Dielectric High Gradient Insulator – A novel approach to insulating structures

Abstract

An insulator structure, periodically altering between dielectric and metallic layers, exhibits significantly greater vacuum surface flashover threshold than a single dielectric material. However, under multiple high voltage pulses, these structures, known as High Gradient Insulators (HGI), suffer from breakdown damage in the dielectric layers, and from metal deposition on the insulator surface. Both phenomena degrade insulator performance. Moreover, implementing these structures is complicated, thus limiting device miniaturization. In this work we demonstrate a novel concept for HGI. By replacing the metallic layers with insulating high dielectric constant material, an equivalent structure, denoted Dielectric High Gradient Insulator (DHGI), is formed. We realize a DHGI structure with an order of magnitude lower number of surface breakdowns during conditioning and ∼18% higher breakdown field, compared with a plain alumina insulator. Electrostatic computer simulations suggest that the DHGI shapes the electric field and deflects incident electrons from insulator surface, in a similar manner to common HGI. The all-dielectric structure is superior to existing HGI structures, since it can support miniaturization and accommodation to various geometries. Furthermore, this structure is not prone to undergo the degradation mechanisms described earlier. Hence, the proposed structure is expected to present improved reliability and endurance, with greater applications versatility.