UMD, College Park, Maryland, USA
Linear perturbation analysis of the RMS envelope equations predicts a frequency splitting of the transverse envelope modes with the onset of space charge. The resulting resonances are a potential source of beam degradation for circular particle accelerators and storage rings encountering space charge. Following WARP simulations that predict measurable consequences of these resonances, an experiment has been designed for their direct detection. This paper provides a detailed description and preliminary results of an experiment to study envelope resonances in the beam at the University of Maryland Electron Ring (UMER), a scalable high intensity electron storage ring.
FROAA1
UMD, College Park, Maryland, USA
Space charge, especially in the beam source and low energy regions, can substantially impact the dynamics of advanced accelerators at the intensity frontier. UMER uses scaled electron beams at nonrelativistic energies (10 keV) to inexpensively access the intense space charge dynamics directly relevant to low-energy hadron and ion beams, in both rings and linacs. In UMER, space charge tune depressions at injection are adjustable in the range of 0.14 - 0.8, enabling scaled examination of a wide range of phenomena. Longitudinal induction focusing is used to counteract the space charge force at the edges of a long rectangular bunch, confining it for 100s of turns. This paper reviews recent experimental, computational, and theoretical research on UMER. Specific topics include longitudinal induction bunch-end focusing; generation and propagation of longitudinal space charge waves, including large-amplitude solitons; bunch end interpenetration and observation of a resulting multi-stream instability; beam halo studies; beam current-dependence of classical ring parameters (natural chromaticity, lattice dispersion and momentum compaction); and diagnostic development.
