FEL2015 - List of Keywords (gun)

Paper	Title	Other Keywords	Page
MOP010	Linac Design of the IR-FEL Project in CHINA	electron, FEL, linac, beam-transport	46
	Z.G. He, Q.K. Jia, L. Wang, W. Xu, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	We are building an infrared free-electron laser (IR-FEL) facility that will operate from 5 um to 200 um. This FEL source is drived by a linac, which is composed of a triode electron gun, a subharmonic prebuncher, a buncher, two accelerators, and a beam transport line. The linac is required to operate from 15 to 60 MeV at 1 nC charge, while delivering a transverse rms emittance of smaller than 30 mm-mrad in a 5 ps rms length, smaller than 240 keV rms energy spread bunch at the Far-infrared and Mid-infrared undulators. In this article, the preliminary Linac design studies are described.
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MOP011	Status of CLARA, a New FEL Test Facility	FEL, laser, undulator, electron	49
	J.A. Clarke, D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, L.S. Cowie, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, P.C. Hornickel, F. Jackson, S.P. Jamison, J.K. Jones, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, M.D. Roper, L.K. Rudge, Y.M. Saveliev, B.J.A. Shepherd, R.J. Smith, S.L. Smith, E.W. Snedden, M. Surman, T.T. Thakker, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.B. Appleby, K. Hanahoe, O. Mete Apsimon, H.L. Owen, G.X. Xia UMAN, Manchester, United Kingdom P. Atkinson, N. Bliss, R.J. Cash, N.A. Collomb, G. Cox, G.P. Diakun, S. Dobson, A. Gallagher, S.A. Griffiths, C. Hill, C. Hodgkinson, D.M.P. Holland, T.J. Jones, B.G. Martlew, J. Williams STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom R. Bartolini, I.P.S. Martin DLS, Oxfordshire, United Kingdom S.T. Boogert, E. Yamakawa Royal Holloway, University of London, Surrey, United Kingdom G. Burt, P.N. Ratoff Lancaster University, Lancaster, United Kingdom L.T. Campbell, A.J.T. Colin, J. Henderson, B. Hidding, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom A.M. Kolano University of Huddersfield, Huddersfield, United Kingdom A. Lyapin JAI, Egham, Surrey, United Kingdom V.V. Paramonov, A.K. Skasyrskaya RAS/INR, Moscow, Russia J.D.A. Smith TXUK, Warrington, United Kingdom S. Spampinati Cockcroft Institute, Warrington, Cheshire, United Kingdom Y. Wei, C.P. Welsch, A. Wolski The University of Liverpool, Liverpool, United Kingdom
	CLARA is a new FEL test facility being developed at STFC Daresbury Laboratory in the UK. The main motivation for CLARA is to test new FEL schemes that can later be implemented on existing and future short wavelength FELs. Particular focus will be on ultra-short pulse generation, pulse stability, and synchronisation with external sources. The project is now underway and the Front End section (photoinjector and first linac) installation will begin later this year. This paper will discuss the progress with the Front End assembly and also highlighting other topics which are currently receiving significant attention.
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MOP024	Status, Plans and Recent Results from the APEX Project at LBNL	cathode, linac, cavity, 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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MOP025	Electron Beam Properties from a Compact Seeded Terahertz FEL Amplifier at Kyoto University	electron, emittance, laser, solenoid	85
	K. Damminsek, S. Rimjaem, S. Suphakul, C. Thongbai Chiang Mai University, Chiang Mai, Thailand H. Ohgaki, H. Zen Kyoto University, Kyoto, Japan
	A compact seeded Terahertz FEL amplifier is started construction at Institute of Advanced Energy, Kyoto University, Japan. The system consists of a 1.6 cell BNL type S-Band photocathode RF-gun, a magnetic bunch compressor in form of a chicane, triplet quadrupole magnets and a short planar undulator. Electron beams from the photocathode RF-gun were measured and compared with the PARMELA simulation results. Numerical and experimental studies on the contribution of the space charge effect were carried out. By using the RF power of 9 MW, the RF phase of 40 degree, the laser pulse energy of 20 μJ, and the solenoid magnet current of 135 A, the electron beam with a bunch charge of 50 pC, a beam energy of around 5 MeV and an RMS emittance of 6-8 mm-mrad was achieved.
	Poster MOP025 [1.837 MB]
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MOP057	Front End Simulations and Design for the CLARA FEL Test Facility	laser, emittance, linac, simulation	171
	J.W. McKenzie, A.D. Brynes, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	We present the design and simulations of the Front End for CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. This is based around an S-band RF photocathode gun. Initially this will be the 2.5 cell gun, currently used on VELA facility at Daresbury, which is limited to 10 Hz repetition rate. Later, this will be up-graded to a 1.5 cell gun, currently under development, which will allow repetition rates of up to 400 Hz to be reached. The beam will be accelerated up to 50 MeV with a booster linac which will be operated in both bunching and boosting modes for different operating regimes of CLARA. Simulations are presented for a currently achieved performance of the RF system and drive laser with optimisation of the laser pulse lengths for various operational modes of CLARA.
