Cathodes for HeNe Lasers

Vapor deposited aluminum cathodes for parallel plate HeNe lasers have been used with considerable success. It is shown that the aluminum cold cathode is improved by the addition of copper and that other alloying elements of bulk Al 2024 do not contribute to cathode performance. The plasma oxidation process of Hochuli improves cathode performance by cleaning the surface and optimizing the oxide film for maximum efficiency. There appears to be a trade-off between life and electron tunneling efficiency for optimum oxide thickness. Auger electron spectroscopy, ellipsometry, and scanning electron microscopy are the techniques used for surface characterization.