Author: O'Shea, P.G.
Paper Title Page
TUPWA058 Experimental Study of Soliton Wave Trains in Intense Electron Beams 1835
  • Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea
    UMD, College Park, Maryland, USA
  Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Longitudinal perturbations in intense beams can lead to instabilities or degradation of beam quality, ultimately affecting the performance of accelerators, especially near the source where space charge is important. In this experimental study, conducted on the University of Maryland Electron Ring (UMER), large-amplitude perturbations are purposefully generated and their propagation observed over a long transport length. It is found that narrow, large-amplitude perturbations on a long-pulse beam develop into Korteweg-deVries (KdV) type soliton wave trains. Each peak in the wave train has a constant width and amplitude over a long propagation distance, with the amplitude inversely proportional to the square of the width. Furthermore, two such pulses are seen to interact with each other and emerge from the collision unchanged. The experimental data is compared with the KdV model and particle-in-cell simulations with good agreement. We induce perturbations using two methods: using photoemission to perturb the density at the cathode, or using an induction cell to directly perturb particle velocities.