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MOD01	Review of Experimental Results from High Brightness DC Guns: Highlights in FEL Applications	cathode, emittance, FEL, brightness	269
	N. Nishimori JAEA, Ibaraki-ken, Japan
	Funding: This work is partially supported by a JSPS Grant-in-Aid for Scientific Research in Japan (15H03594). Future ERL light sources and high repetition rate X-ray FELs require high-brightness and high-current electron guns. A DC photoemission gun is one of the most promising candidates for such guns, because a record high current of 65 mA and generation of high brightness beam with 90% normalized emittances of 0.3 mm-mrad with bunch charge of 77 pC were recently demonstrated at the Cornell photoinjector with a 350 kV photoemission gun [1,2]. Further increase of the gun high voltage is desirable to reduce space charge induced emittance growth especially for high bunch charge application such as X-ray FEL. Employment of a segmented insulator is a key to reach higher voltage [3]. This technique led to generation of 500 keV beam from the JAEA gun with 160mm acceleration gap [4], conditioning voltage more than 500 kV at the Cornell gun with gap < 50 mm [5], and demonstration of 500 kV holding for 10 hours at the KEK gun with 70 mm gap [6]. In this talk, we present recent experimental results of high brightness DC guns and discuss highlights and limitations in FEL applications. [1] Dunham, APL 102, 034105. [2] Gulliford, PRSTAB 16, 073401. [3] Nagai, RSI 81, 033304. [4] Nishimori, APL 102, 234103. [5] Maxson, RSI 85, 093306. [6] Yamamoto, private communication.
	Slides MOD01 [3.051 MB]
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MOD03	Alkali Cathode Testing for LCLS-II at APEX	cathode, electron, operation, laser	280
	H.J. Qian, J. Feng, D. Filippetto, J.R. Nasiatka, H.A. Padmore, F. Sannibale LBNL, Berkeley, California, USA R.K. Li, J.F. Schmerge, F. Zhou SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 Electron sources of high brightness and high bunch charge (~300 pC) with MHz repetition rate are one of the key technologies for next generation X-FEL facilities such as the LCLS-II at SLAC and the Euro XFEL at DESY. The Advanced Photoinjector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is developing such an electron source based on high quantum efficiency (QE) alkali photocathodes and the VHF-Gun, a new scheme normal conducting RF gun developed at LBNL. The VHF-Gun already demonstrated stable CW operation with high gradient (~ 20 MV/m), high gun voltage (~ 750 kV) and low vacuum pressure (~ 3 E-10 torr) laying the foundation for the generation of high brightness electron beams. In this paper, we report the test and characterization of several different alkali cathodes in high average current (several hundreds of pC/bunch with MHz repetition rate) operation at APEX. Measurements include cathode life time, QE map evolution and thermal emittance characterization, to investigate the compatibility of such cathodes with the challenging requirements of LCLS-II.
	Slides MOD03 [6.030 MB]
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MOD04	Emittance Measurements of the Electron Beam at PITZ for the Commissioning Phase of the European X-FEL	laser, electron, emittance, simulation	285
	G. Vashchenko, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, G. Kourkafas, M. Krasilnikov, D. Malyutin, D. Melkumyan, A. Oppelt, M. Otevřel, Y. Renier, T. Rublack, F. Stephan DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. A. Bakr Assiut University, Assiut, Egypt C. Hernandez-Garcia JLab, Newport News, Virginia, USA O. Lishilin, G. Pathak Uni HH, Hamburg, Germany Q.T. Zhao IMP/CAS, Lanzhou, People's Republic of China
	For the operation of free electron lasers (FELs) like the European X-FEL and FLASH located at DESY, Hamburg Site, high quality electron beams are required already from the source. The Photo Injector Test facility at DESY, Zeuthen Site (PITZ) was established to develop, characterize and optimize electron sources for such FELs. Last year the work at PITZ focused on the optimization of a photo injector operated with the startup parameters of the European X-FEL. This implies photocathode laser pulses with a Gaussian temporal profile of about 11-12 ps FWHM to drive the photo gun operated at a gradient of 53 MV/m. Significant effort was spent on the electron beam characterization and optimization for various bunch charges. Emittance measurements were performed as a function of major accelerator parameters such as main solenoid current, laser spot size on the cathode and the gun launching phase. The requirement on the beam emittance for bunch charge of 500 pC for the European XFEL commissioning phase has been demonstrated. Results of these studies accompanied with the corresponding simulations are presented in this paper.
	Slides MOD04 [1.603 MB]
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TUP014	Beam Commissioning and Initial Measurements on the MAX IV 3 GeV Linac	linac, storage-ring, sextupole, electron	375
