| Paper |
Title |
Page |
| THP001 |
Conceptual LLRF Design for the European X-FEL
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559 |
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- S. Simrock, V. Ayvazyan, A. Brandt, M. Huening, W. Koprek, F. Ludwig, K. Rehlich, E. Vogel, H. C. Weddig
DESY, Hamburg
- M. K. Grecki, T. Jezynski
TUL-DMCS, Lodz
- W. J. Jalmuzna
Warsaw University of Technology, Institute of Electronic Systems, Warsaw
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The LLRF System for the superconducting cavities of the European X-FEL must support an amplitude and phase stability of the accelerating fields of up to 0.01% and 0.01 deg. respectively. The stability must be achieved in pulsed operation with one klystron driving 32 cavities. This goal can only be achieved with low noise downconverters for field detection, high gain feedback loops and sophisticated feedforward techniques. State-of-the art technology including analog multipliers for downconversion, fast ADCs (>100 MHz) with high resolution (up to 16 bit), and high performance data processing with FPGAs with low latency (few hundred ns) allow to meets these goals. The large number of input channels ( >100 including probe, forward and reflected signal of each of the 32 cavities) and output channels (>34 including piezo tuners for each cavity) combined with the tremendous processing power requires a distributed architecture using Gigalink interfaces for low latency data exchange.
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| THP002 |
Exception Detection and Handling for Digital RF Control Systems
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562 |
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- S. Simrock, V. Ayvazyan, M. G. Hoffmann, M. Huening, W. Koprek, K. Rehlich, E. Vogel
DESY, Hamburg
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Exception detection and handling routines will play an important role in future large scale accelerator to ensure high availability and beam stability in presence of interlock trips, varying operational parameters, and operation close to the performance limit. For superconducting linacs typical examples for exception situations include cavity quenches, coupler and klystron gun sparcs, operation close to klystron saturation, and errors in vector-sum calibration. The goal is to identify all possible exception situations which will lead to performance degradation or downtime, detect these situations and take appropriate actions as necessary.
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| THP003 |
Integrated Optical Timing and RF Reference Distribution System for Large-Scale Linear Accelerators
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565 |
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- A. Winter, J. Becker, F. Loehl, K. Rehlich, S. Simrock
DESY, Hamburg
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Highly-stable timing and RF reference distribution systems are required to meet the tight specifications in large scale accelerators for next generation light sources. In this paper, we present an approach based on the distribution of an optical pulse train from a mode-locked laser via timing stabilized fiber links. The timing information is contained in the precise repetition rate of the optical pulse train (~50 MHz), so RF can be extracted at end stations with a stability on the order of 10 fs. Less timing critical signals such as ADC clocks and trigger signals can be transmitted through the same stabilized fiber using a modulated cw laser operating at a different wavelength with sub-ps stability. As multiple wavelengths can propagate without interference through the fiber, it is also possible to integrate data communication in such a fiber system. This paper will review the timing system requirements and present a conceptual layout of an optical timing and reference frequency distribution system based on work done at MIT and DESY for the XFEL.
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