IPAC2016 - List of Authors (Hong, J.H.)

Paper	Title	Page
MOPMB058	Bunch Arrival Time Monitor Test at PAL-XFEL ITF	223
	J.H. Hong, J.H. Han, C. Kim, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	Femtosecond resolution electron bunch arrival time monitor (BAM) will be required for the beam-based RF phase feedback during PAL-XFEL operation. Two S-band cavity-type BAMs were manufactured for the test at the PAL-XFEL injector test facility (ITF). The resonance frequencies of the cavities are 2856 MHz and 2826.25 MHz. Electron beam induced signal from the cavities was digitized using a low level RF (LLRF) module. In this paper, the resolution of these cavities are analyzed and a possible improvement for better resolution are discussed.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB058
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MOPMR001	Micro-mover Development and Test in the PAL-XFEL	229
	B.G. Oh, J.H. Han, H. Heo, J.H. Hong, H.-S. Kang, C. Kim, D.E. Kim, K.-H. Park, Y.J. Suh PAL, Pohang, Republic of Korea
	Two micro-movers, which are able to control the horizontal, vertical and longitudinal positions as well as the yaw and pitch angles remotely, were developed and installed in the PAL-XFEL linac. The solenoid micro-mover in the gun section allows beam-based alignment of an electron beam to the solenoid field and the gun RF field. The X-band cavity micro-mover minimizes the transverse wake field effect caused by transverse misalignment between the beam and X-band cavity. Two micro-movers has similar specifications and the same mechanism, but the sizes are different from each other. In this paper, we present the design, manufacture and test results of the micro-movers.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR001
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TUOAB01	Optimization of the Dechirper for Electron Bunches of Arbitrary Longitudinal Shapes	1054
SUPSS049	use link to see paper's listing under its alternate paper code
	J.M. Seok, M. Chung UNIST, Ulsan, Republic of Korea J.H. Han, J.H. Hong, H.-S. Kang PAL, Pohang, Kyungbuk, Republic of Korea
	Dechirper is a passive device composed of a vacuum chamber of two corrugated, metallic plates with an adjustable gap. By introducing a small offset in the dechirper with respect to the reference axis, one might generate transverse wakefields and use the dechirper as a deflector. Understanding the interactions between electron beams of various longitudinal shapes with the wakefields generated by the dechirper is important to assess the feasibility of the dechirper for use as a deflector. Recently, using a set of alpha-BBO crystals, shaping of laser pulses and electron bunches on the order of ps is tested at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Furthermore, we have investigated propagation of electron bunches of arbitrary longitudinal shapes through the dechirper. In the numerical simulations, we observed that the arbitrary electron beams were successful deflected except for lethal beam shape problems. Hence, in this work, we study optimization of the dechirper for electron bunches of arbitrary longitudinal shapes, using analytical theory and numerical simulations with the ASTRA and ELEGANT codes.
	Slides TUOAB01 [1.631 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOAB01
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WEYB01	Diagnostic Systems of the PAL-XFEL	2091
	C. Kim, S.Y. Baek, H. J. Choi, J.H. Hong, H.-S. Kang, G. Kim, J.H. Kim, I.S. Ko, S.J. Lee, G. Mun, B.G. Oh, B.R. Park, D.C. Shin, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	The Pohang Accelerator Laboratory (PAL) started an x-ray free electron laser project (PAL-XFEL) in 2011. The construction was finished at the end of 2015 and the commissioning is planned from the beginning of 2016. In the PAL-XFEL, an electron beam with 200 pC will be generated from a photocathode RF gun and will be accelerated to 10 GeV by using a linear accelerator. The electron beam will pass through undulator section to produce hard X-ray radiation. For the successful commissioning and beam operation, various kinds of instruments were prepared.
	Slides WEYB01 [11.770 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEYB01
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WEPOY028	Laser Heater System Test at PAL-XFEL ITF	3048
	J. H. Lee POSTECH, Pohang, Kyungbuk, Republic of Korea J.H. Han, J.H. Hong, C.H. Kim, I.S. Ko, S.J. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	Coherent x-ray photons are generated by a free electron laser (FEL). In PAL-XFEL, a photon beam with a 0.1 nm wavelength is generated from an electron bunch based on self-amplified spontaneous emission (SASE). An electron bunch with an uncorrelated energy spread in a level of 3 keV, which is generated from the photocathode RF gun, may be sensitive to longitudinal micro-bunching instability. The energy spread of an electron bunch can be increased to suppress the instability by Landau damping. In order to control the uncorrelated energy spread, a laser heater system, which has a chicane with four dipoles chicane and a 0.5 m long undulator, was installed in the injector test facility (ITF) of PAL. In this paper, we introduce the parameters of the laser heater and heating effect on the electron bunch.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY028
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Paper

