Imaging of Feedstock Particle Dynamics in Thermal Plasma for Nanoparticle Sythesis by Laser-Strobe Measurement

Nanoparticles are particles with a size of 100 nm or less, which have different properties from bulk materials. For various applications of such nanoparticles, it is desired to develop a high-rate synthesis method for nanoparticles. The authors have developed pulse modulated induction thermal plasma (PMITP) and time-controlled feedstock feeding (TCFF) method, as a method for synthesizing large amounts of nanoparticles [1]. In PMITP, the temperature of thermal plasma can be controlled in the order of milliseconds by amplitude-modulating the high-frequency coil current in a rectangular waveform. To this PMITP, feedstock particles are intermittently injected to be evaporated in high-temperature period, and then the evaporated feedstock vapor is transported to downstream of the plasma torch, where nucleation occurs due to supersaturation state, generating nanoparticles.