IPAC2016 - Classification: 02 Photon Sources and Electron Accelerators / A08 Linear Accelerators

Paper	Title	Page
TUOCA01	LCLS Bunch Compressor Configuration Study for Soft X-ray Operation	1037
	S. Li, Y. Ding, Z. Huang, A. Marinelli, T.J. Maxwell, D.F. Ratner, F. Zhou SLAC, Menlo Park, California, USA C. Behrens DESY, Hamburg, Germany
	The microbunching instability (MBI) is a well-known problem for high brightness electron beams and has been observed at accelerator facilities around the world. Free-electron lasers (FELs) are particularly susceptible to MBI, which can distort the longitudinal phase space and increase the beam's slice energy spread (SES). Past studies of MBI at the Linac Coherent Light Source (LCLS) relied on optical transition radiation to infer the existence of microbunching. With the development of the x-band transverse deflecting cavity (XTCAV), we can for the first time directly image the longitudinal phase space at the end of the accelerator and complete a comprehensive study of MBI, revealing both detailed MBI behavior as well as insights into mitigation schemes [1]. The fine time resolution of the XTCAV also provides the first LCLS measurements of the final SES, a critical parameter for many advanced FEL schemes. Detailed MBI and SES measurements can aid in understanding MBI mechanisms, benchmarking simulation codes, and designing future high-brightness accelerators.
	Slides TUOCA01 [4.436 MB]
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TUPMY038	Preliminary Measurement of the Transfer Matrix of a TESLA-type Cavity at FAST	1632
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, J.K. Santucci, J.K. Santucci, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359. Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread application in Science and Industry. Many current and planned projects employ 1.3-GHz 9-cell superconducting cavities of the TESLA design. In the present paper we discuss the transverse-focusing properties of such a cavity and non-ideal transverse-map effects introduced by field asymmetries in the vicinity of the input and high-order-mode radiofrequency (RF) couplers. We especially consider the case of a cavity located downstream of an RF-gun in a setup similar to the photoinjector of the Fermilab Accelerator Science and Technology (FAST) facility. Preliminary experimental measurements of the CC2 cavity transverse matrix were carried out at the FAST facility. The results are discussed and compared with analytical and numerical simulations. A. Aunes et al., Phys. Rev.ST Accel. Beams 3, 092001 (2000). ** P. Piot, el. al., Proc. 2005 Part. Accel. Conf., Knoxville, TN, p. 4135 (2005).
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TUPOR026	Final Design and Status of the Third Recirculation for the S-DALINAC*	1717
	M. Arnold, T. Kürzeder, N. Pietralla TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: *Work supported by DFG through CRC 634 and RTG 2128 Since 1991 the twice-recirculating superconducting accelerator S-DALINAC is providing electron beams for nuclear physics experiments. Due to a reduced quality factor of its cavities in comparison to their design values it was not possible to operate the accelerator with its maximum design energy of 130 MeV in cw mode. To provide electron beams of this energy in the future it was decided to add one recirculation beam line in order to use the main linac four times, operating the cavities on decreased accelerating gradients. The necessary modifications consist of several different aspects: A new beamline needs to be installed and other pre-existing beam line sections have to be modified for matching new boundary conditions. These new conditions are mainly a result of beam dynamics simulations and of the design of a new separation dipole magnet, which will bend the different beams energy-dependent in the various recirculation beam lines. We will present the implemented design and give a status report on the project.
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TUPOW002	Current Status of the Milliampere Booster for the Mainz Energy-recovering Superconducting Accelerator	1741
	R.G. Heine, K. Aulenbacher, L.M. Hein, C. Matejcek IKP, Mainz, Germany
	Funding: Work supported by German Science Foundation (DFG) under the Cluster of Excellence "PRISMA" EXC1098/2014 The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. The MESA facility is currently under design at the Institut für Kernphysik (KPH) at Johannes Gutenberg University of Mainz (JGU). In this paper we will present the current design status of the linac.
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TUPOW003	High Average RF Power Tests With 2 RF Vacuum Windows at PITZ	1744
	Y. Renier, G. Asova, M. A. Bakr, P. Boonpornprasert, J.D. Good, M. Groß, C. Hernandez-Garcia, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Malyutin, D. Melkumyan, A. Oppelt, M. Otevřel, G. Pathak, T. Rublack, I.V. Rybakov, F. Stephan, G. Vashchenko, Q.T. Zhao DESY Zeuthen, Zeuthen, Germany M. Bousonville, S. Choroba, S. Lederer DESY, Hamburg, Germany
	The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built with the aim to develop and characterize electron sources for future usage at FLASH and at the European XFEL. Recently, the main focus at PITZ has been the study of gun reliability and photoinjector performance at high average power. The goal is to get stable and reliable operation with 6.4 MW peak power in the gun at 650 us RF pulse length and 10 Hz repetition rate. To achieve this, a new RF feed system with two RF windows was installed at PITZ in 2014. During this test, the old gun 4.2 with a modified back-plane design for better cathode contact has been used. In this contribution the results of the RF conditioning of gun 4.2 with a detailed interlock analysis will be reported as well as results from recent electron beam characterization.
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TUPOW004	Status of the STAR Project	1747
	A. Bacci, I. Drebot, L. Serafini, V. Torri Istituto Nazionale di Fisica Nucleare, Milano, Italy R.G. Agostino, R. Barberis, M. Ghedini, F. Martire, C. Pace UNICAL, Arcavacata di Rende, Italy D. Alesini, M. Bellaveglia, J.J. Beltrano, F.G. Bisesto, G. Borgese, B. Buonomo, G. Di Pirro, G. Di Raddo, A. Esposito, A. Gallo, A. Ghigo, F. Iungo, L. Pellegrino, A. Stella, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi INFN-Roma II, Roma, Italy G. D'Auria, A. Fabris, M. Marazzi Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy V. Petrillo Universita' degli Studi di Milano, Milano, Italy E. Puppin Politecnico/Milano, Milano, Italy M. Rossetti Conti Universita' degli Studi di Milano & INFN, Milano, Italy
