New developments in power grid electron tubes

The reduction of costs, the enhancement of lifetime of tubes and the search for environmentally friendly processes and materials gave the main impact for research and development efforts within the last years for power grid electron tubes. Physical and chemical effects are discussed that determine the performance of todays devices. New material compositions are reported for directly heated cathodes. Ways to enhance the lifetime of emitting filaments are described. Important physical properties limiting the performance of grids in electron tubes are given. Due to the progress made in the fundamental understanding, the reliability and reproducibility of electron tubes could be improved considerably. Modern computer controlled manufacturing methods ensure a high reproducibility of production, while continuous quality certification according to ISO 9001 guarantees future high quality standards. Some typical applications of these tubes are given as an example