Compare options: simulations recent history Cloud density near (r=1mm) beam (m -3 ) before bunch passage, values are taken at a cloud equilibrium density. Solenoids decrease the cloud density in DRIFT regions, where they are only effective. Compare options LowQ and LowQ+train gaps. All cases wiggler aperture 46mm.

Electron Cloud: need for mitigation Outstanding Questions about key remedies: 1)Are thin film coatings effective to stably decrease SEY < 1.2 ? Is “conditioning” effective to stably decrease SEY < 1.2 ? 2) Fins: are fin-chambers viable to suppressing electron cloud in magnets ? (resolve simulation discrepancy) 3) Clearing electrodes: is RF power load tolerable ? are impedance and HOM tolerable ?

ILC DAMPING RING R&D OBJECTIVES Electron Cloud Characterize electron-cloud build-up Required for Baseline Priority: Develop electron-cloud suppression techniques Required for Baseline Priority: Develop modeling tools for e-cloud instabilities Required for Baseline Priority: Determine electron-cloud instability thresholds Required for Baseline Priority: Ion Effects Characterize ion effects Required for Baseline Priority: Specify techniques for suppressing ion effects Required for Baseline Priority: 1 COLLECTIVE INSTABILITIES: PRIORITIES

4 Electron cloud issues: Milestones 1. Test clearing electrodes (a) characterize impedance, HOM, power load (b) machine studies 2. Test groove concepts (a) characterize impedance, HOM, power load (b) machine studies 3. Test coating techniques (a) Secondary electron yield measurements (b) machine studies 4. Characterize the electron cloud build up 5. Characterize the electron cloud instability 6. Integrated modeling: cloud, impedance, space charge.. Investigate alternative solutions

5 Ion issues: Milestones 1. Characterize ion effects 2. Specify techniques for suppressing ion effects

R&D MILENSTONES TOWARDS A TECHNICAL DESIGN REPORT TDR (2008)

7 Electron cloud issues: Milestones Test clearing electrodes (a) characterize impedance, HOM, power load analytical estimates simulate MAFIA, A. Krasnyhk, Cho Ng simulate with VORPAL, V. Ivanov (?) simulate, F. Caspers (b) machine studies test in HCX in a quadrupole or drift region, A. Molvik test in ESA preliminary to PEPII installation, M. Pivi, test in PEPII in bend chicane, M. Pivi test in CESR in wiggler section, M. Palmer test in KEKB arc section bend or wiggler section, Y. Suetsugu test in LHC arc section bend section, F. Caspers (c)develop diagnostic electron cloud diagnostic for test chambers, A. Molvik electron cloud diagnostic for test chambers, R. Macek

8 Electron cloud issues: Milestones Test groove concepts (a) characterize impedance, HOM K. Bane numerical estimation, G. Stupakov analytical (b) machine studies rectangular grooves drift SLAC, M. Pivi triangular grooves in bend section SLAC, M.Pivi triangular grooves in wiggler section CESR, M. Palmer (c)develop diagnostic electron cloud diagnostic for test chambers, A. Molvik electron cloud diagnostic for test chambers, R. Macek

9 Electron cloud issues: Milestones Test coating techniques and determine conditioning effectiveness (a) Secondary electron yield measurements measuring SEY, Y. Suetsugu measuring SEY, R. Kirby measuring SEY, (N. Hilleret) (b) machine studies installation of test chambers in KEKB Cu, TiN, NEG, Y. Suetsugu SEY conditioning test in PEP-II, M. Pivi Installation of chambers in CESR, M. Palmer (c) manufacturing and diagnostics building chambers for installations, S. Marks

10 Electron cloud issues: Investigators Characterize the electron cloud build up wiggler 3D simulations CLOUDLAND, L. Wang wiggler 3D simulations WARP/POSINST, C. Celata characterize ecloud in quadrupole, M. Pivi characterize ecloud in quadrupole, C. Celata fill pattern as possible mitigation, M. Venturini compile e-cloud density over the machine, M. Pivi optimize clearing electrode design, (Cornell) optimize clearing electrode design, L. Wang optimize clearing grooves design, W. Bruns optimize clearing grooves design, L. Wang optimize clearing grooves design, M. Venturini

11 Electron cloud issues: Milestones Characterize the electron cloud instability Characterize single-bunch instability PEHTS, K. Ohmi Characterize single-bunch instability HEAD-TAIL, F. Zimmermann Characterize single-bunch instability quasi-static QUICKPIC, P. Spentzouris Characterize single-bunch instability in wiggler 3D WARP, C. Celata Characterize single-bunch instability in lattice CMAD, M. Pivi

12 Electron cloud issues: Milestones 6. Integrated modeling Characterize instability FRAMEWORK, P. Spentzouris

13 Electron cloud issues: Timescale Test clearing electrodes In PEP-II by 2007 In CESR by 2008 Test groove concepts In PEP-II by 2007 In CESR by 2008 Test coating techniques In KEKB, by 2007 In PEPII, by 2007 In CESR, by 2008 Characterize the electron cloud build up Compile list of electron cloud density in ring by 2007 Characterize the electron cloud instability by TDR Integrated modeling by TDR

14 Ion issues: Milestones 1. Characterize ion effects to be discussed 2. Specify techniques for suppressing ion effects to be discussed

15 Ion issues: Timescale 1. Characterize ion effects by date … 2. Specify techniques for suppressing ion effects by date …