THP2WB —  WG-B   (08-Mar-18   16:00—18:00)
Chair: M. Borland, ANL, Argonne, Illinois, USA
Paper Title Page
Survey and Outlook for Short-Pulse Schemes in Storage Rings  
  • A. Jankowiak
    HZB, Berlin, Germany
  Whereas the generation of photon pulses in the fs or even sub-fs regime is governed by single pass accelerators, the usage of short photon pulses in the ps to sub-ps regime with high repetition rates up to the MHz level and the very high stability provided by storage rings is still of growing interest. In this talk an overview of schemes to generate adequate phase space distributions of the electron bunches for the generation of short photon pulses is given. In particular electron-laser and electron-electron interactions for slicing , as well as manipulation schemes of the transversal and longitudinal beam dynamics, as low alpha-operation, the variable pulse length storage ring scheme, or two-frequency crab cavities, are addressed.  
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THP2WB02 An Overview of the Progress on SSMB 166
  • C.-X. Tang, X.J. Deng, W.-H. Huang, T. Rui
    TUB, Beijing, People's Republic of China
  • A. Chao, D.F. Ratner
    SLAC, Menlo Park, California, USA
  • J. Feikes, J. Li, M. Ries
    HZB, Berlin, Germany
  • C. Feng, B.C. Jiang, X.F. Wang
    SINAP, Shanghai, People's Republic of China
  • E. Granados
    MIT, Cambridge, Massachusetts, USA
  • A. Hoehl
    PTB, Berlin, Germany
  Steady State Microbunching (SSMB) is an electron stor- age ring based scheme proposed by Ratner and Chao to generate high average power coherent radiation and is one of the promising candidates to address the need of kW level EUV source for lithography. After the idea of SSMB was put forward, it has attracted much attention. Recently, with the promote of Chao, in collaboration with colleagues from other institutes, a SSMB task force has been established in Tsinghua University. The experimental proof of the SSMB principle and a feasible lattice design for EUV SSMB are the two main tasks at this moment. SSMB related physics for the formation and maintenance of microbunches will be explored in the first optical proof-of-principle experiment at the MLS storage ring in Berlin. For EUV SSMB lattice design, longitudinal strong focusing and reversible seeding are the two schemes on which the team focuses. The pro- gresses made as well as some challenges from physical and technological aspects for EUV SSMB will be presented in this paper.
on behalf of the SSMB team: C. Tang, Alex Chao, X. Deng, W. Huang, and T. Rui of THU; D. Ratner of SLAC; J. Feikes and M. Ries of Helmholtz-Zentrum Berlin; C. Feng, B. Jiang, and X. Wang of SINAP
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THP2WB03 Transparent Lattice Characterization with Gated Turn-by-Turn Data of Diagnostic Bunch-Train 171
  • Y. Li, W.X. Cheng, K. Ha, R.S. Rainer
    BNL, Upton, Long Island, New York, USA
  Funding: This work was supported by Depart- ment of Energy Contract No. DE-SC0012704.
Methods of characterization of a storage ring's lattice have traditionally been intrusive to routine operations. More importantly, the lattice seen by particles can drift with the beam current due to collective effects. To circumvent this, we have developed a novel approach for dynamically characterizing a storage ring's lattice that is transparent to operations. Our approach adopts a dedicated filling pattern which has a short, separate Diagnostic Bunch-Train (DBT). Gated functionality of a beam position monitor system is capable of collecting turn-by-turn data of the DBT, from which the lattice can then be characterized after excitation. As the DBT comprises only about one percent of the total operational bunches, the effects of its excitation are negligible to users. This approach allows us to localize the distributed quadrupolar wake fields generated in the storage ring vacuum chamber during beam accumulation. While effectively transparent to operations, our approach enables us to dynamically control the beta-beat and phase-beat, and unobtrusively optimize performance of National Synchrotron Light Source-II accelerator during routine operations.
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THP2WB04 Laser Seeding of Electron Bunches for Future Ring-Based Light Sources 177
  • S. Khan, B. Büsing, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, B. Riemann, B. Sawadski, M. Schmutzler, P. Ungelenk
    DELTA, Dortmund, Germany
  Funding: Funded by BMBF (05K16PEA, 05K16PEB), MERCUR (Pr-2014-0047), DFG (INST 212/236-1 FUGG) and the Land NRW.
In contrast to free-electron lasers (FELs), ring-based light sources are limited in intensity by incoherent emission and in pulse duration by the bunch length. However, FEL seeding schemes can be adopted to generate intense and ultrashort radiation pulses in storage rings by creating laser-induced microbunches within a short slice of the electron bunch. Microbunching gives rise to coherent emission at harmonics of the seed wavelength. In addition, terahertz (THz) radiation is coherently emitted over many turns. At DELTA, a storage ring operated by the TU Dortmund University, coherent harmonic generation (CHG) with single and double 40-fs pulses is routinely performed at seed wavelengths of 800 and 400 nm. Seeding with intensity-modulated pulses to generate tunable narrowband THz radiation is also studied. As a preparation for echo-enabled harmonic generation (EEHG), simultaneous seeding with 800/400-nm pulses in two undulators has been demonstrated. The DELTA storage ring is an excellent testbed to study many aspects of laser seeding and related diagnostics. In addition to short-pulse generation, steady-state microbunching at ring-based light sources will be discussed in the paper.
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