2011 Particle Accelerator Conference - List of Keywords (linac)

Paper	Title	Other Keywords	Page
MOOBN3	Comparison of Accelerator Technologies for use in ADSS	target, proton, cyclotron, SRF	4
	W.-T. Weng, H. Ludewig, D. Raparia, M. Todosow, D. Trbojevic BNL, Upton, Long Island, New York, USA P.M. McIntyre, A. Sattarov Texas A&M University, College Station, Texas, USA
	Funding: Work performed under the auspices of the US Department of Energy Accelerator Driven Subcritical (ADS) fission is an interesting candidate basis for nuclear waste transmutation and for nuclear power generation. ADS can use either thorium or depleted uranium as fuel, operate below criticality, and consume rather than produce long-lived actinides. A case study with a hypothetical, but realistic nuclear core configuration is used to evaluate the performance requirements of the driver proton accelerator in terms of beam energy, beam current, duty factor, beam distribution delivered to the fission core, reliability, and capital and operating cost. Comparison between a CW IC and that of an SRF proton linac is evaluated. Future accelerator R&D required to improve each candidate accelerator design is discussed.
	Slides MOOBN3 [1.540 MB]

MOOBS1	Beam Dynamics Issues in the SNS Linac	laser, ion, emittance, optics	12
	A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA
	Funding: This research is supported by UT-Battelle, LLC for the U. S. Department of Energy under contract No. DE-AC05-00OR22725 A review of the Spallation Neutron Source (SNS) linac beam dynamics is presented. It describes transverse and longitudinal beam optics, losses, activation, and comparison between the initial design and the existing accelerator. The SNS linac consists of normal conducting and superconducting parts. The peculiarities in operations with the superconducting part of the SNS linac (SCL), estimations of total losses in SCL, the possible mechanisms of these losses, and the progress in the transverse matching are discussed.
	Slides MOOBS1 [1.270 MB]

MOODS1	Space-Charge Effects in Bunched and Debunched Beams	focusing, space-charge, electron, emittance	85
	B.L. Beaudoin, S. Bernal, K. Fiuza, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea, M. Reiser, D.F. Sutter UMD, College Park, Maryland, USA
	Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office The University of Maryland Electron Ring (UMER) is a machine designed to study high-intensity beam physics. With the application of axial fields to the bunch ends, we are able to keep a beam with an injected tune shift of 1.0, bunched over multiple turns. This is feasible with the application of tailored fields to optimally match the space-charge self-fields while minimizing the excitation of longitudinal space-charge waves. With this scheme, we have been able to extend the number of turns at the University of Maryland Electron Ring (UMER) by a factor of ten. Without the use of longitudinal focusing, head and tail effects begin to dominate, especially with the higher current beams. Time resolved measurements of the peak correlated energy spread have shown in some cases a change in the overall spread of 1.8% for the 0.6 mA beam, from the injected beam energy.
	Slides MOODS1 [2.834 MB]

MOODS5	3D Electromagnetic Design and Beam Dynamics Simulations of a Radio-Frequency Quadrupole	rfq, simulation, cavity, target	97
	B. Mustapha, A. Kolomiets, P.N. Ostroumov ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. During the design of the 60.635 MHz RFQ for the ATLAS efficiency and intensity upgrade, we have established a new full 3D approach for the electromagnetic and beam dynamics simulations of a RFQ. A Detailed full 3D model (four meter long) including vane modulation was built and simulated using CST Microwave Studio, which is made possible by the ever advancing computing capabilities. The approach was validated using experimental measurements on a prototype 57.5 MHz RFQ. The effects of the radial matchers, vane modulation and tuners on the resonant frequency and field flatness have been carefully studied. The full 3D field distribution was used for beam dynamics simulations using both CST Particle Studio and the beam dynamics code TRACK. In the final design we have used trapezoidal modulation instead of the standard sinusoidal in the accelerating section of the RFQ to achieve more energy gain for the same length, following the leading work of the Protvino group*. In our case, the output energy increased from 260 keV/u to 295 keV/u with minimal change in the beam dynamics. P.N. Ostroumov et al, Proceedings of LINAC-2010 P.N. Ostroumov et al, Proceedings of LINAC-2006 * TRACK @ http://www.phy.anl.gov/atlas/TRACK **** O.K. Belyaev et al, Proceedings of LINAC-2000
	Slides MOODS5 [2.531 MB]

MOP008	Upgrade of the Argonne Wakefield Accelerator Facility (AWA) and Commissioning of a New RF Gun for Drive Beam Generation	wakefield, gun, electron, acceleration	115
	M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. The AWA Facility is presently undergoing several upgrades that will enable it to further study wakefield acceleration driven by high charge electron beams. The facility employs an L-band photocathode RF gun to generate high charge short electron bunches, which are used to drive wakefields in dielectric loaded structures as well as in metallic structures (iris loaded, photonic band gap, etc). Several facility upgrades are underway: (a) a new RF gun with a higher quantum efficiency photocathode will replace the RF gun that has been used to generate the drive bunches; (b) the existing RF gun will be used to generate a witness beam to probe the wakefields; (c) three new L-band RF power stations, each providing 25 MW, will be added to the facility; (d) five linac structures will be added to the drive beamline, bringing the beam energy up from 15 MeV to 75 MeV. The drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The goal of future experiments is to reach accelerating gradients of several hundred MV/m and to extract RF pulses with GW power level.

MOP012	Ultra-High Gradient Compact S-Band Accelerating Structure	klystron, coupling, vacuum, simulation	127
	L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh RadiaBeam, Santa Monica, USA V.A. Dolgashev SLAC, Menlo Park, California, USA J.B. Rosenzweig UCLA, Los Angeles, California, USA V. Yakimenko BNL, Upton, Long Island, New York, USA
	Funding: Dept. of Energy DE-SC0000866 In this paper, we present the radio-frequency design of the DECA (Doubled Energy Compact Accelerator) S-band accelerating structure operating in the pi-mode at 2.856 GHz, where RF power sources are commonly available. The development of the DECA structure will offer an ultra-compact drop-in replacement for a conventional S-band linac in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design has been performed with the codes SuperFish and HFSS. The choice of the single cell shape derives from an optimization process aiming to maximize RF efficiency and minimize surface fields at very high accelerating gradients, i.e. 50 MV/m and above. Such gradients can be achieved utilizing shape-optimized elliptical irises, dual-feed couplers with the "fat-lip" coupling slot geometry, and specialized fabrication procedures developed for high gradient structures. The thermal-stress analysis of the DECA structure is also presented. * V. Dolgashev, "Status of X-band Standing Wave Structure Studies at SLAC", SLAC-PUB-10124, (2003). ** C. Limborg et al., "RF Design of LCLS Gun", LCLS-TN-05-03 (2005).

MOP043	Simulations of a Muon Linac for a Neutrino Factory	simulation, acceleration, synchrotron, factory	181
	K.B. Beard Muons, Inc, Batavia, USA S.A. Bogacz, V.S. Morozov, Y. Roblin JLAB, Newport News, Virginia, USA
	Funding: Supported in part by DOE grant DE-FG-08ER86351 The Neutrino Factory baseline design involves a complex chain of accelerators including a single-pass linac, two recirculating linacs and an FFAG. The first linac follows the capture and bunching section and accelerates the muons from about 244 to 900 MeV. It must accept a high emittance beam about 30 cm wide with a 10% energy spread. This linac uses counterwound, shielded superconducting solenoids and 201 MHz superconducting cavities. Simulations have been carried out using several codes including Zgoubi, OptiM, GPT, and G4beamline, both to determine the optics and to estimate the radiation loads on the elements due to beam loss and muon decay.

MOP052	Matched Optics of Muon RLA and Non-Scaling FFAG ARCS	optics, quadrupole, lattice, dynamic-aperture	196
	V.S. Morozov, S.A. Bogacz, Y. Roblin JLAB, Newport News, Virginia, USA K.B. Beard Muons, Inc, Batavia, USA D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Supported in part by US DOE STTR Grant DE-FG02-08ER86351 Recirculating Linear Accelerators (RLA) are an efficient way of accelerating short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. To reduce the number of required return arcs, we employ a Non-Scaling Fixed-Field Alternating-Gradient (NS-FFAG) arc lattice design. We present a complete linear optics design of a muon RLA with two-pass linear NS-FFAG droplet return arcs. The arcs are composed of symmetric cells with each cell designed using combined function magnets with dipole and quadrupole magnetic field components so that the cell is achromatic and has zero initial and final periodic orbit offsets for both passes’ energies. Matching to the linac is accomplished by adjusting linac quadrupole strengths so that the linac optics on each pass is matched to the arc optics. We adjust the difference of the path lengths and therefore of the times of flight of the two momenta in each arc to ensure proper synchronization with the linac. We investigate the dynamic aperture and momentum acceptance of the arcs.

MOP071	Terahertz Light Source and User Area at FACET	radiation, electron, photon, site	238
	Z. Wu, A.S. Fisher, M.J. Hogan, S.Z. Li, M.D. Litos SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET at SLAC provides high charge, high peak current, low emittance electron beam that is bunched at THz wavelength scale during its normal operation. A THz light source based coherent transition radiation (CTR) from this beam would potentially be the brightest short-pulse THz source ever constructed. Efforts have been put into building this photon source together with a user area, to provide a platform to utilize this unique THz radiation for novel nonlinear and ultrafast phenomena researches and experiments.

MOP117	Beam Test of a Tunable Dielectric Wakefield Accelerator	wakefield, gun, acceleration, electron	316
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, J.G. Power ANL, Argonne, USA
	Funding: Work supported by US DoE SBIR Grant under Contract # DE-FG02-07ER84822 We report on a collinear wakefield experiment using the first tunable dielectric loaded accelerating structure. Dielectric-based accelerators are generally lacking in approaches to tune the frequency after fabrication. However, by introducing an extra layer of nonlinear ferroelectric which has a dielectric constant sensitive to temperature and DC voltage, the frequency of a DLA structure can be tuned on the fly by controlling the temperature or DC bias. The experiment demonstrated that by varying the temperature of the structure over a 50°C temperature range, the energy of a witness bunch at a fixed delay with respect to the drive beam could be changed by an amount corresponding to more than half of the nominal structure wavelength.

MOP145	Physics Design of the Project X CW Linac	lattice, cryomodule, simulation, focusing	364
	N. Solyak, J.-P. Carneiro, J.S. Kerby, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, A. Saini, A. Vostrikov, V.P. Yakovlev Fermilab, Batavia, USA
	The general design of the 3 GeV superconducting CW linac of the Project X is presented. Different physical and technical issues and limitations that determine the linac concept are discussed. The results of the RF system optimization are presented as well as the lattice design and beam dynamics analysis.

MOP177	Design and Cold Test of Re-entrant Cavity BPM for HLS	cavity, coupling, pick-up, controls	420
	Q. Luo, Q.K. Jia, B.G. Sun, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by Natural Science Foundation of China, National 985 Project, China Postdoctoral Science Foundation and the Fundamental Research Funds for the Central Universities An S-band cavity BPM is designed for a new injector in National Synchrotron Radiation Laboratory. A re-entrant position cavity is tuned to TM110 mode as position cavity. Theoretical resolution of the BPM is 31 nm. A prototype cavity BPM system is manufactured for cold test. Wire scanning method is used to calibrate the BPM and estimate the performance of the on-line BPM system. Cold test results showed that position resolution of prototype BPM is better than 3 μm. Cross-talk has been detected during the cold test. Racetrack cavity can be used to suppress cross-talk. Ignoring nonlinear effect, transformation matrix is a way to correct cross-talk.

MOP184	Beam Instrumentation for the European Spallation Source	diagnostics, cryomodule, target, rfq	432
	A. Jansson, H. Danared, M. Eshraqi, L. Tchelidze ESS, Lund, Sweden
	The European Spallation Source, which will be built in the south of Sweden, is a neutron source based on a 5MW, 2.5GeV proton linac. The project is currently in the design update phase, and will deliver a Technical Design Report at the end of 2012. Construction is expected to begin in 2013. This paper discusses the initial beam diagnostics specifications, along with some possible instrument design options.

MOP194	A Laser-Wire Beam-Energy and Beam-Profile Monitor at the BNL Linac	electron, laser, optics, ion	456
	R. Connolly, L. DeSanto, C. Degen, R.J. Michnoff, M.G. Minty, D. Raparia BNL, Upton, Long Island, New York, USA
	Funding: Work performed under Contract #DE-AC02-98CH10886 under the auspices of the US Department of Energy. In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H⁻ beam by background gas. Electrons are stripped by the 1.7x10-7torr residual gas at a rate of ~2.4x10^-8/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by mp/me=1836. A 183.6MeV H⁻ beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. The chamber in which the laser light passes through the ion beam is upstream of a dipole magnet which deflects the electrons into a biased retarding-grid (V<125kV) Faraday-cup detector. To measure beam profiles, a narrow laser beam is stepped across the ion beam removing electrons from the portion of the H⁻ beam intercepted by the laser. The laser also gives us energy measurements on the 0.2mA polarized proton beam.

MOP234	Beam Position and Phase Monitors for the LANSCE Linac	controls, neutron, monitoring, instrumentation	548
	R.C. McCrady, J.D. Gilpatrick, J.F. Power LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the US Department of Energy under contract DE-AC52-06NA25396 New beam-position and phase monitors are under development for the linac at the Los Alamos Neutron Science Center. Transducers have been designed and are being fabricated. We are considering many options for the electronic instrumentation to process the signals and provide position and phase data with the necessary precision and flexibility to serve the various required functions. We’ll present the requirements of the system and the various options under consideration for instrumentation along with the advantages and shortcomings of these options.

MOP235	LANSCE Wire Scanning Diagnostics Device Prototype	vacuum, diagnostics, proton, acceleration	551
	S. Rodriguez Esparza, Y.K. Batygin, J.D. Gilpatrick, M.E. Gruchalla, A.J. Maestas, C. Pillai, J.L. Raybun, F.D. Sattler, J.D. Sedillo, B.G. Smith LANL, Los Alamos, New Mexico, USA
	The Accelerator Operations & Technology Division at Los Alamos National Laboratory operates a linear particle accelerator which utilizes 110 wire scanning diagnostics devices to gain position and intensity information of the proton beam. In the upcoming LANSCE improvements, 51 of these wire scanners are to be replaced with a new design, up-to-date technology and off-the-shelf components. This document outlines the requirements for the mechanical design of the LANSCE wire scanner and presents the recently developed linac wire scanner prototype. Additionally, this document presents the design modifications that have been implemented into the fabrication and assembly of this first linac wire scanner prototype. Also, this document will present the design for the second and third wire scanner prototypes being developed. These last two prototypes belong to a different section of the particle accelerator and therefore have slightly different design specifications. Lastly, the paper concludes with a plan for future work on the wire scanner development.

MOP237	Large Dynamic Range Beam Profile Measurements at SNS: Challenges and Achievements	background, coupling, electron, DTL	557
	A.V. Aleksandrov, W. Blokland, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. Beam profile diagnostics with large dynamic range is an important tool for understanding origin and evolution of the beam halo in accelerators. Typical dynamic range for conventional wire scanners has been in the range of 100. In high power machines like SNS fractional losses of 1 to 100 part per million is of concern and, therefore, higher dynamic range of profile measurements is desirable. Our near term goal was set to achieve a dynamic range of at least 10000 for all profile measurements in the SNS linac and transport lines. We will discuss present status of this program, challenges, and solutions.

MOP241	Beam Diagnostics for FACET	plasma, radiation, diagnostics, electron	565
	S.Z. Li, M.J. Hogan SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23 GeV, 3 nC electron bunches compressed to ~20 μm long and focussed to ~10 μm wide. Characterization of the beam- plasma interaction requires complete knowledge of the incoming beam parameters on a pulse-to- pulse basis. FACET diagnostics include Beam Position Monitors, Toroidal current monitors, X-ray and Cerenkov based energy spectrometers, optical transition radiation (OTR) profile monitors and coherent transition radiation (CTR) bunch length measurement systems. The compliment of beam diagnostics and their expected performance are reviewed.

MOP256	Upgrading the Data Acquisition and Control System of the LANSCE LINAC	controls, EPICS, proton, neutron	588
	D. Baros LANL, Los Alamos, New Mexico, USA
	Funding: This work has benefited from the use of the LANSCE at LANL. This facility is funded by the US DOE and operated by LANS for NSSA under Contract DE-AC52-06NA25396. Los Alamos National Laboratory LANL is in the process of upgrading the control system for the Los Alamos Neutron Science Center (LANSCE) linear accelerator. The 38 year-old data acquisition and control equipment is being replaced with COTS hardware. An overview of the current system requirements and how the National Instruments cRIO system meets these requirements will be given, as well as an update on the installation and operation of a prototype system in the LANSCE LINAC. LANL Release Number: LA-UR 10-06605

MOP257	High Power RF Distribution and Control for Multi-Cavity Cryomodule Testing	cryomodule, controls, cavity, klystron	591
	Y.W. Kang, M. Broyles, M.T. Crofford, X. Geng, S.-H. Kim, S.W. Lee, C.L. Phibbs, K.R. Shin, W.H. Strong ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. The SNS has been successfully operating 81 superconducting six-cell cavities in 23 cryomodules in its linac to achieve the goals in beam power and energy. For near-term production of spare cryomodules and the upcoming power upgrade project that will need 36 additional cavities in 9 cryomodules, high RF power testing and qualification of the cavities is required in the RF test facility. Simultaneously powering all the cavities in a cryomodule is considered desirable for robust conditioning and studying of cavity field emission since certain cavities exhibit field emissions that could be mutually coupled. A four-way variable output power waveguide splitting system is being prepared for testing cryomodules with up to four cavities. The splitting system is fed by an 805 MHz, 5 MW peak power pulsed klystron. The power output at each arm can be adjusted in both amplitude and phase to wide ranges of values using two mechanical waveguide phase shifters that form a vector modulator. The system control is implemented in the EPICS environment similar to the main accelerator controls. The work performed on the design, integration, operation, and test of the system are presented.

MOP261	The CEBAF Element Database	controls, lattice, background, alignment	594
	T. L. Larrieu, M.E. Joyce, C.J. Slominski JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. With inauguration of the CEBAF Element Database(CED) in Fall 2010, Jefferson Lab computer scientists have taken a first step toward the eventual goal of a model-driven accelerator. Once fully populated, the database will be the primary repository of information used for everything from generating lattice decks to booting iocs to building controls screens. A requirement influencing the CED design is that it provide access to not only present, but also future, and eventually past, configurations of the accelerator. To accomplish this, an introspective database schema was designed that allows new elements, types, and properties to be defined on-the-fly with no changes to table structure. Used in conjunction with Oracle Workspace Manager, it allows users to query data from any time in the database history with the same tools used to query the present configuration. Users can also check-out workspaces to use as staging areas for upcoming machine configurations. All Access to the CED is through a well-documented API that is translated automatically from original C++ into native libraries for script languages such as perl, php, and TCL making access to the CED easy and ubiquitous. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

MOP277	The Machine Protection System for the R&D Energy Recovery LINAC	controls, status, interlocks, collider	630
	Z. Altinbas, J.P. Jamilkowski, D. Kayran, R.C. Lee, B. Oerter BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The Machine Protection System (MPS) is a device-safety system that is designed to prevent damage to hardware by generating interlocks, based upon the state of input signals generated by selected sub-systems. It protects all the key machinery in the R&D Project called the Energy Recovery LINAC (ERL) against the high beam current. The MPS is capable of responding to a fault with an interlock signal within several microseconds. The ERL MPS is based on a National Instruments CompactRIO platform, and is programmed by utilizing National Instruments' development environment for a visual programming language. The system also transfers data (interlock status, time of fault, etc.) to the main server. Transferred data is integrated into the pre-existing software architecture which is accessible by the operators. This paper will provide an overview of the hardware used, its configuration and operation, as well as the software written both on the device and the server side.

MOP293	Performance of Analog Signal Distribution in the ATCA Based LLRF System	LLRF, controls, radio-frequency, FEL	666
	K. Czuba, L. Butkowski, S. Jabłoński, P. Przybylski, D. Sikora Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Jałmużna, D.R. Makowski TUL-DMCS, Łódź, Poland T. Jezynski, F. Ludwig DESY, Hamburg, Germany
	The Low Level Radio Frequency System (LLRF) for the European X-FEL must provide exceptional stability of the accelerating RF field in the accelerating cavities. The regulation requirements of 0.01% and 0.01 degrees in amplitude and phase respectively must be achieved at a frequency of 1.3 GHz while keeping low drifts (during RF pulse). The quality of analog signal processing and distribution plays a crucial role in achieving these goals. The RF signals are connected to the Rear Transition Module (RTM), downconverted there into intermediate frequency (IF) signals and finally sampled at AMC-ADC module. The high quality of the signals (SNR, low crosstalk) must be assured across all the way. The paper presents the results of development of ATCA based LLRF system for XFEL. The special attention is paid to RTM module with downconverters and carrier board conducting analog signals to the AMC-ADC and the AMC Vector Modulator module in the presence of digital processing components (FPGA, DSP).

TUOAN2	High Luminosity Electron-Hadron Collider eRHIC	electron, proton, luminosity, ion	693
	V. Ptitsyn, E.C. Aschenauer, M. Bai, J. Beebe-Wang, S.A. Belomestnykh, I. Ben-Zvi, M. Blaskiewicz, R. Calaga, X. Chang, A.V. Fedotov, H. Hahn, L.R. Hammons, Y. Hao, P. He, W.A. Jackson, A.K. Jain, E.C. Johnson, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, M.G. Minty, B. Parker, A.I. Pikin, T. Rao, T. Roser, B. Sheehy, J. Skaritka, S. Tepikian, R. Than, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, Q. Wu, W. Xu, A. Zelenski BNL, Upton, Long Island, New York, USA E. Pozdeyev FRIB, East Lansing, Michigan, USA E. Tsentalovich MIT, Middleton, Massachusetts, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We present the design of future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 10³⁴ cm^-2 s^-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling and the compact magnets for recirculating passes. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs and a potential of adding polarized positrons are also presented.
	Slides TUOAN2 [4.244 MB]

TUOAN3	Lattice Design for the Future ERL-Based Electron Hadron Colliders eRHIC and LHeC	electron, lattice, collider, dipole	696
	D. Trbojevic, J. Beebe-Wang, Y. Hao, D. Kayran, V. Litvinenko, V. Ptitsyn, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work performed under a Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy. We present a lattice design of a CW Electron Recovery Linacs (ERL) for future electron-hadron colliders eRHIC and LHeC. In eRHIC, an six-pass ERL installed in the existing Relativistic Heavy Ion Collider (RHIC) tunnel will collide 5-30 GeV polarized electrons with RHIC’s 50-250 (325) GeV polarized protons or 20-100 (130) GeV/u heavy ions. In LHeC, a stand-along 3-pass 60 GeV CW ERL will collide polarized electrons with 7 TeV protons. After collision, electron beam energy is recovered and electrons are dumped at low energy. Two superconducting linacs are located in the two straight sections in both ERLs. . The multiple arcs are made of Flexible Momentum Compaction lattice (FMC) allowing adjustable momentum compaction for electrons with different energies. The multiple arcs, placed above each other, are matched to the two linacs straight sections with splitters and combiners.
	Slides TUOAN3 [3.002 MB]

TUOBS1	Technical Challenges in the Linac Coherent Light Source, Commissioning and Upgrades	undulator, electron, photon, laser	724
	Z. Huang, J.N. Galayda SLAC, Menlo Park, California, USA P.A. Heimann LBNL, Berkeley, California, USA
	Funding: DOE Five months after first lasing in April 2009, the Linac Coherent Light Source (LCLS) began its first round of x-ray experiments. The facility rapidly attained and surpassed its design goals in terms of spectral tuning range, peak power, energy per pulse and pulse duration. There is an ongoing effort to further expand capabilities while supporting a heavily subscribed user program. The facility continues to work toward new capabilities such as multiple-pulse operation, pulse durations in the femtosecond range, and production of >16 keV photons by means of a second-harmonic “afterburner” undulator. Future upgrades will include self-seeding and polarization control. The facility is already planning to construct a major expansion, with two new undulator sources and space for four new experiment stations.
	Slides TUOBS1 [12.513 MB]

TUOBS2	Cornell ERL Research and Development	emittance, electron, FEL, gun	729
	C.E. Mayes, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, E. Fontes, C.M. Gulliford, D.L. Hartill, G.H. Hoffstaetter, V.O. Kostroun, F.A. Laham, Y. Li, M. Liepe, X. Liu, F. Löhl, A. Meseck, A.A. Mikhailichenko, H. Padamsee, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, V.D. Shemelin, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, Y. Xie CLASSE, Ithaca, New York, USA S.S. Karkare, J.M. Maxson Cornell University, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731. Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.
	Slides TUOBS2 [5.632 MB]

TUOBS4	Challenge of MAX IV Towards a Multi-Purpose Highly Brilliant Light Source	emittance, lattice, storage-ring, vacuum	737
	M. Eriksson, J. Ahlbäck, Å. Andersson, M.A.G. Johansson, D. Kumbaro, S.C. Leemann, C. Lenngren, P. Lilja, F. Lindau, L.-J. Lindgren, L. Malmgren, J.H. Modéer, R. Nilsson, M. Sjöström, J. Tagger, P.F. Tavares, S. Thorin, E.J. Wallén, S. Werin MAX-lab, Lund, Sweden B. Anderberg AMACC, Uppsala, Sweden L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada
	A design study of the MAX-IV light source complex in Sweden has been completed. One of MAX-IV's main light sources, a 3 GeV storage ring, is designed to achieve a natural emittance of ~0.2 nm rad. The facility will also provide SASE-XFEL using a 3 GeV high performance linear accelerator. The speaker will discuss facility targets, the concept and accelerator design, and show some possibilities approaching two-dimensional diffraction-limited X-ray generation at MAX-IV.
	Slides TUOBS4 [6.719 MB]

TUOCS1	Energy Recovery Linacs for Light Source Applications	electron, FEL, gun, cavity	761
	G. Neil JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under DOE Contract No. DE-AC05-06OR23177. The U.S.Government retains a non-exclusive, paid-up, irrevocable, world-wide license. Energy Recovery Linacs are being considered for applications in present and future light sources. ERLs take advantage of the continuous operation of superconducting rf cavities to accelerate high average current beams with low losses. The electrons can be directed through bends, undulators, and wigglers for high brightness x ray production. They are then decelerated to low energy, recovering power so as to minimize the required rf drive and electrical draw. When this approach is coupled with advanced continuous wave injectors, very high power, ultra-short electron pulse trains of very high brightness can be achieved. This paper reviews the status of worldwide programs and discusses the technology challenges to provide such beams for photon production.
	Slides TUOCS1 [9.930 MB]

TUOCS4	Upgrade of Accelerator Complex at Pohang Light Source Facility (PLS-II)	emittance, storage-ring, vacuum, insertion	772
	K.R. Kim, H.-S. Kang, C. Kim, D.E. Kim, S.H. Kim, S.-C. Kim, H.-G. Lee, J.W. Lee, S.H. Nam, C.D. Park, S.J. Park, S. Shin PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This upgrade project of PLS-II is supported by MEST, in Korea In order to meet the domestic Korean synchrotron user’s requirements demanding high beam stability and extended photon energies, PLS-II upgrade program has been launched in January 2009 through a 3-year project plan. PLS-II storage ring is newly designed a modified achromatic version of Double Bend Achromat (DBA) to achieve almost twice as many straight sections as the current PLS (TBA) with a design goal of the natural emittance of 5.8 nm·rad, 3.0 GeV beam energy and 400 mA beam current. In the PLS-II, the top-up injection using full energy linac of 3.0 GeV beam energy will be routinely operated for higher stable photon beam as well and therefore the production of hard x-ray undulator radiation of 8 to13 keV is anticipated to allow for more competitive scientific research activities namely x-ray bio-imaging and protein crystallography.
	Slides TUOCS4 [17.914 MB]

TUOCS5	A Next Generation Light Source Facility at LBNL	FEL, electron, laser, photon	775
	J.N. Corlett, B. Austin, K.M. Baptiste, J.M. Byrd, P. Denes, R.J. Donahue, L.R. Doolittle, R.W. Falcone, D. Filippetto, D.S. Fournier, J. Kirz, D. Li, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, T. Vecchione, M. Venturini, R.P. Wells, R.B. Wilcox, J.S. Wurtele LBNL, Berkeley, California, USA A.E. Charman, E. Kur UCB, Berkeley, California, USA A. Zholents ANL, Argonne, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multi‐beamline soft x‐ray FEL array powered by a 2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.
	Slides TUOCS5 [4.758 MB]

TUP012	Computer Simulations of Waveguide Window and Coupler Iris for Precision Matching	DTL, coupling, simulation, cavity	832
	S.W. Lee ORNL RAD, Oak Ridge, Tennessee, USA Y.W. Kang, K.R. Shin, A.V. Vassioutchenko ORNL, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. A tapered ridge waveguide iris input coupler and a waveguide ceramic disk windows are used on each of six drift tube linac (DTL) cavities in the Spallation Neutron Source (SNS). The coupler design employs rapidly tapered double ridge waveguide to reduce the cross section down to a smaller low impedance transmission line section that can couple to the DTL tank easily. The impedance matching is done by adjusting the dimensions of the thin slit aperture between the ridges that is the coupling element responsible for the power delivery to the cavity. Since the coupling is sensitive to the dimensional changes of the aperture, it requires careful tuning for precise matching. Accurate RF simulation using latest 3-D EM code is desirable to help the tuning for maintenance and spare manufacturing. Simulations are done for the complete system with the ceramic window and the coupling iris on the cavity to see mutual interaction between the components as a whole.

TUP014	Broad-band Beam Chopper for a CW Proton Linac at Fermilab	kicker, coupling, rfq, emittance	838
	N. Solyak, E. Gianfelice-Wendt, V.A. Lebedev, S. Nagaitsev, D. Sun Fermilab, Batavia, USA
	The specifications and the initial conceptual ides for a broad-band proton chopper for a Fermilab Project X linac will be presented. The chopper will form bunch patterns required by physics experiments and will work with downstream beam splitter, allowing for a variable bunch pattern to be delivered to up to three experiment concurrently.

TUP015	Conceptual Design of the Project-X 1.3 GHz, 3-8 GeV Pulsed Linac	cavity, controls, klystron, feedback	841
	N. Solyak, Y.I. Eidelman, S. Nagaitsev, J.-F. Ostiguy, A. Vostrikov, V.P. Yakovlev Fermilab, Batavia, USA
	The Project-X, a multi-MW proton source, is under development at Fermilab. It enables a Long Baseline Neutrino Experiment via a new beam line pointed to DUSEL in Lead, South Dakota, and a broad suite of rare decay experiments. The facility contains 3-GeV 1-mA CW superconducting linac. In the second stage of about 5% of the H⁻ beam is accelerated up to 8 GeV in a 1.3 GHz SRF pulse linac to Recycler/Main Injector. In order to mitigate the problem with the stripping foil heating during injection to the Main Injector, the pulses with higher current are accelerated in CW linac together with 1 mA beam for further acceleration in the pulse linac. The optimal current in the pulse linac is discussed as well as limitations that determine it's selection. A concept design of the pulse linac is described. The lattice design is presented as well as RF stability analysis. The necessity of the HOM couplers is discussed also.

