Author: Veitzer, S.A.
Paper Title Page
WEP112 Accurate Simulation of the Electron Cloud in the Fermilab Main Injector with VORPAL 1692
 
  • P. Lebrun, P. Spentzouris
    Fermilab, Batavia, USA
  • J.R. Cary, P. Stolz, S.A. Veitzer
    Tech-X, Boulder, Colorado, USA
 
  Precision simulations of the electron cloud at the Fermilab Main Injector (MI) have been studied using the plasma simulation code VORPAL. Fully 3D and self consistent solutions that includes Yee-type E.M. field maps, electron spatial distributions and the time evolution of the cloud with respect to the bunch structure in the MI. The microwave absorption experiment has been simulated in detail and the response of the antennas has been derived from the VORPAL's pseudo-potential data. Based on the results of these simulations and the ongoing experimental program, two distinct new experimental techniques are proposed. The first one is based on the use BPM plates placed in dipole fields and that are made of material(s) for which the secondary emission is well characterized. The second technique would be based on the optical, or ultra-violet, detection of the radiation emitted (inverse photo-electric effect) when the cloud interacts with the inner surface of the beam pipe. As the microwave absorption experiment, this techique is non-invasise and has the advantage of providing spatial images of the cloud as well as accurate timing (ns) information.  
 
WEP165 Advanced Modeling of TE Microwave Diagnostics of Electron Clouds 1803
 
  • S.A. Veitzer, D.N. Smithe, P. Stoltz
    Tech-X, Boulder, Colorado, USA
 
  Funding: Part of this work is being performed under the auspices of the U.S. Department of Energy as part of the ComPASS SciDAC project, #DE-FC02-07ER41499.
Numerical simulations of electron cloud buildup and in particular rf microwave diagnostics provide important insights into the dynamics of particle accelerators and the potential for mitigation of destabilizing effects of electron clouds on particle beams. Typical Particle-In-Cell (PIC) simulations may accurately model cloud dynamics; however, due to the large range of temporal scales needed to model side band production due to ecloud modulation, typical PIC models may not be the best choice. We present here preliminary results for advance numerical modeling of rf electron cloud diagnostics, where we replace kinetic particles with an equivalent plasma dielectric model. This model provides significant speedup and increased numerical stability, while still providing accurate models of rf phase shifts induced by electron cloud plasmas over long time scales.