LINAC2014 - List of Keywords (radiation)

Paper	Title	Other Keywords	Page
MOPP018	Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule	cavity, cryomodule, SRF, linac	88
	D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A. Grassellino, A. Romanenko Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP041	Commissioning Plan for the FRIB Driver Linac*	linac, ion, cryomodule, operation	152
	M. Ikegami, L.T. Hoff, S.M. Lidia, F. Marti, G. Pozdeyev, T. Russo, R.C. Webber, J. Wei, Y. Yamazaki FRIB, East Lansing, Michigan, USA
	Funding: * Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The FRIB driver linac accelerates CW beams of all stable ions up to uranium to the energy of 200 MeV/u with the beam power of 400 kW. We plan to start staged beam commissioning in December 2017 in parallel with ongoing installation activities. This allows early recognition of technical issues, which is essential for smooth commissioning and early completion of commissioning goals. As the interlaced nature of commissioning and installation poses both scheduling challenges and special safety issues, it is essential to develop a commissioning plan with focused consideration of each. In this paper, we present a commissioning plan with emphasis on its characteristic features.

MOPP058	Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac	electron, laser, dipole, cavity	183
	J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA W.B. Wortley University of Rochester, Rochester, New York, USA
	Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP083	Helical Waveguides for Short Wavelength Accelerators and RF Undulators	undulator, electron, FEL, focusing	248
	S.V. Kuzikov, A.V. Savilov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.
	Poster MOPP083 [2.139 MB]

MOPP138	Fabrication and Measurements of 500 MHz Double Spoke Cavity	cavity, electron, simulation, target	385
	H. Park, J.R. Delayen JLab, Newport News, Virginia, USA J.R. Delayen, C.S. Hopper, H. Park ODU, Norfolk, Virginia, USA
	The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.
	Poster MOPP138 [2.144 MB]

TUPP020	Beam Dynamics Simulation for FLASH2 HGHG Option	simulation, FEL, undulator, electron	471
	G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov DESY, Hamburg, Germany K.E. Hacker DELTA, Dortmund, Germany T. Plath Uni HH, Hamburg, Germany
	The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP043	Design of the Phase Reference Distribution System at ESS	controls, LLRF, cavity, linac	529
	R. Zeng, H. Hassanzadegan, M. Jensen, J.M. Jurns, O.A. Persson, A. Sunesson ESS, Lund, Sweden K. Strniša Cosylab, Ljubljana, Slovenia
	PRDS (Phase reference distribution system) at ESS will provide phase reference signals for all LLRF systems and BPM systems with low phase noise and low phase drift. Phase stability requirement is currently 0.1° for short term (during pulse), 1° for long term (days to months). There are 155 LLRF systems and 165 BPM systems in total at current ESS accelerator design.

TUPP078	High Gain FEL with a Micro-bunch Structured Beam by the Transverse-Longitudinal Phase Space Rotation	FEL, cavity, electron, cathode	607
	M. Kuriki, Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, K. Ohmi KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan R. Kato ISIR, Osaka, Japan
	FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. That results the longitudinal micro-bunch structure. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. A compact FEL facility based on this method is proposed.
	Poster TUPP078 [0.594 MB]

TUPP086	RAON Superconducting Radio Frequency Test Facility Construction	cavity, cryogenics, SRF, electron	625
	H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin IBS, Daejeon, Republic of Korea
	Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP117	Commissioning of Vertical Test Stand Facility for 2 K Testing of Superconducting Cavities at RRCAT	cavity, shielding, controls, cryogenics	695
	S.C. Joshi, A. Chauhan, P. Fatnani, P.D. Gupta, M.K. Kumar, P.K. Kush, P. Mohania, S. Raghvendra, P. Shrivastava, S.K. Suhane RRCAT, Indore (M.P.), India
	Raja Ramanna Centre for Advanced Technology (RRCAT) has developed a 2K vertical Test Stand (VTS) facility for characterization of Superconducting RF (SCRF) cavities, under Indian Institution Fermilab Collaboration (IIFC). The VTS facility comprises of a large size liquid helium (LHe) cryostat, cryogenic system, RF power supply, control and data acquisition system and radiation monitoring system. It will facilitate testing of superconducting cavities of different frequencies ranging from 325 MHz low beta to 650 MHz / 1.3 GHz medium and high beta cavities. The helium vessel has a capacity to store up to 2900 litres of liquid Helium. The cryostat is installed inside a vertical pit. It is equipped with facilities for supply of liquid nitrogen and liquid helium and vacuum system for pumping out helium gas to lower the temperature of liquid helium bath down to 1.8 K. A 200 W, 1.3 GHz RF system has been indigenously developed for testing of the SCRF cavities. The VTS facility has now been commissioned and its performance validation has been successfully carried out by benchmarking it with respect to the facility at the Fermilab.