Title

Page

Bunch Arrival Time Monitor Test at PAL-XFEL ITF

223

J.H. Hong, J.H. Han, C. Kim, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

Femtosecond resolution electron bunch arrival time monitor (BAM) will be required for the beam-based RF phase feedback during PAL-XFEL operation. Two S-band cavity-type BAMs were manufactured for the test at the PAL-XFEL injector test facility (ITF). The resonance frequencies of the cavities are 2856 MHz and 2826.25 MHz. Electron beam induced signal from the cavities was digitized using a low level RF (LLRF) module. In this paper, the resolution of these cavities are analyzed and a possible improvement for better resolution are discussed.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB058

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MOPMR001

Micro-mover Development and Test in the PAL-XFEL

229

B.G. Oh, J.H. Han, H. Heo, J.H. Hong, H.-S. Kang, C. Kim, D.E. Kim, K.-H. Park, Y.J. Suh
PAL, Pohang, Republic of Korea

Two micro-movers, which are able to control the horizontal, vertical and longitudinal positions as well as the yaw and pitch angles remotely, were developed and installed in the PAL-XFEL linac. The solenoid micro-mover in the gun section allows beam-based alignment of an electron beam to the solenoid field and the gun RF field. The X-band cavity micro-mover minimizes the transverse wake field effect caused by transverse misalignment between the beam and X-band cavity. Two micro-movers has similar specifications and the same mechanism, but the sizes are different from each other. In this paper, we present the design, manufacture and test results of the micro-movers.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR001

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TUOAB01

Optimization of the Dechirper for Electron Bunches of Arbitrary Longitudinal Shapes

1054

SUPSS049

use link to see paper's listing under its alternate paper code

J.M. Seok, M. Chung
UNIST, Ulsan, Republic of Korea
J.H. Han, J.H. Hong, H.-S. Kang
PAL, Pohang, Kyungbuk, Republic of Korea

Dechirper is a passive device composed of a vacuum chamber of two corrugated, metallic plates with an adjustable gap. By introducing a small offset in the dechirper with respect to the reference axis, one might generate transverse wakefields and use the dechirper as a deflector. Understanding the interactions between electron beams of various longitudinal shapes with the wakefields generated by the dechirper is important to assess the feasibility of the dechirper for use as a deflector. Recently, using a set of alpha-BBO crystals, shaping of laser pulses and electron bunches on the order of ps is tested at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Furthermore, we have investigated propagation of electron bunches of arbitrary longitudinal shapes through the dechirper. In the numerical simulations, we observed that the arbitrary electron beams were successful deflected except for lethal beam shape problems. Hence, in this work, we study optimization of the dechirper for electron bunches of arbitrary longitudinal shapes, using analytical theory and numerical simulations with the ASTRA and ELEGANT codes.

Slides TUOAB01 [1.631 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOAB01

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WEYB01

Diagnostic Systems of the PAL-XFEL

2091

C. Kim, S.Y. Baek, H. J. Choi, J.H. Hong, H.-S. Kang, G. Kim, J.H. Kim, I.S. Ko, S.J. Lee, G. Mun, B.G. Oh, B.R. Park, D.C. Shin, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

The Pohang Accelerator Laboratory (PAL) started an x-ray free electron laser project (PAL-XFEL) in 2011. The construction was finished at the end of 2015 and the commissioning is planned from the beginning of 2016. In the PAL-XFEL, an electron beam with 200 pC will be generated from a photocathode RF gun and will be accelerated to 10 GeV by using a linear accelerator. The electron beam will pass through undulator section to produce hard X-ray radiation. For the successful commissioning and beam operation, various kinds of instruments were prepared.

Slides WEYB01 [11.770 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEYB01

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPOY028

Laser Heater System Test at PAL-XFEL ITF

3048

J. H. Lee
POSTECH, Pohang, Kyungbuk, Republic of Korea
J.H. Han, J.H. Hong, C.H. Kim, I.S. Ko, S.J. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Coherent x-ray photons are generated by a free electron laser (FEL). In PAL-XFEL, a photon beam with a 0.1 nm wavelength is generated from an electron bunch based on self-amplified spontaneous emission (SASE). An electron bunch with an uncorrelated energy spread in a level of 3 keV, which is generated from the photocathode RF gun, may be sensitive to longitudinal micro-bunching instability. The energy spread of an electron bunch can be increased to suppress the instability by Landau damping. In order to control the uncorrelated energy spread, a laser heater system, which has a chicane with four dipoles chicane and a 0.5 m long undulator, was installed in the injector test facility (ITF) of PAL. In this paper, we introduce the parameters of the laser heater and heating effect on the electron bunch.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY028

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