Numerical study on the discharge properties of a dual-coil pulsed power inductively coupled plasma torch

Inductively Coupled Plasma (ICP) is one of widely used thermal plasmas characterized by high density, high purity, and high temperature. It demonstrates significant advantages in the field of nano-powder production of refractory metals, thus necessitating a more detailed study of its discharge properties. In this paper, the discharge process of the non-equilibrium dual-coil pulsed-power ICP torch is simulated with argon as the working gas. The coupling of the electromagnetic-, chemical-, and flow-field equations is considered for the dual-coil arrangement ICP torch at different operating conditions. A multi-physics mathematical model, which includes Maxwell equations, Navier–Stokes equations, gas transport equations, and seven chemical reactions of argon, is established to calculate the non-equilibrium characteristics of a dual-coil pulsed power ICP torch. Moreover, the effects of different working conditions, such as different coil frequency and pulsed-power ratio on the flow properties of the ICP torch are also studied and discussed. It is found that as the coil frequency or coil distance increases, the plasma electrical conductivity decreases, leading to higher impedance and a weakened induced magnetic field, while the electron temperature rises, causing an increase in plasma voltage. Furthermore, increasing the distance between the coil and the quartz tube enhances the electromagnetic field but reduces electron-coupling energy, resulting in lower electron temperatures. These findings might provide theoretical support for optimizing the system design of the ICP torch.