Abstract
We present studies of space-charge-induced beam profile broadening at high intensities in the Proton Storage Ring (PSR) at Los Alamos National Laboratory. We investigate the profile broadening through detailed particle-in-cell simulations of several experiments and obtain results in good agreement with the measurements. We interpret these results within the framework of coherent resonance theory. With increasing intensity, our simulations show strong evidence for the presence of a quadrupole-mode resonance of the beam envelope with the lattice in the vertical plane. Specifically, we observe incoherent tunes crossing integer values, and large amplitude, nearly periodic envelope oscillations. At the highest operating intensities, we observe a continuing relaxation of the beam through space charge forces leading to emittance growth. The increase of emittance commences when the beam parameters encounter an envelope stop band. Once the stop band is reached, the emittance growth balances the intensity increase to maintain the beam near the stop band edge. Additionally, we investigate the potential benefit of a stop band correction to the high intensity PSR beam.
| Original language | English |
|---|---|
| Article number | 074202 |
| Pages (from-to) | 45-59 |
| Number of pages | 15 |
| Journal | Physical Review Special Topics - Accelerators and Beams |
| Volume | 6 |
| Issue number | 7 |
| DOIs | |
| State | Published - 2003 |
Funding
We are very grateful to the LANSCE support team ?>for setting up and executing experiments, and to ?>T. Spickermann for hunting down data files and clarifying parameters. We would also like to thank V. Danilov and S. Y. Lee for their many useful insights. This work is supported by SNS through UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. DOE, by Indiana University through a DOE grant, DE-FG02-92ER40747, and by Los Alamos National Laboratory under Contract No. W-7405-ENG-36. The Los Alamos National Laboratory is operated by the University of California for the U.S. DOE. The SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.