuations of less than ±5.1% even under the in-situ oxygen radical treatment. Therefore, the extremely stable and environment-hard Transfer Mold FEAs might be expected for the highly efficient and reliable vacuum electronic devices such as electric propulsion engines for aerospace applications to a great extent. Also, the panel type and pixel type electric thrusters have been proposed using Transfer Mold FEAs, having ion emitter arrays and electron emitter arrays whose electrons can neutralize positively charged particles. The panel type and pixel type electric thrusters give the easiness of getting large and small size thruster.