Characteristics of space charge limited field

“Space charge limited field” (SCLF) is important to applications ranging from end turn grading in rotating machines to defect tolerance in solid dielectrics. While an analytical basis is available for estimating the SCLF as a function of frequency given the electric field-dependent conductivity, no good basis exists for estimating the extent of the SCLF as a function of applied voltage. The extent of the SCLF is important under nearly all conditions that the SCLF is important and is addressed based on a reasonable approximation for the velocity of the SCLF front through the ratio of the current density to space charge density.