The influence of thermal disequilibrium on a plasma consisting of insulator vapours
Résumé
With the Gibbs free energy minimization method, we determine the molar fraction in a plasma out of thermal equilibrium consisting of ablated vapours of polymer (polyethylene and polyoxymethylene) in the temperature range 1000-6000 K. We indicate the formulae and the numerical method used to perform the calculation, taking the graphite phase into account. We show that there is an increase in the electronic mole fraction and a decrease in the mole fraction of negatively charged species when the plasma is out of thermal equilibrium. We clarify the role played by the vibrational temperature in determining the molar fraction and we show that the higher the vibration the higher the diatomic molar fraction. The calculation for vapours ablated from polyethylene has shown that it is possible to produce graphite in the presence of a plasma. The comparison of the two polymers studied has shown that polyoxymethylene produced less graphite than polyethylene does and that the polyoxymethylene insulator is bound to be less consumed by the plasma.