Plane-wave based electron tunneling through field emission resonance states
We acknowledge support from the Basque Departamento de Educacion and the UPV/EHU (Grant No. IT-756-13), the Spanish Ministerio de Ciencia e Innovacion (Grant No. FIS2010-19609-C02-00), and the ETORTEK program funded by the Basque Departamento de Industria and the Diputacion Foral de Gipuzkoa. L.W. Wang is supported by the US DOE/SC/BES under contract No. DE-AC02-05CH11231.
Low-Energy Electron Diffraction
The essential elements are an ultrahigh vacuum (UHV) chamber to preserve surface cleanliness, an electron gun to produce a collimated beam of electrons in the energy range 0 to 500 eV, a crystal holder and manipulator, and some means of observing the diffracted electrons, typically a fluorescent screen. Further details may be found elsewhere.(1–3) The major difficulty is common to all surface experiments, namely, to keep the surface clean. The UHV chamber will normally contain an array of techniques for cleaning the surface (provision for heating the sample, ion bombardment) as well as some means of detecting impurities at the surface, usually by detection of Auger signals from adsorbed atoms. LEED is very sensitive to cleanliness of the surface and small amounts of contaminant can produce quite spurious results. Experiments conducted on clean, perfect, surfaces can produce a large amount of structural information of high precision. Obviously it is only possible to produce precise data for surfaces which are well defined in the first place.
Microwave source with enhanced radiation power based on orbitron MASERs
We have proposed the design of high power microwave source in a vacuum tube based on the theory of negative mass instability. The proposed source does not operate based on a slow-wave structure but instead makes use of accelerated charged particles. In our structure, an electron emitter injects the charged particles into to the cavity. Emitted particles move around the anode, which leads to electron acceleration and emission of electromagnetic waves with a specific frequency. In this paper, we have enhanced the output power and frequency of microwave source by variation of particles initial energy and the number of anodes incorporating their specific arrangement and applied voltages. Working at room temperature, compactness, wide bandwidth, and tunability of output frequency are among the advantages of the proposed source.