FEL2015 - List of Authors (Kim, H.W.)

Paper	Title	Page
MOP018	Comparison of Astra Simulations With Beam Parameter Measurements at the Kaeri Ultrashort Pulse Facility	74
	H.W. Kim, I.H. Baek, M.S. Chae, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, Y. Kim, K. Lee, S.V. Miginsky, S. H. Park, S. Park, S. Setiniyaz, N. Vinokurov KAERI, Daejon, Republic of Korea K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, S. H. Park, N. Vinokurov University of Science and Technology of Korea (UST), Daejeon, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	An RF-photogun-based linear accelerator for ultra-short electron beam generation is under construction at Korea Atomic Energy Research Institute (KAERI). This facility are mainly composed of an 1.5 cell S-band (2856 MHz) RF gun, a travelling wave type linac 3 m long and 90-degree achromatic bends. The emitted electron beams are accelerated in high RF field to ~ 3 MeV. The electrons can be deflected by a first bending magnet installed right after the RF gun. Each beamline has second bending magnet similar to the first one and three quadrupoles between the bending magnets. Two bending and three quadrupole magnets compose the 90-degree achromatic bend. The deflected electron beams will be used for ultrafast electron diffraction (UED) experiments. We have performed computer simulation using ASTRA code to investigate the electron beam dynamics in the system with the input data of bead tested gun electric field distribution and the magnetic fields of the magnets. We will present the simulated and experimental electron beam parameters.
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MOP038	Stabilization of Magnetron Frequency for a Microtron-Driven FEL	107
	B.A. Gudkov, S. Bae, K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, J. Mun, S. H. Park, G.I. Shim, N. Vinokurov KAERI, Daejon, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	Under KAERI WCI program we develop a compact pulsed microtron-driven FEL. Electron bunches trains are accelerated in the microtron and transported by the beamline to the undulator. The RF cavity in the microtron is fed by a magnetron. Any accelerator driver for a FEL should provide an electron beam having very stable parameters such as electron energy, current, and especially the bunch repetition rate in a train. All mentioned parameters depend on magnetron current. It means that special attention should be paid for the shape of the current pulse, supplied to the magnetron from the modulator. We developed the modulator project with a computer control that will provide an arbitrary shape of the magnetron current. A simplified prototype was fabricated and tested. The methods of controlling of the pulse shape are considered. Simulation and experimental results are presented.
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MOP063	Transverse Emittance Measurement of KAERI Linac with Thick Lens Quadrupole Scan	185
	S. Setiniyaz, I.H. Baek, M.S. Chae, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, S.V. Miginsky, J.H. Nam, S. Park, N. Vinokurov KAERI, Daejon, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	The UED (Ultrafast Electron Diffraction) beamline of KAERI (Korea Atomic Energy Research Institute) WCI (World Class Institute) Center has been completed and successfully commissioned. Transverse emittance of the electron beam was measured at the entrance of the UED chamber with the quadrupole scan technique. In this technique, larger drift distance between the quad and screen is preferred because it gives better thin lens approximation. A space charge dominated beam however, will undergo emittance growth in the long drift caused by the space charge force. We suggest mitigating this growth by introducing quadrupole scan with short drift and without thin lens approximation. We shall discuss the measurement process and results.
	Poster MOP063 [1.287 MB]
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MOP066	Electron Bunch Length Measurement using an RF Deflecting Cavity	188
	S. Park, E.-S. Kim Kyungpook National University, Daegu, Republic of Korea S. Bae, K.H. Jang, Y.U. Jeong, H.W. Kim, J. Mun, N. Vinokurov KAERI, Daejon, Republic of Korea
	Recently, the RF photogun based-ultrafast electron diffraction (UED) system has been developed in KAERI. In the system, the emitted electron bunches are experimentally confirmed to be accelerated up to 3 MeV at 5MW of RF power. And the time duration of the each bunch is initially designed to be less than 50 fs at the sample position. To analyses the performance of the system and to measure exactly the length of the electron bunches, we developed a rectangular type of S-band deflecting cavity working on TM120 mode. The principle of electron deflecting in the cavity, design & mechanical fabrication process and test results will be present in the conference.
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WEB02	Waveguide THz FEL Oscillators	576
	S.V. Miginsky, S. Bae, B.A. Gudkov, K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, J. Mun, S. H. Park, G.I. Shim, N. Vinokurov KAERI, Daejon, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	In today's world there is a significant demand for FEL-based THz radiation sources. They have a wide tuning range, a narrow band of radiation, and comparably high peak and average emission power. There are a significant number of these machines in the world, operating or in the development. The main difference between a long-wave FEL, of THz or a millimeter band, and a conventional one is a too big transverse size of the fundamental mode of an open optical resonator. It claims a large gap in an undulator that dramatically decreases its strength. Both factors sorely decrease the amplification and the efficiency, and often make lasing impossible. The main way to solve this problem is to use a waveguide optical resonator. It decreases and controls the transverse size of the fundamental mode. However, the waveguide causes a number of problems: power absorption in its walls; higher modes generation by inhomogeneities, as it is not ideal; electron beam injection into a FEL is more sophisticated; also outcoupling is more complicated; finally, the resonator detuning control claims some special solutions. The waveguide dispersion relation differs from one in the free space. It shifts up the wavelength of the FEL, changes the optimal detuning, and creates a parasitic mode near the critical wavelength of the waveguide. These problems and possible solutions to them are considered.
	Slides WEB02 [20.394 MB]
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Paper

