ENEA C.R. Frascati, Frascati (Roma)
INFN/LNF, Frascati (Roma)
Rome University La Sapienza, Roma
LBNL, Berkeley, California
The SPARX X-FEL accelerator will be the first FEL facility to operate with a hybrid (RF plus magnetic chicane) compression scheme. Numerical studies of propagation of beam density modulations stemming from photogun laser, through the photoinjector operating under velocity bunching conditions have been carried out. A semi-analytical model for the linear gain in a RF compressor is also being developed and some preliminary results are presented.
INFN/LNF, Frascati (Roma)
ENEA C.R. Frascati, Frascati (Roma)
Rome University La Sapienza, Roma
LBNL, Berkeley, California
The modeling of the microbunching instability has been carried out for the SPARX FEL accelerator, two configurations have been considered and compared: hybrid compression scheme (velocity bunching plus magnetic compressor) and purely magnetic. The effectiveness of a laser heather in reducing this instability drawbacks on the electron beam quality has also been exploited. Analytical predictions and start to end simulation results are reported in this paper.
LBNL, Berkeley, California
LLNL, Livermore, California
FZK, Karlsruhe
Funding: Supported by the US-DOE under Contract DE-AC02-05CH11231, the US-LHC LARP, and the US-DOE SciDAC program ComPASS. Used resources of NERSC, supported by the US-DOE under Contract DE-AC02-05CH11231.
At PAC05, we presented the package WARP-POSINST for the modeling of the effect of electron clouds on high-energy beams. We present here the latest developments in the package. Three new modes of operations were implemented: 1) “build-up mode” where, similarly to Posinst (LBNL) or Ecloud (CERN), the build-up of electron clouds is modeled in one region of an accelerator driven by a legislated bunch train; 2) “quasi-static mode” where, similarly to Headtail (CERN) or Quickpic (USC/UCLA), the “frozen beam” approximation is used to split the modeling of the beam and the electrons into two components evolving on their respective time scales; and 3) “Lorentz boosted mode” where the simulation is performed into a moving frame where the space and time scales related to the beam and electron dynamics fall in the same range. The implementation of modes (1) and (2) was primary motivated by the need for benchmarking with other codes, while the implementation of mode (3) fulfills the drive toward fully self-consistent simulations of e-cloud effect on the beam including the build-up phase. We also present benchmarking with other codes and selected results from its application to e-cloud effects.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
KEK, Ibaraki
ANL, Argonne
Fermilab, Batavia
CalPoly, San Luis Obispo, CA
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
SLAC, Menlo Park, California
Cornell University, Ithaca, New York
Cockcroft Institute, Warrington, Cheshire
Funding: Support provided by the US National Science Foundation, the US Department of Energy, and the Japan/US Cooperation Program.
In March of 2008, the Cornell Electron Storage Ring (CESR) concluded twenty eight years of colliding beam operations for the CLEO high energy physics experiment. We have reconfigured CESR as an ultra low emittance damping ring for use as a test accelerator (CesrTA) for International Linear Collider (ILC) damping ring R&D. The primary goals of the CesrTA program are to achieve a beam emittance approaching that of the ILC Damping Rings with a positron beam, to investigate the interaction of the electron cloud with both low emittance positron and electron beams, to explore methods to suppress the electron cloud, and to develop suitable advanced instrumentation required for these experimental studies (in particular a fast x-ray beam size monitor capable of single pass measurements of individual bunches). We report on progress with the CESR conversion activities, the status and schedule for the experimental program, and the first experimental results that have been obtained.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
ANL, Argonne
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: Supported by the US National Science Foundation, the US Department of Energy under Contracts No. DE-AC02-06CH11357, DE-AC02-05CH11231, and DE-AC02-76SF00515, and by the Japan/US Cooperation Program.
CESR at Cornell has been operating as a damping ring test accelerator (CesrTA) with beam parameters approaching those anticipated for the ILC damping rings. A core component of the research program is to fully understand electron cloud effects in CesrTA. As a local probe of the electron cloud, several segmented retarding field analyzers (RFAs) have been installed in CesrTA in dipole, drift and wiggler regions. Using these RFAs, the energy spectrum of the time-average electron cloud current density striking the walls has been measured for a variety of bunch train patterns; with bunch populations up to 2x1010 per bunch, beam energies from 2 to 5 GeV, horizontal geometric emittances from roughly 10 to 133 nm, and bunch lengths of about 1 cm; and for both positron and electron beams. The effect of mitigation measures, such as coatings, has also been studied. This paper will compare these measurements with the predictions of simulation programs, and discuss the implications of these comparisons for our understanding of the physics of electron cloud generation and mitigation in ILC-like damping rings.
CLASSE, Ithaca, New York
LBNL, Berkeley, California
ANL, Argonne
CalPoly, San Luis Obispo, CA
KEK, Ibaraki
SLAC, Menlo Park, California
Funding: National Science Foundation award 0734867 Office of Science, U.S. Department of Energy contracts DE-AC02-05CH11231 and DE-AC02-06CH11357
The Cornell Electron Storage Ring Test Accelerator (CesrTA) has commenced operation as a linear collider damping ring test bed following its conversion from an e+e- collider in 2008. A core component of the research program is the measurement of effects of synchrotron-radiation-induced electron cloud formation on beam dynamics. We have studied the interaction of the beam with the cloud in a number of experiments, including measurements of coherent tune shifts and emittance growth in various bunch train configurations, with different bunch currents, beam energies, beam emittance, and bunch lengths, for both positron and electron beams. This paper compares these measurements to modeling results from several advanced cloud simulation algorithms and discusses the implications of these comparisons for our understanding of the physics of electron cloud formation and decay in damping rings of the type proposed for future high-energy linear colliders.