IPAC2016 - List of Authors (Ko, I.S.)

Paper	Title	Page
MOPMR003	Electron Bunch Length Measurement Using Coherent Radiation Source of fs-THz accelerator at Pohang Accelerator Laboratory	235
SUPSS071	use link to see paper's listing under its alternate paper code
	J.H. Ko, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea S.H. Jung, H.-S. Kang, I.S. Ko, J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	A Michelson interferometer was installed at the femtosecond (fs) terahertz (THz) Accelerator of Pohang Accelerator Laboratory(PAL) to measure a subpicosecond order electron bunch length. To measure an ultra-short electron bunch length, we use reconstruction process and fast fourier transform. Currently, we are generating THz radiation with the pulse energy of 7μJ by means of coherent transition radiation (CTR) from a 65-MeV electron beam of the fs-THz accelerator. In this paper, we show the how to make a longitudinal distribution of electron bunch and the radiation intensity difference between CTR and Coherent edge radiation (CER) for nondestructive electron bunch length measurement. And we report the measurement methods to get the fine electron bunch length information.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR003
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TUPMB013	PAL-XFEL Magnet Design and Magnetic Measurement	1136
	H.S. Suh, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park PAL, Pohang, Kyungbuk, Republic of Korea
	We have designed and tested magnets for PAL-XFEL of 10GeV in Pohang, Korea. These magnets consist of 6 families of 52 dipole magnets, 11 families of 236 quadrupole magnets, and 4 families of 10⁸ corrector magnets. Two hall probe benches are used to measure the magnetic field. This paper reviews the main parameters of these magnets and the results of magnetic field measurements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB013
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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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THOBB01	PAL-XFEL Linac RF System	3192
	H.-S. Lee, H. Heo, J. Hu, H.-S. Kang, K.W. Kim, K.H. Kim, S.H. Kim, I.S. Ko, S.S. Park, Y.J. Park PAL, Pohang, Kyungbuk, Republic of Korea H. Matsumoto KEK, Tokai, Ibaraki, Japan
	The PAL-XFEL hard X-ray linac has a 716 m long gallery and tunnel for 10 GeV. Forty nine modulators are necessary in the hard X-ray gallery for an X-band linearizer, an S-band RF gun, two S-band deflectors and 45 S-band klystrons for accelerating structures. They have been installed completely from March 15, 2015 to December 30, 2015 after completing the building construction. There are 51 modulators, 178 accelerators structures, 42 SLEDs in the hard X-ray linac and the soft X-ray linac. The RF conditioning of the klystrons, SLEDs and accelerating structures were stated from November 24, 2015. We describe the PAL-XFEL system and the current status of the linac RF system.
	Slides THOBB01 [22.023 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBB01
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THPMW010	PAL-XFEL Dipole Magnet Power Supplies	3555
	S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, D.H. Na, B.G. Oh, K.-H. Park, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea
	Total 632 magnet power supplies (MPSs) are under operating in PAL-XFEL. These magnet power supplies can be categorized as three types - corrector, quadrupole and dipole. The dipole MPSs are ranging from 110A/80V bipolar PS to 310A/200V unipolar PS. The long term stability of bipolar power supply is 10 ppm with 250 A 40V output for gun solenoid. The three types of dipole MPSs are developed for PAL-XFEL. Precise measurement results show that all power supplies meet the required specifications. The long term operation stability of the MPSs are appeared to be sufficient for a stable operation of the PAL-XFEL.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW010
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THPMW013	Development of PAL-XFEL Magnet Power Supply	3564
	K.-H. Park, S.-H. Jeong, Y.-G. Jung, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea W.S. Choi POSTECH, Pohang, Kyungbuk, Republic of Korea
	All magnets and magnet power supplies (MPS) for PAL-XFEL had been installed at the site. The all MPSs had been tested with the magnets at the field. The total number of assembled MPSs was amounted to 688, which were grouped into nine categories by their power capacities in order to reduce the manufacturing cost and make maintenance easy. The general specifications for the MPS for the PAL- XFEL were summarized. The design configurations of the MPS were also explained to satisfy the given requirements such as the output current stability. The test results of performances of the MPSs for corrector magnets were described here.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW013
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THPOW045	Development of PAL-XFEL Undulator System	4044
	D.E. Kim, Y.-G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, B.G. Oh, K.-H. Park, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea J. Pflüger XFEL. EU, Hamburg, Germany
	Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL is developing undulator magnetic structure based on EU-XFEL concepts. In this report, the results of final pole height tuning results, and magnetic measurement results will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW045
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THPOY057	RF Timing Distribution and Laser Synchronization Commissioning of PAL-XFEL	4234
	C.-K. Min, S.H. Jung, H.-S. Kang, C. Kim, I.S. Ko, S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	PAL-XFEL requires <100 fs synchronization of LLRF systems and optical lasers for stable operation and even lower jitter is favorable in higher performance and pump-probe experiments. The RF timing distribution system is based on a 476 MHz reference line, which is converted to 2.856 GHz at 16 locations over 1.5 km distance using phase-locked DRO. The 2.856 GHz signals are amplified and split to 10 outputs, which is connected to LLRFs, BAMs, and DCMs through low timing drift cables. The jitter between two different PLDRO units is estimated to ~1 fs from 1 Hz to 1 MHz. The synchronization jitter between a Ti:sapphire laser and the 2.856 GHz signal is measured less than 20 fs.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY057
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THPMW012	The Fast Interlock Controller for High Power Pulse Modulator at PAL-XFEL	3561
	S.H. Kim, H.-S. Kang, K.H. Kim, S.J. Kwon, H.-S. Lee, S.S. Park, Y.J. Park PAL, Pohang, Kyungbuk, Republic of Korea I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea
	Funding: This work is supported by Ministry of Science, ICT(Information/Communication Technology) and Future Planning. The modulator control system for PAL-XFEL consists of a PLC unit (Programmable Logic Controller) and FPSCM (Fast Pulse Signal Conditioning Module). There are two kinds of interlock, which are dynamic and static interlocks categorized as analogue monitor and control signals, digital monitor and control signals. In case of dynamic interlocks, the internal interface of the PLC unit had to be modified due to operating within 10 ms time response from the interlock event. The fast pulse signal conditioning module is adopted for preconditioning the fast pulse and DC signals that inherently have high noise levels generated from a beam voltage, a beam current and EOLC current. Those EM (Electro-Magnetic) noises are generated by thyratron switching. The amplitude of the thyratron noise is large which causes the problem at the control devices, frequently. In this paper, the test results of the interlock control system will be described.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW012
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THPMY028	Technical Overview of the PAL-XFEL Conventional Facility	3715
	I. Mok, M.S. Hwang, T.-H. Kang, K.W. Kim, K.R. Kim, S.H. Kim, S.N. Kim, Y. C. Kim, B.H. Lee, H.M. Lee, M.S. Lee, B.I. Moon, K.W. Seo, C.H. Son, C.W. Sung, J. Yang PAL, Pohang, Republic of Korea Y.C. Kim, J.H. Lee Haenglim Architecture & Engineering Co. Ltd, Seoul, Republic of Korea I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea S.W. Yong Posco Engineering & Construction., Ltd., Gyeongsangbuk-do, Republic of Korea
	Pohang Accelerator Laboratory (PAL) has finished construction of a 1,110m long 10GeV X-ray free electron laser (XFEL) linear accelerator building in FY2015. In order to secure high-sensitive of XFEL accelerating devices, more advanced and well proven technologies were adopted in the design of the building. These are the ground improvement underneath the tunnel and tunnel structure itself against the possible ground deformation, air conditioning system to maintain the temperature and humidity in the tolerable ranges and architectural zoning. In this paper we describe the features of design and construction of the XFEL accelerator building.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY028
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THPMY029	Technical Overview of the PAL-XFEL Low-Conductivity Water Cooling System	3718
	B.H. Lee, H.-G. Kim, K.W. Kim, K.R. Kim, S.H. Kim, Y. C. Kim, H.M. Lee, M.S. Lee, H. Matsumoto, I. Mok, C.W. Sung, J. Yang PAL, Pohang, Republic of Korea J.H. Jeon Taeyoung, Seoul, Republic of Korea K.T. Kim HMT, Pohang, Republic of Korea I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory (PAL) started operation of an X-ray Free Electron Laser (XFEL) based on 10GeV linear accelerator in FY2015. For accurate temperature control of the various XFEL accelerator devices, a low-conductivity water (LCW) cooling system were installed. The LCW pump station generates LCW controlling the temperature variation within ±0.1°C. The LCW is supplied to klystrons including modulators and various control devices. On the other hand, the precision temperature controlled water to minimize temperature variation down to ±0.02°C. This water is supplied to accelerating columns, wave guide and SLED. Therefore, this paper shows the design, construction and operation of the LCW cooling system.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY029
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Paper

