| 1. |
- De Prisco, R., et al.
(author)
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Influence of the cavity field flatness and effect of the phase reference line errorson the beam dynamics of the ESS LINAC
- 2018
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In: HB2018 : Proceedings of the 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams - Proceedings of the 61st ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams. - 9783954502028 ; , s. 377-382
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Conference paper (peer-reviewed)abstract
- The particle longitudinal dynamics is affected by errors on the phase and amplitude of the electro-magnetic field in each cavity that cause emittance growth, beam degradation and losses. One of the causes of the phase error is the change of the ambience temperature in the LINAC tunnel, in the stub and in the klystron gallery that induces a phase drift of the signal travelling through the cables and radio frequency components. The field flatness error of each multiple cell cavity is caused by volume perturbation, cell to cell coupling, tuner penetration, etc. In this paper the influences of these two types of errors on the beam dynamics are studied and tolerances for keeping beam quality within acceptable limits are determined.
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| 2. |
- Engblom, C., et al.
(author)
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Overview of some feedback-&control systems at synchrotron SolEIL
- 2016
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In: Proceedings of the 11th International Workshop on Personal Computers and Particle Accelerator Controls, PCaPAC 2016. - 9783954501892 ; , s. 132-136
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Conference paper (peer-reviewed)abstract
- This paper gives an overview of some feedback & control systems at Synchrotron SOLEIL that are in use or in development today. Beam stability is crucial and adressed in all SOLEIL aspects; Fast Orbit Feedback is a multi-input multi-output control system made to stabilize beam position perturbations in the low- & high frequency band. In addition, active RF cavities are used to maintain stable beam energy & spread as well as keeping electron density even throughout the storage ring. Beam stability also comes from feedforward non-linear control in particle trajectory compensation on both sides of electromagnetic undulators. On some beamlines, multi-actuator piezos or pneumatics are used to regulate photon flux to keep within detector operating range; a method to maximize the photon flux while still keeping below detector damage thresholds. Currently in development & at the sample stage level, the Nanoprobe Project collaboration (MAXIV & SOLEIL) focuses on sample stabilization during step- & fly- scans which is realized through multi-axis nano-positioning with high- & low- frequency closed-loop control implementing interferometer feedback &/or compensation tables.
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| 3. |
- Lundquist, J. S., et al.
(author)
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MACHINE LEARNING METHODS FOR SINGLE SHOT RF TUNING
- 2021
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In: 10th International Beam Instrumentation Conference, IBIC 2021 - Proceedings. - 2078-8835. - 9783954502301 ; , s. 313-316
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Conference paper (peer-reviewed)abstract
- The European Spallation Source, currently under construction in Lund, Sweden, will be the world’s most powerful neutron source. It is driven by a proton linac with a current of 62.5 mA, 2.86 ms long pulses at 14 Hz. The final section of its normal-conducting front-end consists of a 39 m long drift tube linac (DTL) divided into five tanks, designed to accelerate the proton beam from 3.6 MeV to 90 MeV. The high beam current and power impose challenges to the design and tuning of the machine and the RF amplitude and phase have to be set within 1% and 1◦ of the design values. The usual method used to define the RF set-point is signature matching, which can be a challenging process, and new techniques to meet the growing complexity of accelerator facilities are highly desirable. In this paper we study the use of ML to determine the RF optimum amplitude and phase, using a single pass of the beam through the ESS DTL1 tank. This novel method is compared with the more established methods using scans over RF phase, providing similar results in terms of accuracy for simulated data with errors. We also discuss the results and future extension of the method to the whole ESS DTL.
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