FEL2015 - List of Keywords (cavity)

Paper	Title	Other Keywords	Page
MOP021	LCLS-II Injector Beamline Design and RF Coupler Correction	emittance, solenoid, cathode, quadrupole	77
	F. Zhou, D. Dowell, R.K. Li, T.O. Raubenheimer, J.F. Schmerge SLAC, Menlo Park, California, USA C.E. Mitchell, C. F. Papadopoulos, F. Sannibale LBNL, Berkeley, California, USA A. Vivoli Fermilab, Batavia, Illinois, USA
	Funding: U.S. DOE contract #DE-AC02-76SF00515. LCLS-II CW injector beamline consists of a 186 MHz normal conducting (NC) RF gun for beam generation and acceleration to 750 keV, two solenoids for the beam focusing, two BPMs, 1.3 GHz NC RF buncher for bunch compression down to 3-4 ps rms, 1.3 GHz superconducting standard 8-cavity cryomodule to boost beam energy to about 98 MeV. The beamline is being optimized to accommodate all essential components and maximize beam quality. The beamline layouts and beam dynamics are presented and compared. The 3D RF field perturbation due to cavity couplers where the beam energy is very low (<1 MeV) causes significant emittance growth especially for a large-size beam. A theory of rotated fields predicted and simulations verified using a weak skew quadrupole located even a significant distance from the perturbation can completely eliminate the emittance growth. A layout for future upgrade is developed. The results are presented and analysed.
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MOP024	Status, Plans and Recent Results from the APEX Project at LBNL	gun, cathode, linac, electron	81
	F. Sannibale, K.M. Baptiste, C.W. Cork, S. De Santis, M.R. Dickinson, L.R. Doolittle, J.A. Doyle, J. Feng, D. Filippetto, G.L. Harris, G. Huang, R. Huang, M.J. Johnson, M.S. Jones, T.D. Kramasz, S. Kwiatkowski, D. Leitner, R.E. Lellinger, C.E. Mitchell, V. Moroz, W.E. Norum, H.A. Padmore, G.J. Portmann, H.J. Qian, J.W. Staples, D. L. Syversrud, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev LBNL, Berkeley, California, USA R. Huang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is dedicated to the demonstration of the capability of an electron injector based on the VHF-gun, the new concept RF gun developed at LBNL, of delivering the beam quality required by MHz-class repetition rate X-Ray free electron lasers. Project status, plans, and recent results are presented.
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MOP030	Study of Smith-Purcell Free Electron Laser Using Electron Bunch Produced By Micro-Pulse Electron Gun	electron, bunching, radiation, simulation	93
	J. Zhao, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, Z.Q. Yang PKU, Beijing, People's Republic of China
	A Micro-Pulse electron Gun (MPG) with the frequency of 2856 MHz has been designed, constructed and tested. Some primary experimental studies have been carried out and electron beam with the average current of 6 mA has been detected which holds promise to use as an electron source of Smith-Purcell Free Electron Laser (SP-FEL) to produced Coherent Radiation. It is well known that Smith-Purcell radiation is one of the achievable ways to produce FEL. After many years study in theory and experiment, lots of new mechanisms and appearances have been discovered. Coherent Smith-Purcell Radiation was discovered in 1990s as well. Compared with incoherent Smith-Purcell Radiation, It can generate a more powerful and frequency locked coherent emission due to displaying all three of these enhancements, Ng (the number of grating periods), Ne (the number of electrons in the bunch), Nb (the number of electron bunch). Obviously, MPG is one of ideal electron sources of CSPR for that (1) S-band electron source can increase energy density at these frequencies, (2) picosecond or subpicosecond pulse can generate THz radiation, (3) low emittance makes the interactions between electron beam and granting more stable. All of the above will be displayed in the simulation of this article. The progress of the experiment with beam energy of 80 Kev, the average current of 6 mA is also introduced.
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MOP038	Stabilization of Magnetron Frequency for a Microtron-Driven FEL	controls, FEL, microtron, electron	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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MOP056	Reversible Electron Beam Heater without Transverse Deflecting Cavities	emittance, electron, optics, synchrotron	166
	G. Stupakov, P. Emma SLAC, Menlo Park, California, USA
	Funding: This work was supported by Department of Energy contract DE-AC03-76SF00515. Suppression of microbunching instability in modern FELs is an important issue that often limits the performance of the machine. A technique to suppress the instability with the help of a reversible electron beam heater was proposed by C. Behrens, Z. Huang, and D. Xiang []. It employs transverse deflecting cavities synchronized in a way that one of the cavities, located before a bunch compressor, generates a slice energy spread, while the other one removes it after the beam passes through the bunch compressor. Being an attractive approach, this concept unfortunately imposes extremely tight tolerances on the synchronization of the cavities. In this paper we demonstrate that a reversible heater equivalent to that of Behrens et al. can be designed using much simpler elements: bend magnets and quadrupoles in combination with the energy chirp of the beam. C. Behrens, Z. Huang, and D. Xiang, PRST-AB 15, 022802 (2012).
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MOP066	Electron Bunch Length Measurement using an RF Deflecting Cavity	electron, simulation, resonance, space-charge	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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TUP015	Status of the ALICE IR-FEL: from ERL Demonstrator to User Facility	FEL, laser, radiation, operation	379
