Keyword: emittance
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MOIOA01 Linear Collider Studies linac, linear-collider, collider, FEL 1
 
  • S. Stapnes
    CERN, Geneva, Switzerland
  
  Status and comparison of the two remaining linear collider designs following publication of their CDRs  
slides icon Slides MOIOA01 [11.279 MB]  
 
MOIOA02 Commissioning of the Low-Energy Part of Linac4 rfq, linac, DTL, solenoid 6
 
  • A.M. Lombardi
    CERN, Geneva, Switzerland
  
  The Linac4 front-end (3MeV) was first commissioned in a dedicated test stand and then moved to its final position in the Linac4 tunnel. Accelerating cavities will be added progressively over two years to allow the characterisation of the beam with a dedicated measurement line at several energy stages (3,12,30,50, 100 and finally160MeV). This paper reports about the progress and the commissioning experience up to today.  
slides icon Slides MOIOA02 [5.339 MB]  
 
MOIOB02 Optimizing RF Linacs as Drivers for Inverse Compton Sources: the ELI-NP Case electron, linac, laser, photon 16
 
  • C. Vaccarezza, D. Alesini, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, B. Spataro, P. Tomassini
    INFN/LNF, Frascati (Roma), Italy
  • A. Bacci, D.T. Palmer, V. Petrillo, A.R. Rossi, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • I.V. Drebot
    Universita' degli Studi di Milano e INFN, Milano, Italy
  • A. Giribono, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma, Italy
  • C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  The design guide-lines of RF Linacs to fulfill the requirements of high spectral density Inverse Compton Sources for the photo-nuclear science are mostly mutuated from the expertise coming from high brightness electron Linacs driving X-ray FEL's. The main difference is the quest for maximum phase space density (instead of peak brightness), but many common issues and techniques are exploited, in order to achieve an optimum design and lay-out for the machine. A relevant example in this field is the design of the hybrid C-band multi-bunch RF Linacs for the ELI-NP Gamma Beam System, aiming at improving by two orders of magnitude the present state of the art in spectral density available for the gamma-ray beam produced.  
slides icon Slides MOIOB02 [2.542 MB]  
 
MOIOB03 Generation and Acceleration of Low-Emittance, High-Current Electron Beams for SuperKEKB gun, laser, electron, wakefield 21
 
  • M. Yoshida, N. Iida, S. Kazama, T. Natsui, Y. Ogawa, S. Ohsawa, L. Zang, X. Zhou
    KEK, Ibaraki, Japan
  
  KEK e−/e+ linac is now in a final stage of upgrade for SuperKEKB. One of the key issues is to stably generate and accelerate a low-emittance, high charge  electron beam for SuperKEKB (a couple of single-bunched beams with a charge of 5 nC and a normalized emittance of 20 mm-mmrad each).  
slides icon Slides MOIOB03 [3.981 MB]  
 
MOIOC02 Single-Knob Beam Line for Transverse Emittance Partitioning solenoid, quadrupole, coupling, scattering 36
 
  • C. Xiao, L. Groening, O.K. Kester, H. Leibrock, M.T. Maier, P. Rottländer
    GSI, Darmstadt, Germany
  • M. Chung
    UNIST, Ulsan, Republic of Korea
  
  Flat beams feature unequal emittances in the horizontal and vertical phase space. Such beams were created successfully in electron machines by applying effective stand-alone solenoid fringe fields in the electron gun. Extension of this method to ion beams was proposed conceptually. The present paper is on the decoupling capabilities of an ion beam emittance transfer line. The proposed beam line provides a single-knob tool to partition the horizontal and vertical rms emittances, while keeping the product of the two emittances constant as well as the transverse rms Twiss parameters (αx,y and βx,y) in both planes. It is shown that this single knob is the solenoid field strength, and now we fully understand the decoupling features.  
slides icon Slides MOIOC02 [1.327 MB]  
 
MOPP023 X-band Technology for FEL Sources FEL, linac, operation, experiment 101
 
  • G. D'Auria, S. Di Mitri, C. Serpico
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • E. Adli
    University of Oslo, Oslo, Norway
  • A.A. Aksoy, O. Yavaş
    Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
  • D. Angal-Kalinin, J.A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C.J. Bocchetta, A.I. Wawrzyniak
    Solaris, Kraków, Poland
  • M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc, Y.E. Tan, K.P. Wootton, D. Zhu
    SLSA, Clayton, Australia
  • G. Burt
    Lancaster University, Lancaster, United Kingdom
  • N. Catalán Lasheras, A. Grudiev, A. Latina, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • W. Fang, Q. Gu
    SINAP, Shanghai, People's Republic of China
  • E.N. Gazis
    National Technical University of Athens, Athens, Greece
  • M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • X.J.A. Janssen
    VDL ETG, Eindhoven, The Netherlands
  
  As is widely recognized, fourth generation Light Sources are based on FELs driven by Linacs. Soft and hard X-ray FEL facilities are presently operational at several laboratories, SLAC (LCLS), Spring-8 (SACLA), Elettra-Sincrotrone Trieste (FERMI), DESY (FLASH), or are in the construction phase, PSI (SwissFEL), PAL (PAL-XFEL), DESY (European X-FEL), SLAC (LCLS II), or are newly proposed in many laboratories. Most of the above mentioned facilities use NC S-band (3 GHz) or C-band (6 GHz) linacs for generating a multi-GeV low emittance beam. The use of the C-band increases the linac operating gradients, with an overall reduction of the machine length and cost. These advantages, however, can be further enhanced by using X-band (12 GHz) linacs that operate with gradients twice that given by C-band technology. With the low bunch charge option, currently considered for future X-ray FELs, X-band technology offers a low cost and compact solution for generating multi-GeV, low emittance bunches. The paper reports the ongoing activities in the framework of a collaboration among several laboratories for the development and validation of X-band technology for FEL based photon sources.  
 
MOPP025 Longitudinal Beam Profile Measurements in Linac4 Commissioning rfq, cavity, linac, electron 108
 
  • G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca
    CERN, Geneva, Switzerland
  • M. Yarmohammadi Satri
    IPM, Tehran, Iran
  
  Linac4, the future 160 MeV H− injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.  
 
