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The physics of high-current beams in the space-charge dominated regime is not sufficiently
well-understood. Traditional circular accelerators and storage rings typically operate in a regime
where space charge is a minor perturbation. However, such applications as future high-energy physics
colliders (e.g. muon colliders), synchrotron light sources, spallation neutron sources, and heavy ion
inertial fusion drivers demand increasingly higher currents. Since the beam quality cannot be
sacrificed, the challenge is to transport the high-current beams for long distances without
substantial degradation.
To address this challenge, the University of Maryland Electron
Ring (which is currently under construction at the Institute for
Research in Electronics and Applied Physics) is designed to be a low-cost, scaled machine to investigate the physics of
highly space-charge-dominated beams transported in a circular lattice. Magnetic quadrupole lenses
are used for strong transverse focusing, while induction modules are used for longitudinal focusing
and acceleration. An innovative feature of the Maryland E-ring is the use of printed-circuit magnets,
a technology that reduces the cost of the magnets down to a few thousand dollars for the entire lattice.
Research issues include resonance traversal, dispersion, longitudinal focusing,
longitudinal-transverse coupling, longitudinal and transverse space-charge waves,
as well as the longitudinal resistive-wall instability. Another purpose for the ring is to serve
as a test bed for benchmarking various computer codes that may be used in designing other, larger
machines, such as hadron colliders, lepton colliders, synchrotron light sources, spallation neutron
sources, and heavy ion inertial fusion drivers.
Funding for the Maryland Electron Ring project is provided by the U.S. Department of Energy.
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