Comparison of micro- and nanocrystalline diamond films for charge exchange injection

Abstract

Carbon foils are regularly used for charge exchange injection in beamline accelerators. As beamlines increase the beam power, the thermal durability and longevity of the stripper foils become critically important to maintaining longer beamline operating times. In this study we examine the current Spallation Neutron Source nanocrystalline diamond stripper foils and compare them to microcrystalline alternatives. To do this, an electron beam mimic is used to emulate the power dissipation and thermal load of the SNS beam on the test stripper foils. The tested foils are analyzed based on the resultant temperature of the film and the fraction of electron beam collected by the Faraday cup during beam exposure. Additionally, postmortem testing was conducted to determine the emissivity, vibrational structure via Raman spectroscopy, and surface morphology of the foils.