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Title |
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| MOPPH077 |
Electron-Linac Based fs-THz Program at Pohang Accelerator Laboratory
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155 |
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- J. Park, H.-S. Kang, C. Kim
PAL, Pohang, Kyungbuk
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A 60 MeV electron linac for the source of coherent fs-THz pulses is under construction at PAL, Korea. The 266 nm pulses provided by the 3rd harmonic conversion of 800nm Ti:Sapphire amplifier system are to be delivered to the photocathode rf-gun. The electron bunches produced from the photocathode rf gun are accelerated and compressed down to several tens of femtosecond in the linac. Then the relativistic electron bunches are used to generate intense fs-THz pulses by coherent transition radiation (CTR). The radiated THz pulses are extracted from the linac vacuum pipe through a CVD diamond window. The beam, which is took up part of the 800nm beam out of the fs-regenerative amplifier, is sent to the THz laboratory to do THz pump-Optical/IR probe experiment.
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| TUAAU06 |
Status of fs-THz Beam Line Project of the PAL
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204 |
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- H.-S. Kang, S. D. Jang, C. Kim, H.-G. Kim, W. W. Lee, C. D. Park, S. J. Park, Y. J. Park, J. H. Seo, Y. G. Son
PAL, Pohang, Kyungbuk
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A femto-second THz radiation (fs-THz) facility is under construction at the Pohang Accelerator Laboratory (PAL), which is one of the beamline projects of Pohang Light Source (PLS). The facility will use a 60-MeV electron linac, which consists of an S-band photocathode RF gun with 1.6 cell cavity, two S-band accelerating structures, and two chicane-type bunch compressors. To generate intense femto-second THz radiation up to 3 THz, the electron beam with charge of 0.5 nC should be compressed down to below 150 fs. Two kinds of radiator will be prepared for pump-probe experiments for beamline: transition radiation for THz radiation (probe) and Cherenkov radiation for visible radiation (pump). The installation of the accelerator components was completed in April 2008 and the rf conditioning will end by July 2008, and the electron beam test will start in August 2008. In this article, we will present the status of the construction and commissioning of the accelerator as well as the beam dynamics design and its simulation results.
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| TUPPH019 |
Laser Pulse Shaping for Generation of Low-Emittance Electron-Beam
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278 |
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- C. Kim, Y. W. Parc, J. Park
PAL, Pohang, Kyungbuk
- K. Hyun, I. S. Ko, C. Yim
POSTECH, Pohang, Kyungbuk
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A photocathode RF gun can provides a high-charge short-bunch-length electron beam, so that it can be used for an injector of the 4th generation light source. However, owing to the high-charge in short-bunch-length, generated electron beam experiences severe space-charge effect in the beginning of acceleration and the emittance becomes bad rapidly. To reduce this space-charge effect, we made a preliminary study of pulse shaping technique. First, Parmela simulations are performed to check the beam quality improvement when the plat-top profile laser is used. Given geometry of the photocathode RF gun in the Pohang Accelerator Laboratory, Parmela simulations show 40% decrease of the emittance in electron beams. Next, by stacking four Gaussian pulses to the longitudinal direction, we tried a generation of a plat-top profile laser, and its profile is checked with a cross-correlator.
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