Numerical study of plasma and air heating process in single-turn coil discharges

Abstract

As a kind of destructive pulsed magnet, single-turn coil generates ultra-high magnetic field beyond 100 T by feeding the Mega-Ampère-level discharge current into a coil with the size of several millimeters. Under the effect of high temperature and high electric field, the air around the coil is ionized and exhibits magnetohydrodynamic characteristics. In this study, a numerical model is built to analyze the air heating and sample thermal destruction. This model uses the collision integral method to calculate the physical parameters of the plasma, and considers not only the heat conduction and convection but also the heat sources of Joule heat, electron-heavy particles collision, work done on air by pressure and pressure change, and air viscous dissipation. The results show that heat conduction and heat convection can only significantly heat the air near the surface of the coil. However, the power density of these two heat sources is greater than the other heat sources, resulting in the highest air temperature near the coil. In addition, Joule heat and electron-heavy particles collision have lower power densities but can heat a larger volume of air outside and inside the coil, respectively.