Routines for modeling the effects of wakefields

Instructions for acquiring wakefields tracking code and bmad routines, and building executables

• Acquiring wakefields (and bmad) code.
• wakefields/ directory tree
• Executables
• Environment Variables
• Structures
• Bunch analyzer Documentation for python bunch train analysis functions
• Bmad references. Includes links to BMAD manual, etc.
  

  ---

  Acquisition Within Wilson Lab of code from the Wilson accelerator code repository

  
  
  1. If you have not done this already, make a directory for your local copy of the Bmad (wakefields) distribution, programs, etc. Henceforth this directory will be referred to as < DIR >. A possible name might be: "root_dir". Substitute the appropriate directory name for " < DIR >" in the following steps.

  2. To make a local copy of a directory, the commands:
     

        cd < DIR >
        svn co https://accserv.lepp.cornell.edu/svn/<REPOS_PATH>.
     

     To find the correct < REPOS_PATH >, use the repository web viewer. For example. to make a local copy of the bmad library, use the commands:

     
       cd <DIR>
       svn co svn+ssh://dlr10@lnx201.lepp.cornell.edu/nfs/acc/user/dlr/svn_repository/wakefields
     

     This will create the directory <DIR>/wakefields

  3. To update your local copy of a library and/or executable so that it has all the revisions that have been introduced into the repository, go to the directory containing the library and/or executable and use the command:
     

        svn update

  4. To compile the library: (see Environment Variables)
     

     cd <DIR>/wakefields
     mk          # Produces production libraries and/or executables

     
     Or use "mkd" instead of "mk" if you want to create the debug versions of the libraries and/or executables.
     

     Production libraries and executables are put in the directory:
     

     <DIR>/production/bin
     

     and debug libraries and executables are put in:
     

     <DIR>/debug/bin

  ---

  wakefields/ directory tree

  
  <DIR>/wakefields
  Subdirectories of wakefields/ include: multibunch  code  doc  files
  

  The executable (so far) is: multibunch  

  • /multibunch
    The main program "multibunch.f90" is here.
  • /code
    
    • write_turn_data ---- Writes a file of phase space coordinates of all of the macroparticles for each bunch on each turn. Computes and writes centroid and sigma matrix data for each bunch on each turn.
  • files/
    
    • periodic.lat --- Simple periodic lattice. The lattice file defines elements (quadrupoles, dipoles, etc) - lengths, strengths, location, also beam energy and wakefields
    • beam_def.in -- Initialization parameters: number of turns, number of bunches, bunch spacing, number of macro-particles/bunch, charge/bunch
    • long_range_wake.dat File with long range wake function parameters in modal form as required by bmad
    • short_range_wake.dat File with short range wake function parameters in modal form as required by bmad
  • doc/
    
    • programs.html --- This document
  • plotting_scripts/
    
    • singlebunch_<N>.gnu where <N> is the bunch number. Reads and plots (with gnuplot) phase space data for bunch <N>

    Executables

    • multibunch :

      Function: Generate and track a distribution of bunches for multiple turns around the ring

      Output

      • bunch.dat --- Centroid of horizontal position of particles in each bunch on each turn.
      • turn<nturn>-<nbunch>.dat Phase space vectors for each particle in bunch <nbunch> on turn <nturn>
      • sigma_<nbunch>.dat Centroid and sigma matrix data for the distribution of particles in bunch <nbunch> for all turns

    ---

    Environment Variables

    In order for the code to build and link various environment variables must be defined. They are for the most part telling the linker where to find the BMAD library subroutines. The easiest way to get these variables is on linux from your home directory to
    

    cp /home/dlr/.bashrc_g2 .bashrc
    

    Before you do this you might want to rename your own .bashrc file so that it is not overwritten and then combine the two.

    ---

    Structures

    For reference
    The BMAD structures are defined in bmad_struct.f90
    The multibunch structures beam_struct and bunch_struct are defined in bmad_def_struct.f90

    ---

    References

    1. Chao-Wakefields/Impedance
    2. Resistive Wall
    3. Zotter
    4. Stupakov - wakes and impedance

  ---

  Last modified: Tue Feb 11 13:22:27 EST 2014