Model the electron-driven instabilities and electron build-up in linear particle accelerators and storage rings. Track a beam through an optical lattice extracted from MAD and model the electron cloud-beam interaction at each element of the ring. Explore single- and coupled bunch instabilities, effective electron wakefields, betatron tune shifts, and dynamic aperture.
Use of parallel computation to be able to increase the number of beam-cloud interactions up to the number of elements in the ring while still running for a reasonable amount of time. The beam line R,T matrices and lattice functions extracted from the MAD output are used for beam tracking. The electron cloud density is distributed in each element of the beam line. The dynamics of the beam and the electron cloud are treated dynamically in 3D including full 3D tracking of the electron motion in magnetic field elements. The beam-cloud forces during the interaction are treated in 2D.
Accelerators for which this code was/is used :
ILC, SPS, LHC
Benchmarking against other codes :
The benchmarking with HEADTAIL for SPS-like parameters as posted on the code comparison web page (http://conf-ecloud02.web.cern.ch/conf-ecloud02/CodeComparison/modelinst.htm ) was performed using a single beam-cloud interaction per turn, with good results as shown in the paper http://www-project.slac.stanford.edu/ilc/testfac/ecloud/cmad/cmad_documentation/THPAS066.pdf
Benchmarking against accelerator experiments :
not yet
Special programming features :
Parallel computation with MPI.
Comments :
The code is based on the experience of HEAD-TAIL, PEHTS, QUICKPIC, and ORBIT for electron cloud driven single-bunch instability simulations and on POSINST, ECLOUD, PEI, CLOUDLAND, and again ORBIT for electron cloud build-up simulations. The electron cloud instabilities module is included in the actual version -CMAD 2.5.0] while the electron cloud build-up will be added in a future upgrade.
