Secondary electron emission from reticulated cellular copper surfaces

Abstract

An experimental and computational study of the secondary electron yield (SEY) of copper foam is presented. Ray-tracing Monte Carlo (MC) simulations, based on primary electron transport and interactions with the electron system in solid and foam-type copper, are also included. The 3D reticulated foam geometry is explicitly represented in the MC model. This allows the influence of the complex copper surface on the energy and angular dependence of the SEY to be determined. Experimental measurements of SEY were performed in a high-vacuum electron gun chamber. Solid copper and copper foam with 100 pores per inch and a 4.6% volume fraction were tested for energy and angular dependence of SEY. Incident angles were varied from 0° to 75° and electron beam energy ranged from 20 eV to 570 eV. The agreement between MC simulations and experiments suggests that a general reduction of the SEY by around 20% is due to the interaction and subsequent adsorption of a fraction of emitted secondary electrons on the internal surfaces of the reticulated foam. Moreover, it is found that the SEY becomes nearly independent of the incident electron energy above 200 eV for steep angles of incidence (θ>45°).

Efficient Combination of Surface Texturing and Functional Coating for Very Low Secondary Electron Yield Surfaces and Rough Nonevaporable Getter Films

“…A SEY reduction can be obtained by surface roughening, [39][40][41][42][43] machining of deep trenches or grooves, [44][45][46][47] and several approaches to create a micro-or nanostructured morphology. Microporous structures [48][49][50] as well as a sponge or foam topology [51][52][53][54] enable trapping of impinging and emitted electrons as efficiently as textured surfaces formed by etching [55] or nanowires created by different techniques. [56][57][58][59] Furthermore, plasma-based nanostructure formation [60] as well as laser-induced surface structuring on different length scales [61][62][63][64] have been validated to reduce secondary electron emission.…”