| 1. |
- Johansson, Anders J, et al.
(författare)
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Challenges for the low level RF design for ESS
- 2011
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Ingår i: ; , s. 460-461
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The European Spallation Source (ESS) is a planned neutron source to be built in Lund, Sweden, which is planned to produce the first neutrons in 2019. It will have an average beam power at the target of 5 MW, an average current along the linac of 50 mA, and a pulse repetition rate and length of 20 Hz and 2.86 ms, respectively. The linac will have around 200 LLRF stations employed to control a variety of RF cavities such as RFQ, DTL, spoke and elliptical superconducting cavities. The challenges on LLRF systems are mainly the high demands on energy efficiency on all parts of the facility, an operational goal of 95% availability of the facility and a comparably short time from start of final design to commissioning. Running with long pulses, high current and spoke cavities also brings new challenges on LLRF design. In this paper we will describe the consequences these challenges have on the LLRF system, and the proposed solutions and development projects that have started in order to reach these demands.
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| 2. |
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| 3. |
- Olofsson, Björn, et al.
(författare)
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Temperature Control of the ESS Phase Reference Line
- 2017
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present the suggested temperature control system of the future ESS phase-reference line. The poster describes modeling, simulation, choice of hardware components, control algorithm, and measurement results from a 4.5 meter prototype developed at the Department of Automatic Control at Lund University in close collaboration with the European Spallation Source (ESS). The measurement results indicate that temperature accuracy within +- 0.1 degree Celsius can be maintained even with significant variations in the ambient temperature. The choice of control architecture is discussed, such as suitable number of sensors and actuators and length of temperature zones.
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| 4. |
- Olofsson, Bjorn, et al.
(författare)
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Temperature Stabilization of the Phase-Reference Line at the European Spallation Source
- 2018
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Ingår i: 2018 IEEE Conference on Control Technology and Applications, CCTA 2018. - 9781538676981 ; , s. 1369-1376
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Konferensbidrag (refereegranskat)abstract
- We consider temperature stabilization of the phase-reference line at the European Spallation Source, a facility for neutron spallation currently under construction. Based on extensive modeling of the heat dynamics, a prototype model-based control system with associated hardware architecture is developed and experimentally evaluated on a small-scale setup. The results indicate that temperature stability within ±0.1°C is possible to achieve, also with significant disturbances in the ambient temperature expected during operation.
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| 5. |
- Qiu, Feng, et al.
(författare)
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A new IQ detection method for LLRF
- 2012
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 675, s. 139-143
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Tidskriftsartikel (refereegranskat)abstract
- Digital LLRF technology has been widely used in new generation particle accelerators. IF quadrature sampling is a common method for amplitude and phase detection. Many strategies, which obey the same rule of f(sample) = (M/N)f(IF) (M/N is a rational number), have been proposed to reduce the effects of spectrum aliasing. However, we found that M/N does not need to be a rational number according to Shannon's theorem. Therefore, we propose a new IQ detection method in this paper. This method is based on a special IIR filter which is derived from an RLC circuit. The unique characteristic of the method is that the value of f(IF) is independent of the value of, f(sample). We have set up an experimental platform to verify our method. A 122.88 MHz sampling clock is used to sample a 3 MHz IF signal. The DOS and PI control techniques are used to realize the closed-loop control. Results show that the stability of the system is within +/- 0.05% (peak to peak) for the amplitude, and with +/- 0.03 degrees (peak to peak) for the phase in 5 h. (C) 2012 Elsevier B.V. All rights reserved.
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| 6. |
- Rathsman, Karin, et al.
(författare)
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The RF power source for the high beta elliptical cavities of the ESS linac
- 2011
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Ingår i: ; , s. 397-399
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The European Spallation Source (ESS) is an intergovernmental project building amultidisciplinary research laboratory based upon the worlds most powerful neutron source. The main facility will be built in Lund, Sweden. Construction is expected to start around 2013 and the first neutrons will be produced in 2019. The ESS linac will deliver 5 MW of power to the target at 2.5 GeV, with a nominal current of 50 mA. The 120 high beta elliptical cavities, which operate at a frequency of 704 MHz and accelerate protons from 600 MeV to 2.5 GeV, account for more than half of the total number of RF cavities in the ESS linac and three quarters of the total beam power needed. Because of the large number of RF power sources and the high power level needed, all the design and development efforts for the RF power source have so far been focused on this part of the accelerator. The design and development status of the RF power source is reported in this paper with emphasis on reliability, maintainability, safety, power efficiency, investment cost and production capacity.
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| 7. |
- Zeng, Rihua, et al.
(författare)
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Investigation to improve efficiency and availability in control and operation of superconducting cavity at ESS
- 2016
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Ingår i: HB 2016 - Proceedings of the 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams. - 9783954501854 ; , s. 474-479
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Konferensbidrag (refereegranskat)abstract
- The higher efficiency and higher availability (fault-tolerant oriented) of RF & Cavity system (with beam loading) to operate at, the more dynamic details needs to be identified, so as to have the abilities (a) to work at nonlinearities, (b) to work close to limitation, and (c) to change operation point quickly and correctly. Dynamic detail identifications rely heavily on high precision measuring and characterizing basic cavity parameters (QL, R/Q, dynamic detuning, phase and amplitude) and system behaviours under beam-RF-cavity interactions. It is especially challenging to characterize these dynamics under varying operating points or environment. Advanced technologies in LLRF and ICS providing real time/online characterizing will be the key enablers for addressing such challenges. However, to be successful, the deployment of these technologies must be embedded within local conditions taking into account available resources, existing hardware/software structures and operation modes. Several improvement approaches will be introduced. For example, 15% or more energy efficiency improvement at ESS will be obtained by reduction of power overhead and optimization of operation.
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| 8. |
- Zeng, Rihua, et al.
(författare)
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Transient beam loading based calibration for cavity phase and amplitude setting
- 2016
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Ingår i: HB 2016 - Proceedings of the 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity, High Brightness and High Power Hadron Beams. - 9783954501854 ; , s. 250-253
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Konferensbidrag (refereegranskat)abstract
- Traditional phase scan method for cavity phase and amplitude setting is offline and hard to track the variations of environment and operation points. An alternative beam loading based calibration method is investigated in this paper, which might become useful online/real time calibration method.
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