	This paper reports on the final design and the work in progress on the STAR project (IPAC2014:WEPRO115), which is under construction at the Univ. of Calabria (Italy). The project is devoted to the construction of an advanced Thomson source of monochromatic tunable, ps-long, polarized X-ray beams, ranging from 40 up to 140 KeV . At present the buildings and main plants have been completed as the acquisition of main components: the RF photo-injector, the accelerating section, laser systems for collision and photo-cathode, RF Power Source and magnets are ready to start installation and site acceptance tests. The design of laser lines is complete and simulated by ZEMAX, aiming to minimize energy losses, optical distortions and providing a tunable experimental setup as well. The RF power network is close to be tested, it's based on a 55MW (2.5us pulse) S-band Klystron driven by a 500kV Pulse Forming Network based modulator and a Low Level RF system, running at 100 Hz. The Control System is been designed using EPICS and allows to manage easily and fastly each machine parameter. We expect to start commissioning the machine by the end of 2016 and obtain the first collisions within the first part of 2017.
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TUPOW005	Update on Third Harmonic XFEL Activities at INFN LASA	1751
	D. Sertore, M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, P. Michelato, L. Monaco, R. Paparella, P. Pierini INFN/LASA, Segrate (MI), Italy C.G. Maiano DESY, Hamburg, Germany C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy
	After the successful installation and beam operation of the first batch of 3.9 GHz cavities into the XFEL Third Harmonic Injector Module, ten more cavities have been tested and delivered to DESY to be assembled into a spare cryomodule. In this paper, we report on the activities related to the cavities fabrication, treatment and vertical testing at INFN LASA.
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TUPOW006	Six-dimensional Phase-space Rotation and its Applications	1754
	M. Kuriki, K. Negishi HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126. Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.
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TUPOW008	Generation of Short Bunch Electron Beam from Compact Accelerator for Terahertz Radiation	1757
	S. Suphakul, T. Kii, K. Masuda, K. Morita, H. Ohgaki, K. Torgasin, H. Zen Kyoto University, Kyoto, Japan
	We are developing a new compact accelerator system to generate a high power terahertz (THz) radiation at the Institute of Advanced Energy, Kyoto University. THz radiations are produced by injecting ultra-short and intense electron pulses to a short plannar undulator. The bunch compression characteristic by the newly installed chicane was investigated by observation of a coherent part of an optical transition radiation (OTR). As the result, the chicane can compress the electron bunch at the laser injection phase from 10 to 40 degree. The beam energy and relative rms energy spread were also measured and the results were 4.6 MeV and 1.3 %, respectively.
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TUPOW009	Generation of Coherent Undulator Radiation using Extremely Short Electron Bunch at t-ACTS, Tohoku University	1760
	S. Kashiwagi, T. Abe, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	An accelerator test facility, t-ACTS, was established at Research Center for Electron Photon Science, Tohoku University, in which an intense coherent terahertz (THz) radiation is generated from an extremely short electron bunch. Velocity bunching scheme in a traveling-wave accelerating structure is employed to produce the short electron bunch, and a production of sub-picosecond electron bunch was demonstrated. A long-period linear undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been developed to produce intense coherent THz radiation. Properties of the radiation from the THz undulator such as radiation fields, spectrum and angular distribution were numerically investigated based on the parameters of short electron bunch and THz undulator. By optimization of bunch compression, it is possible to extract a coherent radiation of fundamental mode excluding higher-order mode. The detail of the numerical studies for the coherent undulator radiation will be reported in the conference.
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TUPOW010	Production of Ultra-short Electron Pulse and Observation of Coherent Transition Radiation at t-ACTS, Tohoku University	1763
	T. Abe, H. Hama, F. Hinode, S. Kashiwagi, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	A test-Accelerator as Coherent Terahertz Source (t-ACTS) project has been under development at Research Center for Electron Photon Science, Tohoku University. In order to generate a coherent radiation in terahertz (THz) region, it is necessary to produce sub-picosecond electron pulses. Velocity bunching scheme is employed for the short electron pulse production in t-ACTS. We experimentally confirmed the production of short electron pulse under 500 fs by measuring the bunch length using a streak camera. Coherent transition radiation in THz region was produced by which the short electron pulses pass through a vacuum-metal interface. Several radiation properties including　spatial distribution, polarization and spectrum were measured and compared with theoretical calculations. The details of the beam experiment at t-ACTS are described.
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TUPOW011	Profile Measurements of Bremsstrahlung Gamma-Rays from Tungsten Plates for Radioactive Isotope Production via Photonuclear Reaction using a 60 MeV Electron Linac	1766
	K. Takahashi, H. Hama, F. Hinode, S. Kashiwagi, H. Kikunaga, T. Muto, I. Nagasawa, K. Nanbu, Y. Shibasaki, T. Suda, C. Tokoku, K. Tsukada Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Radioactive isotopes have been produced via photo-nuclear reaction using a 60 MeV high-power electron linac for research fields of nuclear chemistry and radioac-tive analysis at Research Center for Electron Photon Science (ELPH), Tohoku University. The electron beam with an average current more than 100 μA is transported to an electron-bremsstrahlung gamma-ray converter of 2 mm thickness platinum or tungsten plate at the irradiation station. A target of 10 mm diameter is placed 3 cm behind a converter. It is enclosed with a quartz glass in the water cooling system and is irradiated for photonuclear reaction. Since the correlation between the spatial profile of bremsstrahlung gamma-rays at the target position and accelerator parameters is of our primary interest, nickel thin films are irradiated and the profiles of bremsstrahlung gamma-rays are measured by intensity distribution measurements of 57Ni radioactivity using the phosphorus imaging plate. In the meantime, the beam emittance and Twiss parameters are measured.
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TUPOW014	Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun	1769
	J.H. Shao, H.B. Chen, J. Shi, X.W. Wu TUB, Beijing, People's Republic of China S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA W. Gai ANL, Argonne, Illinois, USA F.Y. Wang SLAC, Menlo Park, California, USA
	Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.
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TUPOW015	Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun	1772
	J.H. Shao, H.B. Chen, J. Shi, X.W. Wu TUB, Beijing, People's Republic of China S.P. Antipov, S.V. Baryshev, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski ANL, Argonne, Illinois, USA F.Y. Wang SLAC, Menlo Park, California, USA
	The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.
