Electrothermics

2.1. Introduction

The fundamental plasma experiment was performed in 1813 by H. Davy, who discovered the capacitive discharge at high current, which is also known as the electric arc. The inductive discharge was only performed later by W. Hittorf in 1884 [HIT 84]. Plasma technology has kept evolving ever since, from a laboratory prototype to plasma technology used on an industrial scale. Plasma was only identified in 1928 by Langmuir during his work on the atomic hydrogen [LAN 28], and the term “plasma” did not become part of the everyday jargon of physics until the late 1950s.

At first, plasma physics was considered to be the physics of gas discharges, and described by laws often more qualitative than quantitative. Today, research in the field must keep track of multiple theories: atomic and molecular theory, kinetic theory, statistics, fundamental gas discharge concepts, continuous medium equations, and properties of thermodynamics, transit, radiation, etc. [CRE 01].

Depending on pressure and the rate of ionization of the plasmagene gas, plasmas are of two types: cold plasma and thermal plasma. In this chapter, we consider thermal plasma at atmospheric pressure. For reasons of clarity and terminology, we define some useful notions on plasmas, thermal plasmas, inductive thermal plasmas, and radiofrequency inductive thermal plasma installations.