• Y.K. Batygin, G. Bollen, C. Campbell, F. Marti, D.J. Morrissey, G.K. Pang, S. Schwarz
  NSCL, East Lansing, Michigan

Cyclotron gas stopper is a newly proposed device to stop energetic ions in a high pressure helium gas and to transport them in a singly charged state with a gas jet to a vacuum region. Radioactive ions are slowed down by gas collisions inside the field of a weakly focusing cyclotron-type magnet and extracted via interaction with the Radio Frequency field of sequence of concentric electrodes (RF carpet). The present study focuses on a detailed understanding of space charge effects in the central ion extraction region. Such space charge effects originate from the ionization of the helium gas during the stopping of the ions and are the cause for beam rate limitations. Particle-in-cell simulation of two-component (electron-helium) plasma interacting via Coulomb forces were performed in a field created by ionized ions. Simulation results indicate beam rate capabilities and efficiencies far beyond those achieved with linear gas cells presently used to stop projectile fragments.