MOPP034 Beam Dynamics Studies of the CLIC Drive Beam Injector bunching, cavity, focusing, quadrupole 131
 
  • S. Sanaye Hajari, S. Döbert, H. Shaker
    CERN, Geneva, Switzerland
  • S. Sanaye Hajari, H. Shaker
    IPM, Tehran, Iran
  
  In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel with the main linac. The beam in the Drive Beam Accelerator is phase coded. This means only every second accelerator bucket is occupied. However, a few percent of particles are captured in wrong buckets, called satellite bunches. The phase coding is done via a sub-harmonic bunching system operating at a half the acceleration frequency. The beam dynamics of the Drive Beam injector complex has been studied in detail and optimised. The model consists of a thermionic gun, the bunching system followed by some accelerating structures and a magnetic chicane. The bunching system contains three sub-harmonic bunchers, a prebuncher and a tapered travelling wave buncher all embedded in a solenoidal magnetic field. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimising the overall bunching process and in particular decreasing the satellite population and the beam loss in magnetic chicane and in transverse plane limiting the beam emittance growth.  
 
MOPP062 Proposal of a Conventional Matching Section as an Alternative to the Existing HSI MEBT Superlens at GSI UNILAC DTL, simulation, rfq, cavity 196
 
  • H. Hähnel, U. Ratzinger, R. Tiede
    IAP, Frankfurt am Main, Germany
  
  We propose a new design for the HSI MEBT section at GSI UNILAC as part of the planned UNILAC upgrade. The existing MEBT section was designed in 1996 and based on a novel concept called the superlens* which uses a magnetic quadrupol doublet lens combined with a short RFQ cavity for transversal and longitudinal focusing. In 2009 the RFQ section in front of the MEBT was upgraded which led to significant changes in the RFQ output particle distribution. Recent LORASR simulations show that the superlens transmission decreases to 90% (related to 20.75 mA, U4+ at input). Moreover, the matching to the following IH-DTL is not ideal. This leads to further losses in the IH and to a decrease of the overall UNILAC efficiency. To reach the FAIR requirement of 18 mA U4+ current for the UNILAC with minimal losses and to provide more flexibility for varying current level operation, a new design based on two magnetic quadrupole triplet lenses and a 2-gap buncher is proposed. The design shows full transmission at 20.75 mA U4+ current and improved matching to the IH-DTL, leading to a drastic decrease of particle losses along the IH-DTL.
* U. Ratzinger, R. Tiede, A New Matcher Type between RFQ and IH-DTL for the GSI High Current Heavy Ion Prestripper LINAC, Proc. LINAC96, Geneva, Switzerland, pp. 128-130 		 
poster icon Poster MOPP062 [9.440 MB]  
 
MOPP063 Development of a Pepper Pot Emittance Measurement Device for FRANZ ion, ion-source, plasma, proton 199
 
  • B. Klump, U. Ratzinger, W. Schweizer, K. Volk
    IAP, Frankfurt am Main, Germany
  
  Funding: This work is supported by HGS-HIRe
Within the FRANZ project [*] on the Institute of Applied Physics, University Frankfurt, a robust and simple pepper pot emittance measurement device for high beam power densities is developed. To use the device directly behind the ion source, a high robustness against HV breakdowns is necessary. This paper gives an overview on experimental setup, on the analysis method and on imaging properties of the screen. Furthermore, the implemented software-based evaluation method is shown. It concludes with a preliminary emittance measurement on the high current ion source for FRANZ.
[*] U. Ratzinger et al., “intense Pulsed Neutron Source FRANZ in the 1-500 keV Range“, Proc. ICANS-XVIII, Dongguan, April 2007, p.210
 		 
 
MOPP064 R&D of the 17 MeV MYRRHA Injector cavity, proton, rfq, linac 202
 
  • D. Mäder, M. Basten, D. Koser, H.C. Lenz, N.F. Petry, H. Podlech, A. Schempp, M. Schwarz, M. Vossberg
    IAP, Frankfurt am Main, Germany
  • C. Zhang
    GSI, Darmstadt, Germany
  
  Funding: Project supported by the EU, FP7 MAX, Contract No. 269565
MYRRHA is designed as an accelerator driven system (ADS) for transmutation of long-lived radioactive waste. The challenge of the linac development is the very high reliability of the accelerator to limit the thermal stress inside the reactor. With the concept of parallel redundancy the injector will supply a cw proton beam with 4 mA and 17 MeV to the main linac. The new MYRRHA injector layout consists of a very robust beam dynamics design with low emittance growth rates. Sufficient drift space provides plenty room for diagnostic elements and increases the mountability. Behind a 4-Rod-RFQ and a pair of two-gap QWR rebunchers at 1.5 MeV the protons are matched into the CH cavity section. A focussing triplet between the rebunchers ensures an ideal transversal matching into the doublet lattice. Each of the 7 RT CH structures has a constant phase profile and does not exceed thermal losses of 29 kW/m. The transition to the 5 SC CH cavities with constant beta profile is at 5.9 MeV. For a safe operation of the niobium resonators the electric and magnetic peak fields are defined below 25 MV/m and 57 mT respectively. 		 
poster icon Poster MOPP064 [4.024 MB]  
 
MOPP070 Final Design for the BERLinPro Main Linac Cavity HOM, cavity, linac, dipole 217
 
  • A. Neumann, J. Knobloch
    HZB, Berlin, Germany
  • K. Brackebusch, T. Flisgen, T. Galek, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • B. Riemann, T. Weis
    DELTA, Dortmund, Germany
  
  Funding: This work is partly funded by BMBF contract no. 05K10PEA and 05K10HRC
The Berlin Energy Recovery Linac Project (BERLinPro) is designed to develop and demonstrate CW LINAC technology for 100-mA-class ERLs. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. We have studied elliptical 7-cell cavities based on a modified Cornell ERL design combined with JLab's waveguide HOM damping approach. This paper will summarize the final optimization of the end-cell tuning for minimum external Q of the HOMs, coupler kick calculations of the single TTF fundamental power coupler as well as multipole expansion analysis of the given modes and a discussion on operational aspects. 		 
poster icon Poster MOPP070 [1.561 MB]  
 
MOPP091 Beam Test of a New RFQ for the J-PARC Linac rfq, linac, simulation, experiment 267
 
  • Y. Kondo, T. Morishita, Y. Sawabe, S. Yamazaki
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • T. Hori
    JAEA, Ibaraki-ken, Japan
  • A. Takagi
    KEK, Ibaraki, Japan
  
  We performed a beam test of a new 324-MHz 3-MeV RFQ (RFQ III) for the beam-current upgrade of the J-PARC linac. RFQ III is the first RFQ developed to meet the requirement of the J-PARC linac. The peak beam current is 50mA, pulse length is 500 micro-sec, and the repetition is 25 Hz. Before the installation to the accelerator tunnel scheduled in summer of 2014, we built a test stand for offline testing of the new ion source and RFQ. Basic performances of RFQ III such as transmission, transverse emittance, and energy spread were measured with short pulse length beams. In this paper, we present the results of the beam test.  
 
