Research on Micro-Thermal Materials Processing with Pulsed Field Emission Current

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In this project the fundamental experiments were carried out to make clear the problems and the mechanisms of the precise thermal materials processing in micro-meter to nano-meter size with high density field emission current. The results obtained are summarized as follows :1.Theoretical prediction of field emission current from a pointed cathode coated with Carbon-Nano-Tube(CNT)The electron current distribution field-emitted from a pointed cathode, of which surface was coated by CNT on the substrate of nickel, was theoretically calculated using Fowler-Nordheim equation. The cathode shape was assumed to be axial symmetric hyperbola. The current distribution on the anode surface is varied depending on the gap length and the tip radius of the cathode.2.Measurement of field emission current from a pointed cathode coated with CNTThe field emission current was precisely measured in the range of 0.1 to 2 μm of the gap length between the cathode and stainless steel anode by applying the sinus … More oidal wave voltage. The current measured increases exponentially with increase of applied voltage. Then, the current was confirmed to be field emission current with the aid of FN plotting. The theoretical prediction of the relationship between the field emission current and the parameters such as gap length and tip radius qualitatively accorded with that by measurement. However, the current value by the measurement was higher than the calculation. It is necessary to make clear the equivalent work function of CNT and/or to treat the cathode shape carefully in the next stage of the research.3.Precise thermal materials processing by field emission currentThe precise materials processing by field emission current was tried with the CNT coated cathode in the SEM vacuum environment. The experiment showed that the melt spot was formed on the surface of stainless anode only when the electrical breakdown between both electrodes occurred. Then, it is necessary to make higher current density on the anode surface in the next stage of the research. Less