| Paper | Title | Page |
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| WEPME004 | A Digital Beam-Phase Control System for a Heavy-Ion Synchrotron with a Double-Harmonic Cavity System | 2926 |
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Funding: Funded by GSI Helmholtzzentrum für Schwerionenforschung GmbH For the new Facility for Antiproton and Ion Research (FAIR) at GSI Helmholtzzentrum für Schwerionenforschung GmbH, the heavy-ion synchrotron SIS18 will be operated with a double-harmonic cavity system*. The second cavity, running at twice the fundamental RF frequency, is used to lengthen the bucket which introduces nonlinearities to the control system. To damp longitudinal rigid dipole oscillations a digital feedback system consisting of a filter and an integrator is used. For the existing single-harmonic setup an FIR-filter is implemented which realizes a multiple bandpass filter with the first passband close to the synchrotron frequency. Both, the feedback gain and the passband frequency of the filter depend on the actual value of the synchrotron frequency**. It was shown by simulations and in an experiment that this setup can be transferred to a double-harmonic cavity system obtaining similar results for the region of stable feedback parameters, if the oscillation frequency of the bunch barycenter*** is considered instead of the synchrotron frequency of a linearized bucket. In this contribution the results of the simulation and the experiment are presented and compared. *Klingbeil et al.: Phys. Rev. Special Topics - Accelerators and Beams 14, 102802, 2011 **Klingbeil et al.: IEEE Trans. on Nucl. Science, Vol. 54, No. 6, 2007 ***Grieser et al.: Proc. 3rd IPAC, 2012 |
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| WEPME005 | Pulsed RF Control for the P-Linac Test Stand at FAIR | 2929 |
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Funding: Supported through BMBF contract no. 06DA9024I The p-linac will be a dedicated proton injector for antiproton production at FAIR (GSI Darmstadt). It will provide a 70 MeV/70 mA pulsed proton beam with a duty cycle of about 10-4. Therefore the RF of the normal conducting, coupled CH cavities* will be pulsed, too. In order to test the operation of those cavities, a test stand is under construction at GSI. The RF control hard- and software for the test stand is developed at TU Darmstadt. It is based on the digital low level RF control system, which is operational at the S-DALINAC**. Hardware as well as software had to be customized, in order to achieve pulsed operation within the given limits. These customizations as well as measurements from pulsed operation will be presented. *R. Brodhage et al. Development and Measurements on a Coupled CH Proton Linac for FAIR, IPAC'10 **M. Konrad et al. Digital base band rf control system for the… , PRL ST Accel. & Beams 15 |
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| THPEA003 | Use of FPGA-based Configurable Electronics to Calibrate Cavities | 3152 |
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| At the GSI Helmholzzentrum für Schwerionen-forschung GmbH the accuracy requirements for synchrotron rf cavities have strongly increased in the last years, especially for multi-harmonic operation. For heavy-ion acceleration the amplitude and phase have to be well adjusted over a whole machine cycle. In order to compensate small deviations induced by low-level rf components (LLRF) and transmission lines in the control paths, a calibration electronic (CEL) with a characteristic map was developed. It is a real-time module which is based on modern FPGA (Field Programmable Gate Array) technology and adaptable to special cavities with various physical dependencies (e.g. attenuation, dispersion, temperature drift, aging etc.). The hardware and software architecture of this CEL module are presented here. | ||
| THPEA004 | Precise Verification of Phase and Amplitude Calibration by means of a Debunching Experiment in SIS18 | 3155 |
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Funding: Work supported by the GSI Helmholtzzentrum für Schwerionenforschung GmbH Several new rf cavity systems have to be realized for the FAIR synchrotrons and for the upgrade of the existing GSI synchrotron SIS18*. For this purpose, a completely new low-level rf system architecture** has been developed, which is now used in SIS18 operation. Closed-loop control systems stabilize the amplitude and the phase of the rf gap voltages. Due to component imperfections the transmission and the detection of the actual values lead to systematic errors without countermeasures. These errors prohibit the operation of the rf systems over the whole amplitude and frequency range within the required accuracy. To compensate the inevitable errors, the target values provided by the central control system are modified by so-called calibration electronics*** modules. The calibration curves can be measured without the beam, but the desired beam behaviour has to be verified by experiments. For this purpose, a debunching scenario was selected as a SIS18 beam experiment that proved to be very sensitive to inaccuracies. In this contribution the results of this experiment are presented, showing for the first time at GSI by beam observation that the accuracy requirements are met based on predefined calibration curves. * “FAIR - Baseline Technical Report,” Volume 2, Accelerator and Scientific Infrastructure, (2006). ** Klingbeil et al.: Phys. Rev. ST Accel. Beams 14, 102802, 2011. *** S. Schaefer et al., “Use of FPGA-based Configurable Electronics to Calibrate Cavities,” THPEA003, these proceedings. |