MOPP095 Emittance Measurement for SPring-8 Linac Using Four Six-Electrode BPMs linac, electron, quadrupole, focusing 279
 
  • K. Yanagida, H. Hanaki, S. Suzuki
    JASRI/SPring-8, Hyogo-ken, Japan
  
  In the SPring-8 linear accelerator (linac) six-electrode beam position monitors (BPMs) have been installed to measure second-order moments. At the end of the linac where the electron beam energy is 1 GeV four quadrupole magnets are utilized for twiss parameter matching toward the following beam transport line. Last year four six-electrode BPMs were installed at the locations of these four quadrupole magnets for an emittance measurement. The relative second-order moments were obtained changing the magnetic field strength of the quadrupole magnets, then beam sizes, emittances and twiss parameters were deduced or calculated. At this time we applied one pair of beam sizes measured by the screen monitor for a precise determination of emittances but we try to implement non-destructive measurement with no screen monitor. Before the emittance measurement a calibration with fifth-order moment correction was carried out changing beam positions at the BPM locations using upstream steering magnets (the entire calibration).  
slides icon Slides MOPP095 [0.984 MB]  
 
MOPP097 The Physics Programme of Next MICE Step IV experiment, scattering, solenoid, lattice 285
 
  • V. Blackmore
    JAI, Oxford, United Kingdom
  
  Funding: DOE, NSF, STFC, INFN and more
The international Muon Ionisation Cooling Experiment (MICE) is progressing toward a full demonstration of the feasibility of the cooling technology required for neutrino physics and muon colliders. Step IV will provide the first precise measurements of emittance and determine the influence of material properties on emittance reduction. The physics programme of the Step IV measurements is described in detail, along with a longer term view to demonstrating and studying (sustainable) ionisation cooling with re-acceleration.
The abstract is submitted by the chair of the MICE Speakers Bureau.
The presentation will be delivered by Dr Victoria Blackmore (Oxford)
Promotion to Oral presentation is be most welcome. 		 
 
MOPP106 3D Mode Analysis of Full Tanks in Drift-Tube Linacs DTL, linac, simulation, drift-tube-linac 300
 
  • S.S. Kurennoy
    LANL, Los Alamos, New Mexico, USA
  
  Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio.
[1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951. 		 
 
MOPP117 Multipole and Field Uniformity Tailoring of a 750 MHz RF Dipole dipole, multipole, cavity, survey 326
 
  • A. Castilla, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • A. Castilla
    DCI-UG, León, Mexico
  • A. Castilla, J.R. Delayen
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In recent years great interest has been shown in developing rf structures for beam separation, correction of geometrical degradation on luminosity, and diagnostic applications in both lepton and hadron machines. The rf dipole being a very promising one among all of them. The rf dipole has been tested and proven to have attractive properties that include high shunt impedance, low and balance surface fields, absence of lower order modes and far-spaced higher order modes that simplify their damping scheme. As well as to be a compact and versatile design in a considerable range of frequencies, its fairly simple geometry dependency is suitable both for fabrication and surface treatment. The rf dipole geometry can also be optimized for lowering multipacting risk and multipole tailoring to meet machine specific field uniformity tolerances. In the present work a survey of field uniformities, and multipole contents for a set of 750 MHz rf dipole designs is presented as both a qualitative and quantitative analysis of the inherent flexibility of the structure and its limitations. 		 
 
MOPP120 Beam Dynamic Design of a 100 mA, 162.5 Mhz High-Current Linac rfq, linac, quadrupole, experiment 336
 
  • F.J. Jia, J.E. Chen, Y.R. Lu, Z. Wang, W.L. Xia, X.Q. Yan, K. Zhu
    PKU, Beijing, People's Republic of China
  • W.P. Dou, Y. He
    IMP, Lanzhou, People's Republic of China
  
  Funding: This work is supported by the 973 program (No. 2014CB845503) and the NSFC (Grants No. 11079001).
The beam dynamic design of a 100 mA, 162.5 MHz Radio Frequency Quadrupole (RFQ) is presented in this paper. The RFQ will accelerate protons from 85 keV to 3 MeV under the operation mode of continuous-wave (CW). The code PARMTEQM is used to carry out the beam dynamics design and the transmission efficiency has been optimized and improved to more than 99%. In the design of this high-current linac, the space charge effect is analyzed as it can cause emittance growth, nonuniform particle density distribution and resonance effect. The electrode structure parameters generated by PARMTEQM also be adopted by the code of Toutatis to verify the result’s veracity. 		 
 
MOPP129 Status of the FETS Project rfq, proton, ion-source, ion 361
 
  • A.P. Letchford, M.A. Clarke-Gayther, D.C. Faircloth, S.R. Lawrie
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • S.M.H. Alsari, M. Aslaninejad, J.K. Pozimski, P. Savage
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • J.J. Back
    University of Warwick, Coventry, United Kingdom
  • G.E. Boorman, A. Bosco, S.M. Gibson
    Royal Holloway, University of London, Surrey, United Kingdom
  • R.T.P. D'Arcy, S. Jolly
    UCL, London, United Kingdom
  • M. Dudman, J.K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  The Front End Test Stand (FETS) under construction at RAL is a demonstrator for front end systems of a future high power proton linac. Possible applications include a linac upgrade for the ISIS spallation neutron source, new future neutron sources, accelerator driven sub-critical systems, high energy physics proton drivers etc. Designed to deliver a 60mA H-minus beam at 3MeV with a 10% duty factor, FETS consists of a high brightness ion source, magnetic low energy beam transport (LEBT), 4-vane 324MHz radio frequency quadrupole, medium energy beam transport (MEBT) containing a high speed beam chopper and non-destructive laser diagnostics. This paper describes the current status of the project and future plans.  
 
MOPP130 A Linac-Based Approach to Modelling an Orbit Separated Cyclotron cavity, linac, cyclotron, simulation 364
 
  • D.C. Plostinar, G.H. Rees
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  An orbit separated cyclotron (OSC) is a new type of accelerator intended as a proton driver for Accelerator Driven Subcritical Reactors (ADSRs). A ring has been designed based on the new concept that accelerates a proton beam from 500 MeV to 1 GeV in four turns using multi-cell superconducting cavities in each period. From a beam dynamics point of view, the ring can be considered as a “wrapped-up” linac at four times the ring circumference. In this paper we present beam dynamics modelling details when using 3D linac codes and cavity field maps. We conclude that the versatility of codes such as TraceWin, allows detailed machine modelling and improved design procedures that take into account various aspects including orbit distortion caused by transverse deflecting fields in the cavities.  
 