TUP019	The S-DALINAC Polarized Injector SPIN - Performance and Results	electron, laser, polarization, site	853
	C. Eckardt, T. Bahlo, P. Bangert, R. Barday, U. Bonnes, M. Brunken, C. Burandt, R. Eichhorn, J. Enders, M. Espig, C. Ingenhaag, J. Lindemann, M. Platz, Y. Poltoratska, M. Roth, F. Schneider, H. Schüßler, M. Wagner, A. Weber, B. Zwicker TU Darmstadt, Darmstadt, Germany W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany K. Aulenbacher IKP, Mainz, Germany
	Funding: * Work supported by DFG through SFB 634. At the superconducting 130 MeV Darmstadt electron linac S-DALINAC the new source of polarized electrons uses a GaAs cathode illuminated with pulsed Ti:Sapphire and diode laser light. The electron source had been set up and commissioned at a test stand with a beam line where a Wien filter for spin manipulation, a Mott polarimeter for polarization measurement and a chopper-prebuncher system were part of the system. Upon completion of the tests, test stand and beam line were dismantled and re-installed at the S-DALINAC. The new photo injector opens up the potential for experiments with polarized electron and photon beams for nuclear structure studies at low momentum transfers. Various polarimeters will be installed at all experimental sites to monitor the beam polarization. We report on the S-DALINAC, the results from the teststand performance, the implementation of the polarized source and the polarimeter research and development. * A. Richter, Proc. of the 5th EPAC, Sitges (1996) 110 Y. Poltoratska et al., AIP Conference Proc. 1149 (2009) 983 * P. Mohr et al., Nucl. Instr. and Meth. A423 (1999) 480

TUP031	Project X Elliptical Cavity Structural Analyses	cavity, simulation, vacuum, cryomodule	868
	E.N. Zaplatin FZJ, Jülich, Germany
	Project X is proposed at Fermi National Accelerator Laboratory high-intensity proton accelerator complex that could provide beam for a variety of physics projects. Superconducting resonators will be used for beam acceleration. Here we report a structural design of elliptical cavities with resonance frequency 650 MHz and β=0.91 and 0.61. Since there is a concern that the pressure in the helium plumbing will not be stable when the cryomodules are connected to the liquid helium supply and helium gas returns it is necessary to provide the cavity stiffening with requirements of 15 Hz amplitude frequency shift. The cavity RF and mechanical properties are investigated. The calculations of the cavity frequency shift with pressure for different schemes of cavity stiffening were provided. The criterion for the optimization was the minimization of a resonant frequency dependence on an external pressure. Based on the results of these simulations several options on cavity stiffening have been proposed. Additionally, the cavity stiffening structural scheme for self-compensation of resonator detuning caused by external pressure fluctuation have been investigated.

TUP046	Superconducting 72 MHz β=0.077 Quarter-wave Cavity for ATLAS	cavity, niobium, ion, cathode	892
	M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	A 72 MHz superconducting (SC) niobium quarter-wave cavity (QWR) optimized for β=0.077 has been built and tested as part of a beam intensity upgrade of the ATLAS SC heavy-ion linac. The two-gap cavity, designed to accelerate ions over the velocity range 0.06<β<0.12 and provide 2.5 MV of accelerating voltage per cavity at T=4.5 Kelvin, is based on a highly optimized electromagnetic design to reduce surface electric and magnetic fields. Horizontal electropolishing on the complete cavity with the helium jacket, is similar to that performed on 1.3 GHz ILC-type cavities and is a first for a low-β TEM cavity. This development is part of a broader effort to demonstrate ~120 mT surface fields with Rs~5 nΩ in 2 K operation for low-β cavities with the aim of substantially reducing the footprint for future ion linacs. First rf cold test results show the highest accelerating gradients (13.4 MV/m, leff=βλ) and voltage/cavity (4.3 MV) achieved for this class of SC cavity.

TUP059	Multipacting in a Grooved Choke Joint at SRF Gun for BNL ERL Prototype	cathode, cavity, gun, simulation	922
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, A. Burrill, D. Kayran, G.T. McIntyre, B. Sheehy BNL, Upton, Long Island, New York, USA D. Holmes AES, Medford, NY, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The 703 MHz superconducting gun for BNL ERL prototype was tested at JLab with and without choke-joint and cathode stalk. Without choke-joint and cathode stalk, the gradient reached 25MV/m with Q0~6·10⁹. The gun cathode insertion port is equipped with a choke joint with triangular grooves for multipacting suppression. We carried out tests with choke-joint and cathode stalk. The test results show that there are at least two barriers at about 5MV/m and 3.5 MV/m. We considered several possibilities and finally found that the limitation was because the triangular grooves were rounded after BCP, which caused strong multipacting in the choke-joint. This paper presents the primary test result of test results of the gun and discusses the multipacting analysis in the choke-joint. It also suggests possible solutions for the gun and multipacting suppressing for a similar structure.

TUP060	New HOM Coupler Design for High Current SRF Cavity	HOM, cavity, higher-order-mode, coupling	925
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, E.C. Johnson BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass filter is nearly flat from first higher order mode to 5 times the fundamental frequency. The simulation results showed that the new couplers effectively damp HOMs for the eRHIC cavity with enlarged beam tube diameter and two 120° HOM couplers at each side of cavity. This paper presents the design of HOM coupler, HOM damping capacity for eRHIC cavity and prototype test results.

TUP064	Designing Multiple Cavity Classes for the Main Linac of Cornell's ERL	cavity, HOM, dipole, higher-order-mode	937
	N.R.A. Valles, M. Liepe CLASSE, Ithaca, New York, USA
	Funding: Work supported by NSF Grant No. PHY-0131508, and NSF/NIH-NIGMS Grant No. DMR-0937466 Cornell is currently developing a high current Energy Recovery Linac. The baseline 7-cell cavity design for the main linac has already been completed, and prototyping has begun, as of Fall 2010. Previous work showed that increasing the relative cavity-to-cavity frequency spread increases the beam break-up current through the linac. Simulations show that expected machining variations will introduce a relative HOM frequency spread of 0.5·10^-3, corresponding to 150 mA of threshold current. The key idea of this work is to increase the relative cavity-to-cavity frequency spread by designing several classes of 7-cell cavities obtained by making small changes to the baseline center cell shape. This allows a threshold current in excess of 450 mA, which is well above the 100 mA goal for the Cornell Energy Recovery Linac.

TUP066	Three-cell Traveling-wave Superconducting Test Structure	cavity, feedback, accelerating-gradient, controls	940
	P.V. Avrakhov, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA S. Kazakov, N. Solyak, G. Wu, V.P. Yakovlev Fermilab, Batavia, USA
	Use of a superconducting traveling wave accelerating (STWA) structure* with a small phase advance per cell rather than a standing wave structure may provide a significant increase of the accelerating gradient in the ILC linac. For the same surface electric and magnetic fields the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing wave cavities. The STWA allows also longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed, manufactured and successfully tested** demonstrating the possibility of a proper processing to achieve a high accelerating gradient. These results open the way to take the next step of the TW SC cavity development: to build and test a traveling-wave three-cell cavity with a feedback waveguide. The latest results of the single-cell cavity tests are discussed as well as the design of the test 3-cell TW cavity. * P. Avrakhov, et al, Phys. of Part. and Nucl. Let, 2008, Vol. 5, No. 7, p. 597 ** G. Wu, et al, IPAC 2010, THPD048

TUP069	Status of the Mechanical Design of the 650 MHz Cavities for Project X	cavity, HOM, simulation, status	943
	S. Barbanotti, M.S. Champion, M.H. Foley, C.M. Ginsburg, I.G. Gonin, C.J. Grimm, T.J. Peterson, L. Ristori, V.P. Yakovlev Fermilab, Batavia, USA
	In the high-energy section of the Project X Linac, acceleration of H^- ions takes place in superconducting cavities operating at 650 MHz. Two families of five-cell elliptical cavities are planned: β = 0.61 and β = 0.9. A specific feature of the Project X Linac is low beam loading, and thus, low bandwidth and higher sensitivity to microphonics. Efforts to optimize the mechanical design of the cavities to improve their mechanical stability in response to the helium bath pressure fluctuations will be presented. These efforts take into account constraints such as cost and ease of fabrication. Also discussed will be the overall design status of the cavities and their helium jackets.

TUP070	EM Design of the Low-Beta SC Cavities for the Project X Front End	cavity, factory, SRF, acceleration	946
	I.G. Gonin, S. Barbanotti, P. Berrutti, L. Ristori, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	The low-energy part of the Project X H-linac includes three types of superconducting single spoke cavities (SSR) with β = 0.11, 0.21 and 0.4 operating at the fundamental TEM-mode at 325MHz. In this paper we present the detailed EM optimization of cavity shapes having the goal to minimize the peak electric and magnetic fields. We also discuss the importance of the integration of EM and mechanical design.

TUP072	High Power Couplers for Project X Linac	coupling, cavity, cryomodule, vacuum	952
	S. Kazakov, M.S. Champion, M. Kramp, Y. Orlov, O. Pronitchev, V.P. Yakovlev Fermilab, Batavia, USA
	Project X, a multi-megawatt proton sources is under development in Fermi National Accelerator Laboratory. The key element of the project is a superconducting (SC) 3GV CW proton liner accelerator (linac). The linac includes 5 types of SC accelerating cavities of three 325 and 650 MHz frequencies. The cavities consumes up to 30 kW average RF power and need proper main couplers. Requirements and approach to the coupler design are discussed in the report. New cost effective schemes of the couplers are described. Results of electrodynamics and thermal simulations are presented.

TUP073	Development of an L-band Ferroelectric Phase Shifter	simulation, insertion, controls, high-voltage	955
	S. Kazakov, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA J.L. Hirshfield Yale University, Physics Department, New Haven, CT, USA A. Kanareykin, E. Nenasheva Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Shchelkunov Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
	Effective operation of the RF cavities in the superconducting accelerators demands fast, high-power RF vector modulators. Recent progress in development of the new materials, ferroelectrics, having tunable dielectric constant and acceptable losses [] gives the possibility development of such devises. In previous papers [-*] the authors described different L-band ferroelectric phase shifter designs . At low RF level high operation speed of 2 degree/nsec was demonstrated in waveguide phase shifter. However, the experiments show that a special technology is to be developed that provides a good electric contact between ceramics and the metallic wall. In present paper a new design of the fast high–power ferroelectric phase shifter is described based on the simple ferroelectric elements. A. Kanareykin, et al, IPAC 2010, p. 3987 S. Kazakov, et al, “Fast Ferroelectric Phase Shifter Design For ERLs,” 45th ICFA Beam Dynamics Workshop, 2009 * S. Kazakov, et al, PAC2007, p. 599.

TUP074	Experiments on HOM Spectrum Manipulation in a 1.3 GHz ILC SC Cavity	HOM, cavity, resonance, emittance	958
	T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Superconducting cavities with high operating Q will be installed in the Project-X, a superconducting linac, which is under development at Fermilab. Possibility of cavity design without HOM couplers considered. Rich spectrum of the beam and large number of cavities in ProjectX linac can result to resonance excitation of some high order modes with high shunt impedance. Under scope of study of High Order Modes (HOM) damping the manipulation with HOM spectrum in cold linac is considered. Results of detuning HOM spectrum of 1.3 GHz cavities at 2K in Horizontal Test Station of Fermilab are presented. Possible explanation of the phenomena is discussed.

TUP075	Cavity Loss Factors of Non-relativistic Beams for Project X	cavity, simulation, factory, cryomodule	961
	A. Lunin, S. Kazakov, V.P. Yakovlev Fermilab, Batavia, USA
	Cavity loss factor calculation is an important part of total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the combining of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.

TUP076	First High Power Pulsed Tests of a Dressed 325 MHz Superconducting Single Spoke Resonator at Fermilab	cavity, klystron, vacuum, resonance	964
	R.L. Madrak, J. Branlard, B. Chase, C. Darve, P.W. Joireman, T.N. Khabiboulline, A. Mukherjee, T.H. Nicol, E. Peoples-Evans, D.W. Peterson, Y.M. Pischalnikov, L. Ristori, W. Schappert, D.A. Sergatskov, W.M. Soyars, J. Steimel, I. Terechkine, V. Tupikov, R.L. Wagner, R.C. Webber, D. Wildman Fermilab, Batavia, USA
	In the recently commissioned superconducting RF cavity test facility at Fermilab (SCTF), a 325 MHz, β=0.22 superconducting single-spoke resonator (SSR1) has been tested for the first time with its input power coupler. Previously, this cavity had been tested CW with a low power, high Qext test coupler; first as a bare cavity in the Fermilab Vertical Test Stand and then fully dressed in the SCTF. For the tests described here, the design input coupler with Q_ext ~ 10⁶ was used. Pulsed power was provided by a Toshiba E3740A 2.5 MW klystron.

TUP084	Design of Single Spoke Resonators for Project X	cavity, proton, ion, niobium	982
	L. Ristori, S. Barbanotti, M.S. Champion, M.H. Foley, I.G. Gonin, C.J. Grimm, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Project X is based on a 3 GeV CW superconducting linac and is currently in the R&D phase awaiting CD-0 approval. The low-energy section of the Project X H-linac includes three types of super-conducting single spoke cavities operating at 325 MHz. SSR0 (26 cavities), SSR1 (18 cavities) and SSR2 (44 cavities) have a geometrical beta of = 0.11, 0.21 and 0.4 respectively. Single spoke cavities were selected for the linac in virtue of their higher r/Q. In this paper we present the decisions and analyses that lead to the final designs. Electro-magnetic and mechanical finite element analyses were performed with the purpose of optimizing the electro-magnetic design, minimizing frequency shifts due to Helium bath pressure fluctuations and providing a pressure rating for the resonators that allow their use in the cryomodules.

TUP085	Assumptions for the RF Losses in the 650 MHz Cavities of the Project X Linac	cavity, niobium, factory, target	985
	A. Romanenko, L.D. Cooley, J.P. Ozelis, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	The requirements for the FNAL Project X cryogenic system depend on the dynamic heat loads of 650 MHz cavities. The heat load is in turn determined by quality factors of the cavities at the operating gradient. In this contribution we use the available experimental data to analyze quality factors achievable in 650 MHz linac cavities taking into account different RF losses contributions such as BCS resistance, residual resistance and a medium field Q-slope.

TUP086	Microphonics control for Project X	cavity, controls, cryomodule, SRF	988
	W. Schappert, S. Barbanotti, J. Branlard, G.I. Cancelo, R.H. Carcagno, M.S. Champion, B. Chase, I.G. Gonin, A.L. Klebaner, D.F. Orris, T.J. Peterson, Y.M. Pischalnikov, L. Ristori, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Funding: Work is supported by the U.S. Department of Energy The proposed multi-MW Project X facility at Fermilab will employ cavities with bandwidths as narrow as 20 Hz. This combination of high RF power with narrow bandwidths combined requires careful attention to detuning control if these cavities are to be operated successfully. Detuning control for Projects X will require a coordinated effort between the groups responsible for various machine subsystems. Considerable progress in this area has been made over the past year.

TUP088	Resonance Effects of Longitudinal HOMs in Project X Linac	HOM, cavity, resonance, kaon	991
	V.P. Yakovlev, I.G. Gonin, T.N. Khabiboulline, A. Lunin, N. Solyak, A.I. Sukhanov, A. Vostrikov Fermilab, Batavia, USA A. Saini University of Delhi, Delhi, India
	High-order mode influence on the beam longitudinal and transverse dynamics is considered for the 650 MHz section of the Project X linac. RF losses caused by HOMs are analyzed. Necessity of HOM dampers in the SC cavities of the linac is discussed.

TUP089	Concept EM Design of the 650 MHz Cavities for the Project X	cavity, HOM, cryomodule, resonance	994
	V.P. Yakovlev, M.S. Champion, I.G. Gonin, T.N. Khabiboulline, A. Lunin, N. Solyak Fermilab, Batavia, USA A. Saini University of Delhi, Delhi, India
	Concept of the 650 MHz cavities for the Project X is presented. Choice of the basic parameters, i.e, number of cells, geometrical β, apertures, coupling coefficients, etc, is discussed. The cavities optimization criteria are formulated. Results of the RF design are presented for the cavities of both low-energy and high energy sections.

TUP090	Design of a β = 0.29 Half-wave Resonator for the FRIB Driver Linac	cavity, simulation, cryomodule, ion	997
	J.P. Holzbauer, W. Hartung, J. Popielarski NSCL, East Lansing, Michigan, USA
	The driver linac for the Facility for Rare Isotope Beams will produce primary beams of ions at 200 MeV per nucleon for nuclear physics research. The driver linac will require 344 superconducting cavities, consisting of two types of Quarter-Wave Resonators (QWRs, β = 0.041 and 0.085) and two types of Half-Wave Resonators (HWRs, β = 0.29 and 0.53). A first-generation β = 0.29 HWR has been designed, prototyped, and tested. Second-generation versions of the other cavities are being developed, with one or more prototype having been tested. A second-generation β = 0.29 HWR design has been developed, making use of the experience with the first-generation β = 0.29 HWR and second-generation β = 0.53 HWR. In the second-generation design, the inner conductor is tapered to reduce the peak surface magnetic field. The outer conductor is a straight tube to increase the mechanical stiffness and reduce the sensitivity of the resonant frequency to bath pressure fluctuations. Optimization was employed to minimize the peak surface electric field. The second-generation β = 0.29 HWR design will be presented, including the RF design and mechanical analysis.

TUP091	Electromagnetic Design of a Multi-harmonic Buncher for the FRIB Driver Linac	ion, rfq, vacuum, coupling	1000
	J.P. Holzbauer, W. Hartung, F. Marti, Q. Zhao NSCL, East Lansing, Michigan, USA E. Pozdeyev FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy under Grant Number DE-FGO2-08ER41553. The driver linac for the Facility for Rare Isotope Beams (FRIB) at MSU will produce primary beams of ions at ≥200 MeV/u for nuclear physics research. A dc ion beam from an ECR ion source will be pre-bunched upstream of the radio frequency quadrupole linac. A multi-harmonic buncher (MHB) was designed for this purpose, using experience gained with a similar buncher for the ReA3 re-accelerator linac, which is presently being commissioned at MSU. The FRIB MHB resonator operates with three frequencies (40.25 MHz, 80.5 MHz, and 120.75 MHz) to produce an approximately linear sawtooth in the voltage as a function of time. The three resonant frequencies are produced via two quarter-wave resonators with a common gridless gap: one resonator is driven at its fundamental mode at 40.25 MHz and its first higher-order mode (120.75 MHz), while the other is driven only at its fundamental mode of 80.5 MHz. The electromagnetic design of the MHB resonator will be presented, including the electrode design and tuning mechanisms.

TUP092	Multi-purpose 805 MHz Pillbox RF Cavity for Muon Acceleration Studies	cavity, vacuum, coupling, acceleration	1003
	G.M. Kazakevich, G. Flanagan, R.P. Johnson, M.L. Neubauer, R. Sah Muons, Inc, Batavia, USA K.C.D. Chan, A.J. Jason, S.S. Kurennoy, H.M. Miyadera, P.J. Turchi LANL, Los Alamos, New Mexico, USA A. Moretti, M. Popovic, K. Yonehara Fermilab, Batavia, USA Y. Torun IIT, Chicago, Illinois, USA
	Funding: Supported by DOE grant DE-FG-08ER86352. An 805 MHz RF pillbox cavity has been designed and constructed to investigate potential muon beam acceleration and cooling techniques. The cavity can operate in vacuum or under pressure to 100 atmospheres, at room temperature or in an LN2 bath at 77 K. The cavity is designed for easy assembly and disassembly with bolted construction using aluminum seals. The surfaces of the end walls of the cavity can be replaced with different materials such as copper, aluminum, beryllium, or molybdenum, and with different geometries such as shaped windows or grid structures. Different surface treatments such as electro polished, high-pressure water cleaned, and atomic layer deposition are being considered for testing. The cavity has been designed to fit inside the 5-Tesla solenoid in the MuCool Test Area at Fermilab. Performance of the cavity, including initial conditioning and operation in the external magnetic field will be reported.

TUP100	Design of Superconducting Spoke Cavities for High-velocity Applications	cavity, HOM, superconductivity, higher-order-mode	1024
	J.R. Delayen, S.U. De Silva, C.S. Hopper ODU, Norfolk, Virginia, USA J.R. Delayen JLAB, Newport News, Virginia, USA
	Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β=0.8 and β=1.

TUP109	Fabrication, Treatment and Testing of a 1.6 Cell Photo-injector Cavity for HZB	cavity, electron, cathode, vacuum	1047
	P. Kneisel JLAB, Newport News, Virginia, USA T. Kamps, J. Knobloch, O. Kugeler, A. Neumann HZB, Berlin, Germany R. Nietubyc The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany
	Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.. As part of a CRADA (Cooperative Research and Development Agreement) between Forschungszentrum Dresden (FZD) and JLab we have fabricated and tested after appropriate surface treatment a 1.5 cell, 1300 MHz RRR niobium photo-injector cavity to be used in a demonstration test at BESSY. Following a baseline test at JLab, the cavity received a lead spot coating of ~8 mm diameter deposited with a cathode arc at the Soltan Institute on the endplate made from large grain niobium. It had been demonstrated in earlier tests with a DESY built 1.5 cell cavity – the original design – that a lead spot of this size can be a good electron source, when irradiated with a laser light of 213 nm . In the initial test with the lead spot we could measure a peak surface electric field of ~ 29 MV/m; after a second surface treatment, carried out to improve the cavity performance, but which was not done with sufficient precaution, the lead spot was destroyed and the cavity had to be coated a second time. This contribution reports about the experiences and results obtained with this cavity. A. Neumann et al., “CW Superconducting RF Photoinjector Development for Energy Recovery Linacs”, LINAC10, September 13-17, 2010, Tsukuba, Japan.

TUP117	Solid State Direct Drive RF LINAC: High Power Experimental Program	cavity, impedance, controls, high-voltage	1056
	T.J.S. Hughes, M. Back, R. Fleck, M. Hergt, R. Irsigler, T. Kluge, J. Sirtl Siemens AG, Erlangen, Germany O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
	We report on a 150MHz λ/4 coaxial resonator driven by 32 integrated class F RF power modules according to our direct drive concept [1,2]. Electric fields of 60MV/m at the resonator gap have been reached, which correspond to 80kW RF power. This power level has been achieved at 160V DC supply voltage, significantly less than the component limits. The observed power and Q values can be explained by a simple equivalent circuit. The model predicts that 64 modules at 160V DC supply voltage may provide 170kW RF power, and that 250V DC supply voltage should yield 400kW. The corresponding 134MV/m gap E field may not be reachable due to vacuum flashover. * Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA * Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan

TUP130	Experiments on Voltage Droop Compensation for High Power Marx Modulators	controls, high-voltage, factory, simulation	1076
	P. Chen, M. Lundquist, D. Yu DULY Research Inc., Rancho Palos Verdes, California, USA
	Funding: Work supported by DOE SBIR Phase II grant DE-FG02-08ER85052 Marx modulators, promising higher efficiency, longer lifetime and reduced cost compared with existing hard tube modulator options, are under intensive research. In this article, we describe the progress of work on our voltage droop compensation scheme for a Marx modulator. Experimental results on a compensation circuit at moderate voltage are presented.

TUP132	50 MW X-Band RF System for a Photoinjector Test Station at LLNL	klystron, electron, high-voltage, emittance	1082
	T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office. In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.

TUP135	RF Design and Operating Results for a New 201.25 MHz RF Power Amplifier for LANSCE	cathode, DTL, coupling, cavity	1091
	J.T.M. Lyles, N.K. Bultman, Z. Chen, J. Davis, A.C. Naranjo, D. Rees, G. M. Sandoval, Jr. LANL, Los Alamos, New Mexico, USA D. Baca, R.E. Bratton, R.D. Summers Compa Industries, Inc., Los Alamos, New Mexico, USA N.W. Brennan Texas A&M University, College Station, Texas, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396 A prototype VHF RF Final Power Amplifier (FPA) for Los Alamos Neutron Science Center (LANSCE) has been designed, fabricated, and tested. The cavity amplifier met the design goals producing 3.2 MW peak and 480 kW of average power, at an elevation of 2.1 km. It was designed to use a Thales TH628 Diacrode®, a state-of-art tetrode power tube that is double-ended, providing roughly twice the power of a conventional tetrode. The amplifier is designed with tunable input and output transmission line cavity circuits, a grid decoupling circuit, an adjustable output coupler, TE mode suppressors, blocking, bypassing and decoupling capacitors, and a cooling system. The tube is connected in a full wavelength output circuit, with the lower main tuner situated ¾λ from the central electron beam region in the tube and the upper slave tuner ¼λ from the same point. We summarize the design processes and features of the FPA along with significant test results. A pair of production amplifiers are planned to be power-combined and installed at the LANSCE DTL to return operation to full beam duty factor.

TUP148	Ion Trapping Study in eRHIC	ion, electron, accumulation, cavity	1109
	Y. Hao, V. Litvinenko, V. Ptitsyn BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The ion trapping effect is an important effect in energy recovery linac (ERL). The ionized residue gas molecules can accumulate at the vicinity of the electron beam pass and deteriorate the quality of the electron beam. In this paper, we present simulation results to address this issue in eRHIC and find best beam pattern to eliminate this effect.

TUP163	Design Construction and Test Results of a HTS Solenoid for Energy Recovery Linac	solenoid, cavity, focusing, superconducting-cavity	1127
	R.C. Gupta, M. Anerella, I. Ben-Zvi, G. Ganetis, D. Kayran, G.T. McIntyre, J.F. Muratore, S.R. Plate, W. Sampson BNL, Upton, Long Island, New York, USA M.D. Cole, D. Holmes AES, Medford, NY, USA
	Funding: This work is supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886. An innovative feature of the proposed Energy Recovery Linac (ERL) at Brookhaven National Laboratory (BNL) is the use of a solenoid made with High Temperature Superconductor (HTS) with the Superconducting RF cavity. The use of HTS in the solenoid offers many advantages. The solenoid is located in the transition region (4 K to room temperature) where the temperature is too high for a conventional low temperature superconductor and the heat load on the cryogenic system too high for copper coils. Proximity to the cavity provides early focusing and thus a reduction in the emittance of the electron beam. In addition, taking full advantage of the high critical temperature of HTS, the solenoid has been designed to reach the required field at ~77 K, which can be obtained with liquid nitrogen. This significantly reduces the cost of testing and allows a variety of critical pre‐tests (e.g. measurements of the axial and fringe fields) which would have been very expensive at 4 K in liquid helium because of the additional requirements for a cryostat and associated facilities. This paper will present the design, construction, test results and current status of this HTS solenoid.

TUP202	Non-Scaling FFAG Proton Driver for Project X	proton, injection, focusing, synchrotron	1199
	C. Johnstone, D.V. Neuffer Fermilab, Batavia, USA M. Berz, K. Makino MSU, East Lansing, Michigan, USA L.J. Jenner, J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom P. Snopok IIT, Chicago, Illinois, USA
	The next generation of high-energy physics experiments requires high intensity protons at multi-GeV energies. Fermilab’s HEP program, for example, requires an 8-GeV proton source to feed the Main Injector to create a 2 MW neutrino beams in the near term and would require a 4 MW pulsed proton beam for a potential Neutrino Factory or Muon Collider in the future. High intensity GeV proton drivers are difficult at best with conventional re-circulating accelerators, encountering duty cycle and space-charge limits in the synchrotron and machine size and stability concerns in the weaker-focusing cyclotrons. Only an SRF linac, which has the highest associated cost and footprint, has been considered. Recent innovations in FFAG design, however, have promoted another re-circulating candidate, the Fixed-field Alternating Gradient accelerator (FFAG), as an attractive, but as yet unexplored, alternative. Its strong focusing optics coupled to large transverse and longitudinal acceptances would serve to alleviate space charge effects and achieve higher bunch charges than possible in a synchrotron and presents an upgradeable option from the 2 MW to the 4 MW program.

TUP267	LANSCE Drift Tube Linac Water Control System Refurbishment	controls, EPICS, drift-tube-linac, monitoring	1319
	P.S. Marroquin, J.D. Bernardin, J.G. Gioia, J.A. Ortiz LANL, Los Alamos, New Mexico, USA
	Funding: Funding Agency: Work performed under the auspices of the U.S. Department of Energy, under contract DE-AC52-06NA25396. There are several refurbishment projects underway at the Los Alamos National Laboratory LANSCE linear accelerator. Systems involved are: RF, water cooling, networks, diagnostics, timing, controls, etc. The Drift Tube Linac (DTL) portion of the accelerator consists of four DTL tanks, each with three independent water control systems. The systems are about 40 years old, use outdated and non-replaceable equipment and NIM bin control modules, are beyond their design life and provide unstable temperature control. Insufficient instrumentation and documentation further complicate efforts at maintaining system performance. Detailed design of the replacement cooling systems is currently in progress. Previous design experience on the SNS accelerator water cooling systems will be leveraged. Plans call for replacement of water piping, manifolds, pumps, valves, mix tanks, instrumentation (flow, pressure and temperature) and control system hardware and software. This presentation will focus on the control system design with specific attention on planned use of the National Instruments Compact RIO platform with the Experimental Physics and Industrial Control System (EPICS) software toolkit.

TUP272	Analysis and Comparison to Test of AlMg3 Seals Near a SRF Cavity	cavity, niobium, SRF, cryomodule	1331
	T. Schultheiss, C.M. Astefanous, M.D. Cole, D. Holmes, J. Rathke AES, Medford, NY, USA I. Ben-Zvi, D. Kayran, G.T. McIntyre, B. Sheehy, R. Than BNL, Upton, Long Island, New York, USA A. Burrill JLAB, Newport News, Virginia, USA
	The Energy Recovery Linac (ERL) presently under construction at Brookhaven National Laboratory is being developed as research and development towards eRHIC, an Electron-Heavy Ion Collider. The experimental 5-cell 703.75 MHz (ECX) cavity was recently evaluated at continuous field levels greater than 10 MV/m. These tests indicated stored energy limits of the cavity on the order of 75 joules. During design of the cavity the cold flange on one side was moved closer to the cavity to allow the cavity to fit into the available chemical processing chamber at Jefferson Laboratory. RF and thermal analysis of the AlMg3 seal region of the closer side indicate this to be the prime candidate limiting the fields. This work presents the analysis results and compares these results to test data.

