Experiments Studying Desorbed Gas and Electron Clouds in Ion Accelerators

Electron clouds and gas pressure rise limit the performance of many major accelerator rings. We are studying these issues experimentally with ∼ 1 MeV heavy-ion beams, coordinated with significant efforts in self-consistent simulation and theory. The experiments use multiple diagnostics, within and between quadrupole magnets, to measure the sources and accumulation of electrons and gas. In support of these studies, we have measured gas desorption and electron emission coefficients for potassium ions impinging on stainless steel targets at angles near grazing incidence. Our goal is to measure the electron particle balance for each source – ionization of gas, emission from beam tubes, and emission from an end wall – determine the electron effects on the ion beam and apply the increased understanding to mitigation. We describe progress towards that goal.