MOPP137 Design Progress of the MYRRHA Low Energy Beam Line rfq, solenoid, ion, proton 381
 
  • R. Salemme, L. Medeiros Romão, D. Vandeplassche
    Studiecentrum voor Kernenergie - Centre d'Étude de l'énergie Nucléaire (SCK•CEN), Mol, Belgium
  • M.A. Baylac, D. Bondoux, F. Bouly, J.-M. De Conto, E. Froidefond
    LPSC, Grenoble Cedex, France
  • J.-L. Biarrotte
    IPN, Orsay, France
  • D. Uriot
    CEA/DSM/IRFU, France
  
  The MYRRHA project, a flexible spectrum neutron irradiation facility, is designed according to the Accelerator Driven System (ADS) reactor concept. The MYRRHA driver consists of a high power superconducting proton LINAC. A prototype of the front end injector is being built up into a test platform conceived to experimentally address its design issues. Currently, the ECR proton source has been industrially procured. LPSC Grenoble designed the subsequent Low Energy Beam Transport (LEBT) section. Right before the RFQ, a short section hosts an electrostatic beam chopper producing carefully controlled beam interruptions. In this paper the status of the LEBT design with the associated beam instrumentation is reviewed. Future experimental plans including LEBT beam characterization and optimization of the beam transmission are presented.  
 
MOPP139 Studies of Coherent Synchrotron Radiation in the Jefferson Lab FEL Driver with Implications for Bunch Compression linac, acceleration, simulation, FEL 388
 
  • C. Tennant, D. Douglas, R. Li
    JLab, Newport News, Virginia, USA
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  
  Funding: Work supported by the Office of Naval Research and the High Energy Laser Joint Technology. Jefferson Laboratory work is supported under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Laboratory IR FEL Driver provides an ideal test bed for studying a variety of beam dynamical effects. Recent studies focused on characterizing the impact of coherent synchrotron radiation (CSR) with the goal of benchmarking measurements with simulation. Following measurements to characterize the beam, we quantitatively characterized energy extraction via CSR by measuring beam position at a dispersed location as a function of bunch compression. In addition to operating with the beam on the rising part of the linac RF waveform, measurements were also made while accelerating on the falling part. For each, the full compression point was moved along the backleg of the machine and the response of the beam (distribution, extracted energy) measured. Initial results of start-to-end simulations using a 1D CSR algorithm show remarkably good agreement with measurements. A subsequent experiment established lasing with the beam accelerated on the falling side of the RF waveform in conjunction with positive momentum compaction (R56) to compress the bunch. The success of this experiment motivated the design of a modified CEBAF-style arc with control of CSR and microbunching effects. 		 
 
MOPP140 Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector coupling, electron, simulation, gun 391
 
  • A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • L. Faillace
    RadiaBeam, Marina del Rey, California, USA
  • B. Spataro
    INFN/LNF, Frascati (Roma), Italy
  • A. Valloni
    CERN, Geneva, Switzerland
  
  A new S-Band photoinjector is being developed at UCLA that will feature a large accelerating gradient at 160 MeV/m creating a beam with approximately 6.5 MeV at the exit. Because of the large accelerating gradient and other considerations, such as cooling and manufacturing, the new Supergun will be coupled into using a coaxial method, rather than side coupling. With the large accelerating gradient we hope to create very low emittance beams on the order of 0.025 mm mrad. These beams can then be used for a number of purposes, mainly for high quality beams used in FELs. Electric simulations have been done using HFSS and Superfish. Heating and mechanical simulations were done using Ansys. Finally, beam simulations were completed with GPT.  
 
TUIOA02 R&D Efforts for ERLs linac, cavity, operation, SRF 394
 
  • R.G. Eichhorn
    Cornell University, Ithaca, New York, USA
  
  The last few years has seen extensive R&D for ERLs, with several prototype facilities now under construction or in operation. The Cornell ERL R&D program has reached major goals, with producing the world’s brightest beam from any photoinjector, reaching CW beam current of greaters than 75 mA, and reaching intrinsic quality factors of 1011 in an SRF cavity installed in a cryomodule. The talk gives an overview of status of ERLs projects, and ERL R&D.  
slides icon Slides TUIOA02 [8.803 MB]  
 
TUPP028 Beam Tests at the CLIC Test Facility, CTF3 experiment, operation, linac, acceleration 487
 
  • R. Corsini, S. Döbert, W. Farabolini, D. Gamba, J.L. Navarro Quirante, T. Persson, P.K. Skowronski, F. Tecker
    CERN, Geneva, Switzerland
  • W. Farabolini
    CEA/DSM/IRFU, France
  • D. Gamba
    JAI, Oxford, United Kingdom
  
  The CLIC Test Facility CTF3 has been built at CERN by the Compact Linear Collider (CLIC) International Collaboration, in order to prove the main feasibility issues of the two-beam acceleration technology on which the collider is based. After the successful completion of its initial task, CTF3 is continuing its experimental program in order to give further indications on cost and performance issues, to act as a test bed for the CLIC technology, and to conduct beam experiments aimed at mitigating technological risks. In this paper we discuss the status of the ongoing experiments and present the more recent results, including improvements in beam quality and stability.  
 
TUPP030 Design of a High Average Current Electron Source for the CLIC Drive Beam Injector gun, cathode, electron, simulation 493
 
  • S. Döbert, N. Chritin
    CERN, Geneva, Switzerland
  • B. Cadilhon, B. Cassany, J. Gardelle, K. Pepitone
    CEA, LE BARP cedex, France
  
  The drive beam injector for CLIC needs to deliver a 4.2 A electron beam for a duration of 140 μs with a repetition rate of 50 Hz. The shot to shot and flat top current stability has to be better than 0.1% to guarantee the beam stability required for CLIC. Based on the experience with the CTF3 injector a thermionic high voltage gun with a gridded cathode has been designed together with a sub-harmonic bunching system to achieve these requirements. The grid will allow controlling the current and eventually feedback on the flattop shape. The gun will operate at 140 kV and an emittance of 14 mm mrad can be obtained. The paper describes the design approach and the results of the systematic electromagnetic simulations to optimize the gun. Care was taken during the mechanical design of the gun to obtain a modular design allowing adjusting for different beam currents and cathode sizes.  
 
TUPP031 Understanding the Error Tolerances Required to Automatically Phase the HIE-ISOLDE Linac linac, cavity, software, experiment 496
 
  • M.A. Fraser, J.C. Broere, S. Haastrup, D. Lanaia, D. Valuch, D. Voulot
    CERN, Geneva, Switzerland
  
  The broad experimental programme at ISOLDE means that the same radioactive beam species and energy are rarely studied twice and the cavities of the linac must be scaled or re-phased for each experiment. A software application was developed to automatically re-phase the cavities of the HIE-ISOLDE superconducting linac to the beam from computed settings. The application was developed to expedite both machine set-up in normal operation and in scenarios involving cavity failures. A beam dynamics error study will be presented in order to better understand the challenges facing the automatic phasing routine. The effects of a variety of different errors on the efficacy of the phasing application were studied, leading to a specification of the tolerances required for the calibration of the rf system and the accuracy of the survey system that monitors the positions of the cavities.  
 
