| Paper | Title | Page |
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| TUPRO056 | Merit Functions for the Linac Optics Design for Colliders and Light Sources | 1159 |
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Optics matching and transverse emittance preservation are key goals for a successful operation of modern high brightness electron linacs. The capability of controlling them in a real machine critically relies on a properly designed magnetic lattice. Conscious of this fact, we introduce an ensemble of optical functions* that permit to solve the often neglected conflict between strong focusing, typically implemented to counteract coherent synchrotron radiation and transverse wakefield instability, and distortion of the transverse phase space induced by chromatic aberrations and focusing errors. A numerical evaluation of the merit functions is applied to existing and planned linac-based free electron lasers.
*S. Di Mitri and M. Cornacchia, Nucl. Instr. Meth. Phys. Research A 735, 60–65 (2014). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO056 | |
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| TUPRO098 | Design and Test of Dipole and Quadrupole Magnets for PAL-XFEL | 1271 |
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| PAL-XFEL, currently under construction in Pohang, Korea, will consist of a 10 GeV linac, three hard X-ray branches and two soft X-ray branches. As the first phase of this project, one hard X-ray (HX1) and one soft X-ray (SX1) branches will be constructed. This facility requires 6 different families of dipole magnets, and 11 families of quadrupole magnets included steering functions. We are designing these magnets with the water cooling or the heat sink system now. In this presentation, we describe the modified design of the magnets for efficient manufacturing, and the magnetic and thermal analysis with the test results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO098 | |
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| WEPRO039 | Status of PAL-XFEL Undulator Program | 2029 |
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| Pohang Accelerator Laboratory (PAL) is developing 10 GeV, 0.1 nm SASE based FEL for high power, short pulse X-ray coherent photon sources named PAL-XFEL. At the first stage PAL-XFEL needs two undulator lines for photon source. PAL is developing undulator magnetic structure based on EU-XFEL design. Recently, the hard X-ray undulator changed its minimum magnetic gap to 8.3 mm from the previous 7.2 mm to alleviate the wake field impact, and to increase the allowances for the re alignment. Accordingly, the period is also changed from 24.4 mm to 26.0 mm to generate 0.1 nm at 10 GeV electron energy. In this report, the modification efforts and the progress on the prototyping of hard x-ray undulator system will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO039 | |
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| WEPME078 | Experimental Test of the Prototype LLRF Systems for PAL-XFEL | 2462 |
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| Two prototype LLRF systems were developed in collaboration with Pohang Accelerator Laboratory(PAL) and domestic companies. They are focused on the control of single klystron system to obtain mainly analogue performance. The low power test of the developed LLRF showed good performance previously. We experimentally tested LLRF in the klystron systems to see performance in the high power situation. They showed performance around the prototype specification for short time and relatively long time. During test some bugs are discovered and fixed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME078 | |
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| THPRO018 | Electron-Magnetic-Phase Mixing in a Linac-driven FEL to Suppress Microbunching in the Optical Regime and Below | 2894 |
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Control of microbunching instability is a fundamental requirement in modern high brightness electron linacs, in order to prevent malfunction of beam optical diagnostics and contamination in the generation of coherent radiation, such as free electron lasers. We present experimental control and suppression of microbunching instability-induced optical transition radiation by means of particles’ longitudinal phase mixing in a magnetic chicane*. In presence of phase mixing, the intensity of the beam-emitted coherent optical transition radiation is reduced by one order of magnitude and brought to the same level provided, alternatively, by beam heating. The experimental results are in agreement with particle tracking and analytical evaluations of the instability gain. A discussion of applications of magnetic phase mixing to the generation of quasi-cold high-brightness ultra-relativistic electron beams is finally given.
* S. Di Mitri and S. Spampinati, Phys. Rev. Lett. 112, 134802 (2014) |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO018 | |
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| THPRO019 | Current Status of PAL-XFEL Project | 2897 |
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| The PAL-XFEL, a 0.1-nm hard X-ray FEL facility consisting of a 10-GeV S-band linac, is being constructed in Pohang, South Korea. The installation of linac, undulator, and beam line will be completed by 2015. Its building construction is at its peak moment to be completed by December 2014. The major procurement contract was made in 2013 for the critical components of S-band linac modules and hard X-ray undulators. The commissioning will start in January 2016. We hope the first lasing will be achieved in early 2016. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO019 | |
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| THPRO020 | Linac Lattice Optimization for PAL-XFEL Hard X-ray FEL Line | 2900 |
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Funding: This work is supported by MSIP, Korea. PAL-XFEL is designed to generate 1 – 0.06-nm FEL in hard x-ray FEL line. The linac for hard x-ray generates 10-GeV, 200-pC, and 3-kA electron beam. It consists of accelerating columns, three bunch compressors, an X-band linearizer, and dog-leg line. We conduct ELEGANT simulations to obtain the optimized lattice for hard x-ray line. The candidates of the optimized lattice are obtained by Multi-Objective Genetic Algorithm (MOGA) whose objectives are the FEL saturation power and length. These are evaluated with their error tolerances. Error tolerances are obtained by two methods of error simulations. First, the linear interpolation method is conducted in order to determine the machine tolerance. Also, we find out the dominant machine parameters to increase the beam jitter by this method. Second, the error simulations with random errors of machine parameters are conducted to verify the results of the linear interpolation method and calculate beam jittering levels. In this paper, we present the details of the optimized linac lattice for hard x-ray FEL. Also, we present the procedure of the linac lattice optimization. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO020 | |
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| THPRO021 | Results Produced after Measuring PAL-ITF Beam Diagnostic Instruments | 2903 |
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| Pohang Accelerator Laboratory (PAL) built a PAL-ITF at the end of 2012 to successfully complete PAL-XFEL in 2015. The PAL-ITF is equipped with various kinds of diagnostic equipment to produce high-quality electron bunches. An ICT and a Turbo-ICT were installed in the PAL-ITF. A Faraday Cup is installed at the end of the linear accelerator. These days, the quantity of electric charge occasionally is measured using a BPM Sum value. This paper focuses on the processes and results of electric charge quantity measurements using ICT, Turbo-ICT, FC and BPM. The PAL-ITF is equipped with Stripline-BPM. It is important to find a way to minimize measurement errors that can appear in the process of installing or measuring the BPM. For this, PAL-ITF separately measured the BPM electrode sensitivity and minimized BPM measurement errors through generally calibrating BPM devices by applying Lambertson's Method. A plan was made to minimize BPM measurement errors through applying the BPM electrical calibration method for BPM devices to be used by the PAL-XFEL. This paper examines the processes for checking the performance of the S-BPM installed in the PAL-ITF and the results of its measurements. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO021 | |
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| THPRI104 | Design and Fabrication of Bunch Compressor Support System for PAL XFEL | 4022 |
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| Pohang Accelerator Laboratory(PAL) is developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. Bunch compressor support systems are developed to be used for the linear accelerator tunnel. The support system design is based on an asymmetric four-dipole magnet chicane in which asymmetry and variable R56. can be optimized. This flexibility is achieved by allowing the middle two dipole magnets to move transversely. Moving system consist of servo motor, rodless ball screw actuator and linear encoder. In this paper, we describe the design of the stages used for precise movement of the bunch compressor magnets and associated diagnostics components. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI104 | |
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