Author: Stem, W.D.
Paper Title Page
WEPPR014 Recovering Measured Dynamics from a DC Circulating Space-Charge-Dominated Storage Ring 2967
  • W.D. Stem, B.L. Beaudoin, I. Haber, T.W. Koeth
    UMD, College Park, Maryland, USA
  Funding: This work is supported by the US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
Space-charge is increasingly significant at high beam intensities such as in FEL injectors and heavy ion inertial fusion drivers, where it dominates the beam dynamics. The University of Maryland Electron Ring (UMER) is a high intensity circular machine that is dedicated to the study of long path length space-charge-dominated beam physics on a small scale. Over multiple turns, longitudinal space charge effects cause the tail and head of an electron bunch to expand and interpenetrate, eventually resulting in a “DC beam”. This leads to complications when trying to measure the beam with UMER’s AC coupled diagnostics. Three techniques are developed to recover the information within the beam. Two “knockout” techniques implement invasive pulsed electric kicks to the beam in combination with either a fluorescent imaging screen or a current monitor. A third technique based on integration of the wall-current signal provides a non-invasive method to study the DC beam dynamics. Experimental results from all three methods are compared. The DC beam profile can then be studied over long trajectories and the existence of any loss mechanisms can be determined.