TUPP034 Commissioning of the CERN LINAC4 Wire Scanner, Wire Grid and Slit-Grid Monitors at 3 and 12 MeV linac, electron, space-charge, diagnostics 502
 
  • F. Roncarolo, U. Raich, F. Zocca
    CERN, Geneva, Switzerland
  
  The CERN LINAC4 has been commissioned up to 12 MeV. The H− beam transverse profile distributions were measured by both wire grids and wire scanners. A slit-grid system located on a temporary diagnostics bench was used to characterize the transverse emittance during the two different stages of commissioning: at the exit of the RFQ (3 MeV) and DTL1 (12 MeV). The wire signal is a balance between the negative charge deposited by the stripped electrons from the H− and the charge lost due to secondary emission. Optimal settings were found for the repelling plates used to suppress secondary emission, which were confirmed by electromagnetic simulations. In addition, suppression of the secondary emission due to the beam space charge was observed. The benefit of changing the wire scanner geometry in order to minimize the cross-talk between horizontal and vertical wires and the observation of thermionic emission on carbon wires are also discussed.  
 
TUPP035 Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV laser, linac, detector, electron 506
 
  • F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca
    CERN, Geneva, Switzerland
  • G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin
    Royal Holloway, University of London, Surrey, United Kingdom
  • C. Gabor
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  
  The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H0 detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.  
 
TUPP036 Space Charge Compensation in the Linac4 LEBT for Three Injected Gas Types simulation, ion, linac, space-charge 510
 
  • C.A. Valerio, R. Scrivens
    CERN, Geneva, Switzerland
  • N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  
  The space charge of unbunched, high intensity beams can be compensated by the trapping of charged particles in the potential well of the beam. The source of these secondary charge particles can be the residual gas in the beam line. The effect is important in the Low energy beam transport (LEBT) regions. At CERN’s Linac4, the LEBT transports a pulsed 45keV H− beam, which is compensated by the positive ions, created by collision of the beam with the neutral gas in the beam pipe. The rise time and amount of compensation may be varied by the density of neutral gas and the type of gas used (through the cross-section for ion production and the mass of the resulting ion). In this paper we present measurement results for the transport of the beam at the Linac4 LEBT with the addition of hydrogen, nitrogen and krypton gases into the line, and compare them with simulations of the beam dynamics including the effect of compensating positive ions . The H− beam is provided by a cesiated 2MHz RF ion source with an external solenoidal antenna, operating with 600us pulses at 0.8Hz repetition rate.  
slides icon Slides TUPP036 [4.084 MB]  
poster icon Poster TUPP036 [1.356 MB]  
 
TUPP037 Transverse Emittance Measurements of the REX-ISOLDE Beams in Preparation for the HIE-ISOLDE Commissioning quadrupole, linac, background, ion 513
 
  • D. Voulot, M.A. Fraser, D. Lanaia
    CERN, Geneva, Switzerland
  • T. Olsson
    MAX-lab, Lund, Sweden
  
  The transverse emittance at the output of the REX-ISOLDE normal conducting linac has been measured at different energies in order to characterise the beam at injection to the future HIE-ISOLDE superconducting linac. The measurements were done with low intensity stable beams (~0.5 enA) in order to avoid compensation effects in the EBIS ion source and obtain representative measurements of the radioactive ion beam emittance. Emittances were measured using a slit-grid emittance meter and compared with results obtained with a quadrupole-scan (three-gradient) method. An analysis of the background suppression is presented and possible source of errors for both type of measurements are discussed.  
poster icon Poster TUPP037 [2.084 MB]  
 
TUPP038 Transverse Beam Profile Measurements in the Linac4 Medium Energy Beam Transport simulation, linac, quadrupole, rfq 516
 
  • M. Yarmohammadi Satri, G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca
    CERN, Geneva, Switzerland
  
  Linac4 is a 160 MeV H− linear accelerator presently under construction at CERN. It will replace the present 50 MeV proton Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The Linac4 front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) which accelerates the beam to 3 MeV and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been commissioned in the Linac4 tunnel. The MEBT is composed of three buncher cavities and 11 quadrupole magnets to match the beam from the RFQ to the next accelerating structure (DTL) and it includes two wire scanners for beam profile measurement. In this paper we present the results of the profile measurements and we compare them with emittance measurements taken with a temporary slit-and-grid emittance measurement device located after the MEBT line.  
 
TUPP039 Accuracy Determination of the ESS MEBT Emittance Measurements scattering, proton, quadrupole, linac 519
 
  • B. Cheymol, A. Ponton
    ESS, Lund, Sweden
  
  The European Spallation Source MEBT will be equipped with a full set of diagnostics in order to characterize the bean properties before the injection in the DTL. The 6D phase space of the beam shall be characterize during the commissioning of the normal conducting as well as on regular basis during retuning phase of the machine. In this paper we will discuss the accuracy of the transverse emittance measurement that will be performed with the slit-grid method. The slit geometric parameters have been determined in order to achieve the required resolution and sensitivity. Scattering effects at the slit have been considered to determine the emittance measurement accuracy.  
 
TUPP054 Study of Beam-Based Alignment for the LCLS-II SC Linac linac, alignment, cryomodule, quadrupole 544
 
  • A. Saini, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  
  The Linac Coherent Light Source (LCLS) is an x-ray free electron laser facility. The proposed upgrade of the LCLS facility is based on construction of 4 GeV superconducting (SC) linac. The achievable performance of linac is determined by beam sensitivity to various component errors. In this paper we review misalignment tolerances of LCLS-II SC linac and discuss possible beam-based alignment algorithm to meet these tolerances.  
 
TUPP059 Advanced Beam Matching to a High Current RFQ rfq, quadrupole, simulation, ion 559
 
  • S.G. Yaramyshev, W.A. Barth, L.A. Dahl, P. Gerhard, L. Groening, M.T. Maier, S. Mickat, A. Orzhekhovskaya, B. Schlitt, H. Vormann
    GSI, Darmstadt, Germany
  
  The High Current Injector (HSI) of the heavy ion linac UNILAC at GSI comprises the transport lines, the RFQ and two DTL tanks. Beam matching to the RFQ acceptance with a magnetic quadrupole quartet has been worked out manually during commissioning and operation of the machine. Due to a strong overlapping of the field from neighboring quadrupole lenses, a standard optics calculation does not provide for the required reliability. Advanced beam dynamics simulations have been done with the macroparticle code DYNAMION. The superposition of the measured magnetic fields of each quadrupole was taken into account. The quadrupole settings were optimized using the Monte-Carlo method. Two solutions have been found in accordance with the general theory of particle optics. Beam dynamics simulations with new quadrupole settings show an increased particle transmission through the RFQ. The results of numerical study have been confirmed during experimental campaigns. An improved performance of the whole HSI has been demonstrated. The proposed algorithm and a comparison of the measured data with result of simulations are presented.  
 