TUP273	RF Thermal and Structural Analysis of the 60.625 MHz RFQ for the ATLAS Upgrade	rfq, cavity, gun, ion	1334
	T. Schultheiss, J. Rathke AES, Medford, NY, USA A. Barcikowski, P.N. Ostroumov ANL, Argonne, USA D.L. Schrage TechSource, Santa Fe, New Mexico, USA
	Funding: This work was supported by Argonne National Lab under contract # 0F-32402 The upgrade for the ATLAS facility is designed to increase the efficiency and intensity of beams for the user facility, . This will be accomplished with a new CW normal conducting RFQ, which will increase both transverse and longitudinal acceptance of the LINAC. This RFQ must operate over a wide range of power levels to accelerate ion species from protons to uranium. The RFQ design is a split coaxial structure and is made of OFE copper. The geometry of the design must be stable during operation. Engineering studies of the design at different RF power levels were conducted to ensure that the geometry requirements were met. Frequency shift analysis was also completed to determine the effects of high power levels. Thermal stress analysis was completed to show that the structure frequency is repeatable. P.N. Ostroumov, et.al, “A New Atlas Efficiency and Intensity Upgrade Project,” SRF2009, tuppo016 **P.N. Ostroumov, et.al., “Efficiency and Intensity Upgrade of the Atlas Facility,” LINAC 2010, MOP045

TUP275	SNS Linac Modulator Operational History and Performance	neutron, high-voltage, klystron, monitoring	1340
	V.V. Peplov, D.E. Anderson, R.I. Cutler, M. Wezensky ORNL, Oak Ridge, Tennessee, USA J.D. Hicks, R.B. Saethre ORNL RAD, Oak Ridge, Tennessee, USA
	Fourteen High Voltage Converter Modulators (HVCM) were initially installed at the Spallation Neutron Source Linear Accelerator (SNS Linac) at the Oak Ridge National Laboratory in 2005. A fifteenth HVCM was added in 2009. Each modulator provides a pulse of up to 140 kV at a maximum width of 1.35 msec. Peak power level is 11 MW with an 8% duty factor. The HVCM system must be available for neutron production (NP) 24/7 with the exception being two, 6-week maintenance periods per year. HVCM reliability is one of the most important factors to maximize Linac availability and achieve SNS performance goals. During the last few years several modifications have been implemented to improve the overall system reliability. This paper presents operational history of the HVCM systems and examines failure mode statistical data since the modulators began operating at 60 Hz. System enhancements and upgrades aimed at providing long term reliable operation with minimal down time are also discussed in the paper.

TUP278	Tuning Method for the 2π/3 Traveling Wave Structures	coupling, controls, beam-loading, impedance	1349
	A.S. Setty THALES, Colombes, France
	To build a constant gradient traveling wave structure, one must perform cold tests under a press in order to tune the different cells individually. For the tests to be valid, the test cells must be terminated by shorting planes located in planes of symmetry in which the electric field vector is normal in such a way that the standing wave "trapped" between them is an exact representation of the instantaneous traveling wave one wishes to study. For the TW structure, the cavities are put three by three under the press. We then try to reduce the contribution of "mixed cells" by adding to one wavelength at 2π/3 mode two-quarter wavelengths. This is possible when the end-cells mode at the same frequency is π/2 instead of 2π/3. These end cells are not included in the final assembly. The setting process will be analysed.

TUP279	A CW RFQ Prototype	rfq, simulation, dipole, vacuum	1352
	U. Bartz, A. Schempp IAP, Frankfurt am Main, Germany
	A short RFQ prototype was built for tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The RF-tests with continues power of 20 kW/m and simulations of thermal effects with ALGOR were finished successfully. Optimization of some details of the facility are on focus now. First results and the status of the project will be presented.

TUP293	ESTB: A New Beam Test Facility at SLAC	kicker, hadron, electron, emittance	1373
	M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, D.R. Walz, S.P. Weathersby, M. Woods SLAC, Menlo Park, California, USA
	End Station Test Beam (ESTB) is an end beam line at SLAC using a small fraction of the 13.6 GeV electron beam from the Linac Coherent Light Source (LCLS), restoring test beam capabilities in the large End Station A (ESA) experimental hall. In the past, 18 institutions participated in the ESA program at SLAC. The ESTB program will provide one of a kind test beams essential for developing accelerator instrumentation and accelerator R&D, performing particle and astroparticle physics detector research, linear collider machine and detector interface (MDI) R&D, developing of radiation-hard detectors and material damage studies with several distinctive features. At this stage, 4 new kicker magnets are added to divert 5 Hz of LCLS beam to the A-line, a new beam dump is installed and a new PPS system is built in ESA. In a second stage, a secondary hadron target will be installed, able to produce pions up to about 12 GeV/c at 1 particle/pulse. In summary, ESTB provides a new test facility for LHC detector upgrades, Super B Factory detector development, and Linear Collider accelerator and detector R&D with the first beam expected by June and users starting operations by July 2011.

WEOBS4	Improved Energy Changes at the Linac Coherent Light Source	feedback, electron, lattice, photon	1424
	N. Lipkowitz, H. Loos, C.R. Melton, G. Yocky SLAC, Menlo Park, California, USA
	The user requirements and beam time scheduling of the LCLS imposes a demand for fast changes in machine energy across the entire operating range of 3.3-15 GeV (480-10000 eV). Early operational experience during LCLS commissioning revealed this process to be problematic and error-prone, sometimes requiring substantial re-tuning at each change. To streamline the process, a software tool has been developed to gradually ramp the machine energy while the beam remains on, allowing beam-based feedbacks to continue to work during the energy change. The tool has considerably improved the speed and reliability of configuration changes, and also extends the capability of the LCLS, allowing for slow scans of the FEL photon energy over a wide range. This poster presents the basic process, analysis of the performance gains, and possible future improvements.
	Slides WEOBS4 [62.503 MB]

WEOBS6	Status and Specifications of a Project X Front-End Accelerator Test Facility at Fermilab	cavity, rfq, ion-source, proton	1430
	J. Steimel, R.L. Madrak, R.J. Pasquinelli, E. Peoples-Evans, R.C. Webber, D. Wildman Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. This paper describes the construction and operational status of an accelerator test facility for Project X. The purpose of this facility is for Project X component development activities that benefit from beam tests and any development activities that require 325 MHz or 650 MHz RF power. It presently includes an H^- beam line, a 325 MHz superconducting cavity test facility, a 325 MHz (pulsed) RF power source, and a 650 MHz (CW) RF power source. The paper also discusses some specific Project X components that will be tested in the facility.
	Slides WEOBS6 [2.401 MB]

WEOCN1	Laser Based Diagnostics for Measuring H^- Beam Parameters	laser, diagnostics, ion, emittance	1433
	Y. Liu, A.V. Aleksandrov, W. Blokland, C. Deibele, C.D. Long, A.A. Menshov, J. Pogge, A. Webster, A.P. Zhukov ORNL, Oak Ridge, Tennessee, USA R.A. Hardin ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: sponsored by the Division of Materials Science, U.S. Department of Energy, under contract number DE-AC05-96OR22464 with UT-Battelle Corporation for Oak Ridge National Laboratory In recent years, a number of laser based H^- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser transverse emittance scanner at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of laser based diagnostics at accelerator facilities will be addressed.
	Slides WEOCN1 [4.710 MB]

WEOCN4	Electron Beam Diagnostics of the JLab UV FEL	FEL, wiggler, electron, cavity	1446
	P. Evtushenko, S.V. Benson, G.H. Biallas, J.L. Coleman, C. Dickover, D. Douglas, M. Marchlik, D.W. Sexton, C. Tennant JLAB, Newport News, Virginia, USA
	In this contribution we describe various systems of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line of existing 10kW IR Upgrade FEL. Here we describe a set of the following systems. A combination of OTR and phosphor viewers used for measurements of a transverse beam profile, transverse emittance, Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurements system is used to setup bunch compression in an optimal way such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of the diagnostics system made its contribution to achieve the first lasing of the FEL after about 60 hours of beam operation.
	Slides WEOCN4 [8.864 MB]

WEOCS6	The Injector Cryomodule for e-Linac at TRIUMF	cryomodule, ISAC, TRIUMF, cavity	1469
	R.E. Laxdal, C.D. Beard, S.R. Koscielniak, A. Koveshnikov, A.K. Mitra, T.C. Ries, I. Sekachev, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada M. Mondal, V. Naik DAE/VECC, Calcutta, India
	The e-Linac project at TRIUMF, now funded, is specified to accelerate 10mA of electrons to 50MeV using 1.3GHz multi-cell superconducting cavities. The linac consists of three cryomodules; an injector cryomodule with one cavity and two accelerating modules with two cavities each. The injector module is being designed and constructed in collaboration with VECC in Kolkata. The design utilizes a unique box cryomodule with a top-loading cold mass. A 4K phase separator, 2K-4K heat exchanger and Joule-Thompson valve are installed within each module to produce 2K liquid. The design and status of the development will be presented.
	Slides WEOCS6 [13.002 MB]

WEODS1	Design and Optimization of Future X-ray FELs based on Advanced High Frequency Linacs	impedance, klystron, FEL, acceleration	1491
	F. Wang SLAC, Menlo Park, California, USA
	To drive future XFELs, normal-conducting linacs at various rf freqencies are being considered. With optimized accelerator structures and rf systems, a higher rf frequency linac has several advantages, such as high acceleration gradient and high rf-to-beam efficiency. This paper presents a comparison of possible S-band, C-band and X-band linac designs for two cases, single bunch operation and multibunch operation, where the bunch train length is longer than the structure fill time and the beam loading is small. General scaling laws for the main linac parameters, which can be useful in the design such linacs, are derived.
	Slides WEODS1 [5.795 MB]

WEP006	Study of Effects of Failure of Beamline Elements & Their Compensation in CW Superconducting Linac	cavity, solenoid, emittance, beam-losses	1513
	A. Saini, K. Ranjan University of Delhi, Delhi, India C.S. Mishra, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Project-X is the proposed high intensity proton facility to be built at Fermilab, US. The first stage of the Project-X consists of superconducting Linac which will be operated in continuous wave (CW) mode to accelerate the beam from 2.5 MeV to 3 GeV. The operation at CW mode puts high tolerances on the beam line components, particularly on radiofrequency (RF) cavity. The failure of beam line elements at low energy is very critical as it results in mis-match of the beam with the following sections due to different beam parameters than designed parameter. It makes the beam unstable which causes emittance dilution, and ultimately results in beam losses. In worst case, it could affect the reliability of the machine and may lead to the shutdown of the Linac to replace the failed elements. Thus, it is important to study these effects and their compensation to get smooth beam propagation in Linac. This paper describes the results of study performed for the failure of RF cavity & solenoid in SSR0 section.

WEP007	Calculation of Acceptance of High Intensity Superconducting Proton Linac for Project-X	cavity, lattice, focusing, proton	1516
	A. Saini, K. Ranjan University of Delhi, Delhi, India C.S. Mishra, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	Project-X is the proposed high intensity proton facility to be built at Fermilab, US. Its Superconducting Linac, to be used at first stage of acceleration, will be operated in continuous wave (CW) mode. The Linac is divided into three sections on the basis of operating frequencies & six sections on the basis of family of RF cavities to be used for the acceleration of beam from 2.5 MeV to 3 GeV. The transition from one section to another can limit the acceptance of the Linac if these are not matched properly. We performed a study to calculate the acceptance of the Linac in both longitudinal and transverse plane. Investigation of most sensitive area which limits longitudinal acceptance and study of influence of failure of beam line elements at critical position, on acceptance are also performed.

WEP010	Design of the Bilbao Accelerator Low Energy Extraction Lines	quadrupole, dipole, DTL, neutron	1519
	Z. Izaola, I. Rodríguez ESS-Bilbao, Zamudio, Spain E. Abad, I. Bustinduy, R. Martinez, F. Sordo Balbin, D. de Cos ESS Bilbao, Bilbao, Spain D.J. Adams, S.J.S. Jago STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom F.J. Bermejo Bilbao, Faculty of Science and Technology, Bilbao, Spain V. Etxebarria, J. Portilla University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	Funding: European Spallation Source - Bilbao The ESS-Bilbao linac will accelerate H+ and H− beams up to 50 MeV, which need to be transported to three laboratories, where different types of experiments will be conducted. This paper reports on the preliminary design of the transfer line, which is mainly performed based on beam dynamics simulations.

WEP041	Weak Resonances Induced by Nonlinear Multipoles in a Quadrupole Doublet Lattice	octupole, quadrupole, lattice, simulation	1570
	Y. Zhang, J. G. Wang ORNL, Oak Ridge, Tennessee, USA
	Funding: This submission was sponsored by a contractor of the United States Government under contract DE-AC05-00OR22725 with the United States Department of Energy. In this paper we report the effects on beam dynamics from two intrinsic multipole components of a quadrupole magnet – dodecapole and psedu-octupole, in a quadrupole doublet lattice. Weak resonances at transverse phase advances 60°; and 90°; per cell, which may contribute to halo formation and beam loss in a linac, are shown from multi-particle tracking simulations. Although the net effect of the psedu-octupole component alone is very small due to substantial cancellations within the same magnet, its existence may significantly enhance the weak resonances which are induced by the dodecapole component of quadrupole magnets. The combined contributions of these two magnetic field components may not be simply linear-scaled because of the extreme nonlinear nature.

WEP048	Comparison of RF Cavity Transport Models for BBU Simulations	cavity, focusing, simulation, optics	1582
	I. Shin University of Connecticut, Storrs, Connecticut, USA S. Ahmed, T. Satogata, B.C. Yunn JLAB, Newport News, Virginia, USA
	The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will cause BBU simulation results to be better matched with analytic calculations and experimental results.

WEP085	Beam Breakup Studies for New Cryo-Unit	HOM, simulation, cavity, damping	1633
	S. Ahmed, F.E. Hannon, A.S. Hofler, R. Kazimi, G.A. Krafft, F. Marhauser, B.C. Yunn JLAB, Newport News, Virginia, USA I. Shin University of Connecticut, Storrs, Connecticut, USA
	In this paper, we report the numerical simulations of cumulative beam breakup studies for a new cryo-unit for injector design at Jefferson lab. The system consists of two 1-cell and one 7-cell superconducting RF cavities. The study has been performed using a 2-dimensional time-domain code TDBBU developed in-house. The stability has been confirmed for the present setup of beamline elements with different initial offsets and currents ranging 1 mA - 100 mA.

WEP091	Implementation of H⁻ Intrabeam Stripping into TRACK	simulation, ion, beam-losses, proton	1642
	J.-P. Carneiro Fermilab, Batavia, USA B. Mustapha, P.N. Ostroumov ANL, Argonne, USA
	H⁻ intrabeam stripping has been presented* as potentially harmful to MW scale H⁻ linacs. If not taken properly into account, intrabeam stripping of the H⁻ beam could lead to losses in excess of the 1 W/m limit and result in non-tolerable beamline elements activation. This paper describes the implementation of the H⁻ intrabeam stripping effect into the beam dynamics code TRACK*. Simulations results and numerical applications will be presented for the SNS linac and the FNAL ProjectX. V. Lebedev, "Intrabeam Stripping in H⁻ Linacs", LINAC2010 ** P. Ostroumov, "TRACK, The Beam Dynamics Code", PAC2005

WEP095	Analysis of the Beam Loss Mechanism in the Project-X Linac	solenoid, quadrupole, beam-losses, simulation	1651
	N. Solyak, J.-P. Carneiro, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy Fermilab, Batavia, USA
	Minimization of the beam losses in a multi-MW H-minus linac of the Project X to the level below 1W/m is a challenging task. Analysis of different mechanisms of beam stripping, including stripping in electric and magnetic fields, residual gas, black-body radiation and intra-beam stripping, is analyzed. Other sources of beam losses are misalignment of beamline elements and errors in RF fields and phase. We presented the requirements for dynamics errors and correction schemes to keep beam losses under control

WEP100	Energy Spread Compensation for Multi-Bunch Linac Operation Mode	electron, wakefield, cavity, simulation	1662
	D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA W. Gai, J.G. Power ANL, Argonne, USA
	Funding: This work was supported under the U.S. Department of Energy contract number: DE-AC02-06CH11357 with Argonne National Laboratory. Higher wakefield gradients can be achieved by increasing the total beam charge which is passed through a dielectric-loaded structure and by reducing the transverse size of the beam. Currently, the Argonne AWA photoinjector operates with electron bunches of up to 100 nC and the goal is to raise the total beam charge to about 1000 nC and to improve the beam focusing to a few 100's microns transverse spot size. The increase of the beam charge can be done by superimposing electron bunches that fill up several consecutive RF buckets. Although the energy stored in a single 7-cell linac is by design large the multi-bunch operation with short bunch trains (~10 ns) is still plagued by large energy spread due to significant beam loading effects. In this paper we present a technique intended to reduce the energy spread for a high charge bunch train by properly choosing the time delay between consecutive bunches. The simulations show that the energy spread can be lowered to about 2.8% from about 6.0% for a 10-bunch train of total charge 1000 nC and kinetic energy of about 70 MeV.

WEP107	CSR Shielding Experiment	wakefield, shielding, dipole, electron	1677
	V. Yakimenko, A.V. Fedotov, M.G. Fedurin, D. Kayran BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA P. Muggli USC, Los Angeles, California, USA
	It is well known that the emission of coherent synchrotron radiation (CSR) in a dipole magnets leads to increase in beam energy spread and emittance. At the Brookhaven National Laboratory Accelerator Test Facility (ATF) we study the suppression of CSR emission affect on electron beam in a dipole magnet by two vertically spaced conducting plates. The gap between the plates is controlled by four actuators and could be varied from 0 to 14 mm. Our experimental results show that closing the plates significantly reduces both the beam energy loss and CSR-induced beam energy spread. In this paper we present selected results of the experiment and compare then with rigorous analytical theory.

WEP115	The FNAL Injector Upgrade	rfq, extraction, quadrupole, DTL	1701
	C.-Y. Tan, D.S. Bollinger, K.L. Duel, J.R. Lackey, W. Pellico Fermilab, Batavia, USA
	The present FNAL linac H⁻ injector has been operational since the 1970s and consists of two magnetron H⁻ sources and a 750keV Cockcroft-Walton Accelerator. In the upgrade, both slit-type magnetron sources will be replaced with circular aperture sources, and the Cockcroft-Walton with a 200MHz RFQ. Operational experience at BNL (Brookhaven National Laboratory) has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.

WEP131	A New Approach to Calculate the Transport Matrix in RF cavities	cavity, acceleration, focusing, space-charge	1725
	Y.I. Eidelman BINP SB RAS, Novosibirsk, Russia N.V. Mokhov, S. Nagaitsev, N. Solyak Fermilab, Batavia, USA
	Funding: Work supported by USDoE A realistic approach to calculate the transport matrix in RF cavities is developed. It is based on joint solution of equations of longitudinal and transverse motion of a charged particle in an electromagnetic field of the linac. This field is a given by distribution (measured or calculated) of the component of the longitudinal electric field on the axis of the linac. New approach is compared with other matrix methods to solve the same problem. The comparison with code ASTRA has been carried out. Complete agreement for tracking results for a TESLA-type cavity is achieved. A corresponding algorithm has been implemented into the MARS15 code.

WEP149	Beam Measurement by a Wall Gap Monitor in ALPHA	dipole, electron, extraction, injection	1761
	T.H. Luo, P.D. McChesney, P.E. Sokol IUCF, Bloomington, Indiana, USA S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	In this report, we present our electron beam measurements with a wall gap monitor (WGM) in ALPHA injection and extraction beam lines. The WGM is first bench mark tested, and then installed in the ALPHA injection line to measure both the macro andμpulse of the injected beam and calibrate the beam current. By scanning the bending magnet before the WGM, and applying a demodulation signal processing scheme, we measured the tomography of the longitudinal phase space of the injected beam. We moved the WGM to extraction beam line and measured the properties of the extracted beam. By comparing the frequency spectrum of injected and extracted beam, we have confirmed the debunching performance of ALPHA.

WEP174	Simulations and Calculations of Cavity-to-cavity Coupling for Elliptical SCRF Cavities in ESS	cavity, coupling, simulation, cryomodule	1813
	R. Ainsworth, S. Molloy Royal Holloway, University of London, Surrey, United Kingdom
	The proton linac of the European Spallation Source (ESS) will rely on two families of superconducting cavities for the medium and high beta regions. Presented here are simulations of various cavity designs for different betas. The simulations are performed using the ACE3P codes developed at SLAC National Accelerator Laboratory, and the simulated eigenmode and R/Q spectrum will be shown for each design. Dangerous modes are identified. Of particular importance is the investigations of multiple cavity (cryomodule) configurations. From this, the simulated cavity-to-cavity coupling within a cryomodule is extracted. A theoretical model of this coupling based on the calculated cutoff frequencies, decay lengths, and resonance conditions, has also been developed, and a comparison made with the results of the simulation.

WEP192	Simulation Results for a Cavity BPM Design for the APS Storage Ring	cavity, simulation, storage-ring, damping	1849
	X. Sun, G. Decker ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A rectangular cavity BPM / tilt monitor for the APS storage ring has been designed to detect residual vertical-longitudinal tilt caused by the proposed short-pulse x-ray (SPX) project crab cavities. Electromagnetic simulations have been performed to verify the conceptual design and evaluate design alternatives. MAFIA and Microwave Studio have been applied to simulate the device in both time and frequency domains. The device geometry has been optimized to efficiently damp strongly driven lower- and higher-order modes while preserving the tilt-sensitive mode of interest. This mode is coupled out to the processing electronics using a waveguide geometry chosen to maximize isolation from the beam-driven modes.

WEP204	An FFAG Accelerator for Project X	proton, lattice, injection, dynamic-aperture	1867
	D.V. Neuffer, L.J. Jenner, C. Johnstone Fermilab, Batavia, USA J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	The next generation of high-energy physics experiments requires high intensity protons in the multi-GeV energy range for efficient production of secondary beams. The Fermilab long-term future requires an 8 GeV proton source to feed the Main Injector for a 2 MW neutrino beam source in the immediate future and to provide 4 MW pulsed proton beam for a future neutrino factory or muon collider. We note that a 3GeV cw linac matched to a 3–8 GeV FFAG ring could provide beam for both of these mission needs, as well as the cw 3 GeV experiments, and would be a natural and affordable scenario. We present details of possible scenarios and outline future design and research directions.

WEP212	Development of a 325 MHz 4-Rod RFQ	rfq, dipole, simulation, resonance	1888
	B. Koubek, U. Bartz, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany
	A 4-Rod RFQ with a frequency of 325 MHz and an output energy of 3 MeV will be build as a part of the FAIR project of GSI. Design studies and model measurements on a short prototype of a 325 MHz 4-Rod RFQ model were made including simulations using CST Microwave Studio. The latest simulation results regarding the dipole field of this structure are presented in this paper.

WEP213	New Development of a RFQ Beam Matching Section	rfq, emittance, ion-source, ion	1891
	M. Baschke, N. Müller, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany
	Funding: BMBF Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with electrostatic lens systems, a Two-Beam-RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ. A funneling deflector combines the bunches to a common beam axis. Current work is the construction and beam tests of a new beam transport system between RFQ accelerator and deflector. With extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefore unwanted emittance growth reduced. First rf-measurements with the improved Two-Beam-RFQ will be presented.

WEP214	Tuning Studies on 4-Rod RFQs	rfq, simulation, resonance, quadrupole	1894
	J.S. Schmidt, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	For the optimization of Radio Frequency Quadrupole (RFQ) design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic properties of an RFQ. A variation can lead to particle losses and reduced beam quality. Our electrode design usually implies a constant longitudinal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-Rod RFQ. Their optimal positions can be found by an iterative process. To structure this tuning process simulations with a NI LabVIEW based Tuning Software and CST Microwave ® are performed and compared to measurements of the ReA3-RFQ of the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The results of this studies are presented in this paper.

WEP220	Development of the Dual-Slot Resonance Linac	cavity, coupling, resonance, impedance	1897
	D.J. Newsham, N. Barov, R.H. Miller Far-Tech, Inc., San Diego, California, USA
	Funding: Work supported by DOE Office of High Energy Physics, DOE-SBIR #DE-FG02-08ER85034. We present the development of a novel electron accelerating structure with strong cell-to-cell coupling. The coupling is provided by a pair of resonant slots, separated by a non-resonant void region, located within the wall between adjacent cells. The 10+2/2 cell standing-wave structure, operating in a phase and amplitude stabilized pi/2 mode, will provide an energy gain of 10 MeV.

WEP221	CW Room-Temperature Bunching Cavity for the Project X MEBT	cavity, simulation, bunching, proton	1900
	G.V. Romanov, S. Barbanotti, E. Borissov, J.A. Coghill, I.G. Gonin, S. Kazakov, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	The Project-X, a multi-MW proton source based on superconducting linac, is under development at Fermilab. The front end of the linac contains a CW room temperature MEBT section which comprises ion source, RFQ and high-bandwidth bunch selective chopper. The length of the chopper exceeds 10 m, so four re-bunching cavities are used to support the beam longitudinal dynamics. The RF and mechanical designs of the re-bunching cavity including stress and thermal analysis are reported.

WEP224	Operational Status and Life Extension Plans for the Los Alamos Neutron Science Center (LANSCE)	neutron, proton, target, scattering	1906
	J.L. Erickson, D. Rees LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the U. S. Department of Energy, National Nuclear Security Administration, Contract No. DE-AC52-06NA25396 – Publication Release LA-UR- 10-06556 The Los Alamos Neutron Science Center (LANSCE) accelerator and beam delivery complex generates the proton beams that serve three neutron production sources, a proton radiography facility and a medical and research isotope production facility. The recent operating history of the facility, including both achievements and challenges, will be reviewed. Plans for performance improvement will be discussed, together with the underlying drivers for the ongoing LANSCE Linac Risk Mitigation project. The details of this latter project will be discussed. The status of accelerator-related plans for the MaRIE Project (Matter-Radiation Interactions in Extremes Experimental Project) will also be discussed. Taken together, the LANSCE Linac Risk Mitigation Project and the MaRIE initiative demonstrate a commitment to investment in the ongoing operation and improvement of the facility, and a resurgent interest in the spectrum of science accessible at LANSCE. These plans will assure continued facility operational and scientific vitality well beyond 2020.

WEP225	H-Mode Accelerating Structures with PMQ Focusing for Low-Beta Beams	focusing, simulation, ion, quadrupole	1909
	S.S. Kurennoy, J.F. O'Hara, E.R. Olivas, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	We report results of the project developing high-efficiency normal-conducting RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. The shunt impedance of IH-PMQ structures is 10^-20 times higher than that of a conventional drift-tube linac, while the transverse size is 4-5 times smaller. The H-PMQ accelerating structures following a short RFQ can be used both in the front end of ion linacs or in stand-alone applications. Results of the combined 3-D modeling – electromagnetic computations, beam-dynamics simulations with high currents, and thermal-stress analysis – for a full IH-PMQ accelerator tank are presented. The accelerating field profile in the tank is tuned to provide the best propagation of a 50-mA deuteron beam using coupled iterations of electromagnetic and beam-dynamics modeling. Multi-particle simulations with Parmela and CST Particle Studio have been used to confirm the design. Measurement results of a cold model of the IH-PMQ tank are in a good agreement with the calculations and will also be presented.

WEP242	Project X Functional Requirements Specification	proton, injection, collider, kaon	1936
	S.D. Holmes, S. Henderson, R.D. Kephart, J.S. Kerby, C.S. Mishra, S. Nagaitsev, R.S. Tschirhart Fermilab, Batavia, USA
	Funding: Work supported by the Fermi Research Alliance, under contract to the U.S. Department of Energy Project X is a multi-megawatt proton facility being designed to support intensity frontier research in elementary particle physics, with possible applications to nuclear physics and nuclear energy research, at Fermilab. A Functional Requirements Specification has been developed in order to establish performance criteria for the Project X complex in support of these multiple missions. This paper will describe the Functional Requirements for the Project X facility and the rationale for these requirements.

WEP249	Intense Muon Beams for Experiments at Project X	target, simulation, collider, proton	1951
	C.M. Ankenbrandt, R.P. Johnson, C. Y. Yoshikawa Muons, Inc, Batavia, USA V.S. Kashikhin, D.V. Neuffer Fermilab, Batavia, USA J. Miller BUphy, Boston, Massachusetts, USA R.A. Rimmer JLAB, Newport News, Virginia, USA
	Funding: Supported in part by DOE SBIR grant DE-SC00002739 A coherent approach for providing muon beams to several experiments for the intensity-frontier program at Project X is described. Concepts developed for the front end of a muon collider/neutrino factory facility, such as phase rotation and ionization cooling, are applied, but with significant differences. High-intensity experiments typically require high-duty-factor beams pulsed at a time interval commensurate with the muon lifetime. It is challenging to provide large RF voltages at high duty factor, especially in the presence of intense radiation and strong magnetic fields, which may preclude the use of superconducting RF cavities. As an alternative, cavities made of materials such as ultra-pure Al and Be, which become very good - but not super - conductors at cryogenic temperatures, can be used.

WEP261	Performance of the New EBIS Preinjector	ion, booster, injection, rfq	1966
	J.G. Alessi, E.N. Beebe, S. Binello, C.J. Gardner, O. Gould, L.T. Hoff, N.A. Kling, R.F. Lambiase, V. LoDestro, R. Lockey, M. Mapes, A. McNerney, J. Morris, M. Okamura, A. Pendzick, D. Phillips, A.I. Pikin, D. Raparia, J. Ritter, T.C. Shrey, L. Smart, L. Snydstrup, C. Theisen, M. Wilinski, A. Zaltsman, K. Zeno BNL, Upton, Long Island, New York, USA U. Ratzinger, A. Schempp IAP, Frankfurt am Main, Germany
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy, and by the National Aeronautics and Space Administration. The construction and initial commissioning phase of a new heavy ion preinjector was completed at Brookhaven in September, 2010, and the preinjector is now operational. This preinjector, using an EBIS source to produce high charge state heavy ions, provided helium and neon ion beams for use at the NASA Space Radiation Laboratory in the Fall of 2010, and gold and uranium beams are being commissioned during the 2011 run cycle for use in RHIC. The EBIS operates with an electron beam current of up to 10 A, to produce mA level currents in 10 to 40 μs beam pulses. The source is followed by an RFQ and IH linac to accelerate ions with q/m > 0.16 to an energy of 2 MeV/amu, for injection into the Booster synchrotron. The performance of the preinjector is presented, including initial operational experience for the NASA and RHIC programs.

WEP267	Estimates of the Number of Foil Hits for Charge Exchange Injection	injection, proton, ion, betatron	1975
	D. Raparia BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. For high intensity circular proton machines, one of the major limitations is the charge exchange injection foil. The number of foil hits due to circulating beam may cause the foil to fail and cause radiation due to multiple nuclear scattering and energy straggling. This paper will describe methods to estimate these quantities without going through lengthy simulations.

WEP268	Changes in LEBT/MEBT at the BNL 200 MeV Linac	polarization, solenoid, rfq, emittance	1978
	D. Raparia, J.G. Alessi, J.M. Fite, O. Gould, V. LoDestro, M. Okamura, J. Ritter, A. Zelenski BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. After reconfiguration of the low energy (35 keV) and the medium energy (750 keV) transport lines in 2009-10, the Brookhaven linac is now delivering the highest intensity beam since it was built in 1970 (~120 μA average current of H⁻ to the Brookhaven Linac Isotope Producer). It is also now delivering lower emittance polarized H⁻ ion beam for the polarized program at RHIC. To increase the intensity further, we are replacing the buncher in the 750 keV line with one with higher Q value, to allow operation at higher power. Also, to improve polarization, we are replacing the magnetic solenoid before the RFQ in the 35 keV line by a solenoid-einzel lens combination. The paper will report on the results of these changes.