TUPP127	R&D of X-band Accelerating Structure for Compact XFEL at SINAP	FEL, linac, simulation, wakefield	715
	W. Fang, Q. Gu, M. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China A.A. Aksoy, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey D. Angal-Kalinin, J.A. Clarke Cockcroft Institute, Warrington, Cheshire, United Kingdom C.J. Bocchetta, A.I. Wawrzyniak Solaris, Kraków, Poland M.J. Boland SLSA, Clayton, Australia G. D'Auria, S. Di Mitri, C. Serpico Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy T.J.C. Ekelöf, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden E.N. Gazis National Technical University of Athens, Athens, Greece A. Grudiev, A. Latina, D. Schulte, S. Stapnes, W. Wuensch CERN, Geneva, Switzerland
	One compact hard X-ray FEL facility is being planned at SINAP, and X-band high gradient accelerating structure is the most competetive scheme for this plan. X-band accelerating structure is designed to switch between 60MV/m and 80MV/m, and carries out 6GeV and 8GeV by 130 meters linac respectively. In this paper, brief layout of compact XFEL will be introduced, and in particular the prototype design of dedicated X-band acceleration RF system is also presented.

TUPP128	ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam	laser, electron, FEL, simulation	719
	D. Huang, Q. Gu, Z. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

TUPP140	Observation of >GV/m Decelerating Fields in Dielectric Lined Waveguides	wakefield, vacuum, experiment, electron	743
	B.D. O'Shea, G. Andonian, K.L. Fitzmorris, S. Hakimi, J. Harrison, J.B. Rosenzweig, O. Williams UCLA, Los Angeles, California, USA M.J. Hogan, V. Yakimenko SLAC, Menlo Park, California, USA
	Recent experimental measurements of the energy lost to wakefields in a dielectric lined waveguide are presented. These measurements demonstrate average decelerating gradients on the order of >1 GV/m, for two different structures. The measurements were made at the Facility for Advanced aCcelerator Experimental Tests (FACET) at SLAC National Laboratory using sub-millimeter diameter fifteen-centimeter long quartz fibers of annular cross section. The unique extremely short, high charge, ultra relativistic beam at FACET (200 fs, 3 nC, 20 GeV) allows the use of dielectric wakefield structures of unprecedented size and length. In addition to experimental results, we support conclusions with simulation and theoretical work. This measurement builds on a large body of work previously performed using dielectric wakefield structures in an effort to provide high gradient accelerating structures for tomorrows linear colliders.

THPP055	High Power Density Test of PXIE MEBT Absorber Prototype	simulation, electron, experiment, focusing	973
	A.V. Shemyakin, C.M. Baffes Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. Two prototypes of the absorber were manufactured from molybdenum alloy TZM, and tested with a 28 keV DC electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototypes and key testing results.

THPP057	Results of Cold Tests of the Fermilab SSR1 Cavities	cavity, cryomodule, SRF, resonance	979
	A.I. Sukhanov, M.H. Awida, P. Berrutti, E. Cullerton, B.M. Hanna, A. Hocker, T.N. Khabiboulline, O.S. Melnychuk, D. Passarelli, R.V. Pilipenko, Y.M. Pischalnikov, L. Ristori, A.M. Rowe, W. Schappert, D.A. Sergatskov Fermilab, Batavia, Illinois, USA
	Fermilab is currently building the Project X Injector experiment (PXIE). The PXIE linac will accelerate a 1 mA H⁻ beam up to 30 MeV and serve as a testbed for validation of Project X concepts and mitigation of technical risks. A cryomodule of eight superconducting RF Single Spoke Resonators of type 1 (SSR1) cavities operating at 325 MHz is an integral part of PXIE. Ten SSR1 cavities were manufactured in industry and delivered to Fermilab. We discuss tests of nine bare SSR1 cavities at the Fermilab Vertical Test Stand (VTS). Recently, one of the SSR1 cavities was welded inside a helium jacket. Results of the test of this cavity in the Fermilab Spoke Test Cryostat (STC) are shown. We report on the measured performance parameters of SSR1 cavities achieved during the tests.