TUPP075 The First Beam Recirculation and Beam Tuning in the Compact ERL at KEK linac, operation, recirculation, quadrupole 599
 
  • S. Sakanaka, M. Adachi, S. Adachi, M. Akemoto, D.A. Arakawa, S. Asaoka, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, O.A. Konstantinova, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, M. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
    KEK, Ibaraki, Japan
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • R. Hajima, S. Matsuba, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
    JAEA, Ibaraki-ken, Japan
  • J.G. Hwang
    KNU, Deagu, Republic of Korea
  • M. Kuriki, Y. Seimiya
    HU/AdSM, Higashi-Hiroshima, Japan
  • A. Valloni
    CERN, Geneva, Switzerland
  
  Superconducting(SC)-linac-based light sources, which can produce ultra-brilliant photon beams in CW operation, are attracting worldwide attention. In KEK, we have been conducting R&D efforts towards the energy-recovery-linac(ERL)-based light source* since 2006. To demonstrate the key technologies for the ERL, we constructed the Compact ERL (cERL)** from 2009 to 2013. In the cERL, high-brightness CW electron beams are produced using a 500-kV photocathode DC gun. The beams are accelerated using SC cavities, transported through a recirculation loop, decelerated in the SC cavities, and dumped. In the February of 2014, we succeeded in accelerating and recirculating the CW beams of 4.5 micro-amperes in the cERL; the beams were successfully transported from the gun to the beam dump under energy recovery operation in the main linac. Then, precise tuning of beam optics and diagnostics of beam properties are under way. We report our experience on the beam commissioning, as well as the results of initial measurements of beam properties.
* N. Nakamura, IPAC2012, TUXB02.
** S. Sakanaka et al., IPAC2013, WEPWA015. 		 
 
TUPP110 Quasi Nonlinear Plasma Wakefield Acceleration Experiments plasma, electron, focusing, experiment 680
 
  • S.K. Barber, G. Andonian, B.D. O'Shea, J.B. Rosenzweig, Y. Sakai, O. Williams
    UCLA, Los Angeles, USA
  • M. Ferrario
    INFN/LNF, Frascati (Roma), Italy
  • P. Muggli
    MPI, Muenchen, Germany
  
  It is generally agreed that the best way forward for beam driven plasma wakefield acceleration (PWFA) is in the nonlinear or blowout regime. In this regime the expulsion of the plasma electrons from the beam occupied region produces a linear transverse focusing effect and position independent longitudinal accelerating fields, which can, in principle, produce high quality beams accelerated over many meters. However, certain aspects of a linear plasma response can be advantageous, such as the possibility for resonant excitation of wakefields through the use of pulse trains. Exploiting advantages of both linear and nonlinear PWFA may be achievable through the use of low emittance and tightly focused beams with relatively small charge. In this case the beam density can be greater than that of the ambient plasma while simultaneously having a smaller total charge than the plasma electrons contained in a cubic plasma skin depth allowing for blowout in the region of the beam while simultaneously maintaining a quasi linear response in the bulk plasma. Recent experiments at BNL have been aimed at probing various salient aspects of this regime and are presented here.  
 
TUPP112 Study of a C-Band TW Electron Gun for SwissFEL gun, cathode, klystron, cavity 686
 
  • M. Schaer, A. Citterio, P. Craievich, L. Stingelin, R. Zennaro
    PSI, Villigen PSI, Switzerland
  
  For a future upgrade of the SwissFEL facility, the replacement of the S-band standing wave electron gun by a C-band standing wave, or traveling wave gun is investigated. The full model of the C-band TW gun is calculated with HFSS and is characterized by an almost vanishing group velocity in the first cell to increase the field at the cathode. ASTRA simulations predict that in the case of the C-band SW gun, a two times higher peak current of ~ 40 A can be generated while still preserving the low slice emittance of ~ 0.2 um at 200 pC, due to the higher electric field on cathode and improved magnetic focusing. This would help to halve the overall beam compression factor, relax the phase stability requirement of S- and X-band systems operated off-crest for compression and decrease the gain curve in theμbunch instability. Compared to the SW gun, a TW gun provides a more homogeneous acceleration and does not require any circulator. In this study, the preliminary RF design and beam performance of a C-band TW gun is presented and compared to a pure C-band SW gun presently under design at Paul Scherrer Institut and to the operating S-band SW gun.  
 
TUPP116 Status of the FERMI II RF Gun at Sincrotrone Trieste gun, cathode, coupling, dipole 692
 
  • L. Faillace, R.B. Agustsson, P. Frigola, A. Verma
    RadiaBeam, Santa Monica, California, USA
  
  Radiabeam Technologies, in collaboration with UCLA, developed a high gradient normal conducting radio frequency (NCRF) 1.6 cell photoinjector system, termed the Fermi Gun II, for the Sincrotrone Trieste (ST) facility. The RF gun has been already in full operation since mid-2013 as the injector for the ST FEL. We report here the current status of the photoinjector system.  
 
TUPP130 Optimization of Beam Parameters in APF Channel linac, controls, simulation, rfq 722
 
  • V.V. Altsybeyev, D.A. Ovsyannikov
    St. Petersburg State University, St. Petersburg, Russia
  
  A new approach based on mathematical optimization methods to obtain a synchronous phase sequence in APF linacs is suggested. The optimization problem of intensity deuteron beam parameters is discussed. As an example, the results of beam dynamics simulations are presented.  
 
