Influence of nanoparticulates and microgrooves on the secondary electron yield and electrical resistance of laser-treated copper surfaces

TL;DR

This study investigates how laser-induced microgrooves and nanoparticles on copper surfaces affect secondary electron yield and electrical resistance, highlighting the importance of surface features and cleaning procedures.

Contribution

It provides a systematic analysis of how microstructure and particulates influence SEY and resistance, offering insights for optimizing laser-treated copper surfaces.

Findings

Microgrooves and nanoparticle coverage significantly affect SEY.

Exposing groove tips reduces SEY and resistance.

Nanoparticles in grooves have a larger impact on SEY.

Abstract

Laser surface structuring has proven to be an effective technique for achieving a copper surface with secondary electron yield (SEY) values close to or below unity. However, the attributes that minimize SEY, such as moderately deep grooves and redeposited nanoparticles, may lead to undesirable consequences, including increased radio frequency surface resistance. This investigation systematically examined data about different cleaning procedures designed to eliminate redeposited adsorbed particulates. Various analysis techniques were used iteratively after each consecutive cleaning step, providing insights into the evolving surface characteristics. The collected experimental results identified distinct impacts of microgrooves, groove orientation, and associated particulates on secondary electron yield and surface resistance. Exposing the crests while retaining high particulate coverage in the grooves leads to reduced SEY values and surface resistance, suggesting that the tips of the grooves exert a more significant influence on surface current density than the groove depth. At the same time, nanoparticles in the grooves have a more significant impact on SEY values than the exposed tips at the surface.