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TUPOW017	Twin Bunches at the FACET-II	1778
	Z. Zhang TUB, Beijing, People's Republic of China M.J. Hogan, Z. Huang, A. Marinelli SLAC, Menlo Park, California, USA
	Twin electron bunches, generated, accelerated and compressed in the same acceleration bucket, have attracted a lot of interest in the free-electron lasers and wakefield acceleration. The recent successful experiment at the LCLS used twin bunches to generate two-color two x-ray pulses with tunable time delay and energy separation. In this note, we apply the twin bunches to the plasma wakefield acceleration. Numerical simulations show that based on the beamline of the FACET-II, we can generate high-intensity two electron bunches with time delay from ∼ 100 fs to picoseconds, which will benefit the control of high-gradient witness bunch acceleration in a plasma.
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TUPOW018	Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation	1782
SUPSS016	use link to see paper's listing under its alternate paper code
	Z. Zhang, H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, X.L. Su, C.-X. Tang, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, L.M. Zheng, Z. Zhou TUB, Beijing, People's Republic of China W. Gai ANL, Argonne, Illinois, USA
	High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.
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TUPOW019	Preliminary Concept of Fast Positron Source Based on Photo-injector	1785
	Z. Chu, J.G. Guo, Q. Luo, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11375178 and 11575181) and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046 Based on the past experience in slow positron beam, researchers at NSRL/USTC proposed a fast positron source for detection of material deep tiny flaws. Different from conventional positron sources used in positron annihilation techniques, the planned positron source will be a positron production linac, similar to positron injectors used in colliders. To compress the positron pulse, the bombarding electron beam comes from a short bunch photo-injector. A computer simulation was performed using EGS4 and PARMELA code. The bombarding electron bunch is 300pC, with an energy of 30MeV. Simulations results showed that it is reasonable to expect a beam of more than 10⁵ positrons per pulse for future positron annihilation studies. Further work is to be done to achieve precise control of beam energy.
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TUPOW021	Beam Dynamics Optimization and Future Plans for LUE-200 Linac Upgrade	1788
	S.M. Polozov, T.V. Bondarenko MEPhI, Moscow, Russia A.V. Butenko, V. Kobets, A.P. Sumbaev JINR, Dubna, Moscow Region, Russia
	The IREN facility (Intense Resonance Neutron Source) is now been tested and upgraded in JINR. The linear electron accelerator LUE-200 is used to generate intense fluxes of resonant photo-neutrons. Linac should deliver up to 200 MeV electron beam with 1 A or more current in 100 - 200 ns pulses. It consists of electron source, LEBT including buncher and two main accelerating sections (only one is installed up to now). Test operations shows that beam loading sufficiently influences the output beam parameters and beam energy after first section decreases from planned 55-60 MeV to 35 MeV. The buncher doesn't provide an efficient beam bunching also and beam recapturing by main section due to this is very low. Dynamics of the electron beam for traveling wave S-band linac LUE-200 was studied by numerical simulations. In report results of beam dynamics simulation and optimization taking into account beam loading discuss, parameters for new more effective buncher presents and first results of such buncher development shows.
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TUPOW022	Hybrid Electron Linac With Standing and Travelling Wave Accelerating Sections	1791
	S.V. Matsievskiy, A.V. Bulanov, V.I. Kaminskiy, E.A. Savin, N.P. Sobenin MEPhI, Moscow, Russia R.Yu. Alekhanov NRNU, Moscow, Russia
	Hybrid electron linacs with standing and travelling wave accelerating sections are not well described in literature. Limited number of studies have shown that application of these systems makes it possible to develop a compact linac with high efficiency and simpler power system. Typically, these systems use well-studied bi-periodical accelerating structure (BAS) cells for a standing wave section and disc-loaded waveguides (DLW) for a traveling wave section. This paper describes the development of such system using DLW cells with magnetic coupling (DLW-M). Here BAS appears as an absorbing load connected to the DLW-M accelerating structure by rectangular waveguide allowing to have theoretical zero reflection at RF input. Such system also provides possibility of plain beam output energy adjustment. Studies of the structure were carried out using equivalent circuits methods and numerical 3D-modeling. Beam dynamics was calculated.
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TUPOW023	New 10 MeV High-power Electron Linac for Industrial Application	1794
	S.M. Polozov, D.S. Bazyl, T.V. Bondarenko, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, V.I. Rashchikov, E.A. Savin MEPhI, Moscow, Russia M.I. Demsky, A.A. Eliseev, V.V. Krotov, D.E. Trifonov CORAD Ltd., St. Petersburg, Russia B.S. Han, W.G. Kang, H.G. Park EB TECH Co. Ltd., Daejeon, Republic of Korea
	Joint team of CORAD and MEPhI developed a new industrial accelerating structure for average beam power up to 20 kW and energy range from 7.5 to 10 MeV. The use of modern methods and codes for beam dynamics simulation, raised coupling coefficient and group velocity of SW biperiodic accelerating structure allowed to reach high pulse power utilization and obtain high efficiency. Gentle buncher provides high capturing coefficient and narrow energy spectrum. The first linear accelerator with this structure was constructed and tested in collaboration with the company EB Tech.
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TUPOW024	Compact Standing Wave Electron Linac with the Hybrid Accelerating and Power Generation Cell	1797
SUPSS015	use link to see paper's listing under its alternate paper code
	E.A. Savin, S.V. Matsievskiy, N.P. Sobenin, I.D. Sokolov MEPhI, Moscow, Russia A.A. Zavadtsev Nano, Moscow, Russia
	Compact electron linear accelerators for small energies are now found their place in the industrial market. Such accelerators are used for cancer treatment, cargo inspection, when one needs higher dose that X-ray source can produce, food and medicaments irradiation etc. Acceleration structures themselves are already developed very well, so the most important issue now ' is to make the whole installation with power supply, RF tracts, cooling system ' as smaller as possible to provide the structure mobility. In this article we present the development how to combine a power supply (usually it is a klystron, IOT, magnetron or solid state amplifier) with the accelerating cell itself, that can decrease installation size at least twice. No RF tracts needed, no reflected power will occur, so no circulator needed. Different power input combinations have been studied, but the smallest and the most efficient one has been manufactured for cold tests at S-band frequency range. In this structure it is very easy to vary accelerating voltage simply changing the generator beam current or the generator beam accelerating voltage.
