| 1. |
- Dabrowski, A. E., et al.
(författare)
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Measuring the bunch frequency multiplication at CTF3
- 2010
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Konferensbidrag (refereegranskat)abstract
- The CTF3 facility is being built and commissioned by an international collaboration in order to test the feasibility of the proposed CLIC drive beam generation scheme. Central to this scheme is the use of RF deflectors to inject bunches into a Delay Loop and a Combiner Ring, in order to transform the initial bunch spacing of 1.5 GHz from the linac to a final bunch spacing of 12 GHz. The optimization procedure relies on several steps. The active length of each ring is carefully adjusted to within a few millimeters accuracy using a two‐period undulator. The transverse optics of the machine must be set-up in a way so as to ensure the beam isochronicity. Diagnostics based on optical streak cameras and RF power measurements have been designed to measure the longitudinal behaviour of the beam during the combination. This paper presents their performance and highlights recent measurements.
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| 2. |
- Dabrowski, A. E., et al.
(författare)
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Measuring the bunch frequency multiplication at the 3rd CLIC Test Facility
- 2012
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Ingår i: Journal of Instrumentation. - 1748-0221 .- 1748-0221. ; 7, s. P01005-
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Tidskriftsartikel (refereegranskat)abstract
- The CLIC Test Facility 3 (CTF3) is being built and commissioned by an international collaboration to test the feasibility of the proposed Compact Linear Collider (CLIC) drive beam generation scheme. Central to this scheme is the use of RF deflectors to inject bunches into a delay loop and a combiner ring, in order to transform the initial bunch frequency of 1.5 GHz from the linac to a final bunch frequency of 12 GHz. To do so, the machine's transverse optics must be tuned to ensure beam isochronicity and each ring's length can finally be adjusted with wiggler magnets to a sub millimeter path length accuracy. Diagnostics based on optical streak camera and RF power measurements, in particular frequency bands, have been designed to measure the longitudinal behaviour of the beam during the combination. This paper presents the diagnostics and recent commissioning measurements.
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| 3. |
- Constance, B., et al.
(författare)
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Experimental Verification of the CLIC Two-Beam Acceleration Technology in CTF3
- 2013
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Ingår i: IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference. - 9783954501229 ; , s. 1436-1438
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Konferensbidrag (refereegranskat)abstract
- The Compact Linear Collider international collaboration is pursuing an extensive R&D program towards a multi- TeV electron-positron collider. In particular, the development of two-beam acceleration technology is the focus of the CLIC test facility CTF3. In this paper we summarise the most recent results obtained at CTF3: The results of the studies on the drive beam generation are presented, the achieved two beam acceleration performance is reported and the measured breakdown rates and related observations are summarised. The stability of the deceleration process performed over 12 subsequent modules and a comparison of the obtained results with the theoretical expectations are discussed. We also outline the future experimental program.
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| 4. |
- Dubrovskiy, A., et al.
(författare)
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Review of the drive beam stabilization in the CLIC test facility CTF3
- 2013
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Ingår i: IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference. - 9783954501229 ; , s. 2666-2668
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Konferensbidrag (refereegranskat)abstract
- CTF3 is a Test Facility focusing on beam-based studies of the key concepts of the Compact Linear Collider CLIC. Over the past several years many aspects of the CLIC two-beam acceleration scheme were studied in CTF3, including the crucial issue of drive beam stability. The main sources of drifts and instabilities have been identified and mitigated, helping to improve the machine performance and showing significant progress towards the experimental demonstration of the very stringent requirements on current, energy and phase stability needed in CLIC. In this paper, the more effective techniques and feed-backs are summarized. The latest measurements on beam stability are reported and their relevance to CLIC is discussed.
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| 5. |
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| 6. |
- Olvegård, Maja, et al.
(författare)
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High intensity profile monitor for time resolved spectrometry at the CLIC Test Facility 3
- 2012
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 683, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- The power source of the Compact Linear Collider (CLIC) relies on the generation and deceleration of a high-intensity electron drive beam. In order to provide the best radio-frequency (RF) to beam-energy transfer efficiency, the electron beam is accelerated using fully loaded RF cavities, which leads to strong beam loading effects resulting in a high-energy transient. The stability of the RF power produced by the drive beam depends on the stability of the drive beam energy and energy spread along the pulse. The control and the monitoring of the time evolution of the beam energy distribution are therefore crucial for the accelerator performance. For this purpose segmented beam dumps, which are simple and robust devices, have been designed and installed at the CLIC Test Facility 3 (CTF3). These devices are located at the end of spectrometer lines and provide horizontal beam profiles with a time resolution better than 10 ns. The segmented dumps are composed of parallel, vertical, metallic plates, and are based on the same principle as a Faraday cup: the impinging beam current is read by a fast acquisition channel. Both FLUKA and Geant4 simulations were performed to define the optimum detector geometry for beam energies ranging from 5 MeV to 150 MeV. This paper presents a detailed description of the different steps of the design: the optimization of the detector spatial resolution, the minimization of the thermal load and the long-term damage resulting from high radiation doses. Four segmented dumps are currently used in the CTF3 complex. Their measured performance and limitations are presented in this paper. Typical beam spectra as measured in the CTF3 linac are also presented along with a description of the RF manipulations needed for tuning the beam energy spectrum.
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| 7. |
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| 8. |
- Persson, Tobias, 1985, et al.
(författare)
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Beam Stability at CTF3
- 2012
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Ingår i: IPAC 2012 - International Particle Accelerator Conference 2012. - 9783954501151 ; , s. 1888-1890
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Konferensbidrag (refereegranskat)abstract
- The two-beam acceleration tested at CTF3 imposes verytight tolerances on the drive beam stability. A descriptionof the specialized monitoring tool developed to identify thedrifts and jitter in the machine is presented. It compares all the relevant signals in an on-line manner to help the operator to identify drifts and to log data for off-line analysis. The main sources for the drifts of the drive beam have been identified and their causes are described. A feedback applied to the RF was implemented to reduce the effects. It works by changing the waveform for the pulse compression to compensate for the drifts.
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| 9. |
- Persson, Tobias, 1985, et al.
(författare)
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Drive beam stability studies and stabilization algorithms in CLIC Test Facility 3
- 2014
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 735, s. 152-156
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the study of the mechanisms responsible for the time varying beam current losses in CTF3 (CLIC Test Facility 3), together with the feedbacks implemented to mitigate them, is presented. The study shows that the losses were linked mainly to the energy variation induced by the RF (Radio frequency) amplitude fluctuations. The RF-amplitude instability sources were identified. A feedback developed to mitigate this instability, acting on the RF-compression system by controlling the phase program of the klystron, is described in detail. The result is a significant improvement of the overall stability in the machine. The energy variation is reduced further with the use of an energy feedback operating on the RF-amplitude of the last klystron in the CTF3 linac. This feedback loop closes on the energy measured from a dispersive pickup after the linac. With the energy stabilized a beam current stability close to the CLIC (Compact Linear Collider) specification for a factor 4 combined beam was achieved.
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| 10. |
- Skowroński, P. K., et al.
(författare)
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Optics performance of the LHC during the 2012 run
- 2013
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Ingår i: IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference. - 9783954501229 ; , s. 1433-1435
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Konferensbidrag (refereegranskat)
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