| Paper | Title | Page |
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| WEPML033 | The FAIR-SIS100 Accelerating RF Station | 2762 |
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| For the Facility for Antiproton and Ion Research (FAIR) 14 ferrite loaded accelerating RF stations are planned for the first stage of realization of the SIS100 synchrotron. Each RF station has to provide a total peak gap voltage of up to 20 kVp in CW operation - tuneable in the range of 1.1 MHz up to 3.2 MHz to allow ion beam acceleration and beam gymnastics at different harmonic numbers and energy levels in the new facility. Each RF station consists of a tuneable ferrite cavity, a single ended tetrode amplifier and a dedicated power supply and control unit (PSU) ' including two bias current supplies for cavity- and control-grid(G1)-circuit-tuning. The ferrite cavity is based on the SIS18 cavity concept but has to provide a 1.25 times higher gap voltage of 20 kVp over a total length of 3 meters. The realization is done by a consortium consisting of RI Research Instruments GmbH as consortium leader and manufacturer of the cavity, Ampegon PPT GmbH (for the tetrode amplifier) and Ampegon AG (for the power supply unit). In this contribution, the system design is discussed, and commissioning results are presented. All main parameters are achieved with the RF station described. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML033 | |
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| THPML088 | Cavity Impedance Reduction Strategies During Multi Cavity Operation in the SIS100 High Intensity Hadron Synchrotron | 4863 |
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Funding: Supported by GSI Helmholtzzentrum für Schwerionenforschung GmbH The planned SIS100 heavy ion synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung will possess twenty ferrite accelerating cavities in its final stage of extension. As at injection and at flat top during slow extraction of the planned acceleration cycles the RF voltage will be relatively low, not all cavities will be active in this part of operation. It is important to analyse the impact of the inactive cavities on the overall RF voltage and subsequently their implication on the longitudinal particle dynamics. Classical approaches for reducing the beam impedance consist of active detuning of the cavities to pre-described parking frequencies. The fact that two out of ten buckets have to stay empty in all SIS100 scenarios is of particular interest as additional frequency components appear in the excitatory beam current, which have to be considered when the cavity is detuned. Therefore multi-cavity particle tracking simulations, consisting of twenty cavities and their attached LLRF control systems, are carried out in order to analyse different possibilities to minimize the impact on the beam dynamics and emittance growth. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML088 | |
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| THPML089 | Tuning of 3-tap Bandpass Filter During Acceleration for Longitudinal Beam Stabilization at FAIR | 4866 |
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During acceleration in the heavy-ion synchrotrons SIS18/SIS100 at GSI/FAIR longitudinal beam oscillations are expected to occur. To reduce longitudinal emittance blow-up, dedi- cated LLRF beam feedback systems are planned. To date, damping of longitudinal beam oscillations has been demon- strated in SIS18 machine experiments with a 3-tap filter controller (e.g. *), which is robust in regard to control pa- rameters and also to noise. On acceleration ramps the control parameters have to be adjusted to the varying synchrotron frequency. Previous results from beam experiments at GSI indicate that a proportional tuning rule for one parameter and an inversely proportional tuning rule for a second parameter is feasible, but the obtained damping rate may not be opti- mal for all synchrotron frequencies during the ramp. In this work, macro-particle simulations are performed to evaluate, whether it is sufficient to adjust the control parameters pro- portionally (inversely proportionally) to the change in the linear synchrotron frequency, or if it is necessary to take more pa- rameters, such as bunch-length and synchronous phase, into account to achieve stability and a considerable high damping rate for excited longitudinal dipole beam oscillations. This is done for single- and dual-harmonic acceleration ramps.
* H. Klingbeil et al., "A Digital Beam-Phase Control System for Heavy-Ion Synchrotrons", in IEEE Transactions on Nuclear Science, vol. 54, no. 6, pp. 2604-2610, Dec. 2007. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML089 | |
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| THPML123 | The ESR Barrier-Bucket LLRF System - Design and First Results | 4964 |
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| At GSI, Darmstadt, Germany, a Barrier-Bucket (BB) RF System is currently under development for the Experimental Storage Ring (ESR). The system consists of two broadband RF cavities, each driven by a solid state amplifier, with the purpose to produce two voltage pulses per beam revolution. This will enable highly sophisticated longitudinal beam manipulations like longitudinal capture, compression and decompression or stacking of the beam. For the LLRF System, several requirements have to be fulfilled. Besides high standards concerning the pulsed gap signal quality (e.g. ringing <2.5%), the system has to provide the flexibility for adiabatic voltage ramp-up and adiabatic pulse shifting with high timing accuracy. A connection to the FAIR Central Control System (CCS) is necessary, as amplitude and phase ramp data will be provided by the CCS. In this contribution, the structure of the ESR BB LLRF system is presented together with experimental results from the first version of the system, which will be installed in the ESR in March 2018. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML123 | |
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