Heavy-Ion-Induced Electronic Desorption of Gas from Metals

During heavy-ion operation in several particle accelerators worldwide, dynamic pressure rises of orders of magnitude were triggered by lost beam ions that bombarded the vacuum chamber walls. This ion-induced molecular desorption, observed at CERN, GSI, and BNL, can seriously limit the ion beam lifetime and intensity of the accelerator. From dedicated test stand experiments we have discovered that heavy-ion-induced gas desorption scales with the electronic energy loss (dEₑ/dx) of the ions slowing down in matter; but it varies only little with the ion impact angle, unlike electronic sputtering.