Polarity Effect Measurements Using the Kerr Electro-Optic Effect with Coaxial Cylindrical Electrodes

Steady state solutions of the electric field and space charge density distributions using a drift dominated unipolar conduction model between coaxial cylindrical electrodes are reviewed and compared to experimental results obtained using the Kerr electro-optic ptic effect. With coaxial cylindrical electrodes, Kerr measurements generally showed weak positive charge injection when the outer cylinder was positive and strong positive charge injection when the inner cylinder was positive. For one case study, positive charge injection at the inner cylindrical electrode was so strong that the space charge shielding caused the electric field at the inner cylinder to be a minimum, with the field increasing to the outer cylindrical electrode in complete contrast to the usual space charge free 1/r field dependence. This polarity effect is observed also for a sinusoidal ac high voltage with an essentially space charge free field when the inner cylindrical electrode was instantaneously negative, and a space charge distorted uniform field when the inner cylinder was instantaneously positive.