WEP275	Highly-Persistent SNS H⁻ Source Fueling 1-MW Beams with 7-9 kC Service Cycles	plasma, ion, rfq, ion-source	1993
	M.P. Stockli, T.W. Hardek, Y.W. Kang, S.N. Murray, T.R. Pennisi, M.F. Piller, M. Santana, R.F. Welton ORNL, Oak Ridge, Tennessee, USA B. Han ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. Running routinely with ~40-mA, 1-MW beams, the SNS linac is fed from the ion source with ~1ms long, ~50-mA H⁻ beam pulses at 60 Hz. This requires the daily extraction of ~230 C of H⁻ ions, which exceeds the routine daily production of other H⁻ accelerator sources by almost an order of magnitude. The source service cycle has been extended from 2, to 3, to 4, and up to 5.6 weeks without age-related failures. The 7-9 kC of H⁻ ions delivered in single service cycles exceed the service cycle yields of other accelerator sources. The paper discusses the findings as well as the issues and their mitigations, which enabled the simultaneous increase of the beam current, the duty factor, the availability, and the service cycle.

WEP277	Operational Findings and Upgrade Plans on the Superconducting Electron Accelerator S-DALINAC	recirculation, electron, controls, quadrupole	1999
	F. Hug, C. Burandt, J. Conrad, R. Eichhorn, M. Kleinmann, M. Konrad, T. Kürzeder, P.N. Nonn, N. Pietralla, S.T. Sievers TU Darmstadt, Darmstadt, Germany
	Funding: DFG through SFB 634. The S-DALINAC is a superconducting recirculating electron accelerator with a final energy of 130 MeV. It operates in cw at 3 GHz. It accelerates beams of either unpolarized or polarized electrons and is used as a source for nuclear- and astrophysical experiments at the university of Darmstadt since 1987. We will report on the operational findings, recent modifications and on the future upgrade plans: First results from the new digital rf control system, the injector current upgrade and the improved longitudinal working point will be presented. In addition, an overview of the future plans, namely installing an additional recirculation path and two scraper systems will be given.

WEP282	Design of the NSLS-II Linac Front End Test Stand	gun, solenoid, emittance, bunching	2011
	R.P. Fliller, M.P. Johanson, M. Lucas, J. Rose, T.V. Shaftan BNL, Upton, Long Island, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The NSLS-II operational parameters place very stringent requirements on the injection system. Among these are the charge per bunch train at low emittance that is required from the linac along with the uniformity of the charge per bunch along the train. The NSLS-II linac is a 200 MeV linac produced by RI Research Instruments GmbH. Part of the strategy for understanding to operation of the injectors is to test the front end of the linac prior to its installation in the facility. The linac front end consists of a 90 keV electron gun, 500 MHz subharmonic prebuncher, focusing solenoids and a suite of diagnostics. The diagnostics in the front end need to be supplemented with an additional suite of diagnostics to fully characterize the beam. In this paper we discuss the design of a test stand to measure the various properties of the beam generated from this section. In particular, the test stand will measure the charge, transverse emittance, energy, energy spread, and bunching performance of the linac front end under all operating conditions of the front end.

WEP283	Simulations of Transverse Stacking in the NSLS-II Booster	booster, emittance, simulation, lattice	2014
	R.P. Fliller, T.V. Shaftan BNL, Upton, Long Island, New York, USA
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The NSLS-II injection system consists of a 200 MeV linac and a 3 GeV booster. The linac needs to deliver 15 nC in 80 - 150 bunches to the booster every minute to achieve current stability goals in the storage ring. This is a very stringent requirement that has not been demonstrated at an operating light source. We have developed a scheme to transversely stack two bunch trains in the NSLS-II booster in order to alleviate the charge requirements on the linac. This scheme has been outlined previously. In this paper we show particle tracking simulations of the tracking scheme. We show that the booster lattice has sufficient orbit correction and dynamic aperture at injection to maintain the charge and emittance of the first beam while it circulates waiting for the next train to arrive. We also show simulations of the booster ramp with a stacked beam for a variety of lattice errors and injected beam parameters. In all cases the performance of the proposed stacking method is sufficient to reduce the required charge from the linac. For this reason the injection system of the NSLS-II booster is being designed to include this feature.

WEP290	A Novel Electron Gun for Off-axis Beam Injection	gun, electron, cathode, emittance	2029
	Yu.A. Kubyshin UPC, Barcelona, Spain A.V. Aloev, N.I. Pakhomov, V.I. Shvedunov MSU, Moscow, Russia
	For certain type of electron accelerators injection from an off-axis cathode is required. This is the case of a race-track microtron (RTM), in which the beam passes several times through the accelerating structure, or of a high power standing wave electron linac, for which the lifetime of an on-axis cathode would be strongly reduced by the electron back-bombardment. The standard solution with the beam injection via a dipole magnet from an electron gun placed off-axis is too bulky, moreover in case of RTMs it requires special compensating dipoles. An annular ring cathode gun used in some accelerators leads to large beam emittance and divergence. As a new solution we describe a 3D on-axis electron gun with an off-axis cathode and a central hole for the beam passage. Results of the design optimization and performance of an electron gun built for a miniature 12 MeV RTM for medical applications are presented. We also discuss results of the beam parameters measurements and estimates of the beam emittance.

WEP295	Status of Laser Stripping at the SNS	laser, optics, quadrupole, injection	2035
	T.V. Gorlov, A.V. Aleksandrov, V.V. Danilov ORNL, Oak Ridge, Tennessee, USA Y. Liu ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: This work was supported by SNS through UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy. This paper presents an overview of experimental and theoretical studies on laser stripping that have been conducted up to the present time in the SNS project. The goal of this work is to develop techniques to achieve the experimental preconditions necessary for the successful realization of a future intermediate experiment on laser stripping. The experimental work consists of the tuning and measurement of H־ beam parameters in readiness for the intermediate experiment, and also takes into account the features and possibilities of the SNS accelerator.

THOAS2	Solid State RF Power - The route to 1W per Euro Cent	electron, klystron, radiation, synchrotron	2047
	O. Heid Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany T.J.S. Hughes Siemens AG, Erlangen, Germany
	In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of power sources based on electron beams i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive technology [,,*] at unprecedented efficiency, power levels and power densities. The proposed solutions allows retrofitting of existing RF solutions and opens the route to novel accelerator designs. Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA * Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan
	Slides THOAS2 [1.776 MB]

THOAS3	Status of the Oak Ridge Spallation Neutron Source (SNS) RF Systems	klystron, controls, rfq, neutron	2050
	T.W. Hardek, M.T. Crofford, Y.W. Kang, M.F. Piller, A.V. Vassioutchenko ORNL, Oak Ridge, Tennessee, USA S.W. Lee, M.E. Middendorf ORNL RAD, Oak Ridge, Tennessee, USA
	The SNS has been delivering production neutrons for five years with first beam delivered to the neutron target at the end of April 2006. On September 18, 2009 SNS officially reached 1 megawatt of beam on target marking the achievement of a decades-old dream of providing a U.S. megawatt class pulsed spallation source. The SNS is now routinely delivering 1 megawatt of beam power to the neutron target at over 85 percent of the scheduled beam time. The present effort is aimed at increasing availability eventually to 95 percent and gradually increasing the intensity to the 1.4 megawatt design level. While the RF systems have performed well since initial installation some improvements have been implemented. This paper provides a review of the SNS RF Systems, an overview of the performance of the various components and a detailed review of RF related issues addressed over the past several years.
	Slides THOAS3 [2.759 MB]

THOCN4	High-Power Options for LANSCE	DTL, neutron, proton, klystron	2107
	R.W. Garnett, E.J. Pitcher, D. Rees, L. Rybarcyk, T. Tajima LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396. The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including schemes for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several plausible options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.
	Slides THOCN4 [2.903 MB]

THOCN5	ATLAS Upgrade	cavity, rfq, cryomodule, ion	2110
	P.N. Ostroumov, A. Barcikowski, Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.W.T. MacDonald, B. Mustapha, R.C. Pardo, S.I. Sharamentov ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. ATLAS (Argonne Tandem Linac Accelerator System) upgrade requires several substantial developments in accelerator technologies, such as CW heavy ion RFQ and high-performance cryomodule with low-beta cavities. The upgrade project is well advanced. The physics and engineering design of the RFQ are complete and fabrication of OFE copper parts is in progress. The 3.9-meter length RFQ is composed from 5 strongly coupled segments. High-temperature furnace brazing of the segments is planned for the summer of 2011. The RFQ design includes several innovative features such as trapezoidal vane tip modulation, compact output radial matcher to form an axially symmetric beam. The upgrade project also includes development and construction of a cryomodule containing seven 72.75 MHz SC quarter wave cavities designed for the geometrical β= 0.077 and four SC solenoids. The cavity is designed to obtain an accelerating voltage higher than 2.5 MV. The prototype cavity together with high-power capacitive coupler and piezoelectric tuner has been developed, fabricated and is being tested. This paper reports innovative design features of both RFQ and SRF linac and current status of the project.
	Slides THOCN5 [3.070 MB]

THOCS6	Progress in Cavity and Cryomodule Design for the Project X Linac	cryomodule, cavity, solenoid, lattice	2133
	M.S. Champion, S. Barbanotti, M.H. Foley, C.M. Ginsburg, I.G. Gonin, C.J. Grimm, J.S. Kerby, S. Nagaitsev, T.H. Nicol, T.J. Peterson, L. Ristori, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	The continuous wave 3 GeV Project X Linac requires the development of two families of cavities and cryomodules at 325 and 650 MHz. The baseline design calls for three types of superconducting single-spoke resonators at 325 MHz having betas of 0.11, 0.22, and 0.42 and two types of superconducting five-cell elliptical cavities having betas of 0.61 and 0.9. These cavities shall accelerate a 1 mA H⁻ beam initially and must support eventual operation at 4 mA. The electromagnetic and mechanical designs of the cavities are in progress and acquisition of prototypes is planned. The heat load to the cryogenic system is up to 25 W per cavity in the 650 MHz section, thus segmentation of the cryogenic system is a major issue in the cryomodule design. Designs for the two families of cryomodules are underway.
	Slides THOCS6 [2.241 MB]

THP001	Hybrid Electron Linac Based on Magnetic Coupled Accelerating Structure	coupling, electron, simulation, impedance	2136
	S.V. Kutsaev, K.I. Nikolskiy, N.P. Sobenin MEPhI, Moscow, Russia
	This paper presents the design of a hybrid linac which consists of a standing wave buncher and a travelling wave accelerating part. Both electric and magnetic-coupled disk-loaded waveguide (DLW) could be used as accelerating structure. The last one has better electrodynamical parameters comparing to classical DLW. Such an accelerator possesses the advantages of both standing wave and travelling wave linacs and has better output beam parameters.

THP006	Status of High Current R&D Energy Recovery Linac at Brookhaven National Laboratory	electron, gun, SRF, emittance	2148
	D. Kayran, Z. Altinbas, D.R. Beavis, I. Ben-Zvi, R. Calaga, D.M. Gassner, H. Hahn, L.R. Hammons, A.K. Jain, J.P. Jamilkowski, N. Laloudakis, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, B. Oerter, D. Pate, D. Phillips, J. Reich, T. Roser, C. Schultheiss, B. Sheehy, T. Srinivasan-Rao, R. Than, J.E. Tuozzolo, D. Weiss, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA
	An ampere-class 20 MeV superconducting energy recovery linac (ERL) is under construction at Brookhaven National Laboratory (BNL) for testing of concepts relevant for high-energy coherent electron cooling and electron-ion colliders. One of the goals is to demonstrate an electron beam with high charge per bunch (~5 nC) and low normalized emittance (~5 mm-mrad) at an energy of 20 MeV. A flexible lattice for the ERL loop provides a test bed for investigating issues of transverse and longitudinal instabilities and diagnostics for CW beam. A superconducting 703 MHz RF photo-injector is considered as an electron source for such a facility. We will start with a straight pass (gun/cavity/beam stop) test for gun performance studies. Later, we will install and test a novel injection line concept for emittance preservation in a lower-energy merger. Here we present the status and our plans for construction and commissioning of this facility.

THP007	FEL Potential of eRHIC	FEL, electron, brightness, SRF	2151

Paper

Title

Other Keywords

Page

MOOBN3

Comparison of Accelerator Technologies for use in ADSS

target, proton, cyclotron, SRF

4

W.-T. Weng, H. Ludewig, D. Raparia, M. Todosow, D. Trbojevic
BNL, Upton, Long Island, New York, USA
P.M. McIntyre, A. Sattarov
Texas A&M University, College Station, Texas, USA

Funding: Work performed under the auspices of the US Department of Energy
Accelerator Driven Subcritical (ADS) fission is an interesting candidate basis for nuclear waste transmutation and for nuclear power generation. ADS can use either thorium or depleted uranium as fuel, operate below criticality, and consume rather than produce long-lived actinides. A case study with a hypothetical, but realistic nuclear core configuration is used to evaluate the performance requirements of the driver proton accelerator in terms of beam energy, beam current, duty factor, beam distribution delivered to the fission core, reliability, and capital and operating cost. Comparison between a CW IC and that of an SRF proton linac is evaluated. Future accelerator R&D required to improve each candidate accelerator design is discussed.

Slides MOOBN3 [1.540 MB]

MOOBS1

Beam Dynamics Issues in the SNS Linac

laser, ion, emittance, optics

12

A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA

Funding: This research is supported by UT-Battelle, LLC for the U. S. Department of Energy under contract No. DE-AC05-00OR22725
A review of the Spallation Neutron Source (SNS) linac beam dynamics is presented. It describes transverse and longitudinal beam optics, losses, activation, and comparison between the initial design and the existing accelerator. The SNS linac consists of normal conducting and superconducting parts. The peculiarities in operations with the superconducting part of the SNS linac (SCL), estimations of total losses in SCL, the possible mechanisms of these losses, and the progress in the transverse matching are discussed.

Slides MOOBS1 [1.270 MB]

MOODS1

Space-Charge Effects in Bunched and Debunched Beams

focusing, space-charge, electron, emittance

85

B.L. Beaudoin, S. Bernal, K. Fiuza, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea, M. Reiser, D.F. Sutter
UMD, College Park, Maryland, USA

Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
The University of Maryland Electron Ring (UMER) is a machine designed to study high-intensity beam physics. With the application of axial fields to the bunch ends, we are able to keep a beam with an injected tune shift of 1.0, bunched over multiple turns. This is feasible with the application of tailored fields to optimally match the space-charge self-fields while minimizing the excitation of longitudinal space-charge waves. With this scheme, we have been able to extend the number of turns at the University of Maryland Electron Ring (UMER) by a factor of ten. Without the use of longitudinal focusing, head and tail effects begin to dominate, especially with the higher current beams. Time resolved measurements of the peak correlated energy spread have shown in some cases a change in the overall spread of 1.8% for the 0.6 mA beam, from the injected beam energy.

Slides MOODS1 [2.834 MB]

MOODS5

3D Electromagnetic Design and Beam Dynamics Simulations of a Radio-Frequency Quadrupole

rfq, simulation, cavity, target

97

B. Mustapha, A. Kolomiets, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
During the design of the 60.635 MHz RFQ for the ATLAS efficiency and intensity upgrade*, we have established a new full 3D approach for the electromagnetic and beam dynamics simulations of a RFQ. A Detailed full 3D model (four meter long) including vane modulation was built and simulated using CST Microwave Studio, which is made possible by the ever advancing computing capabilities. The approach was validated using experimental measurements on a prototype 57.5 MHz RFQ**. The effects of the radial matchers, vane modulation and tuners on the resonant frequency and field flatness have been carefully studied. The full 3D field distribution was used for beam dynamics simulations using both CST Particle Studio and the beam dynamics code TRACK***. In the final design we have used trapezoidal modulation instead of the standard sinusoidal in the accelerating section of the RFQ to achieve more energy gain for the same length, following the leading work of the Protvino group****. In our case, the output energy increased from 260 keV/u to 295 keV/u with minimal change in the beam dynamics.
* P.N. Ostroumov et al, Proceedings of LINAC-2010
** P.N. Ostroumov et al, Proceedings of LINAC-2006
*** TRACK @ http://www.phy.anl.gov/atlas/TRACK
**** O.K. Belyaev et al, Proceedings of LINAC-2000

Slides MOODS5 [2.531 MB]

MOP008

Upgrade of the Argonne Wakefield Accelerator Facility (AWA) and Commissioning of a New RF Gun for Drive Beam Generation

wakefield, gun, electron, acceleration

115

M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
The AWA Facility is presently undergoing several upgrades that will enable it to further study wakefield acceleration driven by high charge electron beams. The facility employs an L-band photocathode RF gun to generate high charge short electron bunches, which are used to drive wakefields in dielectric loaded structures as well as in metallic structures (iris loaded, photonic band gap, etc). Several facility upgrades are underway: (a) a new RF gun with a higher quantum efficiency photocathode will replace the RF gun that has been used to generate the drive bunches; (b) the existing RF gun will be used to generate a witness beam to probe the wakefields; (c) three new L-band RF power stations, each providing 25 MW, will be added to the facility; (d) five linac structures will be added to the drive beamline, bringing the beam energy up from 15 MeV to 75 MeV. The drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The goal of future experiments is to reach accelerating gradients of several hundred MV/m and to extract RF pulses with GW power level.

MOP012

Ultra-High Gradient Compact S-Band Accelerating Structure

klystron, coupling, vacuum, simulation

127

L. Faillace, R.B. Agustsson, P. Frigola, A.Y. Murokh
RadiaBeam, Santa Monica, USA
V.A. Dolgashev
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

Funding: Dept. of Energy DE-SC0000866
In this paper, we present the radio-frequency design of the DECA (Doubled Energy Compact Accelerator) S-band accelerating structure operating in the pi-mode at 2.856 GHz, where RF power sources are commonly available. The development of the DECA structure will offer an ultra-compact drop-in replacement for a conventional S-band linac in research and industrial applications such as drivers for compact light sources, medical and security systems. The electromagnetic design has been performed with the codes SuperFish and HFSS. The choice of the single cell shape derives from an optimization process aiming to maximize RF efficiency and minimize surface fields at very high accelerating gradients, i.e. 50 MV/m and above. Such gradients can be achieved utilizing shape-optimized elliptical irises, dual-feed couplers with the "fat-lip" coupling slot geometry, and specialized fabrication procedures developed for high gradient structures. The thermal-stress analysis of the DECA structure is also presented.
* V. Dolgashev, "Status of X-band Standing Wave Structure Studies at SLAC", SLAC-PUB-10124, (2003).
** C. Limborg et al., "RF Design of LCLS Gun", LCLS-TN-05-03 (2005).

MOP043

Simulations of a Muon Linac for a Neutrino Factory

simulation, acceleration, synchrotron, factory

181

K.B. Beard
Muons, Inc, Batavia, USA
S.A. Bogacz, V.S. Morozov, Y. Roblin
JLAB, Newport News, Virginia, USA

Funding: Supported in part by DOE grant DE-FG-08ER86351
The Neutrino Factory baseline design involves a complex chain of accelerators including a single-pass linac, two recirculating linacs and an FFAG. The first linac follows the capture and bunching section and accelerates the muons from about 244 to 900 MeV. It must accept a high emittance beam about 30 cm wide with a 10% energy spread. This linac uses counterwound, shielded superconducting solenoids and 201 MHz superconducting cavities. Simulations have been carried out using several codes including Zgoubi, OptiM, GPT, and G4beamline, both to determine the optics and to estimate the radiation loads on the elements due to beam loss and muon decay.

MOP052

Matched Optics of Muon RLA and Non-Scaling FFAG ARCS

optics, quadrupole, lattice, dynamic-aperture

196

V.S. Morozov, S.A. Bogacz, Y. Roblin
JLAB, Newport News, Virginia, USA
K.B. Beard
Muons, Inc, Batavia, USA
D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Supported in part by US DOE STTR Grant DE-FG02-08ER86351
Recirculating Linear Accelerators (RLA) are an efficient way of accelerating short-lived muons to multi-GeV energies required for Neutrino Factories and TeV energies required for Muon Colliders. To reduce the number of required return arcs, we employ a Non-Scaling Fixed-Field Alternating-Gradient (NS-FFAG) arc lattice design. We present a complete linear optics design of a muon RLA with two-pass linear NS-FFAG droplet return arcs. The arcs are composed of symmetric cells with each cell designed using combined function magnets with dipole and quadrupole magnetic field components so that the cell is achromatic and has zero initial and final periodic orbit offsets for both passes’ energies. Matching to the linac is accomplished by adjusting linac quadrupole strengths so that the linac optics on each pass is matched to the arc optics. We adjust the difference of the path lengths and therefore of the times of flight of the two momenta in each arc to ensure proper synchronization with the linac. We investigate the dynamic aperture and momentum acceptance of the arcs.

MOP071

Terahertz Light Source and User Area at FACET

radiation, electron, photon, site

238

Z. Wu, A.S. Fisher, M.J. Hogan, S.Z. Li, M.D. Litos
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET at SLAC provides high charge, high peak current, low emittance electron beam that is bunched at THz wavelength scale during its normal operation. A THz light source based coherent transition radiation (CTR) from this beam would potentially be the brightest short-pulse THz source ever constructed. Efforts have been put into building this photon source together with a user area, to provide a platform to utilize this unique THz radiation for novel nonlinear and ultrafast phenomena researches and experiments.

MOP117

Beam Test of a Tunable Dielectric Wakefield Accelerator

wakefield, gun, acceleration, electron

316

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Funding: Work supported by US DoE SBIR Grant under Contract # DE-FG02-07ER84822
We report on a collinear wakefield experiment using the first tunable dielectric loaded accelerating structure. Dielectric-based accelerators are generally lacking in approaches to tune the frequency after fabrication. However, by introducing an extra layer of nonlinear ferroelectric which has a dielectric constant sensitive to temperature and DC voltage, the frequency of a DLA structure can be tuned on the fly by controlling the temperature or DC bias. The experiment demonstrated that by varying the temperature of the structure over a 50°C temperature range, the energy of a witness bunch at a fixed delay with respect to the drive beam could be changed by an amount corresponding to more than half of the nominal structure wavelength.

MOP145

Physics Design of the Project X CW Linac

lattice, cryomodule, simulation, focusing

364

N. Solyak, J.-P. Carneiro, J.S. Kerby, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, A. Saini, A. Vostrikov, V.P. Yakovlev
Fermilab, Batavia, USA

The general design of the 3 GeV superconducting CW linac of the Project X is presented. Different physical and technical issues and limitations that determine the linac concept are discussed. The results of the RF system optimization are presented as well as the lattice design and beam dynamics analysis.

MOP177

Design and Cold Test of Re-entrant Cavity BPM for HLS

cavity, coupling, pick-up, controls

420

Q. Luo, Q.K. Jia, B.G. Sun, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by Natural Science Foundation of China, National 985 Project, China Postdoctoral Science Foundation and the Fundamental Research Funds for the Central Universities
An S-band cavity BPM is designed for a new injector in National Synchrotron Radiation Laboratory. A re-entrant position cavity is tuned to TM110 mode as position cavity. Theoretical resolution of the BPM is 31 nm. A prototype cavity BPM system is manufactured for cold test. Wire scanning method is used to calibrate the BPM and estimate the performance of the on-line BPM system. Cold test results showed that position resolution of prototype BPM is better than 3 μm. Cross-talk has been detected during the cold test. Racetrack cavity can be used to suppress cross-talk. Ignoring nonlinear effect, transformation matrix is a way to correct cross-talk.

MOP184

Beam Instrumentation for the European Spallation Source

diagnostics, cryomodule, target, rfq

432

A. Jansson, H. Danared, M. Eshraqi, L. Tchelidze
ESS, Lund, Sweden

The European Spallation Source, which will be built in the south of Sweden, is a neutron source based on a 5MW, 2.5GeV proton linac. The project is currently in the design update phase, and will deliver a Technical Design Report at the end of 2012. Construction is expected to begin in 2013. This paper discusses the initial beam diagnostics specifications, along with some possible instrument design options.

MOP194

A Laser-Wire Beam-Energy and Beam-Profile Monitor at the BNL Linac

electron, laser, optics, ion

456

R. Connolly, L. DeSanto, C. Degen, R.J. Michnoff, M.G. Minty, D. Raparia
BNL, Upton, Long Island, New York, USA

Funding: Work performed under Contract #DE-AC02-98CH10886 under the auspices of the US Department of Energy.
In 2009 a beam-energy monitor was installed in the high energy beam transport (HEBT) line at the Brookhaven National Lab linac. This device measures the energies of electrons stripped from the 40mA H⁻ beam by background gas. Electrons are stripped by the 1.7x10-7torr residual gas at a rate of ~2.4x10^-8/cm. Since beam electrons have the same velocities as beam protons, the beam proton energy is deduced by multiplying the electron energy by mp/me=1836. A 183.6MeV H⁻ beam produces 100keV electrons. In 2010 we installed an optics plates containing a laser and optics to add beam-profile measurement capability via photodetachment. Our 100mJ/pulse, Q-switched laser neutralizes 70% of the beam during its 10ns pulse. The chamber in which the laser light passes through the ion beam is upstream of a dipole magnet which deflects the electrons into a biased retarding-grid (V<125kV) Faraday-cup detector. To measure beam profiles, a narrow laser beam is stepped across the ion beam removing electrons from the portion of the H⁻ beam intercepted by the laser. The laser also gives us energy measurements on the 0.2mA polarized proton beam.

MOP234

Beam Position and Phase Monitors for the LANSCE Linac

controls, neutron, monitoring, instrumentation

548

R.C. McCrady, J.D. Gilpatrick, J.F. Power
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the US Department of Energy under contract DE-AC52-06NA25396
New beam-position and phase monitors are under development for the linac at the Los Alamos Neutron Science Center. Transducers have been designed and are being fabricated. We are considering many options for the electronic instrumentation to process the signals and provide position and phase data with the necessary precision and flexibility to serve the various required functions. We’ll present the requirements of the system and the various options under consideration for instrumentation along with the advantages and shortcomings of these options.

MOP235

LANSCE Wire Scanning Diagnostics Device Prototype

vacuum, diagnostics, proton, acceleration

551

S. Rodriguez Esparza, Y.K. Batygin, J.D. Gilpatrick, M.E. Gruchalla, A.J. Maestas, C. Pillai, J.L. Raybun, F.D. Sattler, J.D. Sedillo, B.G. Smith
LANL, Los Alamos, New Mexico, USA

The Accelerator Operations & Technology Division at Los Alamos National Laboratory operates a linear particle accelerator which utilizes 110 wire scanning diagnostics devices to gain position and intensity information of the proton beam. In the upcoming LANSCE improvements, 51 of these wire scanners are to be replaced with a new design, up-to-date technology and off-the-shelf components. This document outlines the requirements for the mechanical design of the LANSCE wire scanner and presents the recently developed linac wire scanner prototype. Additionally, this document presents the design modifications that have been implemented into the fabrication and assembly of this first linac wire scanner prototype. Also, this document will present the design for the second and third wire scanner prototypes being developed. These last two prototypes belong to a different section of the particle accelerator and therefore have slightly different design specifications. Lastly, the paper concludes with a plan for future work on the wire scanner development.

MOP237

Large Dynamic Range Beam Profile Measurements at SNS: Challenges and Achievements

background, coupling, electron, DTL

557

A.V. Aleksandrov, W. Blokland, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Beam profile diagnostics with large dynamic range is an important tool for understanding origin and evolution of the beam halo in accelerators. Typical dynamic range for conventional wire scanners has been in the range of 100. In high power machines like SNS fractional losses of 1 to 100 part per million is of concern and, therefore, higher dynamic range of profile measurements is desirable. Our near term goal was set to achieve a dynamic range of at least 10000 for all profile measurements in the SNS linac and transport lines. We will discuss present status of this program, challenges, and solutions.

MOP241

Beam Diagnostics for FACET

plasma, radiation, diagnostics, electron

565

S.Z. Li, M.J. Hogan
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration beginning in summer 2011. The nominal FACET parameters are 23 GeV, 3 nC electron bunches compressed to ~20 μm long and focussed to ~10 μm wide. Characterization of the beam- plasma interaction requires complete knowledge of the incoming beam parameters on a pulse-to- pulse basis. FACET diagnostics include Beam Position Monitors, Toroidal current monitors, X-ray and Cerenkov based energy spectrometers, optical transition radiation (OTR) profile monitors and coherent transition radiation (CTR) bunch length measurement systems. The compliment of beam diagnostics and their expected performance are reviewed.

MOP256

Upgrading the Data Acquisition and Control System of the LANSCE LINAC

controls, EPICS, proton, neutron

588

D. Baros
LANL, Los Alamos, New Mexico, USA

Funding: This work has benefited from the use of the LANSCE at LANL. This facility is funded by the US DOE and operated by LANS for NSSA under Contract DE-AC52-06NA25396.
Los Alamos National Laboratory LANL is in the process of upgrading the control system for the Los Alamos Neutron Science Center (LANSCE) linear accelerator. The 38 year-old data acquisition and control equipment is being replaced with COTS hardware. An overview of the current system requirements and how the National Instruments cRIO system meets these requirements will be given, as well as an update on the installation and operation of a prototype system in the LANSCE LINAC.
LANL Release Number: LA-UR 10-06605

MOP257

High Power RF Distribution and Control for Multi-Cavity Cryomodule Testing

cryomodule, controls, cavity, klystron

591

Y.W. Kang, M. Broyles, M.T. Crofford, X. Geng, S.-H. Kim, S.W. Lee, C.L. Phibbs, K.R. Shin, W.H. Strong
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The SNS has been successfully operating 81 superconducting six-cell cavities in 23 cryomodules in its linac to achieve the goals in beam power and energy. For near-term production of spare cryomodules and the upcoming power upgrade project that will need 36 additional cavities in 9 cryomodules, high RF power testing and qualification of the cavities is required in the RF test facility. Simultaneously powering all the cavities in a cryomodule is considered desirable for robust conditioning and studying of cavity field emission since certain cavities exhibit field emissions that could be mutually coupled. A four-way variable output power waveguide splitting system is being prepared for testing cryomodules with up to four cavities. The splitting system is fed by an 805 MHz, 5 MW peak power pulsed klystron. The power output at each arm can be adjusted in both amplitude and phase to wide ranges of values using two mechanical waveguide phase shifters that form a vector modulator. The system control is implemented in the EPICS environment similar to the main accelerator controls. The work performed on the design, integration, operation, and test of the system are presented.

