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The paper describes a technique for training multi-tip field cathodes with high voltage, which makes it possible to optimize the emission current on the basis of field projector data. The paper presents an algorithm for obtaining and analyzing experimental data, which allows for controlled training of the cathode surface, and also presents the results of the analysis of experimental data obtained for a promising nanocomposite structure of carbon nanotubes in polystyrene. [ABSTRACT FROM AUTHOR]

The emission area is one of the main parameters of field emission systems. A variety of formal determination techniques for the emission area is studied. Using the model hemisphere-on-cylindrical-post constructed with the COMSOL Multiphysics software package, the relation between well-known estimates of the emission area is shown. The corresponding fractions of the emission currents are computed. It is demonstrated that the formal emission area (the ratio of the total current to the current density at the vertex) ensures approximately 75% of the emission current. The effect of abnormal behavior on the effective emission area is obtained (cutoff from the trend line of the current–voltage characteristics) for varying voltage level in standard Fowler–Nordheim coordinates. An experimental assessment of the area with application of modified Fowler–Nordheim coordinates ln(I/U2–η/6) vs 1/U is proposed. The method is applied for analysis of field emission data of the multipoint nanocomposite emitter with carbon nanotubes. [ABSTRACT FROM AUTHOR]

A test for the correspondence of experimental current–voltage (I–U) characteristics to the regime of cold field emission is described. The proposed method is based on the variation of voltage power index in semilogarithmic coordinates ln(I/U k)–1/U and the statistical analysis of fluctuations in experimental data. It is established that I–U characteristics obtained by the method of fast high-voltage sweep provide a better correspondence to the field emission law than do the characteristics measured using slow voltage sweep. The test sample was a multitip nanocomposite field emitter based on carbon nanotubes in a polymer matrix. Experimental data have been processed in modified Fowler–Nordheim coordinates with power exponent k = 1.24. [ABSTRACT FROM AUTHOR]

Statistical properties of the characteristics of a field-electron emitter based on a polystyrene-carbon nanotube composite have been studied. Experimental data have been used to plot the slope versus intercept of I-U curve in the Fowler-Nordheim coordinates and a histogram of the effective heights of emission centers. Numerical estimations show that this statistics obeys the lognormal distribution law. A series of experiments have been performed for determining the influence of the level of emission current on the character of distribution, and a model describing this dependence is proposed. [ABSTRACT FROM AUTHOR]

Rapid progress in investigations of the field-electron emission from polymer-carbon nanotube composite cathodes poses a key question concerning the effect of the properties of matrix molecules on the parameters of emission. In this context, the results of a comparative investigation of the characteristics of field-electron emitters prepared from compositions based on various polymer matrices are presented. Data on the influence of rigidity and polarity of macromolecules on the emissivity of nanocomposite emitters have been obtained for the first time. [ABSTRACT FROM AUTHOR]

The present work concerns the evaluation of emitting multiwall carbon nanotube (MWCNT) temperature, here referred to as “emission point” temperature. The latter is related to the onset of thermal degradation of polymer molecules neighboring to the MWCNT. The investigation method combines the registration of both current voltage characteristics and thermal degradation volatile products for “polymer-MWCNT” composite emitter during the emitting process. Our experimental setup involves a time-of-flight mass spectrometer and field emission unit. [ABSTRACT FROM AUTHOR]