	S. Thorin, J. Andersson, F. Curbis, M. Eriksson, L. Isaksson, O. Karlberg, D. Kumbaro, F. Lindau, E. Mansten, D.F. Olsson, S. Werin MAX-lab, Lund, Sweden
	The linear accelerator at the MAX IV facility in Lund, Sweden, was constructed for injection and top up of the two storage rings and as a high brightness driver for the Short Pulse Facility. It is also prepared to be used as an injector for a possible future Free Electron Laser. Installation of the linac was completed and beam commissioning started in the early fall of 2014. In this paper we present the progress during the first phase of commissioning along with results from initial measurements of optics, emittance, beam energy and charge.
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TUP034	New Ellipsoidal Photocathode Laser Pulses at the Upgraded PITZ Facility	laser, cathode, simulation, electron	439
	J.D. Good, P. Boonpornprasert, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, G. Kourkafas, M. Krasilnikov, D. Melkumyan, A. Oppelt, M. Otevřel, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany A.V. Andrianov, E. Gacheva, E. Khazanov, S. Mironov, A. Poteomkin, V. Zelenogorsky IAP/RAS, Nizhny Novgorod, Russia G. Asova INRNE, Sofia, Bulgaria M. A. Bakr Assiut University, Assiut, Egypt I. Hartl, S. Schreiber DESY, Hamburg, Germany C. Hernandez-Garcia JLab, Newport News, Virginia, USA M. Khojoyan SOLEIL, Gif-sur-Yvette, France O. Lishilin, G. Pathak Uni HH, Hamburg, Germany D. Malyutin HZB, Berlin, Germany E. Syresin JINR, Dubna, Moscow Region, Russia Q.T. Zhao IMP/CAS, Lanzhou, People's Republic of China
	High brightness electron sources for free electron lasers like FLASH and the European XFEL are developed, optimized and characterized at the Photo Injector Test facility at DESY in Zeuthen (PITZ). Last year the facility was significantly upgraded with a new prototype photocathode laser capable of producing homogeneous ellipsoidal pulses. Previous simulations have shown that the corresponding pulses produce high brightness electron bunches with minimized emittance. Furthermore, a new normal conducting RF gun cavity was installed with a modified two-window waveguide RF feed layout for stability and reliability tests, as required for the European XFEL. Other relevant additions to the facility include beamline modifications for improved electron beam transport through the PITZ accelerator, refinement of both the cooling and RF systems for improved parameter stability, and preparations for the installation of a plasma cell. This paper describes the facility upgrades and reports on the operational experience with the new components.
	Poster TUP034 [1.211 MB]
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TUP035	Operation of a Slit Emittance Meter in the MAX IV Gun Test Stand	emittance, cathode, laser, background	444
	J. Andersson, F. Curbis, M. Isinger, F. Lindau, S. Werin MAX-lab, Lund, Sweden
	The MAX IV facility in Lund, Sweden is currently under commissioning. There are two guns in the current MAX IV injector, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. There is a possibility of extending the facility to include a Free Electron Laser. To investigate how the beam from the injector can be improved and how to match it to the future requirements for a FEL, the emittance meter from SPARC has been recommissioned at the MAX IV gun test stand. In this paper we report on the progress of this work and results from the first measurements.
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TUP036	Initial Commissioning Results of the MAX IV Injector	linac, laser, emittance, cathode	448
	J. Andersson, F. Curbis, M. Eriksson, D. Kumbaro, F. Lindau, E. Mansten, D.F. Olsson, S. Thorin, S. Werin MAX-lab, Lund, Sweden
	The MAX IV facility in Lund, Sweden is currently under commissioning. In the MAX IV injector there are two guns, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. The commissioning of the injector and the LINAC has been ongoing for the last year and ring commissioning is due to start shortly. In this paper we will present the results from beam performance experiments for the injector at the current stage of commissioning.
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TUP040	Simulation and Design of Low Emittance RF Electron Gun	electron, emittance, cavity, 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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TUP042	Lifetime of Cs2Te Cathodes Operated at the FLASH Facility	laser, cathode, operation, electron	464
	S. Schreiber, S. Lederer DESY, Hamburg, Germany
	The injector of the free-electron laser facility FLASH at DESY (Hamburg, Germany) uses Cs2Te photocathodes. We report on the lifetime, quantum efficiency (QE), and darkcurrent of photocathodes operated at FLASH during the last year. Cathode 618.3 has been operated for a record of 439 days with a stable QE in the order of 3%. The fresh cathode 73.3 shows an enhancement of emitted electrons for a few microseconds of a 1 MHz pulse train.