MOP261

The CEBAF Element Database

controls, lattice, background, alignment

594

T. L. Larrieu, M.E. Joyce, C.J. Slominski
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
With inauguration of the CEBAF Element Database(CED) in Fall 2010, Jefferson Lab computer scientists have taken a first step toward the eventual goal of a model-driven accelerator. Once fully populated, the database will be the primary repository of information used for everything from generating lattice decks to booting iocs to building controls screens. A requirement influencing the CED design is that it provide access to not only present, but also future, and eventually past, configurations of the accelerator. To accomplish this, an introspective database schema was designed that allows new elements, types, and properties to be defined on-the-fly with no changes to table structure. Used in conjunction with Oracle Workspace Manager, it allows users to query data from any time in the database history with the same tools used to query the present configuration. Users can also check-out workspaces to use as staging areas for upcoming machine configurations. All Access to the CED is through a well-documented API that is translated automatically from original C++ into native libraries for script languages such as perl, php, and TCL making access to the CED easy and ubiquitous.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

MOP277

The Machine Protection System for the R&D Energy Recovery LINAC

controls, status, interlocks, collider

630

Z. Altinbas, J.P. Jamilkowski, D. Kayran, R.C. Lee, B. Oerter
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Machine Protection System (MPS) is a device-safety system that is designed to prevent damage to hardware by generating interlocks, based upon the state of input signals generated by selected sub-systems. It protects all the key machinery in the R&D Project called the Energy Recovery LINAC (ERL) against the high beam current. The MPS is capable of responding to a fault with an interlock signal within several microseconds. The ERL MPS is based on a National Instruments CompactRIO platform, and is programmed by utilizing National Instruments' development environment for a visual programming language. The system also transfers data (interlock status, time of fault, etc.) to the main server. Transferred data is integrated into the pre-existing software architecture which is accessible by the operators. This paper will provide an overview of the hardware used, its configuration and operation, as well as the software written both on the device and the server side.

MOP293

Performance of Analog Signal Distribution in the ATCA Based LLRF System

LLRF, controls, radio-frequency, FEL

666

K. Czuba, L. Butkowski, S. Jabłoński, P. Przybylski, D. Sikora
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Jałmużna, D.R. Makowski
TUL-DMCS, Łódź, Poland
T. Jezynski, F. Ludwig
DESY, Hamburg, Germany

The Low Level Radio Frequency System (LLRF) for the European X-FEL must provide exceptional stability of the accelerating RF field in the accelerating cavities. The regulation requirements of 0.01% and 0.01 degrees in amplitude and phase respectively must be achieved at a frequency of 1.3 GHz while keeping low drifts (during RF pulse). The quality of analog signal processing and distribution plays a crucial role in achieving these goals. The RF signals are connected to the Rear Transition Module (RTM), downconverted there into intermediate frequency (IF) signals and finally sampled at AMC-ADC module. The high quality of the signals (SNR, low crosstalk) must be assured across all the way. The paper presents the results of development of ATCA based LLRF system for XFEL. The special attention is paid to RTM module with downconverters and carrier board conducting analog signals to the AMC-ADC and the AMC Vector Modulator module in the presence of digital processing components (FPGA, DSP).

TUOAN2

High Luminosity Electron-Hadron Collider eRHIC

electron, proton, luminosity, ion

693

V. Ptitsyn, E.C. Aschenauer, M. Bai, J. Beebe-Wang, S.A. Belomestnykh, I. Ben-Zvi, M. Blaskiewicz, R. Calaga, X. Chang, A.V. Fedotov, H. Hahn, L.R. Hammons, Y. Hao, P. He, W.A. Jackson, A.K. Jain, E.C. Johnson, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, M.G. Minty, B. Parker, A.I. Pikin, T. Rao, T. Roser, B. Sheehy, J. Skaritka, S. Tepikian, R. Than, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, G. Wang, Q. Wu, W. Xu, A. Zelenski
BNL, Upton, Long Island, New York, USA
E. Pozdeyev
FRIB, East Lansing, Michigan, USA
E. Tsentalovich
MIT, Middleton, Massachusetts, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We present the design of future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 10³⁴ cm^-2 s^-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling and the compact magnets for recirculating passes. A natural staging scenario of step-by-step increases of the electron beam energy by builiding-up of eRHIC's SRF linacs and a potential of adding polarized positrons are also presented.

Slides TUOAN2 [4.244 MB]

TUOAN3

Lattice Design for the Future ERL-Based Electron Hadron Colliders eRHIC and LHeC

electron, lattice, collider, dipole

696

D. Trbojevic, J. Beebe-Wang, Y. Hao, D. Kayran, V. Litvinenko, V. Ptitsyn, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work performed under a Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy.
We present a lattice design of a CW Electron Recovery Linacs (ERL) for future electron-hadron colliders eRHIC and LHeC. In eRHIC, an six-pass ERL installed in the existing Relativistic Heavy Ion Collider (RHIC) tunnel will collide 5-30 GeV polarized electrons with RHIC’s 50-250 (325) GeV polarized protons or 20-100 (130) GeV/u heavy ions. In LHeC, a stand-along 3-pass 60 GeV CW ERL will collide polarized electrons with 7 TeV protons. After collision, electron beam energy is recovered and electrons are dumped at low energy. Two superconducting linacs are located in the two straight sections in both ERLs. . The multiple arcs are made of Flexible Momentum Compaction lattice (FMC) allowing adjustable momentum compaction for electrons with different energies. The multiple arcs, placed above each other, are matched to the two linacs straight sections with splitters and combiners.

Slides TUOAN3 [3.002 MB]

TUOBS1

Technical Challenges in the Linac Coherent Light Source, Commissioning and Upgrades

undulator, electron, photon, laser

724

Z. Huang, J.N. Galayda
SLAC, Menlo Park, California, USA
P.A. Heimann
LBNL, Berkeley, California, USA

Funding: DOE
Five months after first lasing in April 2009, the Linac Coherent Light Source (LCLS) began its first round of x-ray experiments. The facility rapidly attained and surpassed its design goals in terms of spectral tuning range, peak power, energy per pulse and pulse duration. There is an ongoing effort to further expand capabilities while supporting a heavily subscribed user program. The facility continues to work toward new capabilities such as multiple-pulse operation, pulse durations in the femtosecond range, and production of >16 keV photons by means of a second-harmonic “afterburner” undulator. Future upgrades will include self-seeding and polarization control. The facility is already planning to construct a major expansion, with two new undulator sources and space for four new experiment stations.

Slides TUOBS1 [12.513 MB]

TUOBS2

Cornell ERL Research and Development

emittance, electron, FEL, gun

729

C.E. Mayes, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, E. Fontes, C.M. Gulliford, D.L. Hartill, G.H. Hoffstaetter, V.O. Kostroun, F.A. Laham, Y. Li, M. Liepe, X. Liu, F. Löhl, A. Meseck, A.A. Mikhailichenko, H. Padamsee, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, V.D. Shemelin, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, Y. Xie
CLASSE, Ithaca, New York, USA
S.S. Karkare, J.M. Maxson
Cornell University, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731.
Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.

Slides TUOBS2 [5.632 MB]

TUOBS4

Challenge of MAX IV Towards a Multi-Purpose Highly Brilliant Light Source

emittance, lattice, storage-ring, vacuum

737

M. Eriksson, J. Ahlbäck, Å. Andersson, M.A.G. Johansson, D. Kumbaro, S.C. Leemann, C. Lenngren, P. Lilja, F. Lindau, L.-J. Lindgren, L. Malmgren, J.H. Modéer, R. Nilsson, M. Sjöström, J. Tagger, P.F. Tavares, S. Thorin, E.J. Wallén, S. Werin
MAX-lab, Lund, Sweden
B. Anderberg
AMACC, Uppsala, Sweden
L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

A design study of the MAX-IV light source complex in Sweden has been completed. One of MAX-IV's main light sources, a 3 GeV storage ring, is designed to achieve a natural emittance of ~0.2 nm rad. The facility will also provide SASE-XFEL using a 3 GeV high performance linear accelerator. The speaker will discuss facility targets, the concept and accelerator design, and show some possibilities approaching two-dimensional diffraction-limited X-ray generation at MAX-IV.

Slides TUOBS4 [6.719 MB]

TUOCS1

Energy Recovery Linacs for Light Source Applications

electron, FEL, gun, cavity

761

G. Neil
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under DOE Contract No. DE-AC05-06OR23177. The U.S.Government retains a non-exclusive, paid-up, irrevocable, world-wide license.
Energy Recovery Linacs are being considered for applications in present and future light sources. ERLs take advantage of the continuous operation of superconducting rf cavities to accelerate high average current beams with low losses. The electrons can be directed through bends, undulators, and wigglers for high brightness x ray production. They are then decelerated to low energy, recovering power so as to minimize the required rf drive and electrical draw. When this approach is coupled with advanced continuous wave injectors, very high power, ultra-short electron pulse trains of very high brightness can be achieved. This paper reviews the status of worldwide programs and discusses the technology challenges to provide such beams for photon production.

Slides TUOCS1 [9.930 MB]

TUOCS4

Upgrade of Accelerator Complex at Pohang Light Source Facility (PLS-II)

emittance, storage-ring, vacuum, insertion

772

K.R. Kim, H.-S. Kang, C. Kim, D.E. Kim, S.H. Kim, S.-C. Kim, H.-G. Lee, J.W. Lee, S.H. Nam, C.D. Park, S.J. Park, S. Shin
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This upgrade project of PLS-II is supported by MEST, in Korea
In order to meet the domestic Korean synchrotron user’s requirements demanding high beam stability and extended photon energies, PLS-II upgrade program has been launched in January 2009 through a 3-year project plan. PLS-II storage ring is newly designed a modified achromatic version of Double Bend Achromat (DBA) to achieve almost twice as many straight sections as the current PLS (TBA) with a design goal of the natural emittance of 5.8 nm·rad, 3.0 GeV beam energy and 400 mA beam current. In the PLS-II, the top-up injection using full energy linac of 3.0 GeV beam energy will be routinely operated for higher stable photon beam as well and therefore the production of hard x-ray undulator radiation of 8 to13 keV is anticipated to allow for more competitive scientific research activities namely x-ray bio-imaging and protein crystallography.

Slides TUOCS4 [17.914 MB]

TUOCS5

A Next Generation Light Source Facility at LBNL

FEL, electron, laser, photon

775

J.N. Corlett, B. Austin, K.M. Baptiste, J.M. Byrd, P. Denes, R.J. Donahue, L.R. Doolittle, R.W. Falcone, D. Filippetto, D.S. Fournier, J. Kirz, D. Li, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, T. Vecchione, M. Venturini, R.P. Wells, R.B. Wilcox, J.S. Wurtele
LBNL, Berkeley, California, USA
A.E. Charman, E. Kur
UCB, Berkeley, California, USA
A. Zholents
ANL, Argonne, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The Next Generation Light Source (NGLS) is a design concept, under development at LBNL, for a multi‐beamline soft x‐ray FEL array powered by a 2 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. The CW superconducting linear accelerator is supplied by a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for EEHG, HGHG, SASE, or oscillator mode of operation, and will produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds.

Slides TUOCS5 [4.758 MB]

TUP012

Computer Simulations of Waveguide Window and Coupler Iris for Precision Matching

DTL, coupling, simulation, cavity

832

S.W. Lee
ORNL RAD, Oak Ridge, Tennessee, USA
Y.W. Kang, K.R. Shin, A.V. Vassioutchenko
ORNL, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
A tapered ridge waveguide iris input coupler and a waveguide ceramic disk windows are used on each of six drift tube linac (DTL) cavities in the Spallation Neutron Source (SNS). The coupler design employs rapidly tapered double ridge waveguide to reduce the cross section down to a smaller low impedance transmission line section that can couple to the DTL tank easily. The impedance matching is done by adjusting the dimensions of the thin slit aperture between the ridges that is the coupling element responsible for the power delivery to the cavity. Since the coupling is sensitive to the dimensional changes of the aperture, it requires careful tuning for precise matching. Accurate RF simulation using latest 3-D EM code is desirable to help the tuning for maintenance and spare manufacturing. Simulations are done for the complete system with the ceramic window and the coupling iris on the cavity to see mutual interaction between the components as a whole.

TUP014

Broad-band Beam Chopper for a CW Proton Linac at Fermilab

kicker, coupling, rfq, emittance

838

N. Solyak, E. Gianfelice-Wendt, V.A. Lebedev, S. Nagaitsev, D. Sun
Fermilab, Batavia, USA

The specifications and the initial conceptual ides for a broad-band proton chopper for a Fermilab Project X linac will be presented. The chopper will form bunch patterns required by physics experiments and will work with downstream beam splitter, allowing for a variable bunch pattern to be delivered to up to three experiment concurrently.

TUP015

Conceptual Design of the Project-X 1.3 GHz, 3-8 GeV Pulsed Linac

cavity, controls, klystron, feedback

841

N. Solyak, Y.I. Eidelman, S. Nagaitsev, J.-F. Ostiguy, A. Vostrikov, V.P. Yakovlev
Fermilab, Batavia, USA

The Project-X, a multi-MW proton source, is under development at Fermilab. It enables a Long Baseline Neutrino Experiment via a new beam line pointed to DUSEL in Lead, South Dakota, and a broad suite of rare decay experiments. The facility contains 3-GeV 1-mA CW superconducting linac. In the second stage of about 5% of the H⁻ beam is accelerated up to 8 GeV in a 1.3 GHz SRF pulse linac to Recycler/Main Injector. In order to mitigate the problem with the stripping foil heating during injection to the Main Injector, the pulses with higher current are accelerated in CW linac together with 1 mA beam for further acceleration in the pulse linac. The optimal current in the pulse linac is discussed as well as limitations that determine it's selection. A concept design of the pulse linac is described. The lattice design is presented as well as RF stability analysis. The necessity of the HOM couplers is discussed also.

TUP019

The S-DALINAC Polarized Injector SPIN - Performance and Results

electron, laser, polarization, site

853

C. Eckardt, T. Bahlo, P. Bangert, R. Barday, U. Bonnes, M. Brunken, C. Burandt, R. Eichhorn, J. Enders, M. Espig, C. Ingenhaag, J. Lindemann, M. Platz, Y. Poltoratska, M. Roth, F. Schneider, H. Schüßler, M. Wagner, A. Weber, B. Zwicker
TU Darmstadt, Darmstadt, Germany
W. Ackermann, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
K. Aulenbacher
IKP, Mainz, Germany

Funding: * Work supported by DFG through SFB 634.
At the superconducting 130 MeV Darmstadt electron linac S-DALINAC the new source of polarized electrons uses a GaAs cathode illuminated with pulsed Ti:Sapphire and diode laser light. The electron source had been set up and commissioned at a test stand with a beam line where a Wien filter for spin manipulation, a Mott polarimeter for polarization measurement and a chopper-prebuncher system were part of the system. Upon completion of the tests, test stand and beam line were dismantled and re-installed at the S-DALINAC. The new photo injector opens up the potential for experiments with polarized electron and photon beams for nuclear structure studies at low momentum transfers. Various polarimeters will be installed at all experimental sites to monitor the beam polarization. We report on the S-DALINAC, the results from the teststand performance, the implementation of the polarized source and the polarimeter research and development.
* A. Richter, Proc. of the 5th EPAC, Sitges (1996) 110
** Y. Poltoratska et al., AIP Conference Proc. 1149 (2009) 983
*** P. Mohr et al., Nucl. Instr. and Meth. A423 (1999) 480

TUP031

Project X Elliptical Cavity Structural Analyses

cavity, simulation, vacuum, cryomodule

868

E.N. Zaplatin
FZJ, Jülich, Germany

Project X is proposed at Fermi National Accelerator Laboratory high-intensity proton accelerator complex that could provide beam for a variety of physics projects. Superconducting resonators will be used for beam acceleration. Here we report a structural design of elliptical cavities with resonance frequency 650 MHz and β=0.91 and 0.61. Since there is a concern that the pressure in the helium plumbing will not be stable when the cryomodules are connected to the liquid helium supply and helium gas returns it is necessary to provide the cavity stiffening with requirements of 15 Hz amplitude frequency shift. The cavity RF and mechanical properties are investigated. The calculations of the cavity frequency shift with pressure for different schemes of cavity stiffening were provided. The criterion for the optimization was the minimization of a resonant frequency dependence on an external pressure. Based on the results of these simulations several options on cavity stiffening have been proposed. Additionally, the cavity stiffening structural scheme for self-compensation of resonator detuning caused by external pressure fluctuation have been investigated.

TUP046

Superconducting 72 MHz β=0.077 Quarter-wave Cavity for ATLAS

cavity, niobium, ion, cathode

892

M.P. Kelly, Z.A. Conway, S.M. Gerbick, M. Kedzie, R.C. Murphy, P.N. Ostroumov, T. Reid
ANL, Argonne, USA

A 72 MHz superconducting (SC) niobium quarter-wave cavity (QWR) optimized for β=0.077 has been built and tested as part of a beam intensity upgrade of the ATLAS SC heavy-ion linac. The two-gap cavity, designed to accelerate ions over the velocity range 0.06<β<0.12 and provide 2.5 MV of accelerating voltage per cavity at T=4.5 Kelvin, is based on a highly optimized electromagnetic design to reduce surface electric and magnetic fields. Horizontal electropolishing on the complete cavity with the helium jacket, is similar to that performed on 1.3 GHz ILC-type cavities and is a first for a low-β TEM cavity. This development is part of a broader effort to demonstrate ~120 mT surface fields with Rs~5 nΩ in 2 K operation for low-β cavities with the aim of substantially reducing the footprint for future ion linacs. First rf cold test results show the highest accelerating gradients (13.4 MV/m, leff=βλ) and voltage/cavity (4.3 MV) achieved for this class of SC cavity.

TUP059

Multipacting in a Grooved Choke Joint at SRF Gun for BNL ERL Prototype

cathode, cavity, gun, simulation

922

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, A. Burrill, D. Kayran, G.T. McIntyre, B. Sheehy
BNL, Upton, Long Island, New York, USA
D. Holmes
AES, Medford, NY, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The 703 MHz superconducting gun for BNL ERL prototype was tested at JLab with and without choke-joint and cathode stalk. Without choke-joint and cathode stalk, the gradient reached 25MV/m with Q0~6·10⁹. The gun cathode insertion port is equipped with a choke joint with triangular grooves for multipacting suppression. We carried out tests with choke-joint and cathode stalk. The test results show that there are at least two barriers at about 5MV/m and 3.5 MV/m. We considered several possibilities and finally found that the limitation was because the triangular grooves were rounded after BCP, which caused strong multipacting in the choke-joint. This paper presents the primary test result of test results of the gun and discusses the multipacting analysis in the choke-joint. It also suggests possible solutions for the gun and multipacting suppressing for a similar structure.

TUP060

New HOM Coupler Design for High Current SRF Cavity

HOM, cavity, higher-order-mode, coupling

925

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, E.C. Johnson
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass filter is nearly flat from first higher order mode to 5 times the fundamental frequency. The simulation results showed that the new couplers effectively damp HOMs for the eRHIC cavity with enlarged beam tube diameter and two 120° HOM couplers at each side of cavity. This paper presents the design of HOM coupler, HOM damping capacity for eRHIC cavity and prototype test results.

TUP064

Designing Multiple Cavity Classes for the Main Linac of Cornell's ERL

cavity, HOM, dipole, higher-order-mode

937

N.R.A. Valles, M. Liepe
CLASSE, Ithaca, New York, USA

Funding: Work supported by NSF Grant No. PHY-0131508, and NSF/NIH-NIGMS Grant No. DMR-0937466
Cornell is currently developing a high current Energy Recovery Linac. The baseline 7-cell cavity design for the main linac has already been completed, and prototyping has begun, as of Fall 2010. Previous work showed that increasing the relative cavity-to-cavity frequency spread increases the beam break-up current through the linac. Simulations show that expected machining variations will introduce a relative HOM frequency spread of 0.5·10^-3, corresponding to 150 mA of threshold current. The key idea of this work is to increase the relative cavity-to-cavity frequency spread by designing several classes of 7-cell cavities obtained by making small changes to the baseline center cell shape. This allows a threshold current in excess of 450 mA, which is well above the 100 mA goal for the Cornell Energy Recovery Linac.

TUP066

Three-cell Traveling-wave Superconducting Test Structure

cavity, feedback, accelerating-gradient, controls

940

P.V. Avrakhov, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Kazakov, N. Solyak, G. Wu, V.P. Yakovlev
Fermilab, Batavia, USA

Use of a superconducting traveling wave accelerating (STWA) structure* with a small phase advance per cell rather than a standing wave structure may provide a significant increase of the accelerating gradient in the ILC linac. For the same surface electric and magnetic fields the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing wave cavities. The STWA allows also longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed, manufactured and successfully tested** demonstrating the possibility of a proper processing to achieve a high accelerating gradient. These results open the way to take the next step of the TW SC cavity development: to build and test a traveling-wave three-cell cavity with a feedback waveguide. The latest results of the single-cell cavity tests are discussed as well as the design of the test 3-cell TW cavity.
* P. Avrakhov, et al, Phys. of Part. and Nucl. Let, 2008, Vol. 5, No. 7, p. 597
** G. Wu, et al, IPAC 2010, THPD048

TUP069

Status of the Mechanical Design of the 650 MHz Cavities for Project X

cavity, HOM, simulation, status

943

S. Barbanotti, M.S. Champion, M.H. Foley, C.M. Ginsburg, I.G. Gonin, C.J. Grimm, T.J. Peterson, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, USA

In the high-energy section of the Project X Linac, acceleration of H^- ions takes place in superconducting cavities operating at 650 MHz. Two families of five-cell elliptical cavities are planned: β = 0.61 and β = 0.9. A specific feature of the Project X Linac is low beam loading, and thus, low bandwidth and higher sensitivity to microphonics. Efforts to optimize the mechanical design of the cavities to improve their mechanical stability in response to the helium bath pressure fluctuations will be presented. These efforts take into account constraints such as cost and ease of fabrication. Also discussed will be the overall design status of the cavities and their helium jackets.

TUP070

EM Design of the Low-Beta SC Cavities for the Project X Front End

cavity, factory, SRF, acceleration

946

I.G. Gonin, S. Barbanotti, P. Berrutti, L. Ristori, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

The low-energy part of the Project X H-linac includes three types of superconducting single spoke cavities (SSR) with β = 0.11, 0.21 and 0.4 operating at the fundamental TEM-mode at 325MHz. In this paper we present the detailed EM optimization of cavity shapes having the goal to minimize the peak electric and magnetic fields. We also discuss the importance of the integration of EM and mechanical design.

TUP072

High Power Couplers for Project X Linac

coupling, cavity, cryomodule, vacuum

952

S. Kazakov, M.S. Champion, M. Kramp, Y. Orlov, O. Pronitchev, V.P. Yakovlev
Fermilab, Batavia, USA

Project X, a multi-megawatt proton sources is under development in Fermi National Accelerator Laboratory. The key element of the project is a superconducting (SC) 3GV CW proton liner accelerator (linac). The linac includes 5 types of SC accelerating cavities of three 325 and 650 MHz frequencies. The cavities consumes up to 30 kW average RF power and need proper main couplers. Requirements and approach to the coupler design are discussed in the report. New cost effective schemes of the couplers are described. Results of electrodynamics and thermal simulations are presented.

TUP073

Development of an L-band Ferroelectric Phase Shifter

simulation, insertion, controls, high-voltage

955

S. Kazakov, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA
J.L. Hirshfield
Yale University, Physics Department, New Haven, CT, USA
A. Kanareykin, E. Nenasheva
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA

Effective operation of the RF cavities in the superconducting accelerators demands fast, high-power RF vector modulators. Recent progress in development of the new materials, ferroelectrics, having tunable dielectric constant and acceptable losses [*] gives the possibility development of such devises. In previous papers [**-***] the authors described different L-band ferroelectric phase shifter designs . At low RF level high operation speed of 2 degree/nsec was demonstrated in waveguide phase shifter. However, the experiments show that a special technology is to be developed that provides a good electric contact between ceramics and the metallic wall. In present paper a new design of the fast high–power ferroelectric phase shifter is described based on the simple ferroelectric elements.
* A. Kanareykin, et al, IPAC 2010, p. 3987
** S. Kazakov, et al, “Fast Ferroelectric Phase Shifter Design For ERLs,” 45th ICFA Beam Dynamics Workshop, 2009
*** S. Kazakov, et al, PAC2007, p. 599.

TUP074

Experiments on HOM Spectrum Manipulation in a 1.3 GHz ILC SC Cavity

HOM, cavity, resonance, emittance

958

T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Superconducting cavities with high operating Q will be installed in the Project-X, a superconducting linac, which is under development at Fermilab. Possibility of cavity design without HOM couplers considered. Rich spectrum of the beam and large number of cavities in ProjectX linac can result to resonance excitation of some high order modes with high shunt impedance. Under scope of study of High Order Modes (HOM) damping the manipulation with HOM spectrum in cold linac is considered. Results of detuning HOM spectrum of 1.3 GHz cavities at 2K in Horizontal Test Station of Fermilab are presented. Possible explanation of the phenomena is discussed.

TUP075

Cavity Loss Factors of Non-relativistic Beams for Project X

cavity, simulation, factory, cryomodule

961

A. Lunin, S. Kazakov, V.P. Yakovlev
Fermilab, Batavia, USA

Cavity loss factor calculation is an important part of total cryolosses estimation for the super conductive (SC) accelerating structures. There are two approaches how to calculate cavity loss factors, the integration of a wake potential over the bunch profile and the combining of loss factors for individual cavity modes. We applied both methods in order to get reliable results for non-relativistic beam. The time domain CST solver was used for a wake potential calculation and the frequency domain HFSS code was used for the cavity eigenmodes spectrum findings. Finally we present the results of cavity loss factors simulations for a non-relativistic part of the ProjectX and analyze it for various beam parameters.

TUP076

First High Power Pulsed Tests of a Dressed 325 MHz Superconducting Single Spoke Resonator at Fermilab

cavity, klystron, vacuum, resonance

964

R.L. Madrak, J. Branlard, B. Chase, C. Darve, P.W. Joireman, T.N. Khabiboulline, A. Mukherjee, T.H. Nicol, E. Peoples-Evans, D.W. Peterson, Y.M. Pischalnikov, L. Ristori, W. Schappert, D.A. Sergatskov, W.M. Soyars, J. Steimel, I. Terechkine, V. Tupikov, R.L. Wagner, R.C. Webber, D. Wildman
Fermilab, Batavia, USA

In the recently commissioned superconducting RF cavity test facility at Fermilab (SCTF), a 325 MHz, β=0.22 superconducting single-spoke resonator (SSR1) has been tested for the first time with its input power coupler. Previously, this cavity had been tested CW with a low power, high Qext test coupler; first as a bare cavity in the Fermilab Vertical Test Stand and then fully dressed in the SCTF. For the tests described here, the design input coupler with Q_ext ~ 10⁶ was used. Pulsed power was provided by a Toshiba E3740A 2.5 MW klystron.

TUP084

Design of Single Spoke Resonators for Project X

cavity, proton, ion, niobium

982

L. Ristori, S. Barbanotti, M.S. Champion, M.H. Foley, I.G. Gonin, C.J. Grimm, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Project X is based on a 3 GeV CW superconducting linac and is currently in the R&D phase awaiting CD-0 approval. The low-energy section of the Project X H-linac includes three types of super-conducting single spoke cavities operating at 325 MHz. SSR0 (26 cavities), SSR1 (18 cavities) and SSR2 (44 cavities) have a geometrical beta of = 0.11, 0.21 and 0.4 respectively. Single spoke cavities were selected for the linac in virtue of their higher r/Q. In this paper we present the decisions and analyses that lead to the final designs. Electro-magnetic and mechanical finite element analyses were performed with the purpose of optimizing the electro-magnetic design, minimizing frequency shifts due to Helium bath pressure fluctuations and providing a pressure rating for the resonators that allow their use in the cryomodules.

TUP085

Assumptions for the RF Losses in the 650 MHz Cavities of the Project X Linac

cavity, niobium, factory, target

985

A. Romanenko, L.D. Cooley, J.P. Ozelis, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

The requirements for the FNAL Project X cryogenic system depend on the dynamic heat loads of 650 MHz cavities. The heat load is in turn determined by quality factors of the cavities at the operating gradient. In this contribution we use the available experimental data to analyze quality factors achievable in 650 MHz linac cavities taking into account different RF losses contributions such as BCS resistance, residual resistance and a medium field Q-slope.

TUP086

Microphonics control for Project X

cavity, controls, cryomodule, SRF

988

W. Schappert, S. Barbanotti, J. Branlard, G.I. Cancelo, R.H. Carcagno, M.S. Champion, B. Chase, I.G. Gonin, A.L. Klebaner, D.F. Orris, T.J. Peterson, Y.M. Pischalnikov, L. Ristori, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Work is supported by the U.S. Department of Energy
The proposed multi-MW Project X facility at Fermilab will employ cavities with bandwidths as narrow as 20 Hz. This combination of high RF power with narrow bandwidths combined requires careful attention to detuning control if these cavities are to be operated successfully. Detuning control for Projects X will require a coordinated effort between the groups responsible for various machine subsystems. Considerable progress in this area has been made over the past year.

TUP088

Resonance Effects of Longitudinal HOMs in Project X Linac

HOM, cavity, resonance, kaon

991

V.P. Yakovlev, I.G. Gonin, T.N. Khabiboulline, A. Lunin, N. Solyak, A.I. Sukhanov, A. Vostrikov
Fermilab, Batavia, USA
A. Saini
University of Delhi, Delhi, India

High-order mode influence on the beam longitudinal and transverse dynamics is considered for the 650 MHz section of the Project X linac. RF losses caused by HOMs are analyzed. Necessity of HOM dampers in the SC cavities of the linac is discussed.

TUP089

Concept EM Design of the 650 MHz Cavities for the Project X

cavity, HOM, cryomodule, resonance

994

V.P. Yakovlev, M.S. Champion, I.G. Gonin, T.N. Khabiboulline, A. Lunin, N. Solyak
Fermilab, Batavia, USA
A. Saini
University of Delhi, Delhi, India

Concept of the 650 MHz cavities for the Project X is presented. Choice of the basic parameters, i.e, number of cells, geometrical β, apertures, coupling coefficients, etc, is discussed. The cavities optimization criteria are formulated. Results of the RF design are presented for the cavities of both low-energy and high energy sections.

TUP090

Design of a β = 0.29 Half-wave Resonator for the FRIB Driver Linac

cavity, simulation, cryomodule, ion

997

J.P. Holzbauer, W. Hartung, J. Popielarski
NSCL, East Lansing, Michigan, USA

The driver linac for the Facility for Rare Isotope Beams will produce primary beams of ions at 200 MeV per nucleon for nuclear physics research. The driver linac will require 344 superconducting cavities, consisting of two types of Quarter-Wave Resonators (QWRs, β = 0.041 and 0.085) and two types of Half-Wave Resonators (HWRs, β = 0.29 and 0.53). A first-generation β = 0.29 HWR has been designed, prototyped, and tested. Second-generation versions of the other cavities are being developed, with one or more prototype having been tested. A second-generation β = 0.29 HWR design has been developed, making use of the experience with the first-generation β = 0.29 HWR and second-generation β = 0.53 HWR. In the second-generation design, the inner conductor is tapered to reduce the peak surface magnetic field. The outer conductor is a straight tube to increase the mechanical stiffness and reduce the sensitivity of the resonant frequency to bath pressure fluctuations. Optimization was employed to minimize the peak surface electric field. The second-generation β = 0.29 HWR design will be presented, including the RF design and mechanical analysis.