THIOA01 Cost Optimized Design of High Power Linacs linac, cavity, neutron, acceleration 785
 
  • M. Eshraqi
    ESS, Lund, Sweden
  
  The research accelerators are growing in energy and power which translates to an increase in their cost, and also size if the conventional acceleration techniques are used. On the other hand, handling megawatts of power requires a design that is robust, respects the known criteria in beam physics to avoid losses in the order of less than one part in million. Traditionally cost increases with power and quality of the accelerator and beam. In this paper, using the ESS linac as an example, this tradition is challenged and ways to reduce the cost while neither quality nor power is compromised are presented.  
slides icon Slides THIOA01 [8.363 MB]  
 
THIOC02 Allison Scanner Emittance Diagnostic Development at TRIUMF electron, ion, gun, TRIUMF 829
 
  • A. Laxdal, F. Ames, R.A. Baartman, W.R. Rawnsley, A. Sen, V.A. Verzilov, G. Waters
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • R.V. Hariwal
    IUAC, New Delhi, India
  • M. Kownacki
    SFU, Burnaby, BC, Canada
  • R.F. Paris
    University of Ottawa, Ottawa, Ontario, Canada
  
  TRIUMF has developed Allison scanners to measure the transverse emittance of both low intensity hadron beams at 104 pps and high intensity electron beams at 10mA for a dynamic range of more than 1012 in intensity. The devices give high resolution transverse emittance information in a compact package that fits in a single diagnostic box. The talk will present the design and performance of the operating devices.  
slides icon Slides THIOC02 [2.349 MB]  
 
THPP019 Low Kick Coupler for Superconducting Cavities cavity, dipole, linac, resonance 876
 
  • R.G. Eichhorn, C. Egerer, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Results from the high current, low emittance photo injector at Cornell revealed that even with two opposing input couplers, the beam emittance is affected by the coupler kick. As a result, a coupler with low transverse kick is proposed for use in superconducting accelerating cavities. In this coupler, a rectangular waveguide transforms into a coaxial line inside the beam pipe. The geometry of the coupler is tuned to minimize the transverse kick that is important for linear accelerators with low emittance. The coupler can be used in ERL injectors or other linacs for high brightness light sources.  
 
THPP030 Status of the Design Study for 10 MHz Post-accelerated Radioactive Ion Beams at HIE-ISOLDE rfq, bunching, linac, ion 901
 
  • M.A. Fraser, R. Calaga
    CERN, Geneva, Switzerland
  
  A ten-fold increase in the bunch spacing of post-accelerated radioactive ion beams has been requested by several research groups at ISOLDE, CERN in order for experiments to use time-of-flight particle identification and background suppression techniques. It is proposed to bunch externally into the existing REX-ISOLDE RFQ at a sub-harmonic frequency of 10.128 MHz to produce the desired 100 ns bunch separation with minimal loss in transmission. The status of a beam dynamics design study carried out to meet this request will be presented in the framework of the HIE-ISOLDE linac upgrade at CERN.  
 
THPP033 Linac4 Transverse and Longitudinal Emittance Reconstruction in the Presence of Space Charge linac, quadrupole, simulation, rfq 913
 
  • J.-B. Lallement, G. Bellodi, V.A. Dimov, A.M. Lombardi, M. Yarmohammadi Satri
    CERN, Geneva, Switzerland
  • M. Yarmohammadi Satri
    IPM, Tehran, Iran
  
  Linac4 is a pulsed, normal-conducting 160 Mev H− linear accelerator presently under construction at CERN. It will replace the present 50 MeV Linac2 as injector of the proton accelerator complex as part of a project to increase the LHC luminosity. The 3 MeV front end, composed of a 45 keV ion source, a Low Energy Beam transport (LEBT), a 352 MHz Radio Frequency Quadrupole (RFQ) at 3 MeV and Medium Energy Beam Transport (MEBT) housing a beam chopper, and the first Drift Tube Linac (DTL) tank at 12 MeV have been commissioned during the first half of 2014. The transverse and longitudinal emittance reconstruction technique in the presence of space charge, that will be used for the next commissioning stages and permanently during the Linac operation, was successfully tested and validated. The reconstruction method and the results obtained at 3 and 12 MeV are presented in this paper.  
 
THPP034 Toolbox for Applying Beam-Based Alignment to Linacs linac, wakefield, interface, controls 916
 
  • A. Latina, D. Pellegrini, J. Pfingstner, D. Schulte
    CERN, Geneva, Switzerland
  • E. Adli
    University of Oslo, Oslo, Norway
  
  Tests of Beam-Based Alignment have been performed at FACET, at SLAC in the USA, and at Fermi, at Elettra in Trieste, Italy, with very promising results. Dispersion-Free Steering and Wakefield-free steering have been successfully applied to both machines. In order to make the correction process as automatic as possible, a set of robust tools has been developed, which allowed to span a large set of parameters. These tools and some of the experimental results performed at both machines are presented in this paper.  
 
THPP037 Commissioning and Operational Experience Gained with the Linac4 RFQ at CERN rfq, linac, cavity, ion 926
 
  • C. Rossi, L. Arnaudon, P. Baudrenghien, G. Bellodi, O. Brunner, J. Hansen, J.-B. Lallement, A.M. Lombardi, J. Noirjean
    CERN, Geneva, Switzerland
  • M. Desmons, A. France, O. Piquet
    CEA/DSM/IRFU, France
  
  The installation of Linac4 has started in 2013 with the 3 MeV Front End, aiming at delivering a fully commissioned 160 MeV H− beam by 2016. During summer 2013 the H− ion source, a clone of the first prototype, and the Low Energy Beam Transport lines have been installed in the Linac4 tunnel followed shortly by the Radiofrequency Quadrupole accelerator (RFQ), operating at the RF frequency of 352.2 MHz and which accelerates the ion beam to the energy of 3 MeV. The RFQ, which had already been commissioned at the 3 MeV Test Stand, was this time driven by a fully digital LLRF system. This paper reports the result of the bead-pull field check performed after the installation in the tunnel, the experience gained during recommissioning and the results of field characterization as a function of the water temperature in the RFQ cooling channels, showing how the accelerating field can be adjusted by simply tuning the different cavity modules.  
 
THPP042 Error Study on the Normal Conducting ESS Linac DTL, linac, rfq, quadrupole 942
 
  • R. De Prisco, M. Eshraqi, R. Miyamoto, E. Sargsyan
    ESS, Lund, Sweden
  • A.R. Karlsson
    Lund University, Lund, Sweden
  
  One of the preliminary, but important test to evaluate the robustness of the accelerator design is performing the statistical error study by introducing realistic tolerances on the machine components. In this paper the guidelines to define the tolerances and the correction system are summarized in order to validate the design. Firstly statistical studies have been performed in order to define the sensitivity to single errors and to fix the tolerances. Then all errors, within the previous defined tolerances, are applied with the correction system to evaluate the beam quality and to check if the system guarantees a radiologically safe operation.  
 
THPP045 ESS Linac Beam Modes rfq, linac, quadrupole, DTL 951
 
  • E. Sargsyan, R. Miyamoto
    ESS, Lund, Sweden
  
  The ESS Linac will ultimately deliver 5 MW of beam power to the target with a long-pulse structure of 2.86 ms and 14 Hz repetition rate, which is essential for the production of long-wavelength neutrons [1]. Ten different beam power levels are requested for the operation. In order to preserve the required time structure of the beam, different beam power levels will be produced by reducing the beam current in ten regular steps using an iris with an adjustable aperture in the LEBT. Low current and low emittance beams may as well be useful for the beam commissioning of the Linac. This paper describes the generation and the beam dynamics of different beam modes in the ESS Linac.  
 
