This book gives an overview of modern cathodes and electron emitters for vacuum tubes and vacuum electron devices in general. It covers the latest developments in field emission theory as well as new methods towards improving thermionic and cold cathodes. It addresses thermionic cathodes, such as oxide cathodes, impregnated and scandate cathodes, as well as photocathodes and field emitters the latter comprising carbon nanotubes, graphene and Spindt-type emitter arrays. Despite the rise and fall of the once dominant types of vacuum tubes, such as radio valves and cathode ray tubes, cathodes are continually being improved upon as new applications with increased demands arise, for example in electron beam lithography, high-power and high-frequency microwave tubes, terahertz imaging and electron sources for accelerators. Written by 17 experts in the field, the book presents the latest developments in cathodes needed for these applications, discussing the state of the art and addressing future trends.

Presents advanced new applications of vacuum electron sources Discusses the state of the art and future perspectives of vacuum cathodes and electron sources for medical X-ray tubes Offers guidance on the application of high-brightness cathodes for high-resolution electron beams

Autorentext

Georg Gärtner received the degrees of Dipl.-Physiker in 1973 and Dr. rer. nat. in 1977 from the Johannes-Gutenberg University in Mainz, Germany. There he was involved in high-resolution spectroscopy of stored electrons and ions, especially in the first direct determination of the proton-electron mass-ratio. In 1978 he worked as a research associate in the Atomic physics group at Texas A&M University in the same field. In 1979 he joined Philips Research Laboratories in Aachen, Germany. There his main focuses were chemical vapor deposition (CVD) and laser ablation deposition (LAD) of thin solid films and ultrafine particles, mainly for preparation and characterization of high-power cathodes. The types of thermionic cathodes he investigated were thoriated tungsten, Ba dispenser cathodes and Ba.oxide cathodes. Since 1995 he and his coworkers have held the world record in thermionic emission, which they achieved with LAD top-layer Scandate cathodes. He also helped to develop the successful oxide plus (cermet) cathode of LG.Philips Displays. In 2004 he became visiting professor of Southeast University Nanjing. At Philips he worked on dielectric barrier discharge lamps and on OLEDs (organic light-emitting diodes). He retired in 2014 and is still active as a consultant in the field of vacuum electronics.

He has authored more than 100 publications and designed 102 inventions, leading to more than 50 patents (US, WO, EU, D). He is a member of the "Deutsche Physikalische Gesellschaft" and the "American Vacuum Society" and acted as coordinator of the European section of IVESC (International Vacuum Electron Sources Conference) for 14 years.

Inhalt

Historical development and advanced new applications of vacuum electron sources .- State of the art and future perspectives of Scandate cathodes.- Review of impregnated and reservoir Ba dispenser cathodes.- New developments in Ba oxide cathodes.- Electron sources for medical X-ray tubes.- High brightness cathodes for high resolution electron beam applications.- Progress in field electron emission science.- Carbon-based field emitters, properties and applications.- Explosive electron emission of carbon based cathodes and applications.- Photocathodes.