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TUP072	Cathode Ion Bombardment in LCLS and LCLS-II RF Gun	ion, cathode, cavity, 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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TUD03	First Results of the SRF Gun Test for CeC PoP Experiment	cathode, laser, electron, cavity	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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WEP001	RF Gun Dark Current Suppression with a Transverse Deflecting Cavity at LCLS	undulator, radiation, FEL, cavity	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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WEP014	LCLS-II: Status of the CW X-ray FEL Upgrade to the LCLS Facility	undulator, linac, FEL, electron	618
	T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE-AC02-76SF00515 The LCLS-II is a CW X-ray FEL based on a 4 GeV superconducting RF linac that will upgrade the LCLS facility at the SLAC National Accelerator Laboratory. The upgrade is being constructed by a collaboration including ANL, Cornell, Fermilab, JLab, LBNL, and SLAC. This talk will describe the status of the LCLS-II project as well as the major technical issues and R&D to address them. Presented on behalf of the LCLS-II collaboration
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WEP042	Commissioning and First Performance of the LINAC-based Injector Applied in the HUST THz-FEL	linac, FEL, target, beam-diagnostic	662
	T. Hu, Q.S. Chen, J. Li, B. Qin, P. Tan, Y.Q. Xiong HUST, Wuhan, People's Republic of China L. Cao, W. Chen Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China Y.J. Pei, Zh. X. Tang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The construction of a compact high-power THz source based on the free electron laser(FEL), which is constructed in HUST, is undergoing. Before the end of 2014, we have installed most of the key components, completed conditioning of the LINAC-based FEL injector, and performed first beam experiment. During last 5 months, we have established a high efficient beam diagnostic system with a reliable online monitor platform and precise data processing methods. At present, longitudinal properties such as the micro-pulse width and the energy spread are kept to a reasonable level, while transverse emittance compensation by adjusting focusing parameters is still undergoing. In this paper, we will give the summary on the commissioning schedule, detailed commissioning plan, the development of the commissioning and first performance of the LINAC, etc.
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WEP058	Emittance Measurements at the PAL-XFEL Injector Test Facility	emittance, laser, quadrupole, electron	690
	J. Lee POSTECH, Pohang, Kyungbuk, Republic of Korea J.H. Han, J.H. Hong, C.H. Kim, I.S. Ko, S.J. Lee, S.J. Park, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	The PAL-XFEL Injector Test Facility (ITF) at PAL has been operating for experimental optimization of electron beam parameters and for beam test of various accelerator components. It consists of a photocathode RF gun, two S-band accelerating structures, a laser heater system, and beam diagnostics such as ICTs, BPMs, screens, beam energy spectrometers and an RF deflector. Projected and slice emittance measurements were carried out by using single quadrupole scan. In this paper, we present the emittance measurements.
	Poster WEP058 [0.646 MB]
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WEP061	Numerical and Experimental Studies on Electron Beam Properties from Asymmetric RF-gun	electron, linac, simulation, emittance	698
	S. Rimjaem, N. Chaisueb, J. Saisut, C. Thongbai, W. Thongpakdi Chiang Mai University, Chiang Mai, Thailand N. Kangrang FNRF, Chiang Mai, Thailand E. Kongmon, K. Kosaentor, P. Wichaisirimongkol IST, 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. The electron linear accelerator at the Plasma and Beam Physics Research Facility (PBP-CMU Linac), Chiang Mai University, Thailand, is used to produce femtosecond electron bunches for generation of THz radiation. The main components of the PBP-CMU Linac are a thermionic RF electron gun, an alpha magnet, a travelling wave linac structure, quadrupole lens, steering magnets, and various diagnostic components. The RF-gun consists of a 1.6 S-band standing wave structure and a side-coupling cavity. The 2856 MHz RF wave is transmitted from the klystron to the gun through a rectangular waveguide input-port. Both the RF input-port and the side-coupling cavity cause an asymmetric electromagnetic field distribution inside the gun. The electron beam from the RF-gun has asymmetric transverse shape with an emittance value, which is higher than the beam from the symmetric fields. The problems are increased when the beam is transported from the gun through the whole accelerator system. Beam dynamic simulations are performed to investigate the effect of the asymmetric fields on the electron properties by using the codes PARMELA and ELEGANT. An integrated electron beam diagnostic station to measure the beam properties will be installed in the system to investigate these effects. Results from numerical and experimental studies are reported in this contribution.
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Paper