	N. Thompson, J.A. Clarke, D.J. Dunning, A.J. Moss, Y.M. Saveliev, M. Surman STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom T. Craig, M.R.F. Siggel-King, P. Weightman The University of Liverpool, Liverpool, United Kingdom O.V. Kolosov, P.D. Tovee Lancaster University, Lancaster, United Kingdom M.R.F. Siggel-King Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The ALICE (Accelerators and Lasers In Combined Experiments) accelerator at STFC Daresbury Laboratory in the UK was conceived in 2003 and constructed as a short-term Energy Recovery Linac demonstrator to develop the underpinning technology and expertise required for a proposed 600MeV ERL-based FEL facility. In this paper we present an update on the performance and status of ALICE which now operates as a funded IR-FEL user facility. We discuss the challenges of evolving a short-term demonstrator into a stable, reliable user facility and present a summary of the current scientific programme.
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TUP028	DESIGN OF THE MID-INFRARED FEL OSCILLATOR IN CHINA	FEL, electron, undulator, laser	427
	H.T. Li, Q.K. Jia, L. Wang, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	In 2014, Xiamen University and other three research organizations received the approval to realize an infrared free electron laser (IR-FEL) for fundamental of energy chemistry. The IR-FEL covers the spectral range of 2.5-200 μm and will be built in NSRL. Two FEL oscillators driven by one Linac will be used to generate mid- infrared and far-infrared lasers. In this article we describe the design studies for the mid-infrared FEL oscillator.
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TUP030	Time Dependent Study for an X-ray FEL Oscillator at LCLS-II	electron, photon, undulator, free-electron-laser	433
	J. Zemella DESY, Hamburg, Germany W.M. Fawley, T.J. Maxwell SLAC, Menlo Park, California, USA R.R. Lindberg ANL, Argonne, Illinois, USA
	The LCLS-II with its high repetition rate and high quality beam will be capable of driving an X-ray free electron laser oscillator at higher harmonics in the hard X-ray regime (0.1 nm). The oscillator consists of a low loss X-ray crystal cavity using diamond Bragg crystals with meV bandwidth. The expected average spectral flux has been estimated to be at least two orders of magnitude greater than present synchrotron-based sources with highly stable, coherent pulses of duration 1 ps or less for applications in Mössbauer spectroscopy and inelastic x-ray scattering. A more detailed study of the start up of a fifth-harmonic X-ray FEL oscillator at LCLS-II will be presented with full, time-dependent simulations.
	Poster TUP030 [0.619 MB]
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TUP040	Simulation and Design of Low Emittance RF Electron Gun	electron, emittance, gun, coupling	455
	C. Saisa-ard, S. Rimjaem Chiang Mai University, Chiang Mai, Thailand
	Funding: This work has been supported by the CMU Junior Research Fellowship Program and the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University. Generation of high-brightness electron beam is one of the most critical issues in development of advanced electron accelerators and light sources. At the Plasma and Beam Physics (PBP) Research Facility, Chiang Mai University, a low emittance RF electron gun is under the development. This RF-gun is planned to be used as an electron source for a future IR/THz FEL facility. An extra resonant cavity is added to the modified design of the existing PBP-CMU RF-gun in order to reduce the transverse sliced emittance. This cell is coupled to the main full-cell via a side-coupling cavity. The electromagnetic field distributions inside the cavities are simulated by using the CST Microwave Studio 2012. Then, beam dynamic simulations utilizing the program PARMELA are performed. Both RF and beam dynamic simulation results are reported and discussed in this contribution. The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Materials Science and the Graduate School, Chiang Mai University.
	Poster TUP040 [2.140 MB]
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TUP043	PAL-XFEL Cavity BPM Prototype Beam Test at ITF	pick-up, electron, dipole, simulation	468
	S.J. Lee, J.H. Han, H.-S. Kang, C. Kim, S.H. Kim, I.S. Ko, Y.J. Park, D.C. Shin PAL, Pohang, Kyungbuk, Republic of Korea
	To achieve sub-micrometer resolution, PAL-XFEL undulator section will use X-band Cavity beam position monitor (BPM) systems. The prototype cavity BPM pick-up was designed and fabricated to test the performance of the cavity BPM system. The fabricated prototype cavity BPM pick-up was installed at Pohang Accelerator Laboratory injector test facility (PAL ITF) for the beam test. Under 200 pC beam charge condition, the signal properties of the cavity BPM pick-up were measured. Also, the dynamic range of the cavity BPM pick-up was measured by using the corrector magnet. In this paper, the design and beam test results of the prototype cavity BPM pick-up will be discussed.
	Poster TUP043 [0.695 MB]
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TUP072	Cathode Ion Bombardment in LCLS and LCLS-II RF Gun	ion, cathode, gun, solenoid	534
	L. Wang, A. Brachmann, F.-J. Decker, Z. Li, T.O. Raubenheimer, J.F. Schmerge, F. Zhou SLAC, Menlo Park, California, USA