THPP103	Low Dose X-Ray Radiation Source for Angiography Based on Channeling Radiation Principle	electron, synchrotron, optics, synchrotron-radiation	1093
	T.V. Bondarenko, Yu.D. Kliuchevskaia, S.M. Polozov MEPhI, Moscow, Russia
	Angiography is one of the most reliable and contemporary procedure of the vascular system imaging. X-ray spectrums provided by all modern medical angiographs are too broad to acquire high contrast images and provide low radiation dose at the same time. The new method of narrow X-ray spectrum achieving is based on the idea of channelling radiation application. The X-ray filters used in this method allows eliminating the high energy part of the spectrum and providing dramatic dose reduction. The scheme of the facility including the X-ray filter is discussed. The results of the spectrum analysis for the channelling radiation source and typical angiography X-ray tube are discussed. Doses obtained by the water phantom and contrast of the iodine agent image are also provided for both cases.

THPP136	Study of Femtosecond Electron Bunch Generation at t-ACTS, Tohoku University	electron, gun, injection, bunching	1178
	S. Kashiwagi, H. Hama, F. Hinode, A. Lueangaramwong, T. Muto, I. Nagasawa, S. Nagasawa, K. Nanbu, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan N.Y. Huang NSRRC, Hsinchu, Taiwan
	We are conducting a beam experiment of sub-picosecond electron bunch generation at a test accelerator as a coherent terahertz source (t-ACTS), Tohoku University. In the t-ACTS, the intense coherent terahertz radiation will be generated from an undulator and an isochronous accumulator ring based on the sub-picoseconds bunches. The accelerator is composed of a thermionic cathode rf gun, alpha magnet and 3 m-long accelerating structure. A velocity bunching scheme in accelerating structure is applied to generate the short electron bunch. The thermionic rf gun consists two independent cavities has been developed, which is capable of manipulating the beam longitudinal phase space. To produced femtosecond electron bunch, the longitudinal phase space distribution of the beam entering the accelerating structure is optimized by changing the rf gun parameters. The bunch length is measured by observing an optical tradition radiation with a streak camera. In the study of femtosecond electron bunch generation, a relation between the rf gun parameters and the bunch length after compression was investigated. The preliminary results of experiments will be described in this conference.

FRIOB01	Positive Trends in Radiation Risk Assessment and Consequent Opportunities for Linac Applications	linac, FEL, controls, simulation	1202
	Y. Socol Falcon Analytics, Netanya, Israel
	Ionizing radiation, an unavoidable by-product of high-energy LINACs, makes them subject to strict regulation and severe public concerns. During the last two decades the attitude to ionizing radiation hazards has been becoming more balanced, as opposed to the historical "radiophobia". The linear no-threshold hypothesis (LNTH), based on the assumption that every radiation dose increment constitutes increased cancer risk for humans, is more and more debated. In particular, the recent memorandum of the International Commission on Radiological Protection admits that the LNTH predictions at low doses are "speculative, unproven, undetectable and "phantom'." Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of ionizing radiation may be beneficial to human health. While these advances in scientific understanding have not yet given fruit regarding radiation regulation and policy, we are hopeful these may happen in near to middle term. The presentation reviews the present status of the low-dose radiation-hazard debate. It also outlines anticipated opportunities for LINAC applications, especially in the prospective field of low-dose radiation therapy.
	Slides FRIOB01 [1.890 MB]

