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Topical Workshop on Instabilities, Impedance and Collective Effects 2014 (TWIICE2014)

16–17 Jan 2014
Synchrotron SOLEIL
Europe/Paris timezone

Contribution List

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  1. 6. Theory of Beam Transverse Instabilities
    Alexey Burov (Fermi National Accelerator Lab. (US))
    16/01/2014, 09:00
    (Review) Main theoretical aspects of beam transverse instabilities in low-emittance rings are successively considered. First, coherent tune shifts are found with the nested head-tail method for arbitrary longitudinal distribution and single and coupled bunches, and with a feedback damper taken into account. Then, the transverse nonlinearity is included, and Landau damping is analyzed by means...
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  2. 27. Impedance and collective effects in Beijing Advanced Photon Source
    Na WANG (BAPS)
    16/01/2014, 09:35
    Beijing Advanced Photon Source (BAPS) is a 5GeV storage ring-based light source. Due to the low emittance and high beam current, the collective effects may bring new challenges to the physical design of the machine. A thorough evaluation of the coupling impedance is necessary in controlling the total impedance of the ring, which can accordingly prevent the occurrence of the beam instability....
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  3. 8. Evaluation of Collective Effects for the ESRF Upgrade Project
    Thomas Perron (ESRF)
    16/01/2014, 09:55
    A project to fully rebuild the main ring in the existing tunnel is underway at the ESRF. A preliminary analysis of the collective effects we may face operating this new machine will be presented. Current thresholds will be evaluated extrapolating data collected on the actual ESRF. Beam emittance growth including bunch lengthening and intra- beam scattering will also be discussed.
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  4. 28. High frequency effects of impedance and coatings in the CLIC damping rings
    Eirini Koukovini Platia (Ecole Polytechnique Federale de Lausanne (CH))
    16/01/2014, 10:15
    Single bunch instability thresholds and the associated coherent tune shifts have been evaluated in the transverse plane for the damping rings (DR) of the Compact Linear Collider (CLIC). A multi-kick version of the HEADTAIL code was used to study the instability thresholds in the case where different impedance contributions are taken into account such as the broad-band resonator model in...
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  5. 10. Recent Developments in Wakefield and Impedance Computations
    Boris PODOBEDOV (BNL)
    16/01/2014, 10:55
    (Review) This talk will review some recent developments in the area of wakefield and impedance calculations. Both for modern light sources and colliding machines these developments were mostly motivated by harder-to-deliver (or more exotic) beam parameters as well as more stringent requirements coming from beam dynamics and other machine constraints. After reviewing these, the talk will...
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  6. 11. Impedance Optimization and Wakefield Codes Comparison for the Brazilian Light Laboratory
    Henrique de Oliveira Caiafa DUARTE (LNLS)
    16/01/2014, 11:30
    For the future 3rd Generation Brazilian Light Source, Sirius, an evaluation of several electromagnetic simulation software was done, motivated by the small ~3 mm Sirius bunch length. User interface was analyzed on CST, ACE3P and GdfidL and their numerical errors were compared with ECHO code. Impedance optimization of some components will be shown as well.
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  7. 12. Longitudinal impedance characterisation of the CLIC stripline in view of its in the ALBA storage ring
    Thomas Guenzel (CELLS/ALBA)
    16/01/2014, 11:50
    In the framework of a collaboration between the CLIC project at CERN and CELLS a 1.7m long prototype stripline will be tested in the ALBA storage ring. The power loss of the stripline flanged to the ALBA vacuum pipe is computed under consideration of an external load connected to the feedthroughs. Although the total power loss at 400mA is still significant (78W), the external load consumes 58W...
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  8. 13. Geometric Beam Coupling Impedance of LHC Collimators
    Oscar Frasciello (I)
    16/01/2014, 12:10
    The High Luminosity LHC project (HiLumi LHC) is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the bunch (and beam) intensity increase. In order to keep under control harmful beam instabilities and to avoid excessive power losses in these conditions a careful design of new vacuum chamber components and an update and...