TUP091

Electromagnetic Design of a Multi-harmonic Buncher for the FRIB Driver Linac

ion, rfq, vacuum, coupling

1000

J.P. Holzbauer, W. Hartung, F. Marti, Q. Zhao
NSCL, East Lansing, Michigan, USA
E. Pozdeyev
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy under Grant Number DE-FGO2-08ER41553.
The driver linac for the Facility for Rare Isotope Beams (FRIB) at MSU will produce primary beams of ions at ≥200 MeV/u for nuclear physics research. A dc ion beam from an ECR ion source will be pre-bunched upstream of the radio frequency quadrupole linac. A multi-harmonic buncher (MHB) was designed for this purpose, using experience gained with a similar buncher for the ReA3 re-accelerator linac, which is presently being commissioned at MSU. The FRIB MHB resonator operates with three frequencies (40.25 MHz, 80.5 MHz, and 120.75 MHz) to produce an approximately linear sawtooth in the voltage as a function of time. The three resonant frequencies are produced via two quarter-wave resonators with a common gridless gap: one resonator is driven at its fundamental mode at 40.25 MHz and its first higher-order mode (120.75 MHz), while the other is driven only at its fundamental mode of 80.5 MHz. The electromagnetic design of the MHB resonator will be presented, including the electrode design and tuning mechanisms.

TUP092

Multi-purpose 805 MHz Pillbox RF Cavity for Muon Acceleration Studies

cavity, vacuum, coupling, acceleration

1003

G.M. Kazakevich, G. Flanagan, R.P. Johnson, M.L. Neubauer, R. Sah
Muons, Inc, Batavia, USA
K.C.D. Chan, A.J. Jason, S.S. Kurennoy, H.M. Miyadera, P.J. Turchi
LANL, Los Alamos, New Mexico, USA
A. Moretti, M. Popovic, K. Yonehara
Fermilab, Batavia, USA
Y. Torun
IIT, Chicago, Illinois, USA

Funding: Supported by DOE grant DE-FG-08ER86352.
An 805 MHz RF pillbox cavity has been designed and constructed to investigate potential muon beam acceleration and cooling techniques. The cavity can operate in vacuum or under pressure to 100 atmospheres, at room temperature or in an LN2 bath at 77 K. The cavity is designed for easy assembly and disassembly with bolted construction using aluminum seals. The surfaces of the end walls of the cavity can be replaced with different materials such as copper, aluminum, beryllium, or molybdenum, and with different geometries such as shaped windows or grid structures. Different surface treatments such as electro polished, high-pressure water cleaned, and atomic layer deposition are being considered for testing. The cavity has been designed to fit inside the 5-Tesla solenoid in the MuCool Test Area at Fermilab. Performance of the cavity, including initial conditioning and operation in the external magnetic field will be reported.

TUP100

Design of Superconducting Spoke Cavities for High-velocity Applications

cavity, HOM, superconductivity, higher-order-mode

1024

J.R. Delayen, S.U. De Silva, C.S. Hopper
ODU, Norfolk, Virginia, USA
J.R. Delayen
JLAB, Newport News, Virginia, USA

Superconducting single- and multi-spoke cavities have been designed to-date for particle velocities from β~0.15 to β~0.65. Superconducting spoke cavities may also be of interest for higher-velocity, low-frequency applications, either for hadrons or electrons. We present the design of spoke cavities optimized for β=0.8 and β=1.

TUP109

Fabrication, Treatment and Testing of a 1.6 Cell Photo-injector Cavity for HZB

cavity, electron, cathode, vacuum

1047

P. Kneisel
JLAB, Newport News, Virginia, USA
T. Kamps, J. Knobloch, O. Kugeler, A. Neumann
HZB, Berlin, Germany
R. Nietubyc
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany

Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177..
As part of a CRADA (Cooperative Research and Development Agreement) between Forschungszentrum Dresden (FZD) and JLab we have fabricated and tested after appropriate surface treatment a 1.5 cell, 1300 MHz RRR niobium photo-injector cavity to be used in a demonstration test at BESSY*. Following a baseline test at JLab, the cavity received a lead spot coating of ~8 mm diameter deposited with a cathode arc at the Soltan Institute on the endplate made from large grain niobium. It had been demonstrated in earlier tests with a DESY built 1.5 cell cavity – the original design – that a lead spot of this size can be a good electron source, when irradiated with a laser light of 213 nm . In the initial test with the lead spot we could measure a peak surface electric field of ~ 29 MV/m; after a second surface treatment, carried out to improve the cavity performance, but which was not done with sufficient precaution, the lead spot was destroyed and the cavity had to be coated a second time. This contribution reports about the experiences and results obtained with this cavity.
* A. Neumann et al., “CW Superconducting RF Photoinjector Development for Energy Recovery Linacs”, LINAC10, September 13-17, 2010, Tsukuba, Japan.

TUP117

Solid State Direct Drive RF LINAC: High Power Experimental Program

cavity, impedance, controls, high-voltage

1056

T.J.S. Hughes, M. Back, R. Fleck, M. Hergt, R. Irsigler, T. Kluge, J. Sirtl
Siemens AG, Erlangen, Germany
O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany

We report on a 150MHz λ/4 coaxial resonator driven by 32 integrated class F RF power modules according to our direct drive concept [1,2]. Electric fields of 60MV/m at the resonator gap have been reached, which correspond to 80kW RF power. This power level has been achieved at 160V DC supply voltage, significantly less than the component limits. The observed power and Q values can be explained by a simple equivalent circuit. The model predicts that 64 modules at 160V DC supply voltage may provide 170kW RF power, and that 250V DC supply voltage should yield 400kW. The corresponding 134MV/m gap E field may not be reachable due to vacuum flashover.
* Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan
** Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA
*** Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan

TUP130

Experiments on Voltage Droop Compensation for High Power Marx Modulators

controls, high-voltage, factory, simulation

1076

P. Chen, M. Lundquist, D. Yu
DULY Research Inc., Rancho Palos Verdes, California, USA

Funding: Work supported by DOE SBIR Phase II grant DE-FG02-08ER85052
Marx modulators, promising higher efficiency, longer lifetime and reduced cost compared with existing hard tube modulator options, are under intensive research. In this article, we describe the progress of work on our voltage droop compensation scheme for a Marx modulator. Experimental results on a compensation circuit at moderate voltage are presented.

TUP132

50 MW X-Band RF System for a Photoinjector Test Station at LLNL

klystron, electron, high-voltage, emittance

1082

T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344, and funded by DHS Domestic Nuclear Detection Office.
In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.

TUP135

RF Design and Operating Results for a New 201.25 MHz RF Power Amplifier for LANSCE

cathode, DTL, coupling, cavity

1091

J.T.M. Lyles, N.K. Bultman, Z. Chen, J. Davis, A.C. Naranjo, D. Rees, G. M. Sandoval, Jr.
LANL, Los Alamos, New Mexico, USA
D. Baca, R.E. Bratton, R.D. Summers
Compa Industries, Inc., Los Alamos, New Mexico, USA
N.W. Brennan
Texas A&M University, College Station, Texas, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
A prototype VHF RF Final Power Amplifier (FPA) for Los Alamos Neutron Science Center (LANSCE) has been designed, fabricated, and tested. The cavity amplifier met the design goals producing 3.2 MW peak and 480 kW of average power, at an elevation of 2.1 km. It was designed to use a Thales TH628 Diacrode®, a state-of-art tetrode power tube that is double-ended, providing roughly twice the power of a conventional tetrode. The amplifier is designed with tunable input and output transmission line cavity circuits, a grid decoupling circuit, an adjustable output coupler, TE mode suppressors, blocking, bypassing and decoupling capacitors, and a cooling system. The tube is connected in a full wavelength output circuit, with the lower main tuner situated ¾λ from the central electron beam region in the tube and the upper slave tuner ¼λ from the same point. We summarize the design processes and features of the FPA along with significant test results. A pair of production amplifiers are planned to be power-combined and installed at the LANSCE DTL to return operation to full beam duty factor.

TUP148

Ion Trapping Study in eRHIC

ion, electron, accumulation, cavity

1109

Y. Hao, V. Litvinenko, V. Ptitsyn
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The ion trapping effect is an important effect in energy recovery linac (ERL). The ionized residue gas molecules can accumulate at the vicinity of the electron beam pass and deteriorate the quality of the electron beam. In this paper, we present simulation results to address this issue in eRHIC and find best beam pattern to eliminate this effect.

TUP163

Design Construction and Test Results of a HTS Solenoid for Energy Recovery Linac

solenoid, cavity, focusing, superconducting-cavity

1127

R.C. Gupta, M. Anerella, I. Ben-Zvi, G. Ganetis, D. Kayran, G.T. McIntyre, J.F. Muratore, S.R. Plate, W. Sampson
BNL, Upton, Long Island, New York, USA
M.D. Cole, D. Holmes
AES, Medford, NY, USA

Funding: This work is supported by the U.S. Department of Energy under Contract No. DE-AC02-98CH10886.
An innovative feature of the proposed Energy Recovery Linac (ERL) at Brookhaven National Laboratory (BNL) is the use of a solenoid made with High Temperature Superconductor (HTS) with the Superconducting RF cavity. The use of HTS in the solenoid offers many advantages. The solenoid is located in the transition region (4 K to room temperature) where the temperature is too high for a conventional low temperature superconductor and the heat load on the cryogenic system too high for copper coils. Proximity to the cavity provides early focusing and thus a reduction in the emittance of the electron beam. In addition, taking full advantage of the high critical temperature of HTS, the solenoid has been designed to reach the required field at ~77 K, which can be obtained with liquid nitrogen. This significantly reduces the cost of testing and allows a variety of critical pre‐tests (e.g. measurements of the axial and fringe fields) which would have been very expensive at 4 K in liquid helium because of the additional requirements for a cryostat and associated facilities. This paper will present the design, construction, test results and current status of this HTS solenoid.

TUP202

Non-Scaling FFAG Proton Driver for Project X

proton, injection, focusing, synchrotron

1199

C. Johnstone, D.V. Neuffer
Fermilab, Batavia, USA
M. Berz, K. Makino
MSU, East Lansing, Michigan, USA
L.J. Jenner, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
P. Snopok
IIT, Chicago, Illinois, USA

The next generation of high-energy physics experiments requires high intensity protons at multi-GeV energies. Fermilab’s HEP program, for example, requires an 8-GeV proton source to feed the Main Injector to create a 2 MW neutrino beams in the near term and would require a 4 MW pulsed proton beam for a potential Neutrino Factory or Muon Collider in the future. High intensity GeV proton drivers are difficult at best with conventional re-circulating accelerators, encountering duty cycle and space-charge limits in the synchrotron and machine size and stability concerns in the weaker-focusing cyclotrons. Only an SRF linac, which has the highest associated cost and footprint, has been considered. Recent innovations in FFAG design, however, have promoted another re-circulating candidate, the Fixed-field Alternating Gradient accelerator (FFAG), as an attractive, but as yet unexplored, alternative. Its strong focusing optics coupled to large transverse and longitudinal acceptances would serve to alleviate space charge effects and achieve higher bunch charges than possible in a synchrotron and presents an upgradeable option from the 2 MW to the 4 MW program.

TUP267

LANSCE Drift Tube Linac Water Control System Refurbishment

controls, EPICS, drift-tube-linac, monitoring

1319

P.S. Marroquin, J.D. Bernardin, J.G. Gioia, J.A. Ortiz
LANL, Los Alamos, New Mexico, USA

Funding: Funding Agency: Work performed under the auspices of the U.S. Department of Energy, under contract DE-AC52-06NA25396.
There are several refurbishment projects underway at the Los Alamos National Laboratory LANSCE linear accelerator. Systems involved are: RF, water cooling, networks, diagnostics, timing, controls, etc. The Drift Tube Linac (DTL) portion of the accelerator consists of four DTL tanks, each with three independent water control systems. The systems are about 40 years old, use outdated and non-replaceable equipment and NIM bin control modules, are beyond their design life and provide unstable temperature control. Insufficient instrumentation and documentation further complicate efforts at maintaining system performance. Detailed design of the replacement cooling systems is currently in progress. Previous design experience on the SNS accelerator water cooling systems will be leveraged. Plans call for replacement of water piping, manifolds, pumps, valves, mix tanks, instrumentation (flow, pressure and temperature) and control system hardware and software. This presentation will focus on the control system design with specific attention on planned use of the National Instruments Compact RIO platform with the Experimental Physics and Industrial Control System (EPICS) software toolkit.

TUP272

Analysis and Comparison to Test of AlMg3 Seals Near a SRF Cavity

cavity, niobium, SRF, cryomodule

1331

T. Schultheiss, C.M. Astefanous, M.D. Cole, D. Holmes, J. Rathke
AES, Medford, NY, USA
I. Ben-Zvi, D. Kayran, G.T. McIntyre, B. Sheehy, R. Than
BNL, Upton, Long Island, New York, USA
A. Burrill
JLAB, Newport News, Virginia, USA

The Energy Recovery Linac (ERL) presently under construction at Brookhaven National Laboratory is being developed as research and development towards eRHIC, an Electron-Heavy Ion Collider. The experimental 5-cell 703.75 MHz (ECX) cavity was recently evaluated at continuous field levels greater than 10 MV/m. These tests indicated stored energy limits of the cavity on the order of 75 joules. During design of the cavity the cold flange on one side was moved closer to the cavity to allow the cavity to fit into the available chemical processing chamber at Jefferson Laboratory. RF and thermal analysis of the AlMg3 seal region of the closer side indicate this to be the prime candidate limiting the fields. This work presents the analysis results and compares these results to test data.

TUP273

RF Thermal and Structural Analysis of the 60.625 MHz RFQ for the ATLAS Upgrade

rfq, cavity, gun, ion

1334

T. Schultheiss, J. Rathke
AES, Medford, NY, USA
A. Barcikowski, P.N. Ostroumov
ANL, Argonne, USA
D.L. Schrage
TechSource, Santa Fe, New Mexico, USA

Funding: This work was supported by Argonne National Lab under contract # 0F-32402
The upgrade for the ATLAS facility is designed to increase the efficiency and intensity of beams for the user facility*, **. This will be accomplished with a new CW normal conducting RFQ, which will increase both transverse and longitudinal acceptance of the LINAC. This RFQ must operate over a wide range of power levels to accelerate ion species from protons to uranium. The RFQ design is a split coaxial structure and is made of OFE copper. The geometry of the design must be stable during operation. Engineering studies of the design at different RF power levels were conducted to ensure that the geometry requirements were met. Frequency shift analysis was also completed to determine the effects of high power levels. Thermal stress analysis was completed to show that the structure frequency is repeatable.
*P.N. Ostroumov, et.al, “A New Atlas Efficiency and Intensity Upgrade Project,” SRF2009, tuppo016
**P.N. Ostroumov, et.al., “Efficiency and Intensity Upgrade of the Atlas Facility,” LINAC 2010, MOP045

TUP275

SNS Linac Modulator Operational History and Performance

neutron, high-voltage, klystron, monitoring

1340

V.V. Peplov, D.E. Anderson, R.I. Cutler, M. Wezensky
ORNL, Oak Ridge, Tennessee, USA
J.D. Hicks, R.B. Saethre
ORNL RAD, Oak Ridge, Tennessee, USA

Fourteen High Voltage Converter Modulators (HVCM) were initially installed at the Spallation Neutron Source Linear Accelerator (SNS Linac) at the Oak Ridge National Laboratory in 2005. A fifteenth HVCM was added in 2009. Each modulator provides a pulse of up to 140 kV at a maximum width of 1.35 msec. Peak power level is 11 MW with an 8% duty factor. The HVCM system must be available for neutron production (NP) 24/7 with the exception being two, 6-week maintenance periods per year. HVCM reliability is one of the most important factors to maximize Linac availability and achieve SNS performance goals. During the last few years several modifications have been implemented to improve the overall system reliability. This paper presents operational history of the HVCM systems and examines failure mode statistical data since the modulators began operating at 60 Hz. System enhancements and upgrades aimed at providing long term reliable operation with minimal down time are also discussed in the paper.

TUP278

Tuning Method for the 2π/3 Traveling Wave Structures

coupling, controls, beam-loading, impedance

1349

A.S. Setty
THALES, Colombes, France

To build a constant gradient traveling wave structure, one must perform cold tests under a press in order to tune the different cells individually. For the tests to be valid, the test cells must be terminated by shorting planes located in planes of symmetry in which the electric field vector is normal in such a way that the standing wave "trapped" between them is an exact representation of the instantaneous traveling wave one wishes to study. For the TW structure, the cavities are put three by three under the press. We then try to reduce the contribution of "mixed cells" by adding to one wavelength at 2π/3 mode two-quarter wavelengths. This is possible when the end-cells mode at the same frequency is π/2 instead of 2π/3. These end cells are not included in the final assembly. The setting process will be analysed.

TUP279

A CW RFQ Prototype

rfq, simulation, dipole, vacuum

1352

U. Bartz, A. Schempp
IAP, Frankfurt am Main, Germany

A short RFQ prototype was built for tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The RF-tests with continues power of 20 kW/m and simulations of thermal effects with ALGOR were finished successfully. Optimization of some details of the facility are on focus now. First results and the status of the project will be presented.

TUP293

ESTB: A New Beam Test Facility at SLAC

kicker, hadron, electron, emittance

1373

M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, D.R. Walz, S.P. Weathersby, M. Woods
SLAC, Menlo Park, California, USA

End Station Test Beam (ESTB) is an end beam line at SLAC using a small fraction of the 13.6 GeV electron beam from the Linac Coherent Light Source (LCLS), restoring test beam capabilities in the large End Station A (ESA) experimental hall. In the past, 18 institutions participated in the ESA program at SLAC. The ESTB program will provide one of a kind test beams essential for developing accelerator instrumentation and accelerator R&D, performing particle and astroparticle physics detector research, linear collider machine and detector interface (MDI) R&D, developing of radiation-hard detectors and material damage studies with several distinctive features. At this stage, 4 new kicker magnets are added to divert 5 Hz of LCLS beam to the A-line, a new beam dump is installed and a new PPS system is built in ESA. In a second stage, a secondary hadron target will be installed, able to produce pions up to about 12 GeV/c at 1 particle/pulse. In summary, ESTB provides a new test facility for LHC detector upgrades, Super B Factory detector development, and Linear Collider accelerator and detector R&D with the first beam expected by June and users starting operations by July 2011.

WEOBS4

Improved Energy Changes at the Linac Coherent Light Source

feedback, electron, lattice, photon

1424

N. Lipkowitz, H. Loos, C.R. Melton, G. Yocky
SLAC, Menlo Park, California, USA

The user requirements and beam time scheduling of the LCLS imposes a demand for fast changes in machine energy across the entire operating range of 3.3-15 GeV (480-10000 eV). Early operational experience during LCLS commissioning revealed this process to be problematic and error-prone, sometimes requiring substantial re-tuning at each change. To streamline the process, a software tool has been developed to gradually ramp the machine energy while the beam remains on, allowing beam-based feedbacks to continue to work during the energy change. The tool has considerably improved the speed and reliability of configuration changes, and also extends the capability of the LCLS, allowing for slow scans of the FEL photon energy over a wide range. This poster presents the basic process, analysis of the performance gains, and possible future improvements.

Slides WEOBS4 [62.503 MB]

WEOBS6

Status and Specifications of a Project X Front-End Accelerator Test Facility at Fermilab

cavity, rfq, ion-source, proton

1430

J. Steimel, R.L. Madrak, R.J. Pasquinelli, E. Peoples-Evans, R.C. Webber, D. Wildman
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
This paper describes the construction and operational status of an accelerator test facility for Project X. The purpose of this facility is for Project X component development activities that benefit from beam tests and any development activities that require 325 MHz or 650 MHz RF power. It presently includes an H^- beam line, a 325 MHz superconducting cavity test facility, a 325 MHz (pulsed) RF power source, and a 650 MHz (CW) RF power source. The paper also discusses some specific Project X components that will be tested in the facility.

Slides WEOBS6 [2.401 MB]

WEOCN1

Laser Based Diagnostics for Measuring H^- Beam Parameters

laser, diagnostics, ion, emittance

1433

Y. Liu, A.V. Aleksandrov, W. Blokland, C. Deibele, C.D. Long, A.A. Menshov, J. Pogge, A. Webster, A.P. Zhukov
ORNL, Oak Ridge, Tennessee, USA
R.A. Hardin
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: sponsored by the Division of Materials Science, U.S. Department of Energy, under contract number DE-AC05-96OR22464 with UT-Battelle Corporation for Oak Ridge National Laboratory
In recent years, a number of laser based H^- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser transverse emittance scanner at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of laser based diagnostics at accelerator facilities will be addressed.

Slides WEOCN1 [4.710 MB]

WEOCN4

Electron Beam Diagnostics of the JLab UV FEL

FEL, wiggler, electron, cavity

1446

P. Evtushenko, S.V. Benson, G.H. Biallas, J.L. Coleman, C. Dickover, D. Douglas, M. Marchlik, D.W. Sexton, C. Tennant
JLAB, Newport News, Virginia, USA

In this contribution we describe various systems of the electron beam diagnostics of the JLab UV FEL. The FEL is installed on a new bypass beam line of existing 10kW IR Upgrade FEL. Here we describe a set of the following systems. A combination of OTR and phosphor viewers used for measurements of a transverse beam profile, transverse emittance, Twiss parameters. This system is also used for alignment of the optical cavity of the UV oscillator and to ensure the overlap between the electron beam and optical mode in the FEL wiggler. A system of beam position monitors equipped with log-amp based BPM electronics. Bunch length on the order of 120 fs RMS is measured with the help of a modified Martin-Puplett interferometer. The longitudinal transfer function measurements system is used to setup bunch compression in an optimal way such that the LINAC RF curvature is compensated using only higher order magnetic elements of the beam transport. This set of the diagnostics system made its contribution to achieve the first lasing of the FEL after about 60 hours of beam operation.

Slides WEOCN4 [8.864 MB]

WEOCS6

The Injector Cryomodule for e-Linac at TRIUMF

cryomodule, ISAC, TRIUMF, cavity

1469

R.E. Laxdal, C.D. Beard, S.R. Koscielniak, A. Koveshnikov, A.K. Mitra, T.C. Ries, I. Sekachev, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
M. Mondal, V. Naik
DAE/VECC, Calcutta, India

The e-Linac project at TRIUMF, now funded, is specified to accelerate 10mA of electrons to 50MeV using 1.3GHz multi-cell superconducting cavities. The linac consists of three cryomodules; an injector cryomodule with one cavity and two accelerating modules with two cavities each. The injector module is being designed and constructed in collaboration with VECC in Kolkata. The design utilizes a unique box cryomodule with a top-loading cold mass. A 4K phase separator, 2K-4K heat exchanger and Joule-Thompson valve are installed within each module to produce 2K liquid. The design and status of the development will be presented.

Slides WEOCS6 [13.002 MB]

WEODS1

Design and Optimization of Future X-ray FELs based on Advanced High Frequency Linacs

impedance, klystron, FEL, acceleration

1491

F. Wang
SLAC, Menlo Park, California, USA

To drive future XFELs, normal-conducting linacs at various rf freqencies are being considered. With optimized accelerator structures and rf systems, a higher rf frequency linac has several advantages, such as high acceleration gradient and high rf-to-beam efficiency. This paper presents a comparison of possible S-band, C-band and X-band linac designs for two cases, single bunch operation and multibunch operation, where the bunch train length is longer than the structure fill time and the beam loading is small. General scaling laws for the main linac parameters, which can be useful in the design such linacs, are derived.

Slides WEODS1 [5.795 MB]

WEP006

Study of Effects of Failure of Beamline Elements & Their Compensation in CW Superconducting Linac

cavity, solenoid, emittance, beam-losses

1513

A. Saini, K. Ranjan
University of Delhi, Delhi, India
C.S. Mishra, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Project-X is the proposed high intensity proton facility to be built at Fermilab, US. The first stage of the Project-X consists of superconducting Linac which will be operated in continuous wave (CW) mode to accelerate the beam from 2.5 MeV to 3 GeV. The operation at CW mode puts high tolerances on the beam line components, particularly on radiofrequency (RF) cavity. The failure of beam line elements at low energy is very critical as it results in mis-match of the beam with the following sections due to different beam parameters than designed parameter. It makes the beam unstable which causes emittance dilution, and ultimately results in beam losses. In worst case, it could affect the reliability of the machine and may lead to the shutdown of the Linac to replace the failed elements. Thus, it is important to study these effects and their compensation to get smooth beam propagation in Linac. This paper describes the results of study performed for the failure of RF cavity & solenoid in SSR0 section.

WEP007

Calculation of Acceptance of High Intensity Superconducting Proton Linac for Project-X

cavity, lattice, focusing, proton

1516

A. Saini, K. Ranjan
University of Delhi, Delhi, India
C.S. Mishra, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Project-X is the proposed high intensity proton facility to be built at Fermilab, US. Its Superconducting Linac, to be used at first stage of acceleration, will be operated in continuous wave (CW) mode. The Linac is divided into three sections on the basis of operating frequencies & six sections on the basis of family of RF cavities to be used for the acceleration of beam from 2.5 MeV to 3 GeV. The transition from one section to another can limit the acceptance of the Linac if these are not matched properly. We performed a study to calculate the acceptance of the Linac in both longitudinal and transverse plane. Investigation of most sensitive area which limits longitudinal acceptance and study of influence of failure of beam line elements at critical position, on acceptance are also performed.

WEP010

Design of the Bilbao Accelerator Low Energy Extraction Lines

quadrupole, dipole, DTL, neutron

1519

Z. Izaola, I. Rodríguez
ESS-Bilbao, Zamudio, Spain
E. Abad, I. Bustinduy, R. Martinez, F. Sordo Balbin, D. de Cos
ESS Bilbao, Bilbao, Spain
D.J. Adams, S.J.S. Jago
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

Funding: European Spallation Source - Bilbao
The ESS-Bilbao linac will accelerate H+ and H− beams up to 50 MeV, which need to be transported to three laboratories, where different types of experiments will be conducted. This paper reports on the preliminary design of the transfer line, which is mainly performed based on beam dynamics simulations.

WEP041

Weak Resonances Induced by Nonlinear Multipoles in a Quadrupole Doublet Lattice

octupole, quadrupole, lattice, simulation

1570

Y. Zhang, J. G. Wang
ORNL, Oak Ridge, Tennessee, USA

Funding: This submission was sponsored by a contractor of the United States Government under contract DE-AC05-00OR22725 with the United States Department of Energy.
In this paper we report the effects on beam dynamics from two intrinsic multipole components of a quadrupole magnet – dodecapole and psedu-octupole, in a quadrupole doublet lattice. Weak resonances at transverse phase advances 60°; and 90°; per cell, which may contribute to halo formation and beam loss in a linac, are shown from multi-particle tracking simulations. Although the net effect of the psedu-octupole component alone is very small due to substantial cancellations within the same magnet, its existence may significantly enhance the weak resonances which are induced by the dodecapole component of quadrupole magnets. The combined contributions of these two magnetic field components may not be simply linear-scaled because of the extreme nonlinear nature.

WEP048

Comparison of RF Cavity Transport Models for BBU Simulations

cavity, focusing, simulation, optics

1582

I. Shin
University of Connecticut, Storrs, Connecticut, USA
S. Ahmed, T. Satogata, B.C. Yunn
JLAB, Newport News, Virginia, USA

The transverse focusing effect in RF cavities plays a considerable role in beam dynamics for low-energy beamline sections and can contribute to beam breakup (BBU) instability. The purpose of this analysis is to examine RF cavity models in simulation codes which will be used for BBU experiments at Jefferson Lab and improve BBU simulation results. We review two RF cavity models in the simulation codes elegant and TDBBU (a BBU simulation code developed at Jefferson Lab). elegant can include the Rosenzweig-Serafini (R-S) model for the RF focusing effect. Whereas TDBBU uses a model from the code TRANSPORT which considers the adiabatic damping effect, but not the RF focusing effect. Quantitative comparisons are discussed for the CEBAF beamline. We also compare the R-S model with the results from numerical simulations for a CEBAF-type 5-cell superconducting cavity to validate the use of the R-S model as an improved low-energy RF cavity transport model in TDBBU. We have implemented the R-S model in TDBBU. It will cause BBU simulation results to be better matched with analytic calculations and experimental results.

WEP085

Beam Breakup Studies for New Cryo-Unit

HOM, simulation, cavity, damping

1633

S. Ahmed, F.E. Hannon, A.S. Hofler, R. Kazimi, G.A. Krafft, F. Marhauser, B.C. Yunn
JLAB, Newport News, Virginia, USA
I. Shin
University of Connecticut, Storrs, Connecticut, USA

In this paper, we report the numerical simulations of cumulative beam breakup studies for a new cryo-unit for injector design at Jefferson lab. The system consists of two 1-cell and one 7-cell superconducting RF cavities. The study has been performed using a 2-dimensional time-domain code TDBBU developed in-house. The stability has been confirmed for the present setup of beamline elements with different initial offsets and currents ranging 1 mA - 100 mA.

WEP091

Implementation of H⁻ Intrabeam Stripping into TRACK

simulation, ion, beam-losses, proton

1642

J.-P. Carneiro
Fermilab, Batavia, USA
B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA

H⁻ intrabeam stripping has been presented* as potentially harmful to MW scale H⁻ linacs. If not taken properly into account, intrabeam stripping of the H⁻ beam could lead to losses in excess of the 1 W/m limit and result in non-tolerable beamline elements activation. This paper describes the implementation of the H⁻ intrabeam stripping effect into the beam dynamics code TRACK**. Simulations results and numerical applications will be presented for the SNS linac and the FNAL ProjectX.
* V. Lebedev, "Intrabeam Stripping in H⁻ Linacs", LINAC2010
** P. Ostroumov, "TRACK, The Beam Dynamics Code", PAC2005

WEP095

Analysis of the Beam Loss Mechanism in the Project-X Linac

solenoid, quadrupole, beam-losses, simulation

1651

N. Solyak, J.-P. Carneiro, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy
Fermilab, Batavia, USA

Minimization of the beam losses in a multi-MW H-minus linac of the Project X to the level below 1W/m is a challenging task. Analysis of different mechanisms of beam stripping, including stripping in electric and magnetic fields, residual gas, black-body radiation and intra-beam stripping, is analyzed. Other sources of beam losses are misalignment of beamline elements and errors in RF fields and phase. We presented the requirements for dynamics errors and correction schemes to keep beam losses under control

WEP100

Energy Spread Compensation for Multi-Bunch Linac Operation Mode

electron, wakefield, cavity, simulation

1662

D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA
W. Gai, J.G. Power
ANL, Argonne, USA

Funding: This work was supported under the U.S. Department of Energy contract number: DE-AC02-06CH11357 with Argonne National Laboratory.
Higher wakefield gradients can be achieved by increasing the total beam charge which is passed through a dielectric-loaded structure and by reducing the transverse size of the beam. Currently, the Argonne AWA photoinjector operates with electron bunches of up to 100 nC and the goal is to raise the total beam charge to about 1000 nC and to improve the beam focusing to a few 100's microns transverse spot size. The increase of the beam charge can be done by superimposing electron bunches that fill up several consecutive RF buckets. Although the energy stored in a single 7-cell linac is by design large the multi-bunch operation with short bunch trains (~10 ns) is still plagued by large energy spread due to significant beam loading effects. In this paper we present a technique intended to reduce the energy spread for a high charge bunch train by properly choosing the time delay between consecutive bunches. The simulations show that the energy spread can be lowered to about 2.8% from about 6.0% for a 10-bunch train of total charge 1000 nC and kinetic energy of about 70 MeV.

