High-field dielectric properties and AC dissipation current waveforms of polyethylene film

The authors have developed a new method for the detection of AC dissipation in dielectric materials under high AC field. Using this technique, high-field dielectric loss properties and their relation to AC dissipation current of low-density polyethylene (LDPE) films are measured. Near room temperature, tan δ of a LDPE film has small electric field dependence. In this temperature region, the dissipation current shows saturation around the voltage peaks in phase even with high-field application. At higher temperatures, however, the high-field tan δ tends to have a strong field dependence, and the AC dissipation current deforms and is nonlinear near the voltage peaks. The nonlinearity of the AC dissipation current decreases under the decrease of tan δ with the voltage application period. These results show that the large increase of tan δ in the high-field and high-temperature region is related to the loss due to DC-like carrier motion