	This paper studies the ions bombardment on the cathode in the LCLS and LCLS-II gun. APEX gun is used here for LCLS-II, which will be operate at 1 MHz repetition rate. Therefore, It is important to estimate the ion bombardment. One specific PIC code is used track arbitrary particles (ions and electron here) in arbitrary 2D/3D electromagnetic field and solenoid field to estimate the possibility of ion bombardment. The LCLS gun has 1.6 cells while the LCLS-II gun (APEX gun) is a half-cell gun. The frequencies of the two guns are also quite different. These characters make the ion dynamics quite differently. We estimated the bombardment for various ion species and studied the effects RF pulse shape and RF phase
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TUP080	Terahertz Source Utilizing Resonant Coherent Diffraction Radiation at KEK ERL Test Accelerator	radiation, photon, extraction, operation	547
	Y. Honda, A. Aryshev, M. Shevelev, M. Shimada KEK, Ibaraki, Japan
	An energy recovery linac test accelerator, cERL, has been developing at KEK. It can produce a high repetition rate short bunched electron beam in a continuous operation mode. We propose to develop a high power THz radiation source at the return loop of the cERL. Coherent diffraction radiation of THz regime is emitted when an electron bunch passes through a conductive mirror with a beam hole at the center. If we form an optical cavity using two mirrors facing each other and the cavity length coincides with the bunch repetition rate, the coherent diffraction radiation of multiple bunches adds up coherently in the cavity. By extracting the power through transmission of one of the mirrors, we can realize a high power and high efficiency THz source. We discuss performance of the source assuming the beam parameters of cERL.
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TUD03	First Results of the SRF Gun Test for CeC PoP Experiment	cathode, gun, laser, electron	564
	I. Pinayev, Z. Altinbas, S.A. Belomestnykh, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, T. Rao, J. Reich, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA
	We have started the first tests of the equipment for the coherent electron cooling proof-of-principle experiment. After tests of the 500 MHz normal conducting cavities we proceeded with the low power beam tests of a CW SRF gun. The results of the tests with record beam parameters are presented.
	Slides TUD03 [1.201 MB]
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WEB01	A Two-Color Storage Ring FEL	FEL, undulator, electron, operation	571
	J. Yan, H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA S. Huang PKU, Beijing, People's Republic of China J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China N. Vinokurov BINP SB RAS, Novosibirsk, Russia J. Wu SLAC, Menlo Park, California, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. Using different undulator configurations on the Duke storage ring, we have successfully achieved lasing with a novel two-color storage ring FEL. Using a pair of dual-band FEL mirrors, simultaneous lasing was realized in IR (around 720 nm) and in UV (around 360 nm). With this two-color FEL, we have demonstrated independent wavelength tuning of either IR or UV lasing. With careful tuning, we have also realized harmonic lasing with the UV lasing tuned to the second harmonic of the IR lasing. The tuning of harmonic two-color lasing has also been demonstrated with the locked wavelengths. Furthermore, we have demonstrated good control of the FEL power sharing between the two colors. The two-color FEL has created new opportunities to drive a two-color Compton gamma-ray beam at the High Intensity gamma-ray Source at Duke.
	Slides WEB01 [18.975 MB]
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WEP001	RF Gun Dark Current Suppression with a Transverse Deflecting Cavity at LCLS	undulator, radiation, FEL, gun	583
	J.R. Lewandowski, R.C. Field, A.S. Fisher, H.-D. Nuhn, J.J. Welch SLAC, Menlo Park, California, USA
	Funding: Work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515. A significant source of radiation signals in the LCLS Undulator have been identified as being generated by dark current emitted from the LCLS RF Photocathode Gun. Radiation damage to magnets over time can lead to degraded performance and significant cost for replacement. A method of using an existing transverse deflector cavity with a modified RF pulse has been tested and shows promise for eliminating the radiation dose from RF gun dark current that is generated in time before and after the production beam pulse. UNDULATOR RADIATION DAMAGE EXPERIENCE AT LCLS: H.-D. Nuhn, C. Field, S. Mao, Y. Levashov, M. Santana, J.N. Welch, Z. Wolf, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, U.S.A
	Poster WEP001 [1.631 MB]
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WEP060	Longitudinal Electron Bunch Shaping Experiments at the PAL-ITF	laser, electron, experiment, FEL	694
	M. Chung, J.M. Seok UNIST, Ulsan, Republic of Korea J.H. Han, J.H. Hong, H.-S. Kang, C.H. Kim PAL, Pohang, Kyungbuk, Republic of Korea J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	Longitudinal shaping of electron beam has received much attention recently, due to its potential applications to THz generation, dielectric wakefield acceleration, improvement of FEL performance, and controlled space-charge modulation. Using a set of alpha-BBO crystals, shaping of laser pulse and electron bunch on the order of ps is tested at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). In particular, we investigate the response of the longitudinally-modulated beam to a dechirper, which is a vacuum chamber of two corrugated, metallic plates. Initial experimental results will be presented with analytical theory and numerical simulations.
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Paper

