| Paper | Title | Page |
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| MOPP074 | Digital Filters Used for Digital Feedback System at cERL | 227 |
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| As a test facility for the future KEK 3-GeV energy recovery linac (ERL) project, the compact ERL (cERL) features three two-cell cavities for the injector and two nine-cell cavities for the main linac. Digital low-level radio frequency (LLRF) systems have been developed to realize highly accurate RF control. In order to reduce the influence of clock jitter and to suppress the parasitic modes in the multi-cell cavities, we have developed several types of digital filters, including a first-order IIR filter, a fourth-order conjugate poles IIR filter and a notch filter. Furthermore, to design a more effective and robust controller (such as an H-infinite controller, or repetitive controller), we need to acquire more detailed system knowledge. This knowledge can be gained by using modern system identification methods. In this paper, we present the latest applications in the LLRF systems of the cERL. identification methods. In this paper, we have compared the performance of these different type filters in cERL. The preliminary result of the system identification will be also described. | ||
| TUPP075 | The First Beam Recirculation and Beam Tuning in the Compact ERL at KEK | 599 |
| TUPOL01 | use link to see paper's listing under its alternate paper code | |
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Superconducting(SC)-linac-based light sources, which can produce ultra-brilliant photon beams in CW operation, are attracting worldwide attention. In KEK, we have been conducting R&D efforts towards the energy-recovery-linac(ERL)-based light source* since 2006. To demonstrate the key technologies for the ERL, we constructed the Compact ERL (cERL)** from 2009 to 2013. In the cERL, high-brightness CW electron beams are produced using a 500-kV photocathode DC gun. The beams are accelerated using SC cavities, transported through a recirculation loop, decelerated in the SC cavities, and dumped. In the February of 2014, we succeeded in accelerating and recirculating the CW beams of 4.5 micro-amperes in the cERL; the beams were successfully transported from the gun to the beam dump under energy recovery operation in the main linac. Then, precise tuning of beam optics and diagnostics of beam properties are under way. We report our experience on the beam commissioning, as well as the results of initial measurements of beam properties.
* N. Nakamura, IPAC2012, TUXB02. ** S. Sakanaka et al., IPAC2013, WEPWA015. |
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| THPP130 | Development of FPGA-based Predistortion-type Linearization Algorithms for Klystrons within Digital LLRF Control Systems for ILC-like Electron Accelerators | 1162 |
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| Two different kinds of predistortion-type linearization algorithms have been implemented and compared on an FPGA within the digital LLRF control system the Advanced Superconducting Test Facility (ASTA) at the Fermi National Accelerator Laboratory (FNAL). The algorithms are based on 2nd order polynomial functions and lookup tables with interpolation by which complex correction factors are obtained. The algorithms were tested in an actual setup including a 5 MW klystron and a superconducting 9-cell TESLA-type cavity at ASTA. By this a proof of concept was demonstrated. | ||
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Poster THPP130 [2.411 MB] | |