Paper | Title | Page |
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MOC3O07 | Low Level RF Control Implementation and Simultaneous Operation of Two FEL Undulator Beamlines at FLASH | 42 |
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The Free-Electron Laser in Hamburg (FLASH) is a user facility delivering femtosecond short radiation pulses in the wavelength range between 4.2 and 45 nm using the SASE principle. The tests performed in the last few years have shown that two FLASH undulator beamlines can deliver FEL radiation simultaneously to users with a large variety of parameters such as radiation wavelength, pulse duration, intra-bunch spacing etc. FLASH has two injector lasers on the cathode of the gun to deliver different bunch trains with different charges, needed for different bunch lengths. Because the compression settings depend on the charge of bunches the low level RF system needs to be able to supply different compression for both beamlines. The functionality of the controller has been extended to provide intra-pulse amplitude and phase changes while maintaining the RF field amplitude and the phase stability requirements. The RF parameter adjustment and tuning for RF gun and accelerating modules can be done independently for both laser systems. Having different amplitudes and phases within the RF pulse in several RF stations simultaneous lasing of both systems has been demonstrated. | ||
Slides MOC3O07 [4.645 MB] | ||
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MOPGF079 | European XFEL Cavities Piezoelectric Tuners Control Range Optimization | 266 |
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The piezo based control of the superconducting cavity tuning has been under the development over last years. Automated compensation of Lorentz force detuning of FLASH and European X-FEL resonators allowed to maintain cavities in resonance operation even for high acceleration gradients (in range of 30 MV/m). It should be emphasized that cavity resonance control consists of two independent subsystems. First of all the slow motor tuner based system can be used for slow, wide range mechanical tuning (range of hundreds of kHz). Additionally the piezo tuning system allows for fine, dynamic compensation in a range of ~1 kHz. In mentioned pulse mode experiments (like FLASH), the piezo regulation budget should be preserved for in-pulse detuning control. In order to maintain optimal cavity frequency adjustment capabilities slow motor tuners should automatically act on the static detuning component at the same time. This paper presents work concerning development, implementation and evaluation of automatic superconducting cavity frequency control towards piezo range optimization. FLASH and X-FEL dedicated cavities tuning control experiences are also summarized. | ||
Poster MOPGF079 [0.936 MB] | ||
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MOPGF093 | Real-time Beam Loading Compensation for Single SRF Cavity LLRF Regulation | 295 |
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Stable and reproducible generation of a photon beam at Free Electron Lasers (FELs) necessitates a low energy spread of the electron beam. A low level radio frequency (LLRF) control system stabilizes the RF field inside accelerating modules. An electron beam passing through the cavity induces a drop in the actual stored field proportional to the charge, the cavity shunt impedance, and the bunch repetition rate. The feedback loop compensates for the perturbation after the accelerating gradient drops. Due to the digital loop delay and limited bandwidth of the closed loop system, this disturbance induces control errors which can increase beam energy spread. An open-loop controller uses information obtained from the beam diagnostic systems accounting in real-time for fluctuations of the beam current. This paper describes the bunch charge detection scheme, its implementation, as well as results of the tests performed on the ELBE (Electron Linac for beams with high Brilliance and low Emittance) radiation source at the HZDR (Helmholtz-Zentrum Dresden-Rossendorf) facility. | ||
Poster MOPGF093 [4.051 MB] | ||
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TUD3O05 | Integrating Control Applications into Different Control Systems | 581 |
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Funding: This work is supported by the Helmholtz Validation Fund HVF-0016 "MTCA.4 for Industry". Porting complex device servers from one control system to another is often a major effort due to the strong code coupling of the business logic to control system data structures. Together with its partners from the Helmholtz Association and from industry, DESY is developing a control system adapter. It allows to write applications in a control system independent way, while still being able to update the process variables and react on control system triggers. We report on the status of the project and the experience we gained trying to write portable device servers. |
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Slides TUD3O05 [0.628 MB] | ||
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WEPGF015 | Drivers and Software for MicroTCA.4 | 725 |
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Funding: This work is supported by the Helmholtz Validation Fund HVF-0016 'MTCA.4 for Industry'. The MicroTCA.4 crate standard provides a powerful electronic platform for digital and analogue signal processing. Besides excellent hardware modularity, it is the software reliability and flexibility as well as the easy integration into existing software infrastructures that will drive the widespread adoption of the new standard. The DESY MicroTCA.4 User Tool Kit (MTCA4U) comprises three main components: A Linux device driver, a C++ API for accessing the MicroTCA.4 devices and a control system interface layer. The main focus of the tool kit is flexibility to enable fast development. The universal, expandable PCI Express driver and a register mapping library allow out of the box operation of all MicroTCA.4 devices which are running firmware developed with the DESY board support package. The tool kit has recently been extended with features like command line tools and language bindings to Python and Matlab. |
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Poster WEPGF015 [0.540 MB] | ||
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WEPGF029 | High Level Software Structure for the European XFEL LLRF System | 757 |
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The Low level RF system for the European XFEL is controlling the accelerating RF fields in order to meet the specifications of the electron bunch parameters. A hardware platform based on the MicroTCA.4 standard has been chosen, to realize a reliable, remotely maintainable and high performing integrated system. Fast data transfer and processing is done by field programmable gate arrays (FPGA) within the crate, controlled by a CPU via PCIe communication. In addition to the MTCA system, the LLRF comprises external supporting modules also requiring control and monitoring software. In this paper the LLRF system high level software used in E-XFEL is presented. It is implemented as a semi-distributed architecture of front end server instances in combination with direct FPGA communication using fast optical links. Miscellaneous server tasks have to be executed, e.g. fast data acquisition and distribution, adaptation algorithms and updating controller parameters. Furthermore the inter-server data communication and integration within the control system environment as well as the interface to other subsystems are described. | ||
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