1 / 8

Warp -POSINST is used to investigate e-cloud effects in the SPS

Warp -POSINST is used to investigate e-cloud effects in the SPS. Warp quasistatic model similar to HEADTAIL, PEHTS, QuickPIC , CMAD. . 2-D slab of electrons. parallellized using pipelining. proc 1 2 N/2 N/2+1 N-1 N

kanan
Download Presentation

Warp -POSINST is used to investigate e-cloud effects in the SPS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Warp-POSINST is used to investigate e-cloud effects in the SPS Warp quasistatic model similar to HEADTAIL, PEHTS, QuickPIC, CMAD. 2-D slab of electrons parallellized using pipelining proc 1 2 N/2 N/2+1 N-1 N Station n n+1 n+N/2-1 n-N/2 n+N-2 n+N-1 s 3-D beam Warp’s mesh refinement & parallelism provide efficiency Posinst provides advanced secondary electrons model Beam ions Electrons true sec. back-scattered elastic Monte-Carlo generation of electrons with energy and angular dependence. re-diffused Spurious image charges from irregular meshing controlled via guard cells

  2. Simulation parameters for SPS at injection • Bunch • energy W=26. GeV • population Np=1.11011 • RMS length z=0.23 m (Gaussian profile) • momentum spread p/p=210-3 • transverse normalized emittancex= y=2.8 mm.mrad • longitudinal normalized emittancez=0.3 eV.s •  : continuous focusing • beta functions x,y= 33.85, 71.87 • betatron tunes x,y= 26.13, 26.185 • chrom. Qx,y=0.,0. • // : continuous focusing • momentum compaction factor =1.9210-3 • cavity voltage V = 2 MV • cavity harmonic number h = 4620. • assumed 100% dipole • Bunch-to-bunch feedback system in horizontal plane (gain=0.1) • 10 interaction stations/turns

  3. Warp and Posinst have been further integrated, enabling fully self-consistent simulation of e-cloud effects: build-up & beam dynamics Turn 1 CERN SPS at injection (26 GeV) Turn 500

  4. Warp-Posinstenabled first direct simulation of a train of 3x72 bunches -- using 9,600CPUs on Franklin supercomputer (NERSC, U.S.A.) Average electron cloud density history at fixed station Substantial density rise in tails of batches between turns 0 and 800. Substantial density rise in tails of batches between turns 0 and 800. J.-L. Vay, et al, IPAC12Proc., (2012) TUEPPB006

  5. Rise also observed on e- density on axis On axis electron cloud density history at fixed station x2 between turns 400 and 600 E- density on axis doubled between turns 400 and 600.

  6. E-cloud density raise coincides with growth of vertical emittance => Positive coupling between the e-cloud buildup and the bunches dynamical response.

  7. Pattern of stripes in the history of vertical bunch offsets Vertical offset (mm) • phase of the oscillations is not purely random • E-cloud provides coupling between bunches.

  8. Comparison with experimental measurements -- collaboration with SLAC/CERN Warp-Posinst2 Experiment1 Good qualitative agreement: separation between core and tail with similar tune shift. Warp is also applied to study of feedback control system (R. Secondo in collaboration with SLAC) Bunch 29, Turn 100-200 Bunch 119, Turn 100-200 Fractional tune Fractional tune head tail head tail Nominal fractional tune=0.185 Bunch slice Bunch slice 1J. Fox, et al, IPAC10 Proc., p. 2806 (2011) 2J.-L. Vay, et al, Ecloud10 Proc., (2010)

More Related