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| THPWO011 | Status of the SIS100 Heavy Ion Synchrotron Project at FAIR | 3782 |
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| SIS100 is a unique superconducting heavy ion synchrotron, optimized for the acceleration of intense beams of intermediate charge state heavy ions. The operation with such beams has required new synchrotron design features and new technical concepts aiming for minimized ionization beam loss and vacuum dynamics. SIS100 is a superconducting synchrotron because of the required vacuum conditions and pumping power to achieve stable XHV conditions at high intensity operation. The project and procurement status will be presented. | ||
| WEPME005 | Pulsed RF Control for the P-Linac Test Stand at FAIR | 2929 |
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Funding: Supported through BMBF contract no. 06DA9024I The p-linac will be a dedicated proton injector for antiproton production at FAIR (GSI Darmstadt). It will provide a 70 MeV/70 mA pulsed proton beam with a duty cycle of about 10-4. Therefore the RF of the normal conducting, coupled CH cavities* will be pulsed, too. In order to test the operation of those cavities, a test stand is under construction at GSI. The RF control hard- and software for the test stand is developed at TU Darmstadt. It is based on the digital low level RF control system, which is operational at the S-DALINAC**. Hardware as well as software had to be customized, in order to achieve pulsed operation within the given limits. These customizations as well as measurements from pulsed operation will be presented. *R. Brodhage et al. Development and Measurements on a Coupled CH Proton Linac for FAIR, IPAC'10 **M. Konrad et al. Digital base band rf control system for the… , PRL ST Accel. & Beams 15 |
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| THPEA003 | Use of FPGA-based Configurable Electronics to Calibrate Cavities | 3152 |
|
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| At the GSI Helmholzzentrum für Schwerionen-forschung GmbH the accuracy requirements for synchrotron rf cavities have strongly increased in the last years, especially for multi-harmonic operation. For heavy-ion acceleration the amplitude and phase have to be well adjusted over a whole machine cycle. In order to compensate small deviations induced by low-level rf components (LLRF) and transmission lines in the control paths, a calibration electronic (CEL) with a characteristic map was developed. It is a real-time module which is based on modern FPGA (Field Programmable Gate Array) technology and adaptable to special cavities with various physical dependencies (e.g. attenuation, dispersion, temperature drift, aging etc.). The hardware and software architecture of this CEL module are presented here. | ||
| THPEA004 | Precise Verification of Phase and Amplitude Calibration by means of a Debunching Experiment in SIS18 | 3155 |
|
||
|
Funding: Work supported by the GSI Helmholtzzentrum für Schwerionenforschung GmbH Several new rf cavity systems have to be realized for the FAIR synchrotrons and for the upgrade of the existing GSI synchrotron SIS18*. For this purpose, a completely new low-level rf system architecture** has been developed, which is now used in SIS18 operation. Closed-loop control systems stabilize the amplitude and the phase of the rf gap voltages. Due to component imperfections the transmission and the detection of the actual values lead to systematic errors without countermeasures. These errors prohibit the operation of the rf systems over the whole amplitude and frequency range within the required accuracy. To compensate the inevitable errors, the target values provided by the central control system are modified by so-called calibration electronics*** modules. The calibration curves can be measured without the beam, but the desired beam behaviour has to be verified by experiments. For this purpose, a debunching scenario was selected as a SIS18 beam experiment that proved to be very sensitive to inaccuracies. In this contribution the results of this experiment are presented, showing for the first time at GSI by beam observation that the accuracy requirements are met based on predefined calibration curves. * “FAIR - Baseline Technical Report,” Volume 2, Accelerator and Scientific Infrastructure, (2006). ** Klingbeil et al.: Phys. Rev. ST Accel. Beams 14, 102802, 2011. *** S. Schaefer et al., “Use of FPGA-based Configurable Electronics to Calibrate Cavities,” THPEA003, these proceedings. |
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