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Other Keywords

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MOP021

LCLS-II Injector Beamline Design and RF Coupler Correction

emittance, solenoid, cathode, quadrupole

77

F. Zhou, D. Dowell, R.K. Li, T.O. Raubenheimer, J.F. Schmerge
SLAC, Menlo Park, California, USA
C.E. Mitchell, C. F. Papadopoulos, F. Sannibale
LBNL, Berkeley, California, USA
A. Vivoli
Fermilab, Batavia, Illinois, USA

Funding: U.S. DOE contract #DE-AC02-76SF00515.
LCLS-II CW injector beamline consists of a 186 MHz normal conducting (NC) RF gun for beam generation and acceleration to 750 keV, two solenoids for the beam focusing, two BPMs, 1.3 GHz NC RF buncher for bunch compression down to 3-4 ps rms, 1.3 GHz superconducting standard 8-cavity cryomodule to boost beam energy to about 98 MeV. The beamline is being optimized to accommodate all essential components and maximize beam quality. The beamline layouts and beam dynamics are presented and compared. The 3D RF field perturbation due to cavity couplers where the beam energy is very low (<1 MeV) causes significant emittance growth especially for a large-size beam. A theory of rotated fields predicted and simulations verified using a weak skew quadrupole located even a significant distance from the perturbation can completely eliminate the emittance growth. A layout for future upgrade is developed. The results are presented and analysed.

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MOP024

Status, Plans and Recent Results from the APEX Project at LBNL

gun, cathode, linac, electron

81

F. Sannibale, K.M. Baptiste, C.W. Cork, S. De Santis, M.R. Dickinson, L.R. Doolittle, J.A. Doyle, J. Feng, D. Filippetto, G.L. Harris, G. Huang, R. Huang, M.J. Johnson, M.S. Jones, T.D. Kramasz, S. Kwiatkowski, D. Leitner, R.E. Lellinger, C.E. Mitchell, V. Moroz, W.E. Norum, H.A. Padmore, G.J. Portmann, H.J. Qian, J.W. Staples, D. L. Syversrud, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev
LBNL, Berkeley, California, USA
R. Huang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The Advanced Photo-injector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is dedicated to the demonstration of the capability of an electron injector based on the VHF-gun, the new concept RF gun developed at LBNL, of delivering the beam quality required by MHz-class repetition rate X-Ray free electron lasers. Project status, plans, and recent results are presented.