Paper

Title

Other Keywords

Page

MOPP018

Nitrogen-Doped 9-Cell Cavity Performance in the Cornell Horizontal Test Cryomodule

cavity, cryomodule, SRF, linac

88

D. Gonnella, R.G. Eichhorn, F. Furuta, G.M. Ge, D.L. Hall, Y. He, G.H. Hoffstaetter, M. Liepe, T.I. O'Connel, S. Posen, P. Quigley, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A. Grassellino, A. Romanenko
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy
Cornell has recently completed construction and qualification of a horizontal cryomodule capable of holding a 9-cell ILC cavity. A nitrogen-doped niobium 9-cell cavity was assembled into the Horizontal Test Cryomodule (HTC) with a high Q input coupler and tested. We report on results from this test of a nitrogen-doped cavity in cryomodule and discuss the effects of cool down rate and thermal cycling on the residual resistance of the cavity.

MOPP041

Commissioning Plan for the FRIB Driver Linac*

linac, ion, cryomodule, operation

152

M. Ikegami, L.T. Hoff, S.M. Lidia, F. Marti, G. Pozdeyev, T. Russo, R.C. Webber, J. Wei, Y. Yamazaki
FRIB, East Lansing, Michigan, USA

Funding: * Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The FRIB driver linac accelerates CW beams of all stable ions up to uranium to the energy of 200 MeV/u with the beam power of 400 kW. We plan to start staged beam commissioning in December 2017 in parallel with ongoing installation activities. This allows early recognition of technical issues, which is essential for smooth commissioning and early completion of commissioning goals. As the interlaced nature of commissioning and installation poses both scheduling challenges and special safety issues, it is essential to develop a commissioning plan with focused consideration of each. In this paper, we present a commissioning plan with emphasis on its characteristic features.

MOPP058

Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac

electron, laser, dipole, cavity

183

J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
W.B. Wortley
University of Rochester, Rochester, New York, USA

Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP083

Helical Waveguides for Short Wavelength Accelerators and RF Undulators

undulator, electron, FEL, focusing

248

S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.

Poster MOPP083 [2.139 MB]

MOPP138

Fabrication and Measurements of 500 MHz Double Spoke Cavity

cavity, electron, simulation, target

385

H. Park, J.R. Delayen
JLab, Newport News, Virginia, USA
J.R. Delayen, C.S. Hopper, H. Park
ODU, Norfolk, Virginia, USA

The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.

Poster MOPP138 [2.144 MB]

TUPP020

Beam Dynamics Simulation for FLASH2 HGHG Option

simulation, FEL, undulator, electron

471

G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov
DESY, Hamburg, Germany
K.E. Hacker
DELTA, Dortmund, Germany
T. Plath
Uni HH, Hamburg, Germany

The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP043

Design of the Phase Reference Distribution System at ESS

controls, LLRF, cavity, linac

529

R. Zeng, H. Hassanzadegan, M. Jensen, J.M. Jurns, O.A. Persson, A. Sunesson
ESS, Lund, Sweden
K. Strniša
Cosylab, Ljubljana, Slovenia

PRDS (Phase reference distribution system) at ESS will provide phase reference signals for all LLRF systems and BPM systems with low phase noise and low phase drift. Phase stability requirement is currently 0.1° for short term (during pulse), 1° for long term (days to months). There are 155 LLRF systems and 165 BPM systems in total at current ESS accelerator design.

TUPP078

High Gain FEL with a Micro-bunch Structured Beam by the Transverse-Longitudinal Phase Space Rotation

FEL, cavity, electron, cathode

607

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

FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. That results the longitudinal micro-bunch structure. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. A compact FEL facility based on this method is proposed.

Poster TUPP078 [0.594 MB]

TUPP086

RAON Superconducting Radio Frequency Test Facility Construction

cavity, cryogenics, SRF, electron

625

H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin
IBS, Daejeon, Republic of Korea

Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP117

Commissioning of Vertical Test Stand Facility for 2 K Testing of Superconducting Cavities at RRCAT

cavity, shielding, controls, cryogenics

695

S.C. Joshi, A. Chauhan, P. Fatnani, P.D. Gupta, M.K. Kumar, P.K. Kush, P. Mohania, S. Raghvendra, P. Shrivastava, S.K. Suhane
RRCAT, Indore (M.P.), India

