Review of heavy-ion induced desorption studies for particle accelerators

Abstract

During high-intensity heavy-ion operation of several particle accelerators worldwide, large dynamic pressure rises of orders of magnitude were caused by lost beam ions that impacted under grazing angle onto the vacuum chamber walls. This ion-induced desorption, observed, for example, at CERN, GSI, and BNL, can seriously limit the ion intensity, luminosity, and beam lifetime of the accelerator. For the heavy-ion program at CERN’s Large Hadron Collider collisions between beams of fully stripped lead (^{208}Pb^{82+}) ions with a beam energy of 2.76 TeV/u and a nominal luminosity of 10^{27} cm^{-2} s^{-1} are foreseen. The GSI future project FAIR (Facility for Antiproton and Ion Research) aims at a beam intensity of 10^{12} uranium (^{238}U^{28+}) ions per second to be extracted from the synchrotron SIS18. Over the past years an experimental effort has been made to study the observed dynamic vacuum degradations, which are important to understand and overcome for present and future particle accelerators. The paper reviews the results obtained in several laboratories using dedicated test setups, the mitigation techniques found, and their implementation in accelerators.