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TUPOW025	First Beam Test of the High Brightness Photo-injector at NSRRC	1800
	A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang, M.T. Tsou NSRRC, Hsinchu, Taiwan P. Wang NTHU, Hsinchu, Taiwan
	A High brightness injector at NSRRC is built for a VUV/THz free electron laser (FEL) facility and light source R&D. This injector with a photocathode rf gun with a solenoid for emittance compensation, a UV laser system, a 5.2 m S-band linac as well as various beam diagnostic tools has been installed in the linac test laboratory. The main goal is to produce beams with emittance smaller than 1 mm-mrad at energy of ~100 MeV. The other goal is to compress bunches to ~100 fs with charge of 100 pc and energy of ~30 MeV. In this contribution, an overview of the commissioning results of the photocathode rf gun and the laser system will be given. The first beam observation downstream the lianc will be presented in this paper.
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TUPOW026	Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory	1803
SUPSS014	use link to see paper's listing under its alternate paper code
	N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai Chiang Mai University, Chiang Mai, Thailand
	Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand. Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution. The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University.
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TUPOW027	Model Independent Analysis of Beam Jitter on VELA	1806
	J.K. Jones, K.D. Dumbell, A.J. Moss, E.W. Snedden STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide high quality electron beams for accelerator systems development, as well as industrial and scientific applications. A key performance indicator for many applications is the inherent beam jitter on the machine (temporal, momentum and positional). Analysis of this beam jitter indicates that there are several independent mechanisms driving the beam motion. We use model independent analysis to correlate various dominant modes of beam jitter and compare them to simulations. We also compare the dominant modes before and after intervention work on the DLLRF timing system, and determine the relevant changes in beam motion.
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TUPOW028	Comparison of Model vs. Reality for VELA	1810
	M.S. Toplis, J.W. McKenzie, B.D. Muratori, D.J. Scott, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide a high quality electron beam for accelerator systems development, as well as industrial and scientific applications. Currently, the RF gun can deliver short bunches, of the order of 100 fs to a few ps, with a charge of up to 250 pC, at the longer bunch lengths, and up to 4.5 MeV/c beam momentum. A model for the injector has been developed in ASTRA, together with a suite of scripts to create scans of the available parameters around an empirically found arbitrarily optimal working point. The space of parameters consists of everything that can be changed in the control room, and ranges from bunch charge to laser spot size on the cathode, together with all magnet settings where and if necessary. The various scans facilitate the task of identifying where exactly the accelerator is in terms of parameters and trends. Initial comparisons of screen images are made between the model and reality. Ultimately, the goal of the model is to robustly and repeatably establish a desired operating setup on a daily basis from an unknown switch on condition.
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TUPOW029	Transverse Cavity Tuning at the Advanced Photon Source	1814
	G.J. Waldschmidt, L.H. Morrison, T.L. Smith ANL, Argonne, Ilinois, USA
	A 15-cell transverse deflecting cavity based on a SLAC design was fabricated at the Advanced Photon Source and is being prepared for installation into the Injector Test Stand. A beadpull method for tuning was selected in lieu of the nodal position method to minimize the possibility of contamination and surface damage to the irises. The process has been successfully documented for many accelerating mode structures, but there has been limited application to dipole mode structures. In this paper, we will discuss the methodology for tuning and conditioning a 2.8 GHz backward-traveling wave deflecting cavity.
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TUPOW030	A CW Normal Conducting RF Cavity for Fast Chirp Control in the LCLS-II	1817
	M.H. Nasr, P. Emma, S.G. Tantawi SLAC, Menlo Park, California, USA
	The LCLS-II is a high repetition-rate Free-Electron Laser (FEL) facility under construction at SLAC. A new 4-GeV continuous wave (CW) superconducting (SC) L-band linac is being built to provide an electron bunch rate of up to 1 MHz, with bunches rapidly switched between two FEL undulators. It is desirable to provide peak current (i.e., pulse length) control in each FEL independently by varying the RF phase (chirp) prior to the first bunch compressor. However, the high-Q, SCRF, with its 1-ms fill-time, cannot be changed within one bunch spacing (1 us). So to provide a small chirp adjustment from bunch to bunch, we propose a short CW copper RF accelerating cavity, located just after the injector, with < 250-ns fill-time designed to adjust the beam chirp at zero-crossing phase. We examined RF cavity designs spanning RF frequencies from L-band to X-band. We considered both SW and TW structures. We found an optimal solution with 2 cm iris diameter, SW RF cavity, operating at C-band with input power of only 10 kW. If one can afford to operate with smaller diameter, from a wakefield point of view, then similar structure at X-band may require only 500 W with 5 mm iris diameter.
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TUPOY010	6/9 MeV S-band Standing Wave Accelerating Structure for Container X-ray Inspection System at RTX	1924
	P. Buaphad, H.D. Park, S. Song, S.Y. Yoo RTX, Daejeon, Republic of Korea H.K. Cha, S.S. Cha, J.H. Ha, Y. Kim, B.C. Lee KAERI, Daejon, Republic of Korea
	Recently, there is a need of X-ray inspection system around the world to combat terrorism, drug and weapons smuggling, illegal immigration, and trade fraud. A compact standing wave (SW) linear accelerator (linac) for container X-ray inspection system has been produced at Radiation Technology eXcellence (RTX) to meet this growing need. The RF accelerating structure uses standing wave side-coupled structure fed by a 5 MW e2v magnetron with frequency of 2856 MHz. The electrons are accelerated from DC gun with energy of 25 keV to the final energy of 6 or 9 MeV at the X-ray target and generate X-ray with the dose rate of 8 Gy/min at 1 m after X-ray target. In this paper, we describe the design and optimization of side-coupled RF structure operating at π/2 mode. The beam dynamic of particle along the RF structure is also included in this paper by using ASTRA code.
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Paper