Raja Ramanna Centre for Advanced Technology (RRCAT) has developed a 2K vertical Test Stand (VTS) facility for characterization of Superconducting RF (SCRF) cavities, under Indian Institution Fermilab Collaboration (IIFC). The VTS facility comprises of a large size liquid helium (LHe) cryostat, cryogenic system, RF power supply, control and data acquisition system and radiation monitoring system. It will facilitate testing of superconducting cavities of different frequencies ranging from 325 MHz low beta to 650 MHz / 1.3 GHz medium and high beta cavities. The helium vessel has a capacity to store up to 2900 litres of liquid Helium. The cryostat is installed inside a vertical pit. It is equipped with facilities for supply of liquid nitrogen and liquid helium and vacuum system for pumping out helium gas to lower the temperature of liquid helium bath down to 1.8 K. A 200 W, 1.3 GHz RF system has been indigenously developed for testing of the SCRF cavities. The VTS facility has now been commissioned and its performance validation has been successfully carried out by benchmarking it with respect to the facility at the Fermilab.

TUPP127

R&D of X-band Accelerating Structure for Compact XFEL at SINAP

FEL, linac, simulation, wakefield

715

W. Fang, Q. Gu, M. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
A.A. Aksoy, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
D. Angal-Kalinin, J.A. Clarke
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.J. Bocchetta, A.I. Wawrzyniak
Solaris, Kraków, Poland
M.J. Boland
SLSA, Clayton, Australia
G. D'Auria, S. Di Mitri, C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
T.J.C. Ekelöf, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
E.N. Gazis
National Technical University of Athens, Athens, Greece
A. Grudiev, A. Latina, D. Schulte, S. Stapnes, W. Wuensch
CERN, Geneva, Switzerland

One compact hard X-ray FEL facility is being planned at SINAP, and X-band high gradient accelerating structure is the most competetive scheme for this plan. X-band accelerating structure is designed to switch between 60MV/m and 80MV/m, and carries out 6GeV and 8GeV by 130 meters linac respectively. In this paper, brief layout of compact XFEL will be introduced, and in particular the prototype design of dedicated X-band acceleration RF system is also presented.

TUPP128

ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam

laser, electron, FEL, simulation

719

D. Huang, Q. Gu, Z. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

TUPP140

Observation of >GV/m Decelerating Fields in Dielectric Lined Waveguides

wakefield, vacuum, experiment, electron

743

B.D. O'Shea, G. Andonian, K.L. Fitzmorris, S. Hakimi, J. Harrison, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
M.J. Hogan, V. Yakimenko
SLAC, Menlo Park, California, USA

Recent experimental measurements of the energy lost to wakefields in a dielectric lined waveguide are presented. These measurements demonstrate average decelerating gradients on the order of >1 GV/m, for two different structures. The measurements were made at the Facility for Advanced aCcelerator Experimental Tests (FACET) at SLAC National Laboratory using sub-millimeter diameter fifteen-centimeter long quartz fibers of annular cross section. The unique extremely short, high charge, ultra relativistic beam at FACET (200 fs, 3 nC, 20 GeV) allows the use of dielectric wakefield structures of unprecedented size and length. In addition to experimental results, we support conclusions with simulation and theoretical work. This measurement builds on a large body of work previously performed using dielectric wakefield structures in an effort to provide high gradient accelerating structures for tomorrows linear colliders.

THPP055

High Power Density Test of PXIE MEBT Absorber Prototype

simulation, electron, experiment, focusing

973

A.V. Shemyakin, C.M. Baffes
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy
One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. Two prototypes of the absorber were manufactured from molybdenum alloy TZM, and tested with a 28 keV DC electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototypes and key testing results.

