3. Introduction to Plasmas Available to Purchase

Plasmas are composed of amixture of electrons, ions, and neutral species in local electrical neutrality. Electrons accelerated by an applied electric field, collide with larger particles, transferring kinetic energy, which contributes to the excitation and ionization of atoms and molecules, and to the heating of the gas (Samal, 2017).As a result, a highly conductive gas is formed, which allows for the flow of current through it. Thermal plasmas are typically produced with direct current (DC) transferred arcs, plasma torches, or radio frequency (RF) inductively coupled discharges. One of the main characteristics of thermal plasmas is that the kinetic temperature of the neutral particles, ions, and electrons are in local thermodynamic equilibrium (LTE), so they can be characterized by a single temperature. However, some deviations from LTE may exist, especially in the presence of steep temperature gradients (Boulos, 1991). Industrial applications of thermal plasmas tend to operate at pressures p ≥ 1 atm, with electron densities in the range between 10²² and 10²⁵ electrons/m³, and electron kinetic temperatures between 0.25 and 1 eV (3000 to 11,600 K). In general, industrial plasmas have only a fraction of the total number of particles in the gas ionized.