THPP054 Study of Coupler's Effect in Third Harmonic Section of LCLS-II SC Linac cavity, cryomodule, linac, HOM 969
 
  • A. Saini, A. Lunin, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  
  The Linac Coherent Light Source (LCLS) is an x-ray free electron laser facility. The proposed upgrade of the LCLS facility is based on construction of 4 GeV superconducting (SC) linac which will use two stage bunch compression scheme in order to achieve short bunches with high peak current. In order to reduce non-linear effects in first bunch compressor, third harmonic section is utilized to linearize longitudinal phase space of the beam. However, transverse phase space of beam may get distorted due to coupler RF kicks and coupler wake kicks resulting from the asymmetry of input and HOM couplers in 3.9 GHz cavity. In this paper, we discuss coupler's effects and estimate resulting emittance dilution in third harmonic section. Local compensation of coupler kicks using different orientation of cavities are also addressed.  
 
THPP056 Status of the Warm Front End of PXIE rfq, kicker, ion, solenoid 976
 
  • A.V. Shemyakin, M.L. Alvarez, R. Andrews, C.M. Baffes, A.Z. Chen, R.T.P. D'Arcy, B.M. Hanna, L.R. Prost, G.W. Saewert, V.E. Scarpine, J. Steimel, D. Sun
    Fermilab, Batavia, Illinois, USA
  • R.T.P. D'Arcy
    UCL, London, United Kingdom
  • D. Li
    LBNL, Berkeley, California, USA
  
  Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy
A CW-compatible, pulsed H− superconducting linac is envisaged as a possible path for upgrading Fermilab’s injection complex. To validate the concept of the front-end of such machine, a test accelerator (a.k.a. PXIE) is under construction. The warm part of this accelerator comprises a 10 mA DC, 30 keV H− ion source, a 2m-long LEBT, a 2.1 MeV CW RFQ, and a 10-m long MEBT that is capable of creating a large variety of bunch structures. The paper will report commissioning results of a partially assembled LEBT, status of RFQ manufacturing, and describe development of the MEBT, in particular, of elements of its chopping system. 		 
 
THPP058 A Review of Emittance Exchanger Beamlines: Past Experiments and Future Proposals cavity, electron, laser, experiment 982
 
  • J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
  
  Emittance exchangers (EEX) are advanced phase space manipulation schemes where the transverse phase space of the electron beam is exchanged with the longitudinal phase space. The first experimentally demonstrated concept of the emittance exchanger at the A0 photoinjector at Fermilab used a transverse deflecting cavity (TDC) sandwiched between two doglegs. In this talk, I will briefly review the history of the emittance exchange beamline experiments from a low charge beam without RF chirp to a high charge beam with RF chirp including collective effects such as coherent synchrotron radiation. I will also describe how shaping application have been spawned based on EEX. I will then review future schemes that has been proposed and propose two additional schemes of EEX that can be implemented in existing modern linacs. As an example, we present an improved emittance exchanger scheme that uses a TDC sandwiched between two chicanes. The significant advantage of this scheme is that it allows the use of the expensive transverse deflecting cavity for diagnostics and still allows the flexibility to use the existing beamline either as a bunch compressor or an emittance exchanger.  
 
THPP060 Effect of Cavity Couplers Field on the Beam Dynamics of the LCLS-II Injector simulation, HOM, cavity, cryomodule 989
 
  • A. Vivoli, A. Lunin, A. Saini, N. Solyak
    Fermilab, Batavia, Illinois, USA
  • A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, C.E. Mayes
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Dowell, Z. Li, T.O. Raubenheimer, J.F. Schmerge, T. Vecchione, F. Zhou
    SLAC, Menlo Park, California, USA
  • D. Filippetto, R. Huang, C. F. Papadopoulos, H.J. Qian, S.P. Virostek, R.P. Wells
    LBNL, Berkeley, California, USA
  
  LCLS-II is a new light source based on a continuous wave (cw) superconducting linac to be built at SLAC. The Injector section of the linac creates the elecron beam and accelerates it up to about 100 MeV. The couplers of the accelerating cavities produce an asymmetric field resulting in a beam offset and, most importantly, in a significant transverse emittance dilution, if not compensated. In this paper we describe the simulations of the LCLS-II injector taking into account the cavity couplers effect and some mitigation techniques to reduce its impact on the beam quality.  
 
THPP063 Beam Diagnostics Layout for the FAIR Proton Linac linac, proton, diagnostics, beam-diagnostic 998
 
  • T. Sieber, M.H. Almalki, C. Dorn, J. Fils, P. Forck, R. Haseitl, W. Kaufmann, W. Vinzenz, M. Witthaus, B. Zwicker
    GSI, Darmstadt, Germany
  • C.S. Simon
    CEA/DSM/IRFU, France
  
  The planned proton Linac for FAIR (Facility of Antiproton an Ion Research) will be - additionally to the existing GSI UNILAC - a second injector for the FAIR accelerator chain. It will inject a 70 MeV, (up to) 70 mA proton beam with a nominal pulse length of 30 us into the SIS18. The beam diagnostics system for the proton Linac comprises nine current transformers for pulse current determination and fourteen BPMs for position, mean beam energy and relative current measurement. SEM-Grids and stepping motor driven slits will be used for profile as well as for emittance measurements. A wire-based bunch shape monitor is foreseen, additionally a bending magnet for longitudinal emittance determination during commissioning. Presently, main efforts are conducted concerning the BPM system. Detailed signal simulations with the finite element code CST are performed. An electronics board using digital signal processing is evaluated by detailed lab-based characterization and beam-based measurements at the UNILAC. In this paper we present the general layout and the status of the diagnostics systems as well as key results from our measurements and simulations.  
 
THPP065 Acceleration of Intense Flat Beams in Periodic Lattices DTL, focusing, space-charge, acceleration 1001
 
  • L. Groening, C. Xiao
    GSI, Darmstadt, Germany
  • I. Hofmann
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Recently a scheme for creation of flat ion beams from linacs has been proposed to increase the efficiency of multi-turn-injection. The proof of principle experiment shall be performed at GSI in Summer 2014. Since the scheme requires charge stripping, it may be necessary to perform the round-to-flat transformation prior to acceleration to the final energy of the linac. This requires preservation of the beam flatness during acceleration along the drift tube linac. This contribution is on simulations of acceleration of flat beams subject to considerable space charge tune depression. It is shown that the flatness can be preserved if the transverse tunes are properly chosen and if mis-match along inter-tank sections is minimized along the DTL.  
 
THPP070 Alternative Compact LEBT Design for the FAIR Injector Upgrade ion, focusing, space-charge, rfq 1013
 
  • K. Schulte, M. Droba, S. Klaