Work

Effect of traps and conductive pathways on electron emission from copper broad-area composite emitters

Year: 2024

Type: article

Abstract: This study investigates electron emission from copper broad-area emitters (CBAEs) and copper broad-area composite emitters (CBACEs) based on the principles of trapping and conductive pathways. Emission current measurements were conducted on two CBACEs, which consisted of copper coated with a 300–400 μm epoxy resin and subjected to high voltages up to 15 kV. The research specifically examines the ‘switch-on’ and collapse phenomena occurring within the epoxy layer. Field emission microscopy (FEM) was utilized in a high-vacuum environment ( 10 − 6 mbar) to observe these effects. A comprehensive model is developed to explain the formation of conductive pathways within the epoxy layer, allowing electrons transfer from traps to the surface. This model treats the composite emitter as a trap-rich capacitor. The study also clarifies the effects of trap density and epoxy layer thickness on the collapse process. To gain a deeper understanding of the model, changes in the I-V curve were examined. Simulations, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) images, and Fourier transform infrared spectroscopy (FTIR) analysis were employed to understand the collapse mechanism of the epoxy collapse. Additionally, Nyquist and Cole–Cole plots were analyzed across frequencies ranging from 1 to 10 6 Hz before and after applying a high electric field on the samples, revealing changes in the capacitive component and the role of diodes in the formation of conductive channels.

Source: Physica Scripta

DOI: 10.1088/1402-4896/ad80df