Collaborators

We want to understand how the maximum fields in high gradient systems depend on the surface material and explore the improvements that modifications can bring. Although high electric fields have been used in DC and RF applications for many years, up to now there has been no fundamental agreement on the cause of breakdown in these systems [1]. Recently, a group from the Muon Collaboration doing accelerator R&D, computer modelers at Argonne, and materials scientists using Atom Probe Field Ion Microscopy (APFIM) at North-western, have had success understanding the process in terms of high mechanical stresses at local field emitters in cavities. We have published this work in Phys Rev STAB, Nuclear In-struments and Methods, and many accelerator conference papers over the 18 months [2][3][4] The most interesting discovery in this work has been that the pre-breakdown environ-ment we measured in rf cavities, (0.1 µm asperities, ∼10 GV/m electric fields) has been used in material science for years, for precisely the sort of measurements we would like to make[5]. This technology has been aggressively developed and has had recent breakthroughs such as the Local Electrode Atom Probe (LEAP) microscope [6]. Our model predicts that high voltage systems will break down when the mechanical stres