| Paper | Title | Page |
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| TUPAB217 | Effect of Undulators on Transverse Resonant Island Orbits | 1927 |
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For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time*. In this Two Orbit mode, the existence of transverse resonant island buckets** are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed.
*Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings **Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021 | |
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| WEPAB131 | Magnetic Tuning and Installation Modifications of U48 Undulator for the Delhi Light Source (DLS) | 2918 |
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| A compact THz radiation facility based on the principle of a pre-bunched Free Electron Laser, called Delhi Light Source (DLS) is at the final stage of commissioning at IUAC, New Delhi, India. For generation of THz radiation in DLS, an undulator with period length of 48 mm (U48), built by HZB and refurbished at DESY will be used. The magnetic tuning and the field measurements have been done on the U48 along with the design and installation of correction coils at the entrance/exit of the U48. In addition, horizontal and vertical ambient field correction coils were integrated into the magnet girders. A quadrupole correction coil along the vacuum chamber in order to mitigate the defocusing effect of the U48 on the electron beam has been designed. The current through all coils has been adjusted as a function of the gap by the new control system designed for the U48. In addition, an extruded aluminium vacuum chamber was designed and fabricated and will be aligned with the the undulator soon. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB131 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021 | |
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| WEPAB133 | First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II | 2925 |
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| While the new in-vacuum cryogenic undulator is in its last commissioning stages, a worldwide new in-vacuum APPLE II undulator is being designed and constructed for BESSY II storage ring. Besides the challenging mechanical design of these small-gap and short-period undulators, challenges arise due to interaction with the electron beam. Therefore, detailed studies of this interaction is required to minimize the adverse effects on beam dynamics and the device itself. For this purpose, the wakefield effects have been computed numerically for critical parts of these devices i.e. the RF-shields, flexible tapers and taper sections. A brief overview of simulation results and discussions are presented in this paper. | ||
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Poster WEPAB133 [0.795 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 23 August 2021 | |
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| WEPAB134 | Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II | 2929 |
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| A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented. | ||
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Poster WEPAB134 [1.079 MB] | |
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134 | |
| About • | paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021 | |
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