Title

Page

Comparison of Astra Simulations With Beam Parameter Measurements at the Kaeri Ultrashort Pulse Facility

74

H.W. Kim, I.H. Baek, M.S. Chae, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, Y. Kim, K. Lee, S.V. Miginsky, S. H. Park, S. Park, S. Setiniyaz, N. Vinokurov
KAERI, Daejon, Republic of Korea
K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, S. H. Park, N. Vinokurov
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

An RF-photogun-based linear accelerator for ultra-short electron beam generation is under construction at Korea Atomic Energy Research Institute (KAERI). This facility are mainly composed of an 1.5 cell S-band (2856 MHz) RF gun, a travelling wave type linac 3 m long and 90-degree achromatic bends. The emitted electron beams are accelerated in high RF field to ~ 3 MeV. The electrons can be deflected by a first bending magnet installed right after the RF gun. Each beamline has second bending magnet similar to the first one and three quadrupoles between the bending magnets. Two bending and three quadrupole magnets compose the 90-degree achromatic bend. The deflected electron beams will be used for ultrafast electron diffraction (UED) experiments. We have performed computer simulation using ASTRA code to investigate the electron beam dynamics in the system with the input data of bead tested gun electric field distribution and the magnetic fields of the magnets. We will present the simulated and experimental electron beam parameters.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP038

Stabilization of Magnetron Frequency for a Microtron-Driven FEL

107

B.A. Gudkov, S. Bae, K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, J. Mun, S. H. Park, G.I. Shim, N. Vinokurov
KAERI, Daejon, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

Under KAERI WCI program we develop a compact pulsed microtron-driven FEL. Electron bunches trains are accelerated in the microtron and transported by the beamline to the undulator. The RF cavity in the microtron is fed by a magnetron. Any accelerator driver for a FEL should provide an electron beam having very stable parameters such as electron energy, current, and especially the bunch repetition rate in a train. All mentioned parameters depend on magnetron current. It means that special attention should be paid for the shape of the current pulse, supplied to the magnetron from the modulator. We developed the modulator project with a computer control that will provide an arbitrary shape of the magnetron current. A simplified prototype was fabricated and tested. The methods of controlling of the pulse shape are considered. Simulation and experimental results are presented.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP063

Transverse Emittance Measurement of KAERI Linac with Thick Lens Quadrupole Scan

185

S. Setiniyaz, I.H. Baek, M.S. Chae, B.A. Gudkov, B. Han, K.H. Jang, Y.U. Jeong, H.W. Kim, S.V. Miginsky, J.H. Nam, S. Park, N. Vinokurov
KAERI, Daejon, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

The UED (Ultrafast Electron Diffraction) beamline of KAERI (Korea Atomic Energy Research Institute) WCI (World Class Institute) Center has been completed and successfully commissioned. Transverse emittance of the electron beam was measured at the entrance of the UED chamber with the quadrupole scan technique. In this technique, larger drift distance between the quad and screen is preferred because it gives better thin lens approximation. A space charge dominated beam however, will undergo emittance growth in the long drift caused by the space charge force. We suggest mitigating this growth by introducing quadrupole scan with short drift and without thin lens approximation. We shall discuss the measurement process and results.

Poster MOP063 [1.287 MB]

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

MOP066

Electron Bunch Length Measurement using an RF Deflecting Cavity

188

S. Park, E.-S. Kim
Kyungpook National University, Daegu, Republic of Korea
S. Bae, K.H. Jang, Y.U. Jeong, H.W. Kim, J. Mun, N. Vinokurov
KAERI, Daejon, Republic of Korea

Recently, the RF photogun based-ultrafast electron diffraction (UED) system has been developed in KAERI. In the system, the emitted electron bunches are experimentally confirmed to be accelerated up to 3 MeV at 5MW of RF power. And the time duration of the each bunch is initially designed to be less than 50 fs at the sample position. To analyses the performance of the system and to measure exactly the length of the electron bunches, we developed a rectangular type of S-band deflecting cavity working on TM120 mode. The principle of electron deflecting in the cavity, design & mechanical fabrication process and test results will be present in the conference.

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

WEB02

Waveguide THz FEL Oscillators

576

S.V. Miginsky, S. Bae, B.A. Gudkov, K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, J. Mun, S. H. Park, G.I. Shim, N. Vinokurov
KAERI, Daejon, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

In today's world there is a significant demand for FEL-based THz radiation sources. They have a wide tuning range, a narrow band of radiation, and comparably high peak and average emission power. There are a significant number of these machines in the world, operating or in the development. The main difference between a long-wave FEL, of THz or a millimeter band, and a conventional one is a too big transverse size of the fundamental mode of an open optical resonator. It claims a large gap in an undulator that dramatically decreases its strength. Both factors sorely decrease the amplification and the efficiency, and often make lasing impossible. The main way to solve this problem is to use a waveguide optical resonator. It decreases and controls the transverse size of the fundamental mode. However, the waveguide causes a number of problems: power absorption in its walls; higher modes generation by inhomogeneities, as it is not ideal; electron beam injection into a FEL is more sophisticated; also outcoupling is more complicated; finally, the resonator detuning control claims some special solutions. The waveguide dispersion relation differs from one in the free space. It shifts up the wavelength of the FEL, changes the optimal detuning, and creates a parasitic mode near the critical wavelength of the waveguide. These problems and possible solutions to them are considered.

Slides WEB02 [20.394 MB]

Export •

reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)