THPP057

Results of Cold Tests of the Fermilab SSR1 Cavities

cavity, cryomodule, SRF, resonance

979

A.I. Sukhanov, M.H. Awida, P. Berrutti, E. Cullerton, B.M. Hanna, A. Hocker, T.N. Khabiboulline, O.S. Melnychuk, D. Passarelli, R.V. Pilipenko, Y.M. Pischalnikov, L. Ristori, A.M. Rowe, W. Schappert, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

Fermilab is currently building the Project X Injector experiment (PXIE). The PXIE linac will accelerate a 1 mA H⁻ beam up to 30 MeV and serve as a testbed for validation of Project X concepts and mitigation of technical risks. A cryomodule of eight superconducting RF Single Spoke Resonators of type 1 (SSR1) cavities operating at 325 MHz is an integral part of PXIE. Ten SSR1 cavities were manufactured in industry and delivered to Fermilab. We discuss tests of nine bare SSR1 cavities at the Fermilab Vertical Test Stand (VTS). Recently, one of the SSR1 cavities was welded inside a helium jacket. Results of the test of this cavity in the Fermilab Spoke Test Cryostat (STC) are shown. We report on the measured performance parameters of SSR1 cavities achieved during the tests.

THPP103

Low Dose X-Ray Radiation Source for Angiography Based on Channeling Radiation Principle

electron, synchrotron, optics, synchrotron-radiation

1093

T.V. Bondarenko, Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia

Angiography is one of the most reliable and contemporary procedure of the vascular system imaging. X-ray spectrums provided by all modern medical angiographs are too broad to acquire high contrast images and provide low radiation dose at the same time. The new method of narrow X-ray spectrum achieving is based on the idea of channelling radiation application. The X-ray filters used in this method allows eliminating the high energy part of the spectrum and providing dramatic dose reduction. The scheme of the facility including the X-ray filter is discussed. The results of the spectrum analysis for the channelling radiation source and typical angiography X-ray tube are discussed. Doses obtained by the water phantom and contrast of the iodine agent image are also provided for both cases.

THPP136

Study of Femtosecond Electron Bunch Generation at t-ACTS, Tohoku University

electron, gun, injection, bunching

1178

S. Kashiwagi, H. Hama, F. Hinode, A. Lueangaramwong, T. Muto, I. Nagasawa, S. Nagasawa, K. Nanbu, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
N.Y. Huang
NSRRC, Hsinchu, Taiwan

We are conducting a beam experiment of sub-picosecond electron bunch generation at a test accelerator as a coherent terahertz source (t-ACTS), Tohoku University. In the t-ACTS, the intense coherent terahertz radiation will be generated from an undulator and an isochronous accumulator ring based on the sub-picoseconds bunches. The accelerator is composed of a thermionic cathode rf gun, alpha magnet and 3 m-long accelerating structure. A velocity bunching scheme in accelerating structure is applied to generate the short electron bunch. The thermionic rf gun consists two independent cavities has been developed, which is capable of manipulating the beam longitudinal phase space. To produced femtosecond electron bunch, the longitudinal phase space distribution of the beam entering the accelerating structure is optimized by changing the rf gun parameters. The bunch length is measured by observing an optical tradition radiation with a streak camera. In the study of femtosecond electron bunch generation, a relation between the rf gun parameters and the bunch length after compression was investigated. The preliminary results of experiments will be described in this conference.

FRIOB01

Positive Trends in Radiation Risk Assessment and Consequent Opportunities for Linac Applications

linac, FEL, controls, simulation

1202

Y. Socol
Falcon Analytics, Netanya, Israel

Ionizing radiation, an unavoidable by-product of high-energy LINACs, makes them subject to strict regulation and severe public concerns. During the last two decades the attitude to ionizing radiation hazards has been becoming more balanced, as opposed to the historical "radiophobia". The linear no-threshold hypothesis (LNTH), based on the assumption that every radiation dose increment constitutes increased cancer risk for humans, is more and more debated. In particular, the recent memorandum of the International Commission on Radiological Protection admits that the LNTH predictions at low doses are "speculative, unproven, undetectable and "phantom'." Moreover, numerous experimental, ecological, and epidemiological studies show that low doses of ionizing radiation may be beneficial to human health. While these advances in scientific understanding have not yet given fruit regarding radiation regulation and policy, we are hopeful these may happen in near to middle term. The presentation reviews the present status of the low-dose radiation-hazard debate. It also outlines anticipated opportunities for LINAC applications, especially in the prospective field of low-dose radiation therapy.

Slides FRIOB01 [1.890 MB]