A Novel Supersonic Plasma Generator with an Interelectrode DC Torch for Preparation of Nano-Structured Materials

Summary form only given. A supersonic plasma jet has attracted much attention as a most promising candidate for the production of high-quality nano-structured materials with high yield rate due to its dual characteristics as a thermal plasma and a quenching jet. In this work, we have designed a novel supersonic plasma generator in one united body integrated with an interelectrode plasma torch, a reaction chamber, and a supersonic nozzle to enhance the chemical reactions for preparation of nano-structured materials before quenching the reactive thermal plasma by supersonic expansion. The design values of the interelectrode torch and the reaction chamber are obtained by numerical analyses on thermal plasma properties and plasma-particle interactions to guarantee the complete chemical reactions for formation of nano-structured materials within the thermal plasma jet. Especially, the supersonic nozzle is designed on the basis of the accurate estimation of the isentropic exponent for the mixture-gas plasma of argon and hydrogen either in a local thermodynamic equilibrium (LTE) or in a non-LTE state. The supersonic plasma jet produced by the nozzle with a Mach number of 1.5 shows a Mach number of 1.63 and the corresponding axial velocity of about 3,300 m/s from the enthalpy probe measurement, which indicates relatively good agreement with the designed value.