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  9. 14. Short-range wake field studies
    Galina SKRIPKA (Univ. of Lund)
    16/01/2014, 12:30
    In order to maintain the high quality of the beam it is crucial to study the effect of the wake fields on the bunches. The linear accelerators often require extreme stability of the beam parameters such as emittance and energy spread. Using the scheme recently proposed by B. Podobedov and G. Stupakov the short-range wake fields are investigated with MAX IV linac as an example. MAX IV linac...
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  10. 15. Impedance Analysis of Insertion Devices
    Alexei BLEDNYKH (NSLS-II)
    16/01/2014, 13:45
    To estimate the vertical impedance of more complex geometry as an In-Vacuum Undulator we cross-checked first the results for simple geometries. Axially symmetric tapered structure and rectangular structures are under discussion. Comparison of analytical results with numerically obtained data using different EM Field Solvers. Two types of the In-Vacuum Undulator have been analyzed, the...
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  11. 16. Beam Coupling Impedance Studies of the CLIC Damping Ring Extraction Kicker
    Carolina BELVER AGUILAR (CERN)
    16/01/2014, 14:05
    The Compact Linear Collider (CLIC) aims for electron-positron collisions with high luminosity at a nominal centre-of-mass energy of 3 TeV. Pre-Damping Rings (PDRs) and Damping Rings (DRs) are required for reducing the emittance of the electron and positron beams before it is injected into the booster linac. Several stripline kicker systems will be used to inject and extract the beam from the...
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  12. 17. Review of Particle Scattering
    Theo DEMMA (LAL)
    16/01/2014, 14:30
    (Review)
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  13. 18. Design of IBS dominated low emittance ring
    Fanouria Antoniou (National Technical Univ. of Athens (GR))
    16/01/2014, 15:05
  14. 19. Intrabeam scaterring studies at CESR-TA
    Suntao Wang (Cornell University)
    16/01/2014, 15:25
    Low emittance electron and positron storage rings with an energy of a few GeV are important tools for scientific research. This will be increasingly true in coming years for next generation colliders such as CLIC and ILC, and for light sources as they approach 'ultimate storage ring' conditions. CESR-TA is a research program at Cornell University aimed at better understanding the physics of...
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  15. 20. Review of Two-Stream Instabilities
    Giovanni Rumolo (CERN)
    16/01/2014, 16:05
    (Review)
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  16. 21. Electron cloud mitigation via new materials and material coating
    Dr Roberto Cimino (LNF-INFN)
    16/01/2014, 16:40
    Electron cloud is an ubiquitous effect in positively charted particle accelerators and has been observed to induce unwanted detrimental effects on beam quality, stability, vacuum etc. In this presentation a short review of the present understanding of the mitigation strategies adopted so far will be given with particular emphasis to the ongoing research on new materials and material coatings...
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  17. 22. Electron cloud build up studies for the CLIC positron damping rings
    Giovanni Iadarola (CERN - University of Naples Federico II)
    16/01/2014, 17:00
    The formation of an Electron Cloud (EC) in the vacuum chambers could significantly limit the performances of the positron damping ring of the Compact Linear Collider (CLIC). Depending on the Secondary Electron Yield (SEY) of the inner surface of the vacuum chambers, electrons generated by photoemission due to synchrotron radiation, can multiply through beam induced multipacting and accumulate...
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  18. 23. Electron-cloud instability in the CLIC damping ring for positrons
    Hannes Bartosik (CERN)
    16/01/2014, 17:20
    Coherent beam instabilities induced by an electron cloud could be a serious performance limitation for the positron damping rings of CLIC. In this context, we present numerical simulations of the electron cloud instability: The electron cloud distribution before each bunch passage is generated with the build-up code PyECLOUD and used as input for HEADTAIL simulations in order to assess the...
