ibsEmittance

• description: ibsEmittance computes growth rates and equilibrium emittances for electron rings due to intrabeam scattering (IBS). It will also integrate the growth rates to show the time evolution of the emittances. The IBS algorithm is based on an extension of the ZIBS routine in the program ZAP (Zisman, et al.).

• examples: This example computes the IBS equilibrium parameters and the contributions to the growth rates vs position in the APS lattice.
  ibsEmittance aps.twi aps.ibs -charge=5 -coupling=0.02 -rf=voltage=9,harmonic=1296

• synopsis:
  ibsEmittance twissFile resultsFile -charge=nC|-particles=value -coupling=value [-emitxInput=value] [-deltaInput=value] [-growthRatesOnly] [-superperiods=value] -RF=Voltage=MV,harmonic=value|-length=mm [-energy=MeV] [-integrate=turns=number[,stepSize=number]]

• files: twissFile is a twiss parameter file from the twiss_output command of elegant. You must use the radiation_integrals flag in twiss_output.

• switches:
  • -charge, -particles -- Give the charge (in nanocoulombs) or the number of electrons.
  • -coupling -- Give the emittance coupling ratio, $\epsilon_y/\epsilon_x$.
  • -emitxInput -- Give the initial x emittance in meters. If not specified, the value from the parameter ex0 in twissFile is used.
  • -deltaInput -- Give the initial rms fractional momentum spread. If not specified, the value from the parameter Sdelta0 in twissFile is used.
  • -growthRatesOnly -- If given, only the growth rates are computed. Equilibrium values are not computed.
  • -superperiods=value -- If given, the number of superperiods in the lattice. twissFile is taken to pertain to a single sector.
  • -RF=Voltage=MV,harmonic=value -- Specify rf voltage and harmonic number.
  • -length=mm -- Specify the rms bunch length.
  • -energy=MeV -- Specify the beam energy. By default, this is taken from the pCentral parameter in twissFile.
  • -integrate=turns=number[,stepSize=number] -- If given, then resultsFile contains the result of integrating the differential equations for the emittances for the given number of turns. The step size is the number of turns for each integration step, and can be adjusted to get faster results.

• author: L. Emery, M. Borland, ANL/APS.