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MOP030

Study of Smith-Purcell Free Electron Laser Using Electron Bunch Produced By Micro-Pulse Electron Gun

electron, bunching, radiation, simulation

93

J. Zhao, X.Y. Lu, W.W. Tan, D.Y. Yang, Y. Yang, Z.Q. Yang
PKU, Beijing, People's Republic of China

A Micro-Pulse electron Gun (MPG) with the frequency of 2856 MHz has been designed, constructed and tested. Some primary experimental studies have been carried out and electron beam with the average current of 6 mA has been detected which holds promise to use as an electron source of Smith-Purcell Free Electron Laser (SP-FEL) to produced Coherent Radiation. It is well known that Smith-Purcell radiation is one of the achievable ways to produce FEL. After many years study in theory and experiment, lots of new mechanisms and appearances have been discovered. Coherent Smith-Purcell Radiation was discovered in 1990s as well. Compared with incoherent Smith-Purcell Radiation, It can generate a more powerful and frequency locked coherent emission due to displaying all three of these enhancements, Ng (the number of grating periods), Ne (the number of electrons in the bunch), Nb (the number of electron bunch). Obviously, MPG is one of ideal electron sources of CSPR for that (1) S-band electron source can increase energy density at these frequencies, (2) picosecond or subpicosecond pulse can generate THz radiation, (3) low emittance makes the interactions between electron beam and granting more stable. All of the above will be displayed in the simulation of this article. The progress of the experiment with beam energy of 80 Kev, the average current of 6 mA is also introduced.

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MOP038

Stabilization of Magnetron Frequency for a Microtron-Driven FEL

controls, FEL, microtron, electron

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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MOP056

Reversible Electron Beam Heater without Transverse Deflecting Cavities

emittance, electron, optics, synchrotron

166

G. Stupakov, P. Emma
SLAC, Menlo Park, California, USA

Funding: This work was supported by Department of Energy contract DE-AC03-76SF00515.
Suppression of microbunching instability in modern FELs is an important issue that often limits the performance of the machine. A technique to suppress the instability with the help of a reversible electron beam heater was proposed by C. Behrens, Z. Huang, and D. Xiang [*]. It employs transverse deflecting cavities synchronized in a way that one of the cavities, located before a bunch compressor, generates a slice energy spread, while the other one removes it after the beam passes through the bunch compressor. Being an attractive approach, this concept unfortunately imposes extremely tight tolerances on the synchronization of the cavities. In this paper we demonstrate that a reversible heater equivalent to that of Behrens et al. can be designed using much simpler elements: bend magnets and quadrupoles in combination with the energy chirp of the beam.
* C. Behrens, Z. Huang, and D. Xiang, PRST-AB 15, 022802 (2012).

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MOP066

Electron Bunch Length Measurement using an RF Deflecting Cavity

electron, simulation, resonance, space-charge

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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TUP015

Status of the ALICE IR-FEL: from ERL Demonstrator to User Facility

FEL, laser, radiation, operation

379

N. Thompson, J.A. Clarke, D.J. Dunning, A.J. Moss, Y.M. Saveliev, M. Surman
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
T. Craig, M.R.F. Siggel-King, P. Weightman
The University of Liverpool, Liverpool, United Kingdom
O.V. Kolosov, P.D. Tovee
Lancaster University, Lancaster, United Kingdom
M.R.F. Siggel-King
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The ALICE (Accelerators and Lasers In Combined Experiments) accelerator at STFC Daresbury Laboratory in the UK was conceived in 2003 and constructed as a short-term Energy Recovery Linac demonstrator to develop the underpinning technology and expertise required for a proposed 600MeV ERL-based FEL facility. In this paper we present an update on the performance and status of ALICE which now operates as a funded IR-FEL user facility. We discuss the challenges of evolving a short-term demonstrator into a stable, reliable user facility and present a summary of the current scientific programme.