Title

Page

LCLS Bunch Compressor Configuration Study for Soft X-ray Operation

1037

S. Li, Y. Ding, Z. Huang, A. Marinelli, T.J. Maxwell, D.F. Ratner, F. Zhou
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany

The microbunching instability (MBI) is a well-known problem for high brightness electron beams and has been observed at accelerator facilities around the world. Free-electron lasers (FELs) are particularly susceptible to MBI, which can distort the longitudinal phase space and increase the beam's slice energy spread (SES). Past studies of MBI at the Linac Coherent Light Source (LCLS) relied on optical transition radiation to infer the existence of microbunching. With the development of the x-band transverse deflecting cavity (XTCAV), we can for the first time directly image the longitudinal phase space at the end of the accelerator and complete a comprehensive study of MBI, revealing both detailed MBI behavior as well as insights into mitigation schemes [1]. The fine time resolution of the XTCAV also provides the first LCLS measurements of the final SES, a critical parameter for many advanced FEL schemes. Detailed MBI and SES measurements can aid in understanding MBI mechanisms, benchmarking simulation codes, and designing future high-brightness accelerators.

Slides TUOCA01 [4.436 MB]

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TUPMY038

Preliminary Measurement of the Transfer Matrix of a TESLA-type Cavity at FAST

1632

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, J.K. Santucci, J.K. Santucci, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread application in Science and Industry. Many current and planned projects employ 1.3-GHz 9-cell superconducting cavities of the TESLA design*. In the present paper we discuss the transverse-focusing properties of such a cavity and non-ideal transverse-map effects introduced by field asymmetries in the vicinity of the input and high-order-mode radiofrequency (RF) couplers**. We especially consider the case of a cavity located downstream of an RF-gun in a setup similar to the photoinjector of the Fermilab Accelerator Science and Technology (FAST) facility. Preliminary experimental measurements of the CC2 cavity transverse matrix were carried out at the FAST facility. The results are discussed and compared with analytical and numerical simulations.
* A. Aunes et al., Phys. Rev.ST Accel. Beams 3, 092001 (2000).
** P. Piot, el. al., Proc. 2005 Part. Accel. Conf., Knoxville, TN, p. 4135 (2005).

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TUPOR026

Final Design and Status of the Third Recirculation for the S-DALINAC*

1717

M. Arnold, T. Kürzeder, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: *Work supported by DFG through CRC 634 and RTG 2128
Since 1991 the twice-recirculating superconducting accelerator S-DALINAC is providing electron beams for nuclear physics experiments. Due to a reduced quality factor of its cavities in comparison to their design values it was not possible to operate the accelerator with its maximum design energy of 130 MeV in cw mode. To provide electron beams of this energy in the future it was decided to add one recirculation beam line in order to use the main linac four times, operating the cavities on decreased accelerating gradients. The necessary modifications consist of several different aspects: A new beamline needs to be installed and other pre-existing beam line sections have to be modified for matching new boundary conditions. These new conditions are mainly a result of beam dynamics simulations and of the design of a new separation dipole magnet, which will bend the different beams energy-dependent in the various recirculation beam lines. We will present the implemented design and give a status report on the project.

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TUPOW002

Current Status of the Milliampere Booster for the Mainz Energy-recovering Superconducting Accelerator

1741

R.G. Heine, K. Aulenbacher, L.M. Hein, C. Matejcek
IKP, Mainz, Germany

Funding: Work supported by German Science Foundation (DFG) under the Cluster of Excellence "PRISMA" EXC1098/2014
The Milliampere Booster (MAMBO) is the injector linac for the Mainz Energy-recovering Superconducting Accelerator MESA. The MESA facility is currently under design at the Institut für Kernphysik (KPH) at Johannes Gutenberg University of Mainz (JGU). In this paper we will present the current design status of the linac.

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TUPOW003

High Average RF Power Tests With 2 RF Vacuum Windows at PITZ

1744

Y. Renier, G. Asova, M. A. Bakr, P. Boonpornprasert, J.D. Good, M. Groß, C. Hernandez-Garcia, H. Huck, I.I. Isaev, D.K. Kalantaryan, M. Krasilnikov, O. Lishilin, G. Loisch, D. Malyutin, D. Melkumyan, A. Oppelt, M. Otevřel, G. Pathak, T. Rublack, I.V. Rybakov, F. Stephan, G. Vashchenko, Q.T. Zhao
DESY Zeuthen, Zeuthen, Germany
M. Bousonville, S. Choroba, S. Lederer
DESY, Hamburg, Germany

The Photo Injector Test facility at DESY, Zeuthen site (PITZ), was built with the aim to develop and characterize electron sources for future usage at FLASH and at the European XFEL. Recently, the main focus at PITZ has been the study of gun reliability and photoinjector performance at high average power. The goal is to get stable and reliable operation with 6.4 MW peak power in the gun at 650 us RF pulse length and 10 Hz repetition rate. To achieve this, a new RF feed system with two RF windows was installed at PITZ in 2014. During this test, the old gun 4.2 with a modified back-plane design for better cathode contact has been used. In this contribution the results of the RF conditioning of gun 4.2 with a detailed interlock analysis will be reported as well as results from recent electron beam characterization.

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TUPOW004

Status of the STAR Project

1747

A. Bacci, I. Drebot, L. Serafini, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
R.G. Agostino, R. Barberis, M. Ghedini, F. Martire, C. Pace
UNICAL, Arcavacata di Rende, Italy
D. Alesini, M. Bellaveglia, J.J. Beltrano, F.G. Bisesto, G. Borgese, B. Buonomo, G. Di Pirro, G. Di Raddo, A. Esposito, A. Gallo, A. Ghigo, F. Iungo, L. Pellegrino, A. Stella, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
INFN-Roma II, Roma, Italy
G. D'Auria, A. Fabris, M. Marazzi
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
E. Puppin
Politecnico/Milano, Milano, Italy
M. Rossetti Conti
Universita' degli Studi di Milano & INFN, Milano, Italy

This paper reports on the final design and the work in progress on the STAR project (IPAC2014:WEPRO115), which is under construction at the Univ. of Calabria (Italy). The project is devoted to the construction of an advanced Thomson source of monochromatic tunable, ps-long, polarized X-ray beams, ranging from 40 up to 140 KeV . At present the buildings and main plants have been completed as the acquisition of main components: the RF photo-injector, the accelerating section, laser systems for collision and photo-cathode, RF Power Source and magnets are ready to start installation and site acceptance tests. The design of laser lines is complete and simulated by ZEMAX, aiming to minimize energy losses, optical distortions and providing a tunable experimental setup as well. The RF power network is close to be tested, it's based on a 55MW (2.5us pulse) S-band Klystron driven by a 500kV Pulse Forming Network based modulator and a Low Level RF system, running at 100 Hz. The Control System is been designed using EPICS and allows to manage easily and fastly each machine parameter. We expect to start commissioning the machine by the end of 2016 and obtain the first collisions within the first part of 2017.

