Abstract:
Homocharge, particularly, positive charge near anode has been observed inside lowdensity polyethylene (LDPE) by many researchers. However, the phenomenon is yet to be
understood theoretically and mathematical analysis is pending, although, simulations
have been reported. Simulation of evolution of space charge in LDPE, with time and
space, using bipolar charge transport model considered only drift component of charge
carriers inside the dielectric. The experimental results suggest significant concentration
gradient in space charge distribution. The authors derived a comprehensive drift and
diffusion based analytical models, for the time/space evolution of space charge and
electric field in dielectrics using Maxwell’s equations, current continuity equation,
conduction and injection mechanisms. The proposed analytic models of electric field and
space charge distribution entwines charge injection at electrodes and charge transport
inside the medium, which seem to have not been reported until now. Remarkable,
believed to be unprecedented, agreement between the analytical and experimental results
has been observed. Using the model, the role of conduction, injection, diffusion on
homocharge accumulation has been investigated. Pulsed electroacoustic method is used
for the measurements of the space charge dynamics.