Title

Page

Electron Bunch Length Measurement Using Coherent Radiation Source of fs-THz accelerator at Pohang Accelerator Laboratory

235

SUPSS071

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

J.H. Ko, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Jung, H.-S. Kang, I.S. Ko, J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

A Michelson interferometer was installed at the femtosecond (fs) terahertz (THz) Accelerator of Pohang Accelerator Laboratory(PAL) to measure a subpicosecond order electron bunch length. To measure an ultra-short electron bunch length, we use reconstruction process and fast fourier transform. Currently, we are generating THz radiation with the pulse energy of 7μJ by means of coherent transition radiation (CTR) from a 65-MeV electron beam of the fs-THz accelerator. In this paper, we show the how to make a longitudinal distribution of electron bunch and the radiation intensity difference between CTR and Coherent edge radiation (CER) for nondestructive electron bunch length measurement. And we report the measurement methods to get the fine electron bunch length information.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR003

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TUPMB013

PAL-XFEL Magnet Design and Magnetic Measurement

1136

H.S. Suh, S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park
PAL, Pohang, Kyungbuk, Republic of Korea

We have designed and tested magnets for PAL-XFEL of 10GeV in Pohang, Korea. These magnets consist of 6 families of 52 dipole magnets, 11 families of 236 quadrupole magnets, and 4 families of 10⁸ corrector magnets. Two hall probe benches are used to measure the magnetic field. This paper reviews the main parameters of these magnets and the results of magnetic field measurements.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB013

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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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THOBB01

PAL-XFEL Linac RF System

3192

H.-S. Lee, H. Heo, J. Hu, H.-S. Kang, K.W. Kim, K.H. Kim, S.H. Kim, I.S. Ko, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
H. Matsumoto
KEK, Tokai, Ibaraki, Japan

The PAL-XFEL hard X-ray linac has a 716 m long gallery and tunnel for 10 GeV. Forty nine modulators are necessary in the hard X-ray gallery for an X-band linearizer, an S-band RF gun, two S-band deflectors and 45 S-band klystrons for accelerating structures. They have been installed completely from March 15, 2015 to December 30, 2015 after completing the building construction. There are 51 modulators, 178 accelerators structures, 42 SLEDs in the hard X-ray linac and the soft X-ray linac. The RF conditioning of the klystrons, SLEDs and accelerating structures were stated from November 24, 2015. We describe the PAL-XFEL system and the current status of the linac RF system.

Slides THOBB01 [22.023 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBB01

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THPMW010

PAL-XFEL Dipole Magnet Power Supplies

3555

S.-H. Jeong, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, D.H. Na, B.G. Oh, K.-H. Park, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea

Total 632 magnet power supplies (MPSs) are under operating in PAL-XFEL. These magnet power supplies can be categorized as three types - corrector, quadrupole and dipole. The dipole MPSs are ranging from 110A/80V bipolar PS to 310A/200V unipolar PS. The long term stability of bipolar power supply is 10 ppm with 250 A 40V output for gun solenoid. The three types of dipole MPSs are developed for PAL-XFEL. Precise measurement results show that all power supplies meet the required specifications. The long term operation stability of the MPSs are appeared to be sufficient for a stable operation of the PAL-XFEL.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW010

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THPMW013

Development of PAL-XFEL Magnet Power Supply

3564

K.-H. Park, S.-H. Jeong, Y.-G. Jung, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
W.S. Choi
POSTECH, Pohang, Kyungbuk, Republic of Korea

All magnets and magnet power supplies (MPS) for PAL-XFEL had been installed at the site. The all MPSs had been tested with the magnets at the field. The total number of assembled MPSs was amounted to 688, which were grouped into nine categories by their power capacities in order to reduce the manufacturing cost and make maintenance easy. The general specifications for the MPS for the PAL- XFEL were summarized. The design configurations of the MPS were also explained to satisfy the given requirements such as the output current stability. The test results of performances of the MPSs for corrector magnets were described here.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW013

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THPOW045

Development of PAL-XFEL Undulator System

4044

D.E. Kim, Y.-G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, B.G. Oh, K.-H. Park, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
J. Pflüger
XFEL. EU, Hamburg, Germany

Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. At the first stage, PAL-XFEL needs two undulator lines for photon source. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator and soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. PAL is developing undulator magnetic structure based on EU-XFEL concepts. In this report, the results of final pole height tuning results, and magnetic measurement results will be presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW045

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THPOY057

RF Timing Distribution and Laser Synchronization Commissioning of PAL-XFEL

4234

C.-K. Min, S.H. Jung, H.-S. Kang, C. Kim, I.S. Ko, S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

PAL-XFEL requires <100 fs synchronization of LLRF systems and optical lasers for stable operation and even lower jitter is favorable in higher performance and pump-probe experiments. The RF timing distribution system is based on a 476 MHz reference line, which is converted to 2.856 GHz at 16 locations over 1.5 km distance using phase-locked DRO. The 2.856 GHz signals are amplified and split to 10 outputs, which is connected to LLRFs, BAMs, and DCMs through low timing drift cables. The jitter between two different PLDRO units is estimated to ~1 fs from 1 Hz to 1 MHz. The synchronization jitter between a Ti:sapphire laser and the 2.856 GHz signal is measured less than 20 fs.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY057

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THPMW012

The Fast Interlock Controller for High Power Pulse Modulator at PAL-XFEL

3561

S.H. Kim, H.-S. Kang, K.H. Kim, S.J. Kwon, H.-S. Lee, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: This work is supported by Ministry of Science, ICT(Information/Communication Technology) and Future Planning.
The modulator control system for PAL-XFEL consists of a PLC unit (Programmable Logic Controller) and FPSCM (Fast Pulse Signal Conditioning Module). There are two kinds of interlock, which are dynamic and static interlocks categorized as analogue monitor and control signals, digital monitor and control signals. In case of dynamic interlocks, the internal interface of the PLC unit had to be modified due to operating within 10 ms time response from the interlock event. The fast pulse signal conditioning module is adopted for preconditioning the fast pulse and DC signals that inherently have high noise levels generated from a beam voltage, a beam current and EOLC current. Those EM (Electro-Magnetic) noises are generated by thyratron switching. The amplitude of the thyratron noise is large which causes the problem at the control devices, frequently. In this paper, the test results of the interlock control system will be described.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW012

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THPMY028

Technical Overview of the PAL-XFEL Conventional Facility

3715

I. Mok, M.S. Hwang, T.-H. Kang, K.W. Kim, K.R. Kim, S.H. Kim, S.N. Kim, Y. C. Kim, B.H. Lee, H.M. Lee, M.S. Lee, B.I. Moon, K.W. Seo, C.H. Son, C.W. Sung, J. Yang
PAL, Pohang, Republic of Korea
Y.C. Kim, J.H. Lee
Haenglim Architecture & Engineering Co. Ltd, Seoul, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.W. Yong
Posco Engineering & Construction., Ltd., Gyeongsangbuk-do, Republic of Korea

Pohang Accelerator Laboratory (PAL) has finished construction of a 1,110m long 10GeV X-ray free electron laser (XFEL) linear accelerator building in FY2015. In order to secure high-sensitive of XFEL accelerating devices, more advanced and well proven technologies were adopted in the design of the building. These are the ground improvement underneath the tunnel and tunnel structure itself against the possible ground deformation, air conditioning system to maintain the temperature and humidity in the tolerable ranges and architectural zoning. In this paper we describe the features of design and construction of the XFEL accelerator building.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY028

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THPMY029

Technical Overview of the PAL-XFEL Low-Conductivity Water Cooling System

3718

B.H. Lee, H.-G. Kim, K.W. Kim, K.R. Kim, S.H. Kim, Y. C. Kim, H.M. Lee, M.S. Lee, H. Matsumoto, I. Mok, C.W. Sung, J. Yang
PAL, Pohang, Republic of Korea
J.H. Jeon
Taeyoung, Seoul, Republic of Korea
K.T. Kim
HMT, Pohang, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) started operation of an X-ray Free Electron Laser (XFEL) based on 10GeV linear accelerator in FY2015. For accurate temperature control of the various XFEL accelerator devices, a low-conductivity water (LCW) cooling system were installed. The LCW pump station generates LCW controlling the temperature variation within ±0.1°C. The LCW is supplied to klystrons including modulators and various control devices. On the other hand, the precision temperature controlled water to minimize temperature variation down to ±0.02°C. This water is supplied to accelerating columns, wave guide and SLED. Therefore, this paper shows the design, construction and operation of the LCW cooling system.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY029

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