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TUPOW005

Update on Third Harmonic XFEL Activities at INFN LASA

1751

D. Sertore, M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, P. Michelato, L. Monaco, R. Paparella, P. Pierini
INFN/LASA, Segrate (MI), Italy
C.G. Maiano
DESY, Hamburg, Germany
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy

After the successful installation and beam operation of the first batch of 3.9 GHz cavities into the XFEL Third Harmonic Injector Module, ten more cavities have been tested and delivered to DESY to be assembled into a spare cryomodule. In this paper, we report on the activities related to the cavities fabrication, treatment and vertical testing at INFN LASA.

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TUPOW006

Six-dimensional Phase-space Rotation and its Applications

1754

M. Kuriki, K. Negishi
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, R. Kato, K. Ohmi, M. Satoh, Y. Seimiya, J. Urakawa
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is partly supported by Grant-in-Aid for Scientific Research by MEXT, Japan (KAKENHI) 25390126.
Recent progress on the accelerator science requires optimized phase space distributions of the beam for each applications. A classical approach to satisfy the requirements is minimizing the beam emittance with a bunch charge as much as possible. This classical approach is not efficient and not compatible to the beam dynamics nature. 6D phase-space rotation, e.g. z-x and x-y, gives a way to optimize the phase space distribution for various applications. In this article, we discus possible applications of the 6D phase space rotation. The x-y rotation generates the high aspect ratio beam for linear colliders directly without DR (Damping Ring). Combination of bunch clipping with a mechanical slit and x-z rotation can generate micro-bunch structure which is applicable for FEL enhancement and drive beam for dielectric acceleration. We present our theoretical and simulation study on these applications.

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TUPOW008

Generation of Short Bunch Electron Beam from Compact Accelerator for Terahertz Radiation

1757

S. Suphakul, T. Kii, K. Masuda, K. Morita, H. Ohgaki, K. Torgasin, H. Zen
Kyoto University, Kyoto, Japan

We are developing a new compact accelerator system to generate a high power terahertz (THz) radiation at the Institute of Advanced Energy, Kyoto University. THz radiations are produced by injecting ultra-short and intense electron pulses to a short plannar undulator. The bunch compression characteristic by the newly installed chicane was investigated by observation of a coherent part of an optical transition radiation (OTR). As the result, the chicane can compress the electron bunch at the laser injection phase from 10 to 40 degree. The beam energy and relative rms energy spread were also measured and the results were 4.6 MeV and 1.3 %, respectively.

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TUPOW009

Generation of Coherent Undulator Radiation using Extremely Short Electron Bunch at t-ACTS, Tohoku University

1760

S. Kashiwagi, T. Abe, H. Hama, F. Hinode, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

An accelerator test facility, t-ACTS, was established at Research Center for Electron Photon Science, Tohoku University, in which an intense coherent terahertz (THz) radiation is generated from an extremely short electron bunch. Velocity bunching scheme in a traveling-wave accelerating structure is employed to produce the short electron bunch, and a production of sub-picosecond electron bunch was demonstrated. A long-period linear undulator, which has 25 periods with a period length of 10 cm and a peak magnetic field of 0.41 T, has been developed to produce intense coherent THz radiation. Properties of the radiation from the THz undulator such as radiation fields, spectrum and angular distribution were numerically investigated based on the parameters of short electron bunch and THz undulator. By optimization of bunch compression, it is possible to extract a coherent radiation of fundamental mode excluding higher-order mode. The detail of the numerical studies for the coherent undulator radiation will be reported in the conference.

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TUPOW010

Production of Ultra-short Electron Pulse and Observation of Coherent Transition Radiation at t-ACTS, Tohoku University

1763

T. Abe, H. Hama, F. Hinode, S. Kashiwagi, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

A test-Accelerator as Coherent Terahertz Source (t-ACTS) project has been under development at Research Center for Electron Photon Science, Tohoku University. In order to generate a coherent radiation in terahertz (THz) region, it is necessary to produce sub-picosecond electron pulses. Velocity bunching scheme is employed for the short electron pulse production in t-ACTS. We experimentally confirmed the production of short electron pulse under 500 fs by measuring the bunch length using a streak camera. Coherent transition radiation in THz region was produced by which the short electron pulses pass through a vacuum-metal interface. Several radiation properties including　spatial distribution, polarization and spectrum were measured and compared with theoretical calculations. The details of the beam experiment at t-ACTS are described.

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TUPOW011

Profile Measurements of Bremsstrahlung Gamma-Rays from Tungsten Plates for Radioactive Isotope Production via Photonuclear Reaction using a 60 MeV Electron Linac

1766

K. Takahashi, H. Hama, F. Hinode, S. Kashiwagi, H. Kikunaga, T. Muto, I. Nagasawa, K. Nanbu, Y. Shibasaki, T. Suda, C. Tokoku, K. Tsukada
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Radioactive isotopes have been produced via photo-nuclear reaction using a 60 MeV high-power electron linac for research fields of nuclear chemistry and radioac-tive analysis at Research Center for Electron Photon Science (ELPH), Tohoku University. The electron beam with an average current more than 100 μA is transported to an electron-bremsstrahlung gamma-ray converter of 2 mm thickness platinum or tungsten plate at the irradiation station. A target of 10 mm diameter is placed 3 cm behind a converter. It is enclosed with a quartz glass in the water cooling system and is irradiated for photonuclear reaction. Since the correlation between the spatial profile of bremsstrahlung gamma-rays at the target position and accelerator parameters is of our primary interest, nickel thin films are irradiated and the profiles of bremsstrahlung gamma-rays are measured by intensity distribution measurements of 57Ni radioactivity using the phosphorus imaging plate. In the meantime, the beam emittance and Twiss parameters are measured.