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MOP010

Linac Design of the IR-FEL Project in CHINA

electron, FEL, linac, beam-transport

46

Z.G. He, Q.K. Jia, L. Wang, W. Xu, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

We are building an infrared free-electron laser (IR-FEL) facility that will operate from 5 um to 200 um. This FEL source is drived by a linac, which is composed of a triode electron gun, a subharmonic prebuncher, a buncher, two accelerators, and a beam transport line. The linac is required to operate from 15 to 60 MeV at 1 nC charge, while delivering a transverse rms emittance of smaller than 30 mm-mrad in a 5 ps rms length, smaller than 240 keV rms energy spread bunch at the Far-infrared and Mid-infrared undulators. In this article, the preliminary Linac design studies are described.

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MOP011

Status of CLARA, a New FEL Test Facility

FEL, laser, undulator, electron

49

J.A. Clarke, D. Angal-Kalinin, A.D. Brynes, R.K. Buckley, S.R. Buckley, L.S. Cowie, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, P.C. Hornickel, F. Jackson, S.P. Jamison, J.K. Jones, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, M.D. Roper, L.K. Rudge, Y.M. Saveliev, B.J.A. Shepherd, R.J. Smith, S.L. Smith, E.W. Snedden, M. Surman, T.T. Thakker, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.B. Appleby, K. Hanahoe, O. Mete Apsimon, H.L. Owen, G.X. Xia
UMAN, Manchester, United Kingdom
P. Atkinson, N. Bliss, R.J. Cash, N.A. Collomb, G. Cox, G.P. Diakun, S. Dobson, A. Gallagher, S.A. Griffiths, C. Hill, C. Hodgkinson, D.M.P. Holland, T.J. Jones, B.G. Martlew, J. Williams
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
R. Bartolini, I.P.S. Martin
DLS, Oxfordshire, United Kingdom
S.T. Boogert, E. Yamakawa
Royal Holloway, University of London, Surrey, United Kingdom
G. Burt, P.N. Ratoff
Lancaster University, Lancaster, United Kingdom
L.T. Campbell, A.J.T. Colin, J. Henderson, B. Hidding, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
A.M. Kolano
University of Huddersfield, Huddersfield, United Kingdom
A. Lyapin
JAI, Egham, Surrey, United Kingdom
V.V. Paramonov, A.K. Skasyrskaya
RAS/INR, Moscow, Russia
J.D.A. Smith
TXUK, Warrington, United Kingdom
S. Spampinati
Cockcroft Institute, Warrington, Cheshire, United Kingdom
Y. Wei, C.P. Welsch, A. Wolski
The University of Liverpool, Liverpool, United Kingdom

CLARA is a new FEL test facility being developed at STFC Daresbury Laboratory in the UK. The main motivation for CLARA is to test new FEL schemes that can later be implemented on existing and future short wavelength FELs. Particular focus will be on ultra-short pulse generation, pulse stability, and synchronisation with external sources. The project is now underway and the Front End section (photoinjector and first linac) installation will begin later this year. This paper will discuss the progress with the Front End assembly and also highlighting other topics which are currently receiving significant attention.

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MOP024

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

cathode, linac, cavity, 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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MOP025

Electron Beam Properties from a Compact Seeded Terahertz FEL Amplifier at Kyoto University

electron, emittance, laser, solenoid

85

K. Damminsek, S. Rimjaem, S. Suphakul, C. Thongbai
Chiang Mai University, Chiang Mai, Thailand
H. Ohgaki, H. Zen
Kyoto University, Kyoto, Japan

A compact seeded Terahertz FEL amplifier is started construction at Institute of Advanced Energy, Kyoto University, Japan. The system consists of a 1.6 cell BNL type S-Band photocathode RF-gun, a magnetic bunch compressor in form of a chicane, triplet quadrupole magnets and a short planar undulator. Electron beams from the photocathode RF-gun were measured and compared with the PARMELA simulation results. Numerical and experimental studies on the contribution of the space charge effect were carried out. By using the RF power of 9 MW, the RF phase of 40 degree, the laser pulse energy of 20 μJ, and the solenoid magnet current of 135 A, the electron beam with a bunch charge of 50 pC, a beam energy of around 5 MeV and an RMS emittance of 6-8 mm-mrad was achieved.

