Photoelectron Emission from Metal Surfaces Induced by Radiation Emitted by a 14 GHz Electron Cyclotron Resonance Ion Source

TL;DR

This study measures photoelectron emission from common plasma chamber materials caused mainly by plasma radiation in a 14 GHz ECR ion source, estimating it to be a significant fraction of plasma electron losses.

Contribution

It provides the first quantitative analysis of photoelectron emission induced by plasma radiation in a 14 GHz ECR ion source, focusing on common chamber materials.

Findings

Photoelectron emission is mainly caused by plasma radiation between 8 eV and 1 keV.

Characteristic X-ray and bremsstrahlung contribute negligibly to emission.

Maximum photoelectron flux is about 10% of total plasma electron losses.

Abstract

Photoelectron emission measurements have been performed using a room-temperature 14 GHz ECR ion source. It is shown that the photoelectron emission from Al, Cu, and stainless steel (SAE 304) surfaces, which are common plasma chamber materials, is predominantly caused by radiation emitted from plasma with energies between 8 eV and 1 keV. Characteristic X-ray emission and bremsstrahlung from plasma have a negligible contribution to the photoelectron emission. It is estimated from the measured data that the maximum conceivable photoelectron flux from plasma chamber walls is on the order of 10 % of the estimated total electron losses from the plasma.