Dielectric Property Alteration and Measurement Techniques of Composite Solid Insulators

High-voltage pulsed power systems are typically insulated with gas or liquid dielectrics, which offer high breakdown strengths and self-healing properties. Dielectrics in these states, however, come with design challenges that can increase the size, weight, and complexity of a system. Potting a system with a solid insulator is not uncommon, and however, it is imperative that the dielectric properties of the insulator is well understood since potted systems are nearly impossible to perform maintenance on, and a single breakdown event can cause a catastrophic failure requiring a full system replacement. There is interest in pursuing functionally graded solid dielectrics, which utilize composites to reduce electric field enhancements between dissimilar materials. By spatially grading the permittivity of the insulator between dissimilar materials, these large field enhancements may be reduced to offer the ability to minimize overall system size and weight. Composite solid dielectrics with the ability to specifically tune their dielectric properties are also attractive for elements in high-power microwave (HPM) system design. In this article, methods for fabrication and dielectric property measurement of composite solids are presented, along with permittivity measurement results across a wide frequency range. Specifically, EPON 815C epoxy is loaded with aluminum oxide (Alumina), barium strontium titanate (BST), calcium copper titanate (CCTO), and calcium titanate (CTO) additives up to 30% by mass, and the permittivity of these composites is measured from 1 MHz up to 12 GHz. It is shown that the permittivity of the base material can be increased up to and beyond 65% of its original value within the scope of these specific material additives and loading percentages.