11.11 ionTrapping

• description: Computes ion trapping conditions using elegant twiss parameter output as input.
• synopsis:

  ionTrapping -twiss filename -superPeriods number -kappa ratio -output filename -current mA -bunches number

• switches:
  • twiss — Give the name of a Twiss output file from elegant. It is advisable to subdivide the elements finely enough to get smooth representations of the lattice functions. The file should be computed the radiation integrals turned on, since the natural emittance and energy spread are needed.
  • superPeriods — Give the number of superperiods of the basic cell described by the Twiss output file.
  • kappa — Give the ratio ϵ_y∕ϵ_x. The emittances are computed from ϵ₀ using ϵ_x = and ϵ_y = κϵ_x.
  • output — Give the name of the output file. The file contains the information in the input file, with the following added elements, among others:
    • Column Acrit — A_crit(s) is defined as[42]

      (20)

      where N_e number of electrons per bunch, r_p is the classical proton radius, S_b is the bunch separation in meters, σ_x(s) is the local horizontal rms beam size, and σ_y(s) is the local vertical rms beam size. Any singly-ionized species with atomic mass greater than A_crit will be trapped.

    • Parameters ex, ey — The horizontal and vertical emittances.
    • Parameter AcritMin — Minimum value of A_crit(s).
    • Parameters speciesTrappedFraction, where species is H2, H2O, CH4, CO, and CO2. These give the fraction of the circumference over which H₂, H₂O, CH₄, CO, and CO₂, respectively, are trapped.
  • current — Give the total beam current milliAmps.
  • bunches — Give the number of bunches.
• authors: M. Borland (ANL/APS).