We realise, with capacitor bank, electrical discharge in various types of insulator. The plasma is initiated by an explosion wire. The tested materials are: the polyethylene (PE (CH2)n), the polyoxymethylene (POM (CH2O)n), the polyamide 6-6 (PA66 (C12H22O2N2)n), the methyl polymethacrylate (PMMA (C5H8O2)n) and the polytetrafluoroethylene (PTFE (CF2)n)...We have shown differences in terms of ablated mass, pressure and plasma thermodynamic properties between these materials.
Evolutions versus time of the current, the voltage and the pressure
With a MEB, we have seen the area of a test tube after the discharge. Various copper molecular structures have shown that only a low fraction of copper interact with the plasma :
Copper granular cluster
The composition of the plasma resulting from the interaction with the insulator wall is calculated, for example in the case of a plasma made of copper and polyethylene. During the cooling of the plasma, graphite is created around 3500 K, and liquid copper is created around 2260 K. Graphite is the first species to condense on the wall.