Poster MOP025 [1.837 MB]

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MOP057

Front End Simulations and Design for the CLARA FEL Test Facility

laser, emittance, linac, simulation

171

J.W. McKenzie, A.D. Brynes, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

We present the design and simulations of the Front End for CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. This is based around an S-band RF photocathode gun. Initially this will be the 2.5 cell gun, currently used on VELA facility at Daresbury, which is limited to 10 Hz repetition rate. Later, this will be up-graded to a 1.5 cell gun, currently under development, which will allow repetition rates of up to 400 Hz to be reached. The beam will be accelerated up to 50 MeV with a booster linac which will be operated in both bunching and boosting modes for different operating regimes of CLARA. Simulations are presented for a currently achieved performance of the RF system and drive laser with optimisation of the laser pulse lengths for various operational modes of CLARA.

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MOD01

Review of Experimental Results from High Brightness DC Guns: Highlights in FEL Applications

cathode, emittance, FEL, brightness

269

N. Nishimori
JAEA, Ibaraki-ken, Japan

Funding: This work is partially supported by a JSPS Grant-in-Aid for Scientific Research in Japan (15H03594).
Future ERL light sources and high repetition rate X-ray FELs require high-brightness and high-current electron guns. A DC photoemission gun is one of the most promising candidates for such guns, because a record high current of 65 mA and generation of high brightness beam with 90% normalized emittances of 0.3 mm-mrad with bunch charge of 77 pC were recently demonstrated at the Cornell photoinjector with a 350 kV photoemission gun [1,2]. Further increase of the gun high voltage is desirable to reduce space charge induced emittance growth especially for high bunch charge application such as X-ray FEL. Employment of a segmented insulator is a key to reach higher voltage [3]. This technique led to generation of 500 keV beam from the JAEA gun with 160mm acceleration gap [4], conditioning voltage more than 500 kV at the Cornell gun with gap < 50 mm [5], and demonstration of 500 kV holding for 10 hours at the KEK gun with 70 mm gap [6]. In this talk, we present recent experimental results of high brightness DC guns and discuss highlights and limitations in FEL applications.
[1] Dunham, APL 102, 034105.
[2] Gulliford, PRSTAB 16, 073401.
[3] Nagai, RSI 81, 033304.
[4] Nishimori, APL 102, 234103.
[5] Maxson, RSI 85, 093306.
[6] Yamamoto, private communication.

Slides MOD01 [3.051 MB]

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MOD03

Alkali Cathode Testing for LCLS-II at APEX

cathode, electron, operation, laser

280

H.J. Qian, J. Feng, D. Filippetto, J.R. Nasiatka, H.A. Padmore, F. Sannibale
LBNL, Berkeley, California, USA
R.K. Li, J.F. Schmerge, F. Zhou
SLAC, Menlo Park, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
Electron sources of high brightness and high bunch charge (~300 pC) with MHz repetition rate are one of the key technologies for next generation X-FEL facilities such as the LCLS-II at SLAC and the Euro XFEL at DESY. The Advanced Photoinjector EXperiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is developing such an electron source based on high quantum efficiency (QE) alkali photocathodes and the VHF-Gun, a new scheme normal conducting RF gun developed at LBNL. The VHF-Gun already demonstrated stable CW operation with high gradient (~ 20 MV/m), high gun voltage (~ 750 kV) and low vacuum pressure (~ 3 E-10 torr) laying the foundation for the generation of high brightness electron beams. In this paper, we report the test and characterization of several different alkali cathodes in high average current (several hundreds of pC/bunch with MHz repetition rate) operation at APEX. Measurements include cathode life time, QE map evolution and thermal emittance characterization, to investigate the compatibility of such cathodes with the challenging requirements of LCLS-II.

Slides MOD03 [6.030 MB]

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MOD04

Emittance Measurements of the Electron Beam at PITZ for the Commissioning Phase of the European X-FEL

laser, electron, emittance, simulation

285

G. Vashchenko, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, G. Kourkafas, M. Krasilnikov, D. Malyutin, D. Melkumyan, A. Oppelt, M. Otevřel, Y. Renier, T. Rublack, F. Stephan
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
M. A. Bakr
Assiut University, Assiut, Egypt
C. Hernandez-Garcia
JLab, Newport News, Virginia, USA
O. Lishilin, G. Pathak
Uni HH, Hamburg, Germany
Q.T. Zhao
IMP/CAS, Lanzhou, People's Republic of China

For the operation of free electron lasers (FELs) like the European X-FEL and FLASH located at DESY, Hamburg Site, high quality electron beams are required already from the source. The Photo Injector Test facility at DESY, Zeuthen Site (PITZ) was established to develop, characterize and optimize electron sources for such FELs. Last year the work at PITZ focused on the optimization of a photo injector operated with the startup parameters of the European X-FEL. This implies photocathode laser pulses with a Gaussian temporal profile of about 11-12 ps FWHM to drive the photo gun operated at a gradient of 53 MV/m. Significant effort was spent on the electron beam characterization and optimization for various bunch charges. Emittance measurements were performed as a function of major accelerator parameters such as main solenoid current, laser spot size on the cathode and the gun launching phase. The requirement on the beam emittance for bunch charge of 500 pC for the European XFEL commissioning phase has been demonstrated. Results of these studies accompanied with the corresponding simulations are presented in this paper.