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TUP028

DESIGN OF THE MID-INFRARED FEL OSCILLATOR IN CHINA

FEL, electron, undulator, laser

427

H.T. Li, Q.K. Jia, L. Wang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

In 2014, Xiamen University and other three research organizations received the approval to realize an infrared free electron laser (IR-FEL) for fundamental of energy chemistry. The IR-FEL covers the spectral range of 2.5-200 μm and will be built in NSRL. Two FEL oscillators driven by one Linac will be used to generate mid- infrared and far-infrared lasers. In this article we describe the design studies for the mid-infrared FEL oscillator.

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TUP030

Time Dependent Study for an X-ray FEL Oscillator at LCLS-II

electron, photon, undulator, free-electron-laser

433

J. Zemella
DESY, Hamburg, Germany
W.M. Fawley, T.J. Maxwell
SLAC, Menlo Park, California, USA
R.R. Lindberg
ANL, Argonne, Illinois, USA

The LCLS-II with its high repetition rate and high quality beam will be capable of driving an X-ray free electron laser oscillator at higher harmonics in the hard X-ray regime (0.1 nm). The oscillator consists of a low loss X-ray crystal cavity using diamond Bragg crystals with meV bandwidth. The expected average spectral flux has been estimated to be at least two orders of magnitude greater than present synchrotron-based sources with highly stable, coherent pulses of duration 1 ps or less for applications in Mössbauer spectroscopy and inelastic x-ray scattering. A more detailed study of the start up of a fifth-harmonic X-ray FEL oscillator at LCLS-II will be presented with full, time-dependent simulations.

Poster TUP030 [0.619 MB]

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TUP040

Simulation and Design of Low Emittance RF Electron Gun

electron, emittance, gun, coupling

455

C. Saisa-ard, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand

Funding: This work has been supported by the CMU Junior Research Fellowship Program and the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University.
Generation of high-brightness electron beam is one of the most critical issues in development of advanced electron accelerators and light sources. At the Plasma and Beam Physics (PBP) Research Facility, Chiang Mai University, a low emittance RF electron gun is under the development. This RF-gun is planned to be used as an electron source for a future IR/THz FEL facility. An extra resonant cavity is added to the modified design of the existing PBP-CMU RF-gun in order to reduce the transverse sliced emittance. This cell is coupled to the main full-cell via a side-coupling cavity. The electromagnetic field distributions inside the cavities are simulated by using the CST Microwave Studio 2012. Then, beam dynamic simulations utilizing the program PARMELA are performed. Both RF and beam dynamic simulation results are reported and discussed in this contribution.
The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Materials Science and the Graduate School, Chiang Mai University.

Poster TUP040 [2.140 MB]

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TUP043

PAL-XFEL Cavity BPM Prototype Beam Test at ITF

pick-up, electron, dipole, simulation

468

S.J. Lee, J.H. Han, H.-S. Kang, C. Kim, S.H. Kim, I.S. Ko, Y.J. Park, D.C. Shin
PAL, Pohang, Kyungbuk, Republic of Korea

To achieve sub-micrometer resolution, PAL-XFEL undulator section will use X-band Cavity beam position monitor (BPM) systems. The prototype cavity BPM pick-up was designed and fabricated to test the performance of the cavity BPM system. The fabricated prototype cavity BPM pick-up was installed at Pohang Accelerator Laboratory injector test facility (PAL ITF) for the beam test. Under 200 pC beam charge condition, the signal properties of the cavity BPM pick-up were measured. Also, the dynamic range of the cavity BPM pick-up was measured by using the corrector magnet. In this paper, the design and beam test results of the prototype cavity BPM pick-up will be discussed.

Poster TUP043 [0.695 MB]

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TUP072

Cathode Ion Bombardment in LCLS and LCLS-II RF Gun

ion, cathode, gun, solenoid

534

L. Wang, A. Brachmann, F.-J. Decker, Z. Li, T.O. Raubenheimer, J.F. Schmerge, F. Zhou
SLAC, Menlo Park, California, USA

This paper studies the ions bombardment on the cathode in the LCLS and LCLS-II gun. APEX gun is used here for LCLS-II, which will be operate at 1 MHz repetition rate. Therefore, It is important to estimate the ion bombardment. One specific PIC code is used track arbitrary particles (ions and electron here) in arbitrary 2D/3D electromagnetic field and solenoid field to estimate the possibility of ion bombardment. The LCLS gun has 1.6 cells while the LCLS-II gun (APEX gun) is a half-cell gun. The frequencies of the two guns are also quite different. These characters make the ion dynamics quite differently. We estimated the bombardment for various ion species and studied the effects RF pulse shape and RF phase

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TUP080

Terahertz Source Utilizing Resonant Coherent Diffraction Radiation at KEK ERL Test Accelerator

radiation, photon, extraction, operation

547

Y. Honda, A. Aryshev, M. Shevelev, M. Shimada
KEK, Ibaraki, Japan

An energy recovery linac test accelerator, cERL, has been developing at KEK. It can produce a high repetition rate short bunched electron beam in a continuous operation mode. We propose to develop a high power THz radiation source at the return loop of the cERL. Coherent diffraction radiation of THz regime is emitted when an electron bunch passes through a conductive mirror with a beam hole at the center. If we form an optical cavity using two mirrors facing each other and the cavity length coincides with the bunch repetition rate, the coherent diffraction radiation of multiple bunches adds up coherently in the cavity. By extracting the power through transmission of one of the mirrors, we can realize a high power and high efficiency THz source. We discuss performance of the source assuming the beam parameters of cERL.

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TUD03

First Results of the SRF Gun Test for CeC PoP Experiment

cathode, gun, laser, electron

564

I. Pinayev, Z. Altinbas, S.A. Belomestnykh, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, T. Rao, J. Reich, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA

We have started the first tests of the equipment for the coherent electron cooling proof-of-principle experiment. After tests of the 500 MHz normal conducting cavities we proceeded with the low power beam tests of a CW SRF gun. The results of the tests with record beam parameters are presented.

Slides TUD03 [1.201 MB]

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WEB01

A Two-Color Storage Ring FEL

FEL, undulator, electron, operation

571

J. Yan, H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
S. Huang
PKU, Beijing, People's Republic of China
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China
N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
J. Wu
SLAC, Menlo Park, California, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
Using different undulator configurations on the Duke storage ring, we have successfully achieved lasing with a novel two-color storage ring FEL. Using a pair of dual-band FEL mirrors, simultaneous lasing was realized in IR (around 720 nm) and in UV (around 360 nm). With this two-color FEL, we have demonstrated independent wavelength tuning of either IR or UV lasing. With careful tuning, we have also realized harmonic lasing with the UV lasing tuned to the second harmonic of the IR lasing. The tuning of harmonic two-color lasing has also been demonstrated with the locked wavelengths. Furthermore, we have demonstrated good control of the FEL power sharing between the two colors. The two-color FEL has created new opportunities to drive a two-color Compton gamma-ray beam at the High Intensity gamma-ray Source at Duke.

Slides WEB01 [18.975 MB]

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WEP001

RF Gun Dark Current Suppression with a Transverse Deflecting Cavity at LCLS

undulator, radiation, FEL, gun

583

J.R. Lewandowski, R.C. Field, A.S. Fisher, H.-D. Nuhn, J.J. Welch
SLAC, Menlo Park, California, USA

Funding: Work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515.
A significant source of radiation signals in the LCLS Undulator have been identified as being generated by dark current emitted from the LCLS RF Photocathode Gun. Radiation damage to magnets over time can lead to degraded performance and significant cost for replacement. A method of using an existing transverse deflector cavity with a modified RF pulse has been tested and shows promise for eliminating the radiation dose from RF gun dark current that is generated in time before and after the production beam pulse.
UNDULATOR RADIATION DAMAGE EXPERIENCE AT LCLS: H.-D. Nuhn, C. Field, S. Mao, Y. Levashov, M. Santana, J.N. Welch, Z. Wolf,
SLAC National Accelerator Laboratory, Menlo Park, CA 94025, U.S.A

Poster WEP001 [1.631 MB]

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WEP060

Longitudinal Electron Bunch Shaping Experiments at the PAL-ITF

laser, electron, experiment, FEL

694

M. Chung, J.M. Seok
UNIST, Ulsan, Republic of Korea
J.H. Han, J.H. Hong, H.-S. Kang, C.H. Kim
PAL, Pohang, Kyungbuk, Republic of Korea
J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Longitudinal shaping of electron beam has received much attention recently, due to its potential applications to THz generation, dielectric wakefield acceleration, improvement of FEL performance, and controlled space-charge modulation. Using a set of alpha-BBO crystals, shaping of laser pulse and electron bunch on the order of ps is tested at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). In particular, we investigate the response of the longitudinally-modulated beam to a dechirper, which is a vacuum chamber of two corrugated, metallic plates. Initial experimental results will be presented with analytical theory and numerical simulations.

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