Millisecond-time range analysis of space charge distribution and electroluminescence in PE and PEN under transient electric stress

The combined analysis of space charge and electroluminescence in insulating polymers provides useful information on charge transport and energy dissipation. We are particularly interested in defining critical transport regimes leading to energy release in a range that is potentially harmful for the material. These critical regimes can be characterized by investigating the internal charge distribution when electroluminescence is detected. If the DC case has been treated recently, very few results are reported concerning transient electric stress because the experiment needs an ultra-fast space charge detection setup. We have carried out such an analysis when low density polyethylene and polyethylene naphthalate films are submitted to transient voltages of 50 ms in duration, by using fast acquisition techniques for the both space charge profile (50 μs time resolution) and electroluminescence acquisition (250 μs time resolution).