BNL, Upton, Long Island, New York
UMD, College Park, Maryland
JLAB, Newport News, Virginia
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
In this paper we report on a proof of principle experiment for demonstrating the possibility of reconstructing the time resolved-phase-space distribution of a space-charge dominated beam by a tomographic technique which provides us with far more information than a time-sliced emittance. We emphasize that this work describes and demonstrates a new methodology which can be applicable to any beam pulse using imaging methods with the appropriate time resolution for the pulse duration. The combination of a high precision tomographic diagnostic with fast imaging screens and a gated camera are used to produce phase space maps of two beams: one with a parabolic current profile and another with a short perturbation atop a rectangular pulse. The correlations between longitudinal and transverse phase spaces are apparent and their impact on the dynamics is discussed.
UMD, College Park, Maryland
Funding: * This work is funded by US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
The containment of beams in the longitudinal direction is fundamental to the operation of accelerators that circulate high intensity beams for long distances such as the University of Maryland Electron Ring (UMER); a scaled accelerator using low-energy electrons to model space-charge dynamics. The longitudinal space-charge forces in the beam, responsible for the expansion of the beam ends, cause a change in energy at the beam head/tail with respect to the main injected energy or flat-top part of the beam. This paper presents the first experimental results on using an induction cell to longitudinally focus the circulating beam within the UMER lattice for multiple turns.
Keywords: electron ring, focusing, induction cell.
UMD, College Park, Maryland
BNL, Upton, Long Island, New York
Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
Beam matching is critical for avoiding envelope mismatch oscillations that can lead to emittance growth and halo formation, especially if the beam has significant space charge. The University of Maryland Electron Ring (UMER) is a research storage ring that is designed for scaled studies that are applicable to many larger machines. Using 10 keV electron beams at relatively high current (0.6 100 mA), space charge forces are relatively strong. Matching of the UMER beam is rendered difficult by the space charge, the crowdedness of the lattice, and especially the unique injection scheme where an offset oversized quadrupole is shared between the ring and the injector. In this paper we discuss several schemes for optimizing the matching at injection, both analytical and beam-based, which we test using particle-in-cell simulations with the code, WARP. Comparison to UMER experimental data is provided where available.