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TUPOW014

Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun

1769

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
W. Gai
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.

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TUPOW015

Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun

1772

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, S.V. Baryshev, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.

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TUPOW017

Twin Bunches at the FACET-II

1778

Z. Zhang
TUB, Beijing, People's Republic of China
M.J. Hogan, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

Twin electron bunches, generated, accelerated and compressed in the same acceleration bucket, have attracted a lot of interest in the free-electron lasers and wakefield acceleration. The recent successful experiment at the LCLS used twin bunches to generate two-color two x-ray pulses with tunable time delay and energy separation. In this note, we apply the twin bunches to the plasma wakefield acceleration. Numerical simulations show that based on the beamline of the FACET-II, we can generate high-intensity two electron bunches with time delay from ∼ 100 fs to picoseconds, which will benefit the control of high-gradient witness bunch acceleration in a plasma.

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TUPOW018

Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation

1782

SUPSS016

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

Z. Zhang, H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, X.L. Su, C.-X. Tang, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, L.M. Zheng, Z. Zhou
TUB, Beijing, People's Republic of China
W. Gai
ANL, Argonne, Illinois, USA

High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.

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TUPOW019

Preliminary Concept of Fast Positron Source Based on Photo-injector

1785

Z. Chu, J.G. Guo, Q. Luo, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11375178 and 11575181) and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046
Based on the past experience in slow positron beam, researchers at NSRL/USTC proposed a fast positron source for detection of material deep tiny flaws. Different from conventional positron sources used in positron annihilation techniques, the planned positron source will be a positron production linac, similar to positron injectors used in colliders. To compress the positron pulse, the bombarding electron beam comes from a short bunch photo-injector. A computer simulation was performed using EGS4 and PARMELA code. The bombarding electron bunch is 300pC, with an energy of 30MeV. Simulations results showed that it is reasonable to expect a beam of more than 10⁵ positrons per pulse for future positron annihilation studies. Further work is to be done to achieve precise control of beam energy.

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TUPOW021

Beam Dynamics Optimization and Future Plans for LUE-200 Linac Upgrade

1788

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia
A.V. Butenko, V. Kobets, A.P. Sumbaev
JINR, Dubna, Moscow Region, Russia

The IREN facility (Intense Resonance Neutron Source) is now been tested and upgraded in JINR. The linear electron accelerator LUE-200 is used to generate intense fluxes of resonant photo-neutrons. Linac should deliver up to 200 MeV electron beam with 1 A or more current in 100 - 200 ns pulses. It consists of electron source, LEBT including buncher and two main accelerating sections (only one is installed up to now). Test operations shows that beam loading sufficiently influences the output beam parameters and beam energy after first section decreases from planned 55-60 MeV to 35 MeV. The buncher doesn't provide an efficient beam bunching also and beam recapturing by main section due to this is very low. Dynamics of the electron beam for traveling wave S-band linac LUE-200 was studied by numerical simulations. In report results of beam dynamics simulation and optimization taking into account beam loading discuss, parameters for new more effective buncher presents and first results of such buncher development shows.

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TUPOW022

Hybrid Electron Linac With Standing and Travelling Wave Accelerating Sections

1791

S.V. Matsievskiy, A.V. Bulanov, V.I. Kaminskiy, E.A. Savin, N.P. Sobenin
MEPhI, Moscow, Russia
R.Yu. Alekhanov
NRNU, Moscow, Russia

Hybrid electron linacs with standing and travelling wave accelerating sections are not well described in literature. Limited number of studies have shown that application of these systems makes it possible to develop a compact linac with high efficiency and simpler power system. Typically, these systems use well-studied bi-periodical accelerating structure (BAS) cells for a standing wave section and disc-loaded waveguides (DLW) for a traveling wave section. This paper describes the development of such system using DLW cells with magnetic coupling (DLW-M). Here BAS appears as an absorbing load connected to the DLW-M accelerating structure by rectangular waveguide allowing to have theoretical zero reflection at RF input. Such system also provides possibility of plain beam output energy adjustment. Studies of the structure were carried out using equivalent circuits methods and numerical 3D-modeling. Beam dynamics was calculated.

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TUPOW023

New 10 MeV High-power Electron Linac for Industrial Application

1794

S.M. Polozov, D.S. Bazyl, T.V. Bondarenko, M. Gusarova, Yu.D. Kliuchevskaia, M.V. Lalayan, V.I. Rashchikov, E.A. Savin
MEPhI, Moscow, Russia
M.I. Demsky, A.A. Eliseev, V.V. Krotov, D.E. Trifonov
CORAD Ltd., St. Petersburg, Russia
B.S. Han, W.G. Kang, H.G. Park
EB TECH Co. Ltd., Daejeon, Republic of Korea

Joint team of CORAD and MEPhI developed a new industrial accelerating structure for average beam power up to 20 kW and energy range from 7.5 to 10 MeV. The use of modern methods and codes for beam dynamics simulation, raised coupling coefficient and group velocity of SW biperiodic accelerating structure allowed to reach high pulse power utilization and obtain high efficiency. Gentle buncher provides high capturing coefficient and narrow energy spectrum. The first linear accelerator with this structure was constructed and tested in collaboration with the company EB Tech.

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TUPOW024

Compact Standing Wave Electron Linac with the Hybrid Accelerating and Power Generation Cell

1797

SUPSS015

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E.A. Savin, S.V. Matsievskiy, N.P. Sobenin, I.D. Sokolov
MEPhI, Moscow, Russia
A.A. Zavadtsev
Nano, Moscow, Russia

Compact electron linear accelerators for small energies are now found their place in the industrial market. Such accelerators are used for cancer treatment, cargo inspection, when one needs higher dose that X-ray source can produce, food and medicaments irradiation etc. Acceleration structures themselves are already developed very well, so the most important issue now ' is to make the whole installation with power supply, RF tracts, cooling system ' as smaller as possible to provide the structure mobility. In this article we present the development how to combine a power supply (usually it is a klystron, IOT, magnetron or solid state amplifier) with the accelerating cell itself, that can decrease installation size at least twice. No RF tracts needed, no reflected power will occur, so no circulator needed. Different power input combinations have been studied, but the smallest and the most efficient one has been manufactured for cold tests at S-band frequency range. In this structure it is very easy to vary accelerating voltage simply changing the generator beam current or the generator beam accelerating voltage.