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  19. 24. Fast Beam-Ion Instability Arising from Local Outgassing
    Ryutaro Nagaoka (Synchrotron SOLEIL)
    16/01/2014, 17:40
    In this talk we shall review a series of observations, experimental analyses and simulations made at SOLEIL on beam instabilities which are now identified as fast beam-ion instability arising from local outgassing. Peculiarity of these phenomena is that despite being ion instability, uniform beam filling is preferred to avoid the instability. An explanation is given, also suggesting that the...
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  20. 25. Impact of Harmonic RF Sysytems on Beam Dynamics in Ultimate Storage Rings
    John BYRD (LBNL)
    17/01/2014, 08:30
    (Review)
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  21. 26. Investigation of transverse beam instabilities in the MAX IV 3 GeV ring using the multibunch code mbtrack
    Marit Klein (Soleil)
    17/01/2014, 09:05
    We developed a macroparticle multibunch tracking code called mbtrack which can account for various collective effects as resistive wall and geometric ring impedance, multiple cavities either active or passive and even ion beam interaction. Besides the presentation of the code's main features we take the MAX IV 3 GeV storage ring as an example to demonstrate its capabilities. The new MAX IV...
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  22. 30. Impedance Optimization of Small Gap Chambers for the High Single Bunch Current Operation at APS
    Yong-Chul CHAE (APS)
    17/01/2014, 09:25
    The high intensity per single bunch is required for the timing mode x-ray users at the APS. In order to keep 16-mA operation with the new smaller gap ID chambers we need to reduce the impedance of the chamber through optimization. In this talk we described the impedance reduction process which resulted in the engineering design for the new 5-mm gap chamber to be installed in September 2014.
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  23. 9. The impedance localization method: theory, measurements and predictions for accelerator machines
    Nicolo Biancacci (Universita e INFN, Roma I (IT))
    17/01/2014, 09:45
    The beam coupling impedance leads to limitations in beam brightness and needs accurate quantification and continuous monitoring in order to detect and mitigate high impedance sources. In the CERN hadron accelerators, kickers and collimators are expected to be major contributors to the total imaginary part of the machine transverse impedance. In order to detect other sources, beam based...
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  24. 29. Impact of Incoherent Transverse Wake Field on Storage Ring Optics
    Pascale BRUNELLE (Synchrotron SOLEIL)
    17/01/2014, 10:05
    In third generation synchrotron light sources such as SOLEIL, the large number of small gap insertion devices imposes vertical limitations of the vacuum chamber aperture. The former induce an incoherent transverse wake field due to the resistive-wall effect in flat chambers and lead to betatron tune variation with stored current and an optical function symmetry break. Since at SOLEIL, the...
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  25. 31. Review of Instrumentation and Feedback for Beam Instabilities
    Guenther Rehm (Diamond Light Source)
    17/01/2014, 10:50
    (Review)
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  26. 32. Bunch-by-bunch feedback system for hybrid filling and recent topics in SPring-8
    Takeshi Nakamura (Japan Synchrotron Radiation Research Institute)
    17/01/2014, 11:25
    The hybrid filling composed of singlets with high bunch current and bunch trains with low bunch current is in user operation at SPring-8, by simultaneously suppressing single-bunch instabilities of singlet and multi-bunch instabilities of trains by the Spring-8 bunch-by-bunch feedback system. To overcome the high contrast of the bunch current between singlets and trains, a bunch current...
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  27. 33. Far-infrared and Terahertz detectors for particle accelerators
    Joanna Barros (LAL in2p3)
    17/01/2014, 11:45
    Different radiative phenomena in the far infrared and terahertz ranges can occur in particle accelerators. Smith-Purcell radiation is emitted when a charged particle passes near a grating. It is being used by the ETALON group at LAL Orsay to determine longitudinal profiles of electron bunches on different Linacs (FACET at SLAC, SOLEIL). Some results will be presented, showing the feasibility...
