نتایج جستجو برای: field emission cathode
تعداد نتایج: 958226 فیلتر نتایج به سال:
Among the various electron emission mechanisms the emission using ferroelectric ceramics is the ‘‘junior’’ process. It was observed at very low current density levels ~10 pA/cm! in 1984 by Rosenman. Five years later, Riege and his co-workers at CERN demonstrated current densities that are 13 orders of magnitude higher. In 1990 Airapetov reported the highest current density so far when measuring...
The gas discharge and photo-luminance properties of a planar lighting source featuring highly uniform light emission and mercury-free design were studied. The current density-voltage characteristics and the associated gas discharge of the devices operating with the values of the ratio of electric field to gas pressure (E/p) between 4.3 kV/Torr-cm and 35.7 kV/Torr-cm indicate that the width of t...
Conversion of solar radiation to electricity with Photon-Enhanced Thermionic Emission (PETE) uses both photonic and thermal excitation of charge carriers in a semiconductor. This device includes a semiconductor cathode (which can be composed of several semiconductor materials) illuminated and heated by concentrated sunlight, and a cooler anode, separated by a small vacuum gap. First theoretical...
Electrical discharge in vacuum is accompanied by X-ray radiation. Knowledge of the generation mechanism of radiation may lead to its practical use. The analysis of this phenomenon indicates that it is only at the discharge development phase until the moment of the anode plasma generation that the proper conditions for X-ray generation are satisfied. The intensity of radiation is dependent on th...
A detailed evaluation of the analytical characteristics of a particle beam/hollow cathode glow discharge atomic emission spectroscopy (PB/HC-AES) system is described for applications in the area of organic sample analysis. The optimization of sample introduction, nebulization parameters, and glow discharge conditions was performed for the elemental analysis (focusing on C and H) of a group of a...
Electrostatic focusing lenses have a vast field of applications in electrostatic accelerators and particularly in electron guns. In this paper, we first express a parametric mathematical analysis of an electrostatic accelerator and focusing system for an electron beam. Next, we At design a system of electron emission slit, accelerating electrodes and focusing lens for an electron beam emitted f...
A great deal of experimental evidence shows that the perveance of high power klystrons is much higher than normal at low voltage. Thus the three-halves power law is violated in that range. It is hypothesized that this is caused by edge emission. A detailed analysis is given. The calculated magnitude is reasonably coincident with experimental results. The analysis is also valid for other thermio...
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