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TUPOW025

First Beam Test of the High Brightness Photo-injector at NSRRC

1800

A.P. Lee, M.C. Chou, N.Y. Huang, J.-Y. Hwang, W.K. Lau, C.C. Liang, M.T. Tsou
NSRRC, Hsinchu, Taiwan
P. Wang
NTHU, Hsinchu, Taiwan

A High brightness injector at NSRRC is built for a VUV/THz free electron laser (FEL) facility and light source R&D. This injector with a photocathode rf gun with a solenoid for emittance compensation, a UV laser system, a 5.2 m S-band linac as well as various beam diagnostic tools has been installed in the linac test laboratory. The main goal is to produce beams with emittance smaller than 1 mm-mrad at energy of ~100 MeV. The other goal is to compress bunches to ~100 fs with charge of 100 pc and energy of ~30 MeV. In this contribution, an overview of the commissioning results of the photocathode rf gun and the laser system will be given. The first beam observation downstream the lianc will be presented in this paper.

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TUPOW026

Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory

1803

SUPSS014

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N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai
Chiang Mai University, Chiang Mai, Thailand

Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand.
Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution.
The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University.

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TUPOW027

Model Independent Analysis of Beam Jitter on VELA

1806

J.K. Jones, K.D. Dumbell, A.J. Moss, E.W. Snedden
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide high quality electron beams for accelerator systems development, as well as industrial and scientific applications. A key performance indicator for many applications is the inherent beam jitter on the machine (temporal, momentum and positional). Analysis of this beam jitter indicates that there are several independent mechanisms driving the beam motion. We use model independent analysis to correlate various dominant modes of beam jitter and compare them to simulations. We also compare the dominant modes before and after intervention work on the DLLRF timing system, and determine the relevant changes in beam motion.

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TUPOW028

Comparison of Model vs. Reality for VELA

1810

M.S. Toplis, J.W. McKenzie, B.D. Muratori, D.J. Scott, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Versatile Electron Linear Accelerator (VELA) is a facility designed to provide a high quality electron beam for accelerator systems development, as well as industrial and scientific applications. Currently, the RF gun can deliver short bunches, of the order of 100 fs to a few ps, with a charge of up to 250 pC, at the longer bunch lengths, and up to 4.5 MeV/c beam momentum. A model for the injector has been developed in ASTRA, together with a suite of scripts to create scans of the available parameters around an empirically found arbitrarily optimal working point. The space of parameters consists of everything that can be changed in the control room, and ranges from bunch charge to laser spot size on the cathode, together with all magnet settings where and if necessary. The various scans facilitate the task of identifying where exactly the accelerator is in terms of parameters and trends. Initial comparisons of screen images are made between the model and reality. Ultimately, the goal of the model is to robustly and repeatably establish a desired operating setup on a daily basis from an unknown switch on condition.

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TUPOW029

Transverse Cavity Tuning at the Advanced Photon Source

1814

G.J. Waldschmidt, L.H. Morrison, T.L. Smith
ANL, Argonne, Ilinois, USA

A 15-cell transverse deflecting cavity based on a SLAC design was fabricated at the Advanced Photon Source and is being prepared for installation into the Injector Test Stand. A beadpull method for tuning was selected in lieu of the nodal position method to minimize the possibility of contamination and surface damage to the irises. The process has been successfully documented for many accelerating mode structures, but there has been limited application to dipole mode structures. In this paper, we will discuss the methodology for tuning and conditioning a 2.8 GHz backward-traveling wave deflecting cavity.

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TUPOW030

A CW Normal Conducting RF Cavity for Fast Chirp Control in the LCLS-II

1817

M.H. Nasr, P. Emma, S.G. Tantawi
SLAC, Menlo Park, California, USA

The LCLS-II is a high repetition-rate Free-Electron Laser (FEL) facility under construction at SLAC. A new 4-GeV continuous wave (CW) superconducting (SC) L-band linac is being built to provide an electron bunch rate of up to 1 MHz, with bunches rapidly switched between two FEL undulators. It is desirable to provide peak current (i.e., pulse length) control in each FEL independently by varying the RF phase (chirp) prior to the first bunch compressor. However, the high-Q, SCRF, with its 1-ms fill-time, cannot be changed within one bunch spacing (1 us). So to provide a small chirp adjustment from bunch to bunch, we propose a short CW copper RF accelerating cavity, located just after the injector, with < 250-ns fill-time designed to adjust the beam chirp at zero-crossing phase. We examined RF cavity designs spanning RF frequencies from L-band to X-band. We considered both SW and TW structures. We found an optimal solution with 2 cm iris diameter, SW RF cavity, operating at C-band with input power of only 10 kW. If one can afford to operate with smaller diameter, from a wakefield point of view, then similar structure at X-band may require only 500 W with 5 mm iris diameter.

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TUPOY010

6/9 MeV S-band Standing Wave Accelerating Structure for Container X-ray Inspection System at RTX

1924

P. Buaphad, H.D. Park, S. Song, S.Y. Yoo
RTX, Daejeon, Republic of Korea
H.K. Cha, S.S. Cha, J.H. Ha, Y. Kim, B.C. Lee
KAERI, Daejon, Republic of Korea

Recently, there is a need of X-ray inspection system around the world to combat terrorism, drug and weapons smuggling, illegal immigration, and trade fraud. A compact standing wave (SW) linear accelerator (linac) for container X-ray inspection system has been produced at Radiation Technology eXcellence (RTX) to meet this growing need. The RF accelerating structure uses standing wave side-coupled structure fed by a 5 MW e2v magnetron with frequency of 2856 MHz. The electrons are accelerated from DC gun with energy of 25 keV to the final energy of 6 or 9 MeV at the X-ray target and generate X-ray with the dose rate of 8 Gy/min at 1 m after X-ray target. In this paper, we describe the design and optimization of side-coupled RF structure operating at π/2 mode. The beam dynamic of particle along the RF structure is also included in this paper by using ASTRA code.

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