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11 pages, 423 KiB

Open AccessArticle

Commissioning of Bunch Compressor to Compress Space Charge-Dominated Electron Beams for THz Applications

by Anusorn Lueangaramwong, Ekkachai Kongmon, Xiangkun Li, Prach Boonpornprasert, Georgi Georgiev, Mikhail Krasilnikov, Zakaria Aboulbanine, Gowri Adhikari, Namra Aftab, Matthias Gross, Raffael Niemczyk, Anne Oppelt, Houjun Qian, Christopher Richard, Grygorii Vashchenko, Tobias Weilbach and Frank Stephan

Appl. Sci. 2024, 14(5), 1982; https://doi.org/10.3390/app14051982 - 28 Feb 2024

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Abstract

The high peak current of the electron beam was found to be the key parameter for the THz SASE FEL at the Photo Injector Test facility at DESY in Zeuthen (PITZ). A multipurpose bunch compressor was implemented at PITZ to expand the parameter space of proof-of-principle studies on the tunable high-power accelerator-based THz source for pump-probe experiments at the European XFEL. The magnetic chicane, consisting of four rectangular dipole magnets, is designed with a bending angle of 19 degrees, due to limited space in the PITZ original beamline, to compress electron bunches with a beam momentum of 15–20 MeV/c and a charge up to 2 nC. The space charge effect and coherent synchrotron radiation are expected to drastically affect the bunch compressor performance for these parameters, thereby challenging the beam transport throughout the bunch compressor. A staged commissioning strategy was developed in order to achieve optimum bunch compressor operation. The first commissioning procedure establishes electron beam transport throughout the reference path and provides minimum beam momentum dispersion after the bunch compressor. This procedure yielded correlations between dipole magnet currents. As a result, the first bunch compression experiments were performed. Full article

(This article belongs to the Special Issue Advanced Technologies of Particle Accelerators and Their Applications)

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10 pages, 3135 KiB

Open AccessArticle

Electron Energy Spectrometer for MIR-THz FEL Light Source at Chiang Mai University

by Kittipong Techakaew, Kanlayaporn Kongmali and Sakhorn Rimjaem

Particles 2023, 6(3), 703-712; https://doi.org/10.3390/particles6030043 - 7 Jul 2023

Cited by 3 | Viewed by 1741

Abstract

The linear accelerator system of the PBP-CMU Electron Linac Laboratory has been designed with the aim of generating free-electron lasers (FELs) in the mid-infrared (MIR) and terahertz (THz) regions. The quality of the radiation is strongly dependent on the properties of the electron beam. Among the important beam parameters, the electron beam energy and energy spread are particularly important. To accurately measure the electron beam energy, the first dipole magnet in the bunch compressor system and the downstream screen station are employed as an energy spectrometer. The A Space Charge Tracking Algorithm (ASTRA) software is used for the design and optimization of this system. Simulation results demonstrate that the developed spectrometer is capable of accurately measuring the energy within the 5–25 MeV range. The screen station system is designed and constructed to have the ability to capture a beam size with a resolution of 0.1 mm per pixel. This resolution is achieved with a screen-to-camera distance of 1.2 m, which proves sufficient for precise energy measurement. The systematic error in energy measurement is found to be less than 10%, with a minimum energy spread of 0.4% achievable when the horizontal beam size remains below 3 mm. Full article

(This article belongs to the Special Issue Generation and Application of High-Power Radiation Sources)

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12 pages, 4801 KiB

Open AccessArticle

Investigation of Bunch Compressor and Compressed Electron Beam Characteristics by Coherent Transition Radiation

by Sikharin Suphakul, Heishun Zen, Toshiteru Kii and Hideaki Ohgaki

Particles 2019, 2(1), 32-43; https://doi.org/10.3390/particles2010003 - 31 Dec 2018

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Abstract

A magnetic chicane bunch compressor for a new compact accelerator-based terahertz (THz) radiation source at the Institute of Advanced Energy, Kyoto University, was completely installed in March 2016. The chicane is employed to compress an electron bunch with an energy of 4.6 MeV generated by a 1.6-cell photocathode radio frequency (RF)-gun. The compressed bunch is injected into a short planar undulator for THz generation by coherent undulator radiation (CUR). The characteristics of the bunch compressor and the compressed bunch were investigated by observing the coherent transition radiation (CTR). The CTR spectra, which were analyzed by using a Michelson interferometer, and the compressed bunch length were also estimated. The results were that the chicane could compress the electron bunch at a laser injection phase less than 45 degrees, and the maximum CTR intensity was observed at a laser injection phase around 24 degrees. The optimum value of the first momentum compaction factor was around −45 mm, which provided an estimated rms bunch length less than 1 ps. Full article

(This article belongs to the Special Issue Superradiances from Ultra Short Electron Bunch Beam)

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15 pages, 7501 KiB

Open AccessArticle

Manipulation of Laser Distribution to Mitigate the Space-Charge Effect for Improving the Performance of a THz Coherent Undulator Radiation Source

by Siriwan Krainara, Shuya Chatani, Heishun Zen, Toshiteru Kii and Hideaki Ohgaki

Particles 2018, 1(1), 238-252; https://doi.org/10.3390/particles1010018 - 7 Nov 2018

Cited by 5 | Viewed by 3444

Abstract

A THz coherent undulator radiation (THz-CUR) source has been developed at the Institute of Advanced Energy, Kyoto University. A photocathode Radio-Frequency (RF) gun and a bunch compressor chicane are used for generating short-bunch electron beams. When the electron beam energy is low, the space-charge effect strongly degrades the beam quality, such as the bunch length and the energy spread at the high bunch charge condition at around 160 pC, and results in the reduction of the highest frequency and the maximum radiated power of the THz-CUR. To mitigate the space charge effect, we have investigated the dependence of the electron beam quality on the laser distribution in transverse and longitudinal directions by using a numerical simulation code, General Particle Tracer GPT. The manipulation of the laser distribution has potential for improving the performance of the THz-CUR source. The electron bunch was effectively compressed with the chicane magnet when the laser transverse distribution was the truncated Gaussian profile, illuminating a cathode. Moreover, the compressed electron bunch was shortened by enlarging the laser pulse width. Consequently, an enhancement of the radiated power of the THz-CUR has been indicated. Full article

(This article belongs to the Special Issue Superradiances from Ultra Short Electron Bunch Beam)

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