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.
Nanocharacterization by Atom Probe Tomography is a practical guide for researchers interested atomic level characterization of materials with atom probe tomography.Readers will find descriptions of the atom probe instrument and atom probe tomography technique, field ionization, field evaporation and field ion microscopy. The fundamental underlying physics principles are examined, in addition to data reconstruction and visualization, statistical data analysis methods and specimen preparation by electropolishing and FIB-based techniques. A full description of the local electrode atom probe - a new state-of-the-art instrument - is also provided, along with detailed descriptions and limitations of laser pulsing as a method to field evaporate atoms. Valuable coverage of the new ionization theory is also included, which underpins the overall technique.