Electron microphysics at plasma-solid interfaces

TL;DR

This paper emphasizes the importance of studying the electronic structure of plasma-facing solids and proposes using modern surface physics techniques to explore the wall charge, a less understood aspect of plasma-solid interfaces.

Contribution

It introduces the need for in-operando electronic structure investigations of plasma-facing solids and suggests infrared reflectivity as a measurement method.

Findings

The wall charge significantly influences plasma-solid interactions.

Infrared reflectivity can potentially measure wall charge in situ.

Encourages interdisciplinary research at plasma and surface physics interface.

Abstract

The most fundamental response of a solid to a plasma and vice versa is electric. An electric double layer forms with a solid-bound electron-rich region-the wall charge-and a plasma-bound electron-depleted region-the plasma sheath. But it is only the plasma sheath which has been studied extensively ever since the beginning of plasma physics. The wall charge received much less attention. Especially little is known about the in-operando electronic structure of plasma-facing solids and how it affects the spatio-temporal scales of the wall charge. The purpose of this perspective is to encourage investigations of this terra incognito by techniques of modern surface physics. Using our own theoretical explorations of the electron microphysics at plasma-solid interfaces and a proposal for measuring the wall charge by infrared reflectivity to couch the discussion, we hope to put together enough convincing reasons for getting such efforts started. They would open up-at the intersection of plasma and surface physics-a new arena for applied as well as fundamental research.