Electron beam characterization of technical surfaces at cryogenic temperatures

Abstract

This dissertation presents applied research on the electron irradiation-induced emission of electrons and molecules and thermally controlled gas adsorption and desorption at cryogenic temperatures. Various technical-grade metal surfaces and functional surface coatings and treatments are studied under conditions relevant to many technical applications. A particular focus is on understanding the electron cloud and dynamic vacuum phenomena in CERN’s Large Hadron Collider (LHC), which operates at cryogenic temperatures below 20 K. Its electron cloud is characterised by low energies in 0–1 keV range but high doses up to 10 mC.mm−2. Such conditions are controllably reproduced in a newly developed cryogenic laboratory setup designed for collector-based measurements of Secondary electron emission (SEY), electron stimulated desorption (ESD), and temperature programmed desorption (TPD) at high sensitivity, precision, and accuracy. The experimental results are acquired, analysed and systematically discussed in detail. Finally, semiempirical parametric models of the SEY and ESD yields are developed to capture the energy, dose, angle, temperature and composition dependencies, allowing further use in the field. While emphasising the LHC’s electron cloud-induced dynamic vacuum effect and related phenomena, the research findings are interpreted in a generalist manner, making them relevant to other accelerators and technical applications