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  28. 34. Simulation of high bandwith feedback systems
    Kevin LI (cern)
    17/01/2014, 12:05
  29. 35. Review of CSR Instabilities
    Karl BANE (SLAC)
    17/01/2014, 13:20
    (Review)
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  30. 36. Recent developments on CSR instability measurements at the ANKA storage ring
    Anke-Susanne Mueller (Max-Planck-Gesellschaft (DE))
    17/01/2014, 13:55
    In the past year, several new additions to the beam diagnostics facilities available at the ANKA storage ring have opened new windows to the study of the CSR instability. A detection system consisting of an ultra-fast superconducting THz detector and data acquisition system, for example, was used to investigate correlations visible on the CSR bursting pattern and to study the interactions...
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  31. 37. CSR-driven longitudinal instability-comparison of theorical and experimental results
    Peter KUSKE (BESSY II)
    17/01/2014, 14:15
    The predictions of numerical solutions of the Vlasov-Fokker-Planck equation for the interaction of electrons moving and radiating on a circle between two perfectly conducting and infinite plates are compared with observations at rings like BESSY II, MLS, ANKA. Comparison is also made with theoretical results obtained for more realistic models of the vacuum chamber which take into account the...
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  32. 38. Measurement of THz bursting thresholds at the Metrology Light Source
    Markus Ries (Helmholtz-Zentrum Berlin)
    17/01/2014, 14:35
    The Metrology Light Source (MLS) of the Physikalisch-Technische Bundesanstalt (PTB) is able to vary the zero current bunch length over more than two orders of magnitude. Bunch length manipulation can be achieved by adjusting momentum compaction factor, RF-cavity voltage as well as electron energy. The MLS is able to control the three leading orders of the momentum compaction factor and is...
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  33. 39. Scaling Law of Coherent Synchrotron Radiation in Rectangular Chamber
    Yunhai Cai (SLAC)
    17/01/2014, 14:55
    We study the threshold of longitudinal instability driven by coherent synchrotron radiation in a rectangular chamber in electron storage rings. Starting with Maxwell’s equation, we first derive a point-charge wakefield for longitudinal motion. Then we use the wake, along with the Vlasov-Fokker-Planck equation, to show that the threshold can be described by a simple scaling law of ξ = ξth(χ,...
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  34. 7. Comparison simulations-measurements of Single Bunch instabilities at DIAMOND
    Dr Riccardo Bartolini (Diamond Light Source and John Adams Institute)
    17/01/2014, 15:15
  35. 45. Dynamics of the microbunching instabilities: studies at PhLAM laboratory in relation with experiments at UVSOR and SOLEIL
    Eléonore ROUSSEL (PhLAM)
    17/01/2014, 15:35
    We present numerical studies the microbunching instability (MBI) in connexion with experiments performed at UVSOR-II and SOLEIL. The focus is made on the spontaneous MBI at SOLEIL, and on laser-induced seeding of the MBI at UVSOR-II. We compare experimental and numerical data using a modeling based on the Vlasov-Fokker-Planck approach. Recent numerical calculations (since mid-2012) were made...
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  36. 40. Session 1 "Impedances and Instabilities"
    Boris PODOBEDOV (Broohaven National Laboratory), John BYRD
    17/01/2014, 16:15
  37. 44. Session 2 "Instrumentation and Feedback"
    Anke-Susanne Mueller (Max-Planck-Gesellschaft (DE)), Guenther Rehm (Diamond Light Source)
    17/01/2014, 16:40
  38. 41. Session 3 "Particle Scattering"
    Emanuel Karantzoulis (Elettra -Sincrotrone Trieste), Theo DEMMA (LAL), Yannis Papaphilippou (CERN)
    17/01/2014, 17:00
  39. 42. Session 4 "Two-stream Instabilities"
    Giovanni Rumolo (CERN), Dr Roberto Cimino (LNF-INFN)
    17/01/2014, 17:20
  40. 43. Session 5 "CSR Instabilities"
    Anke-Susanne Mueller (Max-Planck-Gesellschaft (DE)), Karl BANE (SLAC National Accelerator Laboratory), Peter KUSKE (BESSY II)
    17/01/2014, 17:40
  41. 1. talk2
  42. 3. talk2
  43. 4. talk3
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  44. 2. Test 1

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