Slides MOD04 [1.603 MB]

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TUP014

Beam Commissioning and Initial Measurements on the MAX IV 3 GeV Linac

linac, storage-ring, sextupole, electron

375

S. Thorin, J. Andersson, F. Curbis, M. Eriksson, L. Isaksson, O. Karlberg, D. Kumbaro, F. Lindau, E. Mansten, D.F. Olsson, S. Werin
MAX-lab, Lund, Sweden

The linear accelerator at the MAX IV facility in Lund, Sweden, was constructed for injection and top up of the two storage rings and as a high brightness driver for the Short Pulse Facility. It is also prepared to be used as an injector for a possible future Free Electron Laser. Installation of the linac was completed and beam commissioning started in the early fall of 2014. In this paper we present the progress during the first phase of commissioning along with results from initial measurements of optics, emittance, beam energy and charge.

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TUP034

New Ellipsoidal Photocathode Laser Pulses at the Upgraded PITZ Facility

laser, cathode, simulation, electron

439

J.D. Good, P. Boonpornprasert, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, G. Kourkafas, M. Krasilnikov, D. Melkumyan, A. Oppelt, M. Otevřel, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
A.V. Andrianov, E. Gacheva, E. Khazanov, S. Mironov, A. Poteomkin, V. Zelenogorsky
IAP/RAS, Nizhny Novgorod, Russia
G. Asova
INRNE, Sofia, Bulgaria
M. A. Bakr
Assiut University, Assiut, Egypt
I. Hartl, S. Schreiber
DESY, Hamburg, Germany
C. Hernandez-Garcia
JLab, Newport News, Virginia, USA
M. Khojoyan
SOLEIL, Gif-sur-Yvette, France
O. Lishilin, G. Pathak
Uni HH, Hamburg, Germany
D. Malyutin
HZB, Berlin, Germany
E. Syresin
JINR, Dubna, Moscow Region, Russia
Q.T. Zhao
IMP/CAS, Lanzhou, People's Republic of China

High brightness electron sources for free electron lasers like FLASH and the European XFEL are developed, optimized and characterized at the Photo Injector Test facility at DESY in Zeuthen (PITZ). Last year the facility was significantly upgraded with a new prototype photocathode laser capable of producing homogeneous ellipsoidal pulses. Previous simulations have shown that the corresponding pulses produce high brightness electron bunches with minimized emittance. Furthermore, a new normal conducting RF gun cavity was installed with a modified two-window waveguide RF feed layout for stability and reliability tests, as required for the European XFEL. Other relevant additions to the facility include beamline modifications for improved electron beam transport through the PITZ accelerator, refinement of both the cooling and RF systems for improved parameter stability, and preparations for the installation of a plasma cell. This paper describes the facility upgrades and reports on the operational experience with the new components.

Poster TUP034 [1.211 MB]

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TUP035

Operation of a Slit Emittance Meter in the MAX IV Gun Test Stand

emittance, cathode, laser, background

444

J. Andersson, F. Curbis, M. Isinger, F. Lindau, S. Werin
MAX-lab, Lund, Sweden

The MAX IV facility in Lund, Sweden is currently under commissioning. There are two guns in the current MAX IV injector, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. There is a possibility of extending the facility to include a Free Electron Laser. To investigate how the beam from the injector can be improved and how to match it to the future requirements for a FEL, the emittance meter from SPARC has been recommissioned at the MAX IV gun test stand. In this paper we report on the progress of this work and results from the first measurements.

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TUP036

Initial Commissioning Results of the MAX IV Injector

linac, laser, emittance, cathode

448

J. Andersson, F. Curbis, M. Eriksson, D. Kumbaro, F. Lindau, E. Mansten, D.F. Olsson, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

The MAX IV facility in Lund, Sweden is currently under commissioning. In the MAX IV injector there are two guns, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. The commissioning of the injector and the LINAC has been ongoing for the last year and ring commissioning is due to start shortly. In this paper we will present the results from beam performance experiments for the injector at the current stage of commissioning.

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TUP040

Simulation and Design of Low Emittance RF Electron Gun

electron, emittance, cavity, 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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TUP042

Lifetime of Cs2Te Cathodes Operated at the FLASH Facility

laser, cathode, operation, electron

464

S. Schreiber, S. Lederer
DESY, Hamburg, Germany

The injector of the free-electron laser facility FLASH at DESY (Hamburg, Germany) uses Cs2Te photocathodes. We report on the lifetime, quantum efficiency (QE), and darkcurrent of photocathodes operated at FLASH during the last year. Cathode 618.3 has been operated for a record of 439 days with a stable QE in the order of 3%. The fresh cathode 73.3 shows an enhancement of emitted electrons for a few microseconds of a 1 MHz pulse train.

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TUP072

Cathode Ion Bombardment in LCLS and LCLS-II RF Gun

ion, cathode, cavity, 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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TUD03

First Results of the SRF Gun Test for CeC PoP Experiment

cathode, laser, electron, cavity

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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WEP001

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

undulator, radiation, FEL, cavity

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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WEP014

LCLS-II: Status of the CW X-ray FEL Upgrade to the LCLS Facility

undulator, linac, FEL, electron

618

T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE-AC02-76SF00515
The LCLS-II is a CW X-ray FEL based on a 4 GeV superconducting RF linac that will upgrade the LCLS facility at the SLAC National Accelerator Laboratory. The upgrade is being constructed by a collaboration including ANL, Cornell, Fermilab, JLab, LBNL, and SLAC. This talk will describe the status of the LCLS-II project as well as the major technical issues and R&D to address them.
Presented on behalf of the LCLS-II collaboration

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WEP042

Commissioning and First Performance of the LINAC-based Injector Applied in the HUST THz-FEL

linac, FEL, target, beam-diagnostic

662

T. Hu, Q.S. Chen, J. Li, B. Qin, P. Tan, Y.Q. Xiong
HUST, Wuhan, People's Republic of China
L. Cao, W. Chen
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
Y.J. Pei, Zh. X. Tang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The construction of a compact high-power THz source based on the free electron laser(FEL), which is constructed in HUST, is undergoing. Before the end of 2014, we have installed most of the key components, completed conditioning of the LINAC-based FEL injector, and performed first beam experiment. During last 5 months, we have established a high efficient beam diagnostic system with a reliable online monitor platform and precise data processing methods. At present, longitudinal properties such as the micro-pulse width and the energy spread are kept to a reasonable level, while transverse emittance compensation by adjusting focusing parameters is still undergoing. In this paper, we will give the summary on the commissioning schedule, detailed commissioning plan, the development of the commissioning and first performance of the LINAC, etc.

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WEP058

Emittance Measurements at the PAL-XFEL Injector Test Facility

emittance, laser, quadrupole, electron

690

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

The PAL-XFEL Injector Test Facility (ITF) at PAL has been operating for experimental optimization of electron beam parameters and for beam test of various accelerator components. It consists of a photocathode RF gun, two S-band accelerating structures, a laser heater system, and beam diagnostics such as ICTs, BPMs, screens, beam energy spectrometers and an RF deflector. Projected and slice emittance measurements were carried out by using single quadrupole scan. In this paper, we present the emittance measurements.

Poster WEP058 [0.646 MB]

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WEP061

Numerical and Experimental Studies on Electron Beam Properties from Asymmetric RF-gun

electron, linac, simulation, emittance

698

S. Rimjaem, N. Chaisueb, J. Saisut, C. Thongbai, W. Thongpakdi
Chiang Mai University, Chiang Mai, Thailand
N. Kangrang
FNRF, Chiang Mai, Thailand
E. Kongmon, K. Kosaentor, P. Wichaisirimongkol
IST, 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.
The electron linear accelerator at the Plasma and Beam Physics Research Facility (PBP-CMU Linac), Chiang Mai University, Thailand, is used to produce femtosecond electron bunches for generation of THz radiation. The main components of the PBP-CMU Linac are a thermionic RF electron gun, an alpha magnet, a travelling wave linac structure, quadrupole lens, steering magnets, and various diagnostic components. The RF-gun consists of a 1.6 S-band standing wave structure and a side-coupling cavity. The 2856 MHz RF wave is transmitted from the klystron to the gun through a rectangular waveguide input-port. Both the RF input-port and the side-coupling cavity cause an asymmetric electromagnetic field distribution inside the gun. The electron beam from the RF-gun has asymmetric transverse shape with an emittance value, which is higher than the beam from the symmetric fields. The problems are increased when the beam is transported from the gun through the whole accelerator system. Beam dynamic simulations are performed to investigate the effect of the asymmetric fields on the electron properties by using the codes PARMELA and ELEGANT. An integrated electron beam diagnostic station to measure the beam properties will be installed in the system to investigate these effects. Results from numerical and experimental studies are reported in this contribution.

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