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MOPRO057 | Undulator Photon Beams with Orbital Angular Momentum | 213 |
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Photons carrying orbital angular momentum (OAM) are present in the off-axis radiation of higher harmonics of helical undulators. Usually, the purity and visibility of OAM photons is blurred by electron beam emittance. However, high brightness OAM beams are expected in ultimate storage rings and FELs, and they may trigger a new class of experiments utilizing the variability of the topological charge, a 3rd degree of freedom besides wavelength and polarization. We report on the first detection of OAM photons in helical undulator radiation in the 3rd generation storage ring BESSY II. Measurements and simulations are compared and the impact of emittance and energy spread is discussed. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO057 | |
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THPRI091 | Machine Protection Considerations for BERLinPro | 3985 |
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Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association The Berlin energy-recovery-linac project BERLinPro at the HZB is a 50 MeV ERL test facility, which addresses physical and technological questions for future superconducting rf based high brightness, high current electron beam sources. The combination of a 100 mA cw beam, electron bunches with normalized emittances lower than 1 mm mrad and the magnet optics of BERLinPro leads to power densities capable to harm the accelerator components within microseconds if total beam loss occurs. Furthermore, continuous beam loss on the level of 10-5 has to be controlled to avoid activation and to protect the SRF, beam diagnostics and other infrastructure components. In this paper, we present the evaluation of the required key parameters of the BERLinPro machine protection system and present its first conceptual design. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI091 | |
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