WEP107

CSR Shielding Experiment

wakefield, shielding, dipole, electron

1677

V. Yakimenko, A.V. Fedotov, M.G. Fedurin, D. Kayran
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
P. Muggli
USC, Los Angeles, California, USA

It is well known that the emission of coherent synchrotron radiation (CSR) in a dipole magnets leads to increase in beam energy spread and emittance. At the Brookhaven National Laboratory Accelerator Test Facility (ATF) we study the suppression of CSR emission affect on electron beam in a dipole magnet by two vertically spaced conducting plates. The gap between the plates is controlled by four actuators and could be varied from 0 to 14 mm. Our experimental results show that closing the plates significantly reduces both the beam energy loss and CSR-induced beam energy spread. In this paper we present selected results of the experiment and compare then with rigorous analytical theory.

WEP115

The FNAL Injector Upgrade

rfq, extraction, quadrupole, DTL

1701

C.-Y. Tan, D.S. Bollinger, K.L. Duel, J.R. Lackey, W. Pellico
Fermilab, Batavia, USA

The present FNAL linac H⁻ injector has been operational since the 1970s and consists of two magnetron H⁻ sources and a 750keV Cockcroft-Walton Accelerator. In the upgrade, both slit-type magnetron sources will be replaced with circular aperture sources, and the Cockcroft-Walton with a 200MHz RFQ. Operational experience at BNL (Brookhaven National Laboratory) has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.

WEP131

A New Approach to Calculate the Transport Matrix in RF cavities

cavity, acceleration, focusing, space-charge

1725

Y.I. Eidelman
BINP SB RAS, Novosibirsk, Russia
N.V. Mokhov, S. Nagaitsev, N. Solyak
Fermilab, Batavia, USA

Funding: Work supported by USDoE
A realistic approach to calculate the transport matrix in RF cavities is developed. It is based on joint solution of equations of longitudinal and transverse motion of a charged particle in an electromagnetic field of the linac. This field is a given by distribution (measured or calculated) of the component of the longitudinal electric field on the axis of the linac. New approach is compared with other matrix methods to solve the same problem. The comparison with code ASTRA has been carried out. Complete agreement for tracking results for a TESLA-type cavity is achieved. A corresponding algorithm has been implemented into the MARS15 code.

WEP149

Beam Measurement by a Wall Gap Monitor in ALPHA

dipole, electron, extraction, injection

1761

T.H. Luo, P.D. McChesney, P.E. Sokol
IUCF, Bloomington, Indiana, USA
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

In this report, we present our electron beam measurements with a wall gap monitor (WGM) in ALPHA injection and extraction beam lines. The WGM is first bench mark tested, and then installed in the ALPHA injection line to measure both the macro andμpulse of the injected beam and calibrate the beam current. By scanning the bending magnet before the WGM, and applying a demodulation signal processing scheme, we measured the tomography of the longitudinal phase space of the injected beam. We moved the WGM to extraction beam line and measured the properties of the extracted beam. By comparing the frequency spectrum of injected and extracted beam, we have confirmed the debunching performance of ALPHA.

WEP174

Simulations and Calculations of Cavity-to-cavity Coupling for Elliptical SCRF Cavities in ESS

cavity, coupling, simulation, cryomodule

1813

R. Ainsworth, S. Molloy
Royal Holloway, University of London, Surrey, United Kingdom

The proton linac of the European Spallation Source (ESS) will rely on two families of superconducting cavities for the medium and high beta regions. Presented here are simulations of various cavity designs for different betas. The simulations are performed using the ACE3P codes developed at SLAC National Accelerator Laboratory, and the simulated eigenmode and R/Q spectrum will be shown for each design. Dangerous modes are identified. Of particular importance is the investigations of multiple cavity (cryomodule) configurations. From this, the simulated cavity-to-cavity coupling within a cryomodule is extracted. A theoretical model of this coupling based on the calculated cutoff frequencies, decay lengths, and resonance conditions, has also been developed, and a comparison made with the results of the simulation.

WEP192

Simulation Results for a Cavity BPM Design for the APS Storage Ring

cavity, simulation, storage-ring, damping

1849

X. Sun, G. Decker
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A rectangular cavity BPM / tilt monitor for the APS storage ring has been designed to detect residual vertical-longitudinal tilt caused by the proposed short-pulse x-ray (SPX) project crab cavities. Electromagnetic simulations have been performed to verify the conceptual design and evaluate design alternatives. MAFIA and Microwave Studio have been applied to simulate the device in both time and frequency domains. The device geometry has been optimized to efficiently damp strongly driven lower- and higher-order modes while preserving the tilt-sensitive mode of interest. This mode is coupled out to the processing electronics using a waveguide geometry chosen to maximize isolation from the beam-driven modes.

WEP204

An FFAG Accelerator for Project X

proton, lattice, injection, dynamic-aperture

1867

D.V. Neuffer, L.J. Jenner, C. Johnstone
Fermilab, Batavia, USA
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

The next generation of high-energy physics experiments requires high intensity protons in the multi-GeV energy range for efficient production of secondary beams. The Fermilab long-term future requires an 8 GeV proton source to feed the Main Injector for a 2 MW neutrino beam source in the immediate future and to provide 4 MW pulsed proton beam for a future neutrino factory or muon collider. We note that a 3GeV cw linac matched to a 3–8 GeV FFAG ring could provide beam for both of these mission needs, as well as the cw 3 GeV experiments, and would be a natural and affordable scenario. We present details of possible scenarios and outline future design and research directions.

WEP212

Development of a 325 MHz 4-Rod RFQ

rfq, dipole, simulation, resonance

1888

B. Koubek, U. Bartz, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

A 4-Rod RFQ with a frequency of 325 MHz and an output energy of 3 MeV will be build as a part of the FAIR project of GSI. Design studies and model measurements on a short prototype of a 325 MHz 4-Rod RFQ model were made including simulations using CST Microwave Studio. The latest simulation results regarding the dipole field of this structure are presented in this paper.

WEP213

New Development of a RFQ Beam Matching Section

rfq, emittance, ion-source, ion

1891

M. Baschke, N. Müller, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

Funding: BMBF
Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with electrostatic lens systems, a Two-Beam-RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ. A funneling deflector combines the bunches to a common beam axis. Current work is the construction and beam tests of a new beam transport system between RFQ accelerator and deflector. With extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefore unwanted emittance growth reduced. First rf-measurements with the improved Two-Beam-RFQ will be presented.

WEP214

Tuning Studies on 4-Rod RFQs

rfq, simulation, resonance, quadrupole

1894

J.S. Schmidt, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

For the optimization of Radio Frequency Quadrupole (RFQ) design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic properties of an RFQ. A variation can lead to particle losses and reduced beam quality. Our electrode design usually implies a constant longitudinal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-Rod RFQ. Their optimal positions can be found by an iterative process. To structure this tuning process simulations with a NI LabVIEW based Tuning Software and CST Microwave ® are performed and compared to measurements of the ReA3-RFQ of the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The results of this studies are presented in this paper.

WEP220

Development of the Dual-Slot Resonance Linac

cavity, coupling, resonance, impedance

1897

D.J. Newsham, N. Barov, R.H. Miller
Far-Tech, Inc., San Diego, California, USA

Funding: Work supported by DOE Office of High Energy Physics, DOE-SBIR #DE-FG02-08ER85034.
We present the development of a novel electron accelerating structure with strong cell-to-cell coupling. The coupling is provided by a pair of resonant slots, separated by a non-resonant void region, located within the wall between adjacent cells. The 10+2/2 cell standing-wave structure, operating in a phase and amplitude stabilized pi/2 mode, will provide an energy gain of 10 MeV.

WEP221

CW Room-Temperature Bunching Cavity for the Project X MEBT

cavity, simulation, bunching, proton

1900

G.V. Romanov, S. Barbanotti, E. Borissov, J.A. Coghill, I.G. Gonin, S. Kazakov, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

The Project-X, a multi-MW proton source based on superconducting linac, is under development at Fermilab. The front end of the linac contains a CW room temperature MEBT section which comprises ion source, RFQ and high-bandwidth bunch selective chopper. The length of the chopper exceeds 10 m, so four re-bunching cavities are used to support the beam longitudinal dynamics. The RF and mechanical designs of the re-bunching cavity including stress and thermal analysis are reported.

WEP224

Operational Status and Life Extension Plans for the Los Alamos Neutron Science Center (LANSCE)

neutron, proton, target, scattering

1906

J.L. Erickson, D. Rees
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the U. S. Department of Energy, National Nuclear Security Administration, Contract No. DE-AC52-06NA25396 – Publication Release LA-UR- 10-06556
The Los Alamos Neutron Science Center (LANSCE) accelerator and beam delivery complex generates the proton beams that serve three neutron production sources, a proton radiography facility and a medical and research isotope production facility. The recent operating history of the facility, including both achievements and challenges, will be reviewed. Plans for performance improvement will be discussed, together with the underlying drivers for the ongoing LANSCE Linac Risk Mitigation project. The details of this latter project will be discussed. The status of accelerator-related plans for the MaRIE Project (Matter-Radiation Interactions in Extremes Experimental Project) will also be discussed. Taken together, the LANSCE Linac Risk Mitigation Project and the MaRIE initiative demonstrate a commitment to investment in the ongoing operation and improvement of the facility, and a resurgent interest in the spectrum of science accessible at LANSCE. These plans will assure continued facility operational and scientific vitality well beyond 2020.

WEP225

H-Mode Accelerating Structures with PMQ Focusing for Low-Beta Beams

focusing, simulation, ion, quadrupole

1909

S.S. Kurennoy, J.F. O'Hara, E.R. Olivas, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

We report results of the project developing high-efficiency normal-conducting RF accelerating structures based on inter-digital H-mode (IH) cavities and the transverse beam focusing with permanent-magnet quadrupoles (PMQ), for beam velocities in the range of a few percent of the speed of light. The shunt impedance of IH-PMQ structures is 10^-20 times higher than that of a conventional drift-tube linac, while the transverse size is 4-5 times smaller. The H-PMQ accelerating structures following a short RFQ can be used both in the front end of ion linacs or in stand-alone applications. Results of the combined 3-D modeling – electromagnetic computations, beam-dynamics simulations with high currents, and thermal-stress analysis – for a full IH-PMQ accelerator tank are presented. The accelerating field profile in the tank is tuned to provide the best propagation of a 50-mA deuteron beam using coupled iterations of electromagnetic and beam-dynamics modeling. Multi-particle simulations with Parmela and CST Particle Studio have been used to confirm the design. Measurement results of a cold model of the IH-PMQ tank are in a good agreement with the calculations and will also be presented.

WEP242

Project X Functional Requirements Specification

proton, injection, collider, kaon

1936

S.D. Holmes, S. Henderson, R.D. Kephart, J.S. Kerby, C.S. Mishra, S. Nagaitsev, R.S. Tschirhart
Fermilab, Batavia, USA

Funding: Work supported by the Fermi Research Alliance, under contract to the U.S. Department of Energy
Project X is a multi-megawatt proton facility being designed to support intensity frontier research in elementary particle physics, with possible applications to nuclear physics and nuclear energy research, at Fermilab. A Functional Requirements Specification has been developed in order to establish performance criteria for the Project X complex in support of these multiple missions. This paper will describe the Functional Requirements for the Project X facility and the rationale for these requirements.

WEP249

Intense Muon Beams for Experiments at Project X

target, simulation, collider, proton

1951

C.M. Ankenbrandt, R.P. Johnson, C. Y. Yoshikawa
Muons, Inc, Batavia, USA
V.S. Kashikhin, D.V. Neuffer
Fermilab, Batavia, USA
J. Miller
BUphy, Boston, Massachusetts, USA
R.A. Rimmer
JLAB, Newport News, Virginia, USA

Funding: Supported in part by DOE SBIR grant DE-SC00002739
A coherent approach for providing muon beams to several experiments for the intensity-frontier program at Project X is described. Concepts developed for the front end of a muon collider/neutrino factory facility, such as phase rotation and ionization cooling, are applied, but with significant differences. High-intensity experiments typically require high-duty-factor beams pulsed at a time interval commensurate with the muon lifetime. It is challenging to provide large RF voltages at high duty factor, especially in the presence of intense radiation and strong magnetic fields, which may preclude the use of superconducting RF cavities. As an alternative, cavities made of materials such as ultra-pure Al and Be, which become very good - but not super - conductors at cryogenic temperatures, can be used.

WEP261

Performance of the New EBIS Preinjector

ion, booster, injection, rfq

1966

J.G. Alessi, E.N. Beebe, S. Binello, C.J. Gardner, O. Gould, L.T. Hoff, N.A. Kling, R.F. Lambiase, V. LoDestro, R. Lockey, M. Mapes, A. McNerney, J. Morris, M. Okamura, A. Pendzick, D. Phillips, A.I. Pikin, D. Raparia, J. Ritter, T.C. Shrey, L. Smart, L. Snydstrup, C. Theisen, M. Wilinski, A. Zaltsman, K. Zeno
BNL, Upton, Long Island, New York, USA
U. Ratzinger, A. Schempp
IAP, Frankfurt am Main, Germany

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy, and by the National Aeronautics and Space Administration.
The construction and initial commissioning phase of a new heavy ion preinjector was completed at Brookhaven in September, 2010, and the preinjector is now operational. This preinjector, using an EBIS source to produce high charge state heavy ions, provided helium and neon ion beams for use at the NASA Space Radiation Laboratory in the Fall of 2010, and gold and uranium beams are being commissioned during the 2011 run cycle for use in RHIC. The EBIS operates with an electron beam current of up to 10 A, to produce mA level currents in 10 to 40 μs beam pulses. The source is followed by an RFQ and IH linac to accelerate ions with q/m > 0.16 to an energy of 2 MeV/amu, for injection into the Booster synchrotron. The performance of the preinjector is presented, including initial operational experience for the NASA and RHIC programs.

WEP267

Estimates of the Number of Foil Hits for Charge Exchange Injection

injection, proton, ion, betatron

1975

D. Raparia
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
For high intensity circular proton machines, one of the major limitations is the charge exchange injection foil. The number of foil hits due to circulating beam may cause the foil to fail and cause radiation due to multiple nuclear scattering and energy straggling. This paper will describe methods to estimate these quantities without going through lengthy simulations.

WEP268

Changes in LEBT/MEBT at the BNL 200 MeV Linac

polarization, solenoid, rfq, emittance

1978

D. Raparia, J.G. Alessi, J.M. Fite, O. Gould, V. LoDestro, M. Okamura, J. Ritter, A. Zelenski
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
After reconfiguration of the low energy (35 keV) and the medium energy (750 keV) transport lines in 2009-10, the Brookhaven linac is now delivering the highest intensity beam since it was built in 1970 (~120 μA average current of H⁻ to the Brookhaven Linac Isotope Producer). It is also now delivering lower emittance polarized H⁻ ion beam for the polarized program at RHIC. To increase the intensity further, we are replacing the buncher in the 750 keV line with one with higher Q value, to allow operation at higher power. Also, to improve polarization, we are replacing the magnetic solenoid before the RFQ in the 35 keV line by a solenoid-einzel lens combination. The paper will report on the results of these changes.

WEP275

Highly-Persistent SNS H⁻ Source Fueling 1-MW Beams with 7-9 kC Service Cycles

plasma, ion, rfq, ion-source

1993

M.P. Stockli, T.W. Hardek, Y.W. Kang, S.N. Murray, T.R. Pennisi, M.F. Piller, M. Santana, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA
B. Han
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Running routinely with ~40-mA, 1-MW beams, the SNS linac is fed from the ion source with ~1ms long, ~50-mA H⁻ beam pulses at 60 Hz. This requires the daily extraction of ~230 C of H⁻ ions, which exceeds the routine daily production of other H⁻ accelerator sources by almost an order of magnitude. The source service cycle has been extended from 2, to 3, to 4, and up to 5.6 weeks without age-related failures. The 7-9 kC of H⁻ ions delivered in single service cycles exceed the service cycle yields of other accelerator sources. The paper discusses the findings as well as the issues and their mitigations, which enabled the simultaneous increase of the beam current, the duty factor, the availability, and the service cycle.

WEP277

Operational Findings and Upgrade Plans on the Superconducting Electron Accelerator S-DALINAC

recirculation, electron, controls, quadrupole

1999

F. Hug, C. Burandt, J. Conrad, R. Eichhorn, M. Kleinmann, M. Konrad, T. Kürzeder, P.N. Nonn, N. Pietralla, S.T. Sievers
TU Darmstadt, Darmstadt, Germany

Funding: DFG through SFB 634.
The S-DALINAC is a superconducting recirculating electron accelerator with a final energy of 130 MeV. It operates in cw at 3 GHz. It accelerates beams of either unpolarized or polarized electrons and is used as a source for nuclear- and astrophysical experiments at the university of Darmstadt since 1987. We will report on the operational findings, recent modifications and on the future upgrade plans: First results from the new digital rf control system, the injector current upgrade and the improved longitudinal working point will be presented. In addition, an overview of the future plans, namely installing an additional recirculation path and two scraper systems will be given.

WEP282

Design of the NSLS-II Linac Front End Test Stand

gun, solenoid, emittance, bunching

2011

R.P. Fliller, M.P. Johanson, M. Lucas, J. Rose, T.V. Shaftan
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The NSLS-II operational parameters place very stringent requirements on the injection system. Among these are the charge per bunch train at low emittance that is required from the linac along with the uniformity of the charge per bunch along the train. The NSLS-II linac is a 200 MeV linac produced by RI Research Instruments GmbH. Part of the strategy for understanding to operation of the injectors is to test the front end of the linac prior to its installation in the facility. The linac front end consists of a 90 keV electron gun, 500 MHz subharmonic prebuncher, focusing solenoids and a suite of diagnostics. The diagnostics in the front end need to be supplemented with an additional suite of diagnostics to fully characterize the beam. In this paper we discuss the design of a test stand to measure the various properties of the beam generated from this section. In particular, the test stand will measure the charge, transverse emittance, energy, energy spread, and bunching performance of the linac front end under all operating conditions of the front end.

WEP283

Simulations of Transverse Stacking in the NSLS-II Booster

booster, emittance, simulation, lattice

2014

R.P. Fliller, T.V. Shaftan
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The NSLS-II injection system consists of a 200 MeV linac and a 3 GeV booster. The linac needs to deliver 15 nC in 80 - 150 bunches to the booster every minute to achieve current stability goals in the storage ring. This is a very stringent requirement that has not been demonstrated at an operating light source. We have developed a scheme to transversely stack two bunch trains in the NSLS-II booster in order to alleviate the charge requirements on the linac. This scheme has been outlined previously. In this paper we show particle tracking simulations of the tracking scheme. We show that the booster lattice has sufficient orbit correction and dynamic aperture at injection to maintain the charge and emittance of the first beam while it circulates waiting for the next train to arrive. We also show simulations of the booster ramp with a stacked beam for a variety of lattice errors and injected beam parameters. In all cases the performance of the proposed stacking method is sufficient to reduce the required charge from the linac. For this reason the injection system of the NSLS-II booster is being designed to include this feature.

WEP290

A Novel Electron Gun for Off-axis Beam Injection

gun, electron, cathode, emittance

2029

Yu.A. Kubyshin
UPC, Barcelona, Spain
A.V. Aloev, N.I. Pakhomov, V.I. Shvedunov
MSU, Moscow, Russia

For certain type of electron accelerators injection from an off-axis cathode is required. This is the case of a race-track microtron (RTM), in which the beam passes several times through the accelerating structure, or of a high power standing wave electron linac, for which the lifetime of an on-axis cathode would be strongly reduced by the electron back-bombardment. The standard solution with the beam injection via a dipole magnet from an electron gun placed off-axis is too bulky, moreover in case of RTMs it requires special compensating dipoles. An annular ring cathode gun used in some accelerators leads to large beam emittance and divergence. As a new solution we describe a 3D on-axis electron gun with an off-axis cathode and a central hole for the beam passage. Results of the design optimization and performance of an electron gun built for a miniature 12 MeV RTM for medical applications are presented. We also discuss results of the beam parameters measurements and estimates of the beam emittance.

WEP295

Status of Laser Stripping at the SNS

laser, optics, quadrupole, injection

2035

T.V. Gorlov, A.V. Aleksandrov, V.V. Danilov
ORNL, Oak Ridge, Tennessee, USA
Y. Liu
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: This work was supported by SNS through UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 for the U.S. Department of Energy.
This paper presents an overview of experimental and theoretical studies on laser stripping that have been conducted up to the present time in the SNS project. The goal of this work is to develop techniques to achieve the experimental preconditions necessary for the successful realization of a future intermediate experiment on laser stripping. The experimental work consists of the tuning and measurement of H־ beam parameters in readiness for the intermediate experiment, and also takes into account the features and possibilities of the SNS accelerator.

THOAS2

Solid State RF Power - The route to 1W per Euro Cent

electron, klystron, radiation, synchrotron

2047

O. Heid
Siemens AG, Healthcare Technology and Concepts, Erlangen, Germany
T.J.S. Hughes
Siemens AG, Erlangen, Germany

In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of power sources based on electron beams i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive technology [*,**,***] at unprecedented efficiency, power levels and power densities. The proposed solutions allows retrofitting of existing RF solutions and opens the route to novel accelerator designs.
* Heid O., Hughes T. THPD002, IPAC10, Kyoto, Japan
** Hergt M et al, 2010 IEEE International Power Modulator and High Voltage Conf., Atlanta GA, USA
*** Heid O., Hughes T. THP068, LINAC10, Tsukuba, Japan

Slides THOAS2 [1.776 MB]

THOAS3

Status of the Oak Ridge Spallation Neutron Source (SNS) RF Systems

klystron, controls, rfq, neutron

2050

T.W. Hardek, M.T. Crofford, Y.W. Kang, M.F. Piller, A.V. Vassioutchenko
ORNL, Oak Ridge, Tennessee, USA
S.W. Lee, M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

The SNS has been delivering production neutrons for five years with first beam delivered to the neutron target at the end of April 2006. On September 18, 2009 SNS officially reached 1 megawatt of beam on target marking the achievement of a decades-old dream of providing a U.S. megawatt class pulsed spallation source. The SNS is now routinely delivering 1 megawatt of beam power to the neutron target at over 85 percent of the scheduled beam time. The present effort is aimed at increasing availability eventually to 95 percent and gradually increasing the intensity to the 1.4 megawatt design level. While the RF systems have performed well since initial installation some improvements have been implemented. This paper provides a review of the SNS RF Systems, an overview of the performance of the various components and a detailed review of RF related issues addressed over the past several years.

Slides THOAS3 [2.759 MB]

THOCN4

High-Power Options for LANSCE

DTL, neutron, proton, klystron

2107

R.W. Garnett, E.J. Pitcher, D. Rees, L. Rybarcyk, T. Tajima
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U. S. Department of Energy Contract DE-AC52-06NA25396.
The LANSCE linear accelerator at Los Alamos National Laboratory has a long history of successful beam operations at 800 kW. We have recently studied options for restoration of high-power operations including schemes for increasing the performance to multi-MW levels. In this paper we will discuss the results of this study including the present limitations of the existing accelerating structures at LANSCE, and the high-voltage and RF systems that drive them. Several plausible options will be discussed and a preferred option will be presented that will enable the first in a new generation of scientific facilities for the materials community. The emphasis of this new facility is "Matter-Radiation Interactions in Extremes" (MaRIE) which will be used to discover and design the advanced materials needed to meet 21st century national security and energy security challenges.

Slides THOCN4 [2.903 MB]

THOCN5

ATLAS Upgrade

cavity, rfq, cryomodule, ion

2110

P.N. Ostroumov, A. Barcikowski, Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.W.T. MacDonald, B. Mustapha, R.C. Pardo, S.I. Sharamentov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
ATLAS (Argonne Tandem Linac Accelerator System) upgrade requires several substantial developments in accelerator technologies, such as CW heavy ion RFQ and high-performance cryomodule with low-beta cavities. The upgrade project is well advanced. The physics and engineering design of the RFQ are complete and fabrication of OFE copper parts is in progress. The 3.9-meter length RFQ is composed from 5 strongly coupled segments. High-temperature furnace brazing of the segments is planned for the summer of 2011. The RFQ design includes several innovative features such as trapezoidal vane tip modulation, compact output radial matcher to form an axially symmetric beam. The upgrade project also includes development and construction of a cryomodule containing seven 72.75 MHz SC quarter wave cavities designed for the geometrical β= 0.077 and four SC solenoids. The cavity is designed to obtain an accelerating voltage higher than 2.5 MV. The prototype cavity together with high-power capacitive coupler and piezoelectric tuner has been developed, fabricated and is being tested. This paper reports innovative design features of both RFQ and SRF linac and current status of the project.

Slides THOCN5 [3.070 MB]

THOCS6

Progress in Cavity and Cryomodule Design for the Project X Linac

cryomodule, cavity, solenoid, lattice

2133

M.S. Champion, S. Barbanotti, M.H. Foley, C.M. Ginsburg, I.G. Gonin, C.J. Grimm, J.S. Kerby, S. Nagaitsev, T.H. Nicol, T.J. Peterson, L. Ristori, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

The continuous wave 3 GeV Project X Linac requires the development of two families of cavities and cryomodules at 325 and 650 MHz. The baseline design calls for three types of superconducting single-spoke resonators at 325 MHz having betas of 0.11, 0.22, and 0.42 and two types of superconducting five-cell elliptical cavities having betas of 0.61 and 0.9. These cavities shall accelerate a 1 mA H⁻ beam initially and must support eventual operation at 4 mA. The electromagnetic and mechanical designs of the cavities are in progress and acquisition of prototypes is planned. The heat load to the cryogenic system is up to 25 W per cavity in the 650 MHz section, thus segmentation of the cryogenic system is a major issue in the cryomodule design. Designs for the two families of cryomodules are underway.

Slides THOCS6 [2.241 MB]

THP001

Hybrid Electron Linac Based on Magnetic Coupled Accelerating Structure

coupling, electron, simulation, impedance

2136

S.V. Kutsaev, K.I. Nikolskiy, N.P. Sobenin
MEPhI, Moscow, Russia

This paper presents the design of a hybrid linac which consists of a standing wave buncher and a travelling wave accelerating part. Both electric and magnetic-coupled disk-loaded waveguide (DLW) could be used as accelerating structure. The last one has better electrodynamical parameters comparing to classical DLW. Such an accelerator possesses the advantages of both standing wave and travelling wave linacs and has better output beam parameters.

THP006

Status of High Current R&D Energy Recovery Linac at Brookhaven National Laboratory

electron, gun, SRF, emittance

2148

D. Kayran, Z. Altinbas, D.R. Beavis, I. Ben-Zvi, R. Calaga, D.M. Gassner, H. Hahn, L.R. Hammons, A.K. Jain, J.P. Jamilkowski, N. Laloudakis, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, B. Oerter, D. Pate, D. Phillips, J. Reich, T. Roser, C. Schultheiss, B. Sheehy, T. Srinivasan-Rao, R. Than, J.E. Tuozzolo, D. Weiss, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA

An ampere-class 20 MeV superconducting energy recovery linac (ERL) is under construction at Brookhaven National Laboratory (BNL) for testing of concepts relevant for high-energy coherent electron cooling and electron-ion colliders. One of the goals is to demonstrate an electron beam with high charge per bunch (~5 nC) and low normalized emittance (~5 mm-mrad) at an energy of 20 MeV. A flexible lattice for the ERL loop provides a test bed for investigating issues of transverse and longitudinal instabilities and diagnostics for CW beam. A superconducting 703 MHz RF photo-injector is considered as an electron source for such a facility. We will start with a straight pass (gun/cavity/beam stop) test for gun performance studies. Later, we will install and test a novel injection line concept for emittance preservation in a lower-energy merger. Here we present the status and our plans for construction and commissioning of this facility.

THP007

FEL Potential of eRHIC

FEL, electron, brightness, SRF

2151

V. Litvinenko, I. Ben-Zvi, Y. Hao, C.C. Kao, D. Kayran, J.B. Murphy, V. Ptitsyn, T. Roser, D. Trbojevic, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Brookhaven National Laboratory plans to build a 5-to-30 GeV energy-recovery linac (ERL) for its future electron-ion collider, eRHIC. In past few months, the Laboratory turned its attention to the potential of this unique machine for free electron lasers (FELS), which we initially assessed earlier*. In this paper, we present our current vision of a possible FEL farm, and of narrow-band FEL-oscillators driven by this accelerator.
* V.N. Litvinenko, I. Ben-Zvi, Proceedings of FEL'2004, http://jacow.org/f04/papers/WEBOS04/

THP009

Collimator Design of 15 MeV Linear Accelerator Based Thermal Neutron Source for Radiography

neutron, target, electron, simulation

2154

B.J. Patil, V.N. Bhoraskar, S.D. Dhole
University of Pune, Pune, India
S.T. Chavan, R. Krishnan, S.N. Pethe
SAMEER, Mumbai, India
A.J. Patil
DANA, Pune, India

Neutron Radiography is a powerful non-destructive testing technique used for the analysis of objects which are widely used in security, medical, nuclear and industrial applications. Optimization of the thermal neutron radiography facility has been carried out using 15 MeV LINAC based neutron source. In this case, a neutron collimator has been designed along with g-n target, moderator, reflector and shielding. The g-n target has been optimized based on their photonuclear threshold. The moderating properties have been studied for few light elements to optimize best suitable moderator for radiography system. The major part of the design was to optimize the collimator for neutron beam which decides quality of the image given. To get best values of collimator parameters such as collimation ratio, gamma content, neuron flux, cadmium ratio, beam uniformity, etc. a FLUKA simulation was carried out. The collimator has been optimized with cadmium lining square cone to capture the scattered thermal neutrons and the collimation ratio to L/D=18. The neutron flux of the optimized facility obtained at the object plane is 1.0·10⁺⁵ n/(cm²-sec¹) and neutron to gamma ratio is 1.0·10⁺⁵ n/(cm²-mR¹).

THP027

Status and Development of a Proton FFAG Accelerator at KURRI for ADSR Study

injection, proton, ion, ion-source

2172

Y. Kuriyama, Y. Ishi, J.-B. Lagrange, Y. Mori, R. Nakano, T. Planche, T. Uesugi, E. Yamakawa
KURRI, Osaka, Japan
Y. Niwa, K. Okabe, I. Sakai
University of Fukui, Faculty of Engineering, Fukui, Japan

In Kyoto University Research Reactor Institute (KURRI), the fixed-field alternating gradient (FFAG) proton accelerator has been constructed to make an experimental study of accelerator driven sub-critical reactor (ADSR) system with spallation neutrons produced by the accelerator. The world first ADSR experiment has been carried out in March of 2009. The proton FFAG accelerator consists of three FFAG rings; injetor (spiral sector FFAG), booster(radial sector FFAG) and main ring(radial sector FFAG), respectively. In March 2010, the experiment conducted with a thorium-loaded accelerator driven system using the proton FFAG accelerator has also been carried out. In order to increase the beam intensity of the proton FFAG accelerator, a new injector with H⁻ ions is under construction. In this scheme, H⁻ ions accelerated up to the energy of 11 MeV with a linac are injected into the main ring with charge-exchange injection. In this paper, the details of ADSR experiments with the proton FFAG accelerator at KURRI, and also the R&Ds of the accelerator will be presented.

THP034

Accelerators for Subcritical Molten Salt Reactors

neutron, target, proton, SRF

2181

R.P. Johnson
Muons, Inc, Batavia, USA
C. Bowman
ADNA, Los Alamos, New Mexico, USA

Funding: Supported in part by Accelerator Technologies Inc.
Accelerator parameters for subcritical reactors that have been considered in recent studies * are based on using solid nuclear fuel much like that used in all operating critical reactors as well as the thorium-burning accelerator-driven energy amplifier ** proposed by Rubbia et al. An attractive alternative reactor design that used molten salts was experimentally studied at ORNL in the 1960s, where a critical molten salt reactor was successfully operated using enriched U235 or U233 tetrafluoride fuels ***. These experiments give confidence that an accelerator-driven subcritical molten salt reactor will work as well or better than conventional reactors, having better efficiency due to their higher operating temperature and having the inherent safety of subcritical operation. Moreover, the requirements to drive a molten salt reactor are considerably relaxed compared to a solid fuel reactor, especially regarding accelerator reliability and spallation neutron targetry, to the point that the required technology exists today.
* http://www.er.doe.gov/hep/files/pdfs/ADSWhitePaperFinal.pdf
** http://wikipedia.org/wiki/Energy_amplifier
*** Paul N. Haubenreich and J. R. Engel, Nuc. Apps & Tech, 8, Feb. 1970

THP037

Design of an e-γ Converter for a 10 MeV Electron Beam

target, electron, neutron, photon

2184

L. Auditore, D. Loria, E. Morgana
INFN - Gruppo Messina, S. Agata, Messina, Italy
L. Auditore, R.C. Barnà, A. Trifirò, M. Trimarchi
Università di Messina, Messina, Italy
G. Di Bella
Università di Messina, Facoltà di Ingegneria, Messina, Italy

In the last years, the INFN-Gruppo Collegato di Messina has designed and setup an x-ray source based on the 5 MeV electron linac hosted at the Dipartimento di Fisica - Università di Messina. In the meanwhile, and in the framework of an European funding, the group has setup the Centro Ricerche at Villafranca Tirrena (Messina, Italy) which holds a 10 MeV electron linac and which is, at the moment, mainly devoted to industrial Radiation Processing applications. Nevertheless, to the aim to provide also x-ray beams, an e-g converter has been designed by means of the MCNP4C2 simulation code and optimized for a 10 MeV electron beam. A wide investigation has been performed to choose material and thickness for the e-g converter in order to provide the highest x-ray yield. Then, angular distribution and energy spectrum have been simulated to characterize the produced bremsstrahlung beam. Also the target activation has been investigated. Finally, thermal analysis has been performed using a finite element model code, Deform 2D, to choose the definitive mechanical settings of the e-g converter.

THP039

Development of a High-power THz-TDS System on the Basis of a Compact Electron Linac

electron, laser, synchrotron, synchrotron-radiation

2190

M. Kumaki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Kuroda, H. Toyokawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

The high-power terahertz time-domain spectroscopy (THz-TDS) system has been developed on the basis of a compact S-band electron linac at AIST, Japan. The linac whose injector is a photocathode rf gun generates about a 40 MeV, 1 nC electron bunch. The bunch is compressed into less than 1ps with a magnetic compressor. It is bended by a 90-degree bending magnet, which causes generation of the THz coherent synchrotron radiation (CSR). It has useful characteristics such as high power, a short pulse and continuous spectrum. In particular, peak power of THz-CSR is estimated to be about 10⁶ times larger than that of the conventional THz source on the basis of the mode-locked fs laser. The THz-TDS is based on the EO sampling methods with the pump-probe technique. The frequency spectrum is obtained by Fourier transform of the measured temporal THz waveform. In addition, it is applied to the ultra-short bunch length monitor by analysing the THz spectrum. In this paper, we will describe details of our system and preliminary experimental results.

THP051

An Overview of Normal Conducting Radio Frequency Projects and Manufacturing Capabilities at Radiabeam Technologies, LLC

gun, simulation, controls, radio-frequency

2214

R.B. Agustsson, S. Boucher, X.D. Ding, L. Faillace, P. Frigola, A.Y. Murokh, S. Storms
RadiaBeam, Santa Monica, USA

Radiabeam Technologies is currently designing, engineering and fabricating 8 different Normal Conducting Radio Frequency (NCRF) accelerating and diagnostic structures. These NCRF programs include compact X-band industrial systems, laboratory grade NCRF photoinjectors, deflecting cavities and High-Gradient structures. Nearly all aspects of these NCRF structures’ lifecycle are performed in house, including design, 3D electromagnetic and thermomechanical modeling, engineering, fabrication, cleaning and RF cold testing, tuning, and RF power testing. An overview of these varied projects along with references to more detailed publications presented in this conference are provided. Details concerning specific processes applicable to all of the above mentioned RF projects are also discussed.

THP057

Optimal Focusing for a Linac-Based Hard X-ray Source

undulator, electron, target, focusing

2229

C. Liu
BNL, Upton, Long Island, New York, USA
G.A. Krafft
JLAB, Newport News, Virginia, USA
R.M. Talman
CLASSE, Ithaca, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In spite of having a small average beam current limit, a linac can have features that make it attractive as an x-ray source: high energy, ultralow emittance and energy spread, and flexible beamline optics. Unlike a storage ring, in which an (undulator) radiation source is necessarily short and positioned at a electron beam waist, in a linac the undulator can be long and the electron beam can be adjusted to have a (virtual) waist far downstream toward the x-ray target. Using a planned CEBAF beamline as an example, this paper shows that a factor of 2000 in beam current can be overcome to produce a monochromatic hard x-ray source comparable with, or even exceeding, the performance of an x-ray line at a third generation storage ring. The optimal electron beam focusing conditions for x-ray flux density and brilliance are derived, and are verified by simulations using the SRW code.

THP077

SC Quadrupole for Cryomodule for ERL/ILC

quadrupole, dipole, cryomodule, focusing

2276

A.A. Mikhailichenko
CLASSE, Ithaca, New York, USA

Funding: NSF
We are considering the SC quadrupole where the field formed not only by the current distributions, but with the poles also. This delivers a good quality field in all aperture allowing compact and inexpensive design. This type of quadrupole designed for Cornell ERL could be recommended for ILC also.

THP078

Study of a TeV Level Linear Collider Using Short rf Pulse (~20ns) Two Beam Accelerator Concept

collider, linear-collider, wakefield, klystron

2279

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Funding: Work is supported by DOE SBIR grant under contract No. DE-SC0004320.
In a general sense, a high gradient is desirable for a TeV level linear collider design because it can reduce the total linac length. More importantly, the efficiency and the cost to sustain such a gradient should be considered as well in the optimization process of an overall design. We propose a high energy linear collider based on a short rf pulse (~22ns flat top), high gradient (~267MV/m loaded gradient), high frequency (26GHz) dielectric two beam accelerator scheme. This scheme is a modular design and its unique locally repetitive drive beam structure allows a flexible configuration to meet different needs. Major parameters of a conceptual 3-TeV linear collider are presented. This preliminary study shows an efficient (~7% overall ) short pulse collider may be achievable. As the first step, a dielectric based broadband accelerating structure is under development.

THP083

Fabrication and Design of the Main Linacs for CLIC with Damped and Detuned Wakefield Suppression and Optimised Surface Electromagnetic Fields

wakefield, dipole, HOM, damping

2291

R.M. Jones, A. D'Elia, V.F. Khan
UMAN, Manchester, United Kingdom
A. Grudiev, G. Riddone, W. Wuensch
CERN, Geneva, Switzerland

Funding: Research leading to these results has received funding from the European commission under the FP7 research infrastructure grant no. 227579.
We report on the suppression of long-range wakefields in the main linacs of the CLIC collider. This structure operates with a 120 degree phase advance per cell. The wakefield is damped using a combination of detuning the frequencies of beam-excited higher order modes and by light damping, through slot-coupled manifolds. This serves as an alternative to the present baseline CLIC design which relies on heavy damping. Detailed simulations of both the optimised surface fields resulting from the monopole mode, and from wakefield damping of the dipole modes, are discussed. We report on fabrication details of a structure consisting of 24 cells, diffusion bonded together. This design, known as CLIC_DDS_A, takes into practical mechanical engineering issues and is the result of several optimisations since the earlier CLIC_DDS designs. This structure is due to be tested for its capacity to sustain high gradients at CERN.

THP107

Source of Microbunching at BNL NSLS Source Development Laboratory

laser, electron, FEL, wakefield

2324

S. Seletskiy, Y. Hidaka, J.B. Murphy, B. Podobedov, H.J. Qian, Y. Shen, X.J. Wang, X. Yang
BNL, Upton, Long Island, New York, USA

We report experimental studies of the origins of electron beam microbunching instability at BNL Source Development Laboratory (SDL). We eliminated laser-induced microbunching by utilizing an ultra-short photocathode laser. The measurements of the resulting electron beam led us to conclude that, at SDL, microbunching arising from shot noise is not amplified to any significant level. Our results demonstrated that the only source of microbunching instability at SDL is the longitudinal modulation of the photocathode laser pulse. Our work shows that assuring a longitudinally smoothed photocathode laser pulse allows mitigating microbunching instability at a typical FEL injector with a moderate microbunching gain.

THP114

Status of the PEP-X Light Source Design Study

emittance, photon, FEL, brightness

2336

R.O. Hettel, K.L.F. Bane, K.J. Bertsche, Y. Cai, A. Chao, X. Huang, Y. Jiao, C.-K. Ng, Y. Nosochkov, A. Novokhatski, T. Rabedeau, C.H. Rivetta, J.A. Safranek, G.V. Stupakov, L. Wang, M.-H. Wang, L. Xiao
SLAC, Menlo Park, California, USA

Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
The SLAC Beam Physics group and collaborators continue to study options for implementing a near diffraction-limited ring-based light source in the 2.2-km PEP-II tunnel that will serve the SSRL scientific program in the future. The study team has completed the baseline design for a 4.5-GeV storage ring having 160-pm-rad emittance with stored beam current of 1.5 A, providing >10²² brightness for multi-keV photon beams from 3.5-m undulator sources. The team is now investigating possible 5-GeV ERL configurations which, similar to the Cornell and KEK ERL plans, would have ~30 pm-rad emittance with 100 mA current, and ~10 pm-rad emittance with 25 mA or less. In the next year, a diffraction-limited storage ring using on-axis injection in order to reach 30 pm-rad or less emittance will be investigated. An overview of the PEP-X design study and SSRL’s plans for defining the performance parameters that will guide the choice of implementation options is presented.

THP133

Modulation of Low Energy Beam to Generate Predefined Bunch Trains for the NSLS-II Top-off Injection

gun, emittance, kicker, storage-ring

2372

G.M. Wang, W.X. Cheng, R.P. Fliller, R. Heese, J. Rose, T.V. Shaftan
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
The NSLS II linac will produce a bunch train, 80-150 bunches long with 2 ns bunch spacing. Having the ability to tailor the bunch train can lead to the smaller bunch to bunch charge variation in the storage ring. A stripline is integrated into the linac baseline to achieve this tailoring. The stripline must have a fast field rise and fall time to tailor each bunch. The beam dynamics is minimally affected by including the extra space for the stripline. This paper discusses the linac beam dynamics with stripline, and the optimal design of the stripline.

THP144

FELs as X-ray Sources in ERL Facilities

FEL, emittance, radiation, electron

2390

A. Meseck
HZB, Berlin, Germany
G.H. Hoffstaetter, F. Löhl, C.E. Mayes
CLASSE, Ithaca, New York, USA

Funding: This work has been supported by NSF award DMR-0807731.
Hard x-ray Energy Recovery Linacs (ERLs) operate with high-brightness electron beams, matching the requirements for X-ray FELs in terms of emittance and energy spread. We have analyzed in how far it is feasible to include X-ray FELs in ERL facilities. X-ray FEL Oscillators require comparatively low peak currents and are therefore good candidates for FEL sources in ERLs. However, also high-gain FELs do not seem out of reach when bunch-compression schemes for higher peak currents are utilized. Using the proposed Cornell ERL as an example, different FEL concepts are discussed and their suitability as X-ray sources are analyzed.

THP163

Pre-Conceptual Design Requirements for an X-Ray Free Electron Laser for the MaRIE Experimental Facility at LANL

photon, electron, site, FEL

2417

R.L. Sheffield, C.W. Barnes, M.A. Bourke, R.W. Garnett, M.S. Gulley, A.J. Taylor
LANL, Los Alamos, New Mexico, USA

Funding: Work performed under the auspices of the U.S. Department of Energy, under contract DE-AC52-06NA25396.
The MaRIE (Matter-Radiation Interactions in Extremes) experimental facility will be used to advance materials science by providing the tools scientists need to develop materials that will perform predictably and on demand for currently unattainable lifetimes in extreme environments. The MaRIE facilities, the Multi-Probe Diagnostic Hall (MPDH), the Fission and Fusion Materials Facility (F³), and the Making, Measuring, and Modeling Materials (M4) Facility will each have experimental needs for one or more high-energy X-ray beam probes. MPDH will also require access to an electron beam probe. These probe beams can be created using a 20-GeV electron linac, both to serve as a source of electrons and as a driver for a set of up to five X-ray undulators for the high-energy X-rays. Because of space considerations at the facility, a high-gradient design is being investigated that will use a normal-conducting linac and X-band RF systems. Experimental requirements are also calling for relatively long pulse lengths, as well as interleaving high- and low-charge electron bunches. This paper will provide an overview of how an XFEL would address the scientific requirements for MaRIE.

THP168

FEL Beam Stability in the LCLS*

FEL, electron, undulator, photon

2423

J.L. Turner, R. Akre, A. Brachmann, F.-J. Decker, Y.T. Ding, P. Emma, Y. Feng, A.S. Fisher, J.C. Frisch, A. Gilevich, P. Hering, K. Horovitz, Z. Huang, R.H. Iverson, D. Kharakh, A. Krasnykh, J. Krzywinski, H. Loos, M. Messerschmidt, S.P. Moeller, H.-D. Nuhn, D.F. Ratner, T.J. Smith, J.J. Welch, J. Wu
SLAC, Menlo Park, California, USA

Funding: *This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515
During commissioning and operation of the Linac Coherent Light Source (LCLS) x-ray Free Electron Laser (FEL) at the SLAC National Accelerator Center electron and x-ray beam size, shape, centroid motion have been studied. The studies, sources, and remediation are summarized in this paper.

THP173

Design of the SRF Driver ERL for the Jefferson Lab UV FEL

FEL, wiggler, controls, quadrupole

2435

C. Tennant, S.V. Benson, G.H. Biallas, K. Blackburn, J.R. Boyce, D.B. Bullard, J.L. Coleman, C. Dickover, D. Douglas, F.K. Ellingsworth, P. Evtushenko, C.W. Gould, J.G. Gubeli, F.E. Hannon, D. Hardy, C. Hernandez-Garcia, K. Jordan, J.M. Klopf, J. Kortze, M. Marchlik, S.W. Moore, G. Neil, T. Powers, D.W. Sexton, M.D. Shinn, R.L. Walker, F.G. Wilson, S. Zhang
JLAB, Newport News, Virginia, USA

Funding: Support by DoE Contract DE-AC05-060R23177.
We describe the design of the SRF ERL providing the CW electron drive beam at the Jefferson Lab UV FEL. Based on the same 135 MeV linear accelerator as – and sharing portions of the recirculator with – the Jefferson Lab 10 kW IR Upgrade FEL, the UV driver ERL uses a novel bypass geometry to provide transverse phase space control, bunch length compression, and nonlinear aberration compensation (including correction of RF curvature effects) without the use of magnetic chicanes or harmonic RF. Stringent phase space requirements at the wiggler, low beam energy, high beam current, and use of a pre-existing facility and legacy hardware subject the design to numerous constraints. These are imposed not only by the need for both transverse and longitudinal phase space management, but also by the potential impact of collective phenomena (space charge, wakefields, beam break-up (BBU), and coherent synchrotron radiation (CSR)), and by interactions between the FEL and the accelerator RF system. This report addresses these issues and presents the accelerator design solution that now successfully supports FEL lasing.

THP178

Design of the MAX IV Ring Injector and SPF/FEL Driver

FEL, injection, electron, simulation

2447

S. Thorin, M. Eriksson, M.A.G. Johansson, D. Kumbaro, F. Lindau, L. Malmgren, J.H. Modéer, M. Sjöström, S. Werin
MAX-lab, Lund, Sweden
D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). Compression is done in two double achromats with positive R56. The natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a linearising harmonic cavity. The design of the linac focuses on flexibility, simplicity and stability, while keeping the costs low. The accelerator structures have been ordered, as well as modulator/klystrons. The linac will be the first accelerator to be assembled and commissioned in the MAX IV project, starting mid 2012.

THP180

Studies of a Linac Driver for a High Repetition Rate X-ray FEL

FEL, emittance, simulation, laser

2450

M. Venturini, J.N. Corlett, L.R. Doolittle, D. Filippetto, C. F. Papadopoulos, G. Penn, D. Prosnitz, J. Qiang, M.W. Reinsch, R.D. Ryne, F. Sannibale, J.W. Staples, R.P. Wells, J.S. Wurtele, M.S. Zolotorev
LBNL, Berkeley, California, USA
A. Zholents
ANL, Argonne, USA

Funding: Work carried out under Department of Energy contract No. DE-AC02-0SCK11231
We report on on-going studies of a superconducting CW linac driver intended to support a high repetition rate FEL operating in the soft x-rays spectrum. We present a point-design for a 1.8 GeV machine tuned for 300~pC bunches and delivering low-emittance, low-energy spread beams as needed for the SASE and seeded beamlines.

THP183

Measurement of Femtosecond LCLS Bunches Using the SLAC A-line Spectrometer*

diagnostics, wakefield, simulation, electron

2459

Z. Huang, A. Baker, M. Boyes, J. Craft, F.-J. Decker, Y.T. Ding, P. Emma, J.C. Frisch, R.H. Iverson, J.J. Lipari, H. Loos, D.R. Walz
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany

We describe a novel technique and the preliminary experimental results to measure the ultrashort bunch length produced by the LCLS low-charge, highly compressed electron bunch. The technique involves adjusting the LCLS second bunch compressor followed by running the bunch on an rf zero-crossing phase of the final 550-m of linac. As a result, the time coordinate of the bunch is directly mapped onto the energy coordinate at the end of the linac. A high-resolution energy spectrometer located at an existing transport line (A-line) is then commissioned to image the energy profile of the bunch in order to retrieve its temporal information. We present measurements of the single-digit femtosecond LCLS bunch length using the A-line as a spectrometer and compare the results with the transverse cavity measurement as well as numerical simulations.

THP184

Tuning of the LCLS Linac for User Operation

RF-structure, diagnostics, electron, feedback

2462

H. Loos, R. Akre, A. Brachmann, F.-J. Decker, Y.T. Ding, P. Emma, A.S. Fisher, J.C. Frisch, A. Gilevich, P. Hering, Z. Huang, R.H. Iverson, N. Lipkowitz, H.-D. Nuhn, D.F. Ratner, J.A. Rzepiela, T.J. Smith, J.L. Turner, J.J. Welch, W.E. White, J. Wu, G. Yocky
SLAC, Menlo Park, California, USA

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515.
With the Linac Coherent Light Source (LCLS) now in its third user run, reliable electron beam delivery at various beam energies and charge levels has become of high operational importance. In order to reduce the beam tuning time required for such changes, several diagnostics and feed-forward procedures have been implemented. We report on improved lattice diagnostics to detect magnet, model, and diagnostics errors as well as on measurements of transverse RF kicks and static field contributions and corresponding correction procedures to facilitate beam energy changes.

THP186

Lattice Design for ERL Options at SLAC

emittance, injection, lattice, extraction

2465

Y. Nosochkov, Y. Cai, X. Huang, M.-H. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract number DE-AC02 76SF00515.
SLAC is investigating long-range options for building a high performance light source machine while reusing the existing linac and PEP-II tunnels. One previously studied option is the PEP-X low emittance storage ring. The alternative option is based on a superconducting Energy Recovery Linac (ERL) and the PEP-X design. The ERL advantages are the low beam emittance, short bunch length and small energy spread leading to better qualities of the X-ray beams. Two ERL configurations differed by the location of the linac have been studied. Details of the lattice design and the results of beam transport simulations with the coherent synchrotron radiation effects are presented

THP187

Design Concept for a Compact ERL to Drive a VUV/Soft X-Ray FEL

FEL, quadrupole, emittance, wiggler

2468

C. Tennant, D. Douglas
JLAB, Newport News, Virginia, USA

Funding: Support by US DOE contract #DE-AC05-060R23177
We explore possible upgrades of the existing Jefferson Laboratory IR/UV FEL driver to higher electron beam energy and shorter wavelength through use of multipass recirculation to drive an amplifier FEL. The system would require beam energy at the wiggler of 600 MeV with 1 mA of average current. The system must generate a high brightness beam, configure it appropriately, and preserve beam quality through the acceleration cycle - including multiple recirculations - and appropriately manage the phase space during energy recovery. The paper will discuss preliminary design analysis of the longitudinal match, space charge effects in the linac, and recirculator design issues, including the potential for the microbunching instability. A design concept for the recirculator and a lattice solution will be presented.

THP191

Recent Progress in Injector Improvement of SPEAR 3

booster, quadrupole, injection, storage-ring

2477

K. Tian, W.J. Corbett, D. Dell'Orco, D. Ernst, S.M. Gierman, J.A. Safranek, J.F. Schmerge, B. Scott
SLAC, Menlo Park, California, USA

The frequent injection and high current operation of SPEAR 3 storage ring requires high stability of the injector system at the Stanford Synchrotron Radiation Laboratory (SSRL). The lattice of linac-to-booster (LTB) transport line was not well understood and controlled prior to this work. In this paper, we discuss the significant efforts that have been made to improve the performance of the LTB. A method to correct the distortion of the closed orbit in the booster by moving 2 quadrupoles is also presented.

THP198

Upgrade of the RF Photo-Injector for the Duke Storage Ring

cathode, booster, laser, electron

2489

V. Popov, J.Y. Li, S.F. Mikhailov, P.W. Wallace, P. Wang, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The accelerator facility for the Duke FEL and High Intensity Gamma-ray Source (HIGS) consists of a linac pre-injector, a top-off booster injector, and the storage ring. The S-band RF gun with the LaB6 cathode was initially operated in the thermionic mode, producing a long electron beam pulse and a large radiation background. In 1997, the thermionic RF gun was converted to a photo-cathode operation using a nitrogen drive laser for single bunch injection into the storage ring. The photo-cathode operation typically delivers 0.1 nC of charge in a 1 ns long pulse to the linac. Since 2006, substantial improvements have been made to the photo-cathode and the linac, including improvements of the nitrogen drive laser, development of driver laser optical transport and beam monitoring system, and optimization of the cathode heater current to minimize the thermionic emission. In addition, two electron beam charge measurement systems using Faraday cup detectors and sample and hold electronics have been developed. In this work, we will present these new developments and discuss the impact of these upgrades on everyday operation of the linac pre-injector.

THP199

Raising Photoemission Efficiency with Surface Acoustic Waves

electron, photon, laser, lattice

2492

A. Afanasev
Hampton University, Hampton, Virginia, USA
R.P. Johnson
Muons, Inc, Batavia, USA

Funding: Supported in part by Muons, Inc.
Current and future synchrotron radiation light sources and free electron laser facilities are in need of improvements in Electron Gun Technology, especially regarding the cost and efficiency of photoinjectors. The generation of Surface Acoustic Waves (SAW) on piezoelectric substrates is known to produce strong piezoelectric fields that propagate on the surface of the material. These fields significantly reduce the recombination probability of electrons and holes which can result in enhanced quantum efficiency of photoemission. Additional advantages are provided by the mobility of charge carriers that can be controlled by SAW. It is expected that this novel feature will result in enhanced efficiency of photocathode operation, leading to the production of intense, low emittance electron bunches at a high repetition rate using laser excitation.

THP213

Traveling Wave Electron Linac for Synchrotron Injector

electron, synchrotron, simulation, injection

2519

S.V. Kutsaev, K.I. Nikolskiy, N.P. Sobenin
MEPhI, Moscow, Russia

In this paper the project design of a travelling wave electron linac used as an injector to synchrotron in Lebedev Physical Institute of the Russian Academy of Sciences (LPI RAS) is presented. The injected beam to the synchrotron should have very small emittance and energy spectrum. Thus, the buncher design is an essential question in this problem. One of the best output beam parameters can be achieved by using a waveguide buncher with the non-uniform parameters. The proposals of optimal buncher design and beam dynamics calculation results are presented.

THP215

Performance of the Diagnostics for NSLS-II Linac Commissioning

booster, diagnostics, simulation, emittance

2525

R.P. Fliller, R. Heese, H.-C. Hseuh, M.P. Johanson, B.N. Kosciuk, D. Padrazo, I. Pinayev, J. Rose, T.V. Shaftan, O. Singh, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac and a 3 GeV booster synchrotron and associated transfer lines. The transfer lines not only provide a means to delivering the beam from one machine to another, they also provide a suite of diagnostics and utilities to measure the properties of the beam to be delivered. In this paper we discuss the suite of diagnostics that will be used to commission the NSLS-II linac and measure the beam properties. The linac to booster transfer line can measure the linac emittance with a three screens measurement or a quadrupole scan. Energy and energy spread are measured in a dispersive section. Total charge and charge uniformity are measured with wall current monitors in the linac and transformers in the transfer line. We show that the performance of the transfer line will be sufficient to ensure the linac meets its specifications and provides a means of trouble shooting and studying the linac in future operation.

THP217

Frequent Fill Top-Off Injection at SPEAR3

injection, controls, feedback, power-supply

2531

J.J. Sebek, S. Allison, S.M. Gierman, X. Huang, J.A. Safranek, J.F. Schmerge, K. Tian, C. Wermelskirchen
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76-SF00515
SPEAR3 beam is now delivered to users in a "frequent fill" mode in which beam is injected into the storage ring, with beam-line shutters open, on a periodic schedule so that the beam current is kept constant to within 1% of its average value. This goal was achieved with the constraints of having the SPEAR3 injector run at very high reliability and ensuring that there would be no challenges to the beam containment system in this operational mode. This paper presents the accelerator development, the hardware changes, and the software developed to implement this operational mode.

FROAN1

The European Spallation Source

target, neutron, proton, cryomodule

2549

S. Peggs, H. Danared, M. Eshraqi, H. Hahn, A. Jansson, M. Lindroos, A. Ponton, K. Rathsman, G. Trahern
ESS, Lund, Sweden
S. Bousson
IPN, Orsay, France
R. Calaga
BNL, Upton, Long Island, New York, USA
G. Devanz, R.D. Duperrier
CEA/DSM/IRFU, France
J. Eguia
Fundación TEKNIKER, Eibar (Gipuzkoa), Spain
S. Gammino
INFN/LNS, Catania, Italy
S.P. Møller
ISA, Aarhus, Denmark
C. Oyon
SPRI, Bilbao, Spain
R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden
T. Satogata
JLAB, Newport News, Virginia, USA

The European Spallation Source (ESS) is a 5 MW, 2.5 GeV long pulse proton linac, to be built and commissioned in Lund, Sweden. The Accelerator Design Update (ADU) project phase is under way, to be completed at the end of 2012 by the delivery of a Technical Design Report. Improvements to the 2003 ESS design will be summarised, and the latest design activities will be presented.

Slides FROAN1 [1.650 MB]

FROBN2

Technical Challenges in Design and Construction of FRIB

ion, target, cryomodule, acceleration

2561

R.C. York, G. Machicoane
NSCL, East Lansing, Michigan, USA
S. Assadi, G. Bollen, T . Glasmacher, W. Hartung, M.J. Johnson, F. Marti, E. Pozdeyev, M.J. Syphers, E. Tanke, J. Wei, X. Wu, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: Work supported by DOE CA DE-SC0000661 and Michigan State University.
The Facility for Rare Isotope Beams (FRIB) will be a world-leading, DOE national users facility for the study of nuclear structure, reactions and astrophysics on the campus of Michigan State University. A superconducting, heavy-ion, driver linac will be used to provide stable beams of >200 MeV/u at beam powers up to 400 kW (~650 electrical micro-amps for uranium) that will be used to produce rare isotopes by in flight fragment separation. The selected rare isotopes will be used at velocity (~0.5 c), stopped, or reaccelerated. FRIB is a challenging technical project. An overview of the project, project challenges, and mitigating strategies will be presented.

Slides FROBN2 [14.690 MB]

FROBN3

Project X - New Multi Megawatt Proton Source at Fermilab

proton, injection, cavity, collider

2566

S. Nagaitsev
Fermilab, Batavia, USA

Fermilab plans to replace its present injection complex consisting of a pulsed linac and 15 Hz Booster with a new injection complex based on a superconducting CW linac. This new proton source should boost the power of the Main Injector to 2 MW and enable new experiments with a high power proton beam in the range of 1-3 GeV. The speaker will present recent developments from the Fermilab Project X R&D.

Slides FROBN3 [2.018 MB]

FROBN4

Commissioning of the 20MV Superconducting Linac Upgrade at TRIUMF

ISAC, target, TRIUMF, ion

2570

M. Marchetto
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

The Phase II upgrade of the ISAC-II Superconducting Heavy Ion Linac involves the addition of twenty quarter-wave bulk niobium resonators housed in three cryomodules. This addition brings the total installed accelerating voltage from 20MV to 40MV. The cavities are produced in Canadian industry with cavity testing and cryomodule assembly at TRIUMF. The speaker will discuss commissioning of, and operations with, this major upgrade, which commenced in April 2010.

Slides FROBN4 [3.990 MB]

FROBS3

Progress on Superconducting RF for the Cornell Energy-Recovery-Linac

cavity, HOM, SRF, cryomodule

2580

M. Liepe, G.H. Hoffstaetter, S. Posen, J. Sears, V.D. Shemelin, M. Tigner, N.R.A. Valles, V. Veshcherevich
CLASSE, Ithaca, New York, USA

Cornell University is developing the superconducting RF technology required for the construction of a 5 GeV, 100 mA light source driven by an energy-recovery linac. Currently, a 100 mA injector cryomodule is under extensive testing and prototypes of the components of the SRF main linac cryomodule are under development, fabrication and testing. In this paper we give an overview of these recent activities at Cornell.

Slides FROBS3 [10.577 MB]

FROBS4

NSLS-II RF Systems

cavity, storage-ring, klystron, coupling

2583

J. Rose, W.K. Gash, B. Holub, Y. Kawashima, H. Ma, N.A. Towne, M. Yeddulla
BNL, Upton, Long Island, New York, USA

The NSLS-II RF systems include solid state modulators for the S-band klystrons powering the traveling wave sections for the 200 MeV injector linac, 7 cell cavity with IOT amplifier for the 3 GeV booster synchrotron and superconducting 500 MHz cavities powered by klystrons and a passive 1500 MHz SRF cavity for the 3 GeV, 500 mA storage ring. The systems are controlled by digital I/Q modulators fed by an ultra-low noise master oscillator. System overviews will be given along with preliminary test data.

Slides FROBS4 [1.041 MB]