Effect of Large Modulation in Lower Coil Current on Nanopowder Synthesis by Two-Coil Tandem Modulated Induction Thermal Plasmas

Nanoparticles are regarded as promising elemental materials for nanotechnologies for various fields such as the next-generation electronics, biomedicals, energy and environmental industries. From this reason, a method for synthesizing them at high production rate is desired for wide applications of nanoparticles. The authors have developed a method: the combination of pulse modulated induction thermal plasma (PMITP) with time-controlled feedstock feeding (TCFF) method, i.e. the PMITP+TCFF method [1] . We use the PMITP to control the temperature field of thermal plasma by amplitude-modulating the coil current into a rectangular waveform periodically with high power duration and low power duration in a milliseconds cycle. In addition, in TCFF method, feedstock powder is intermittently injected to the PMITP during high power duration, which results in efficient evaporation of feedstock. During low power duration, the evaporated feedstock vapor is cooled down rapidly to make nucleation under supersaturation condition. Thus, the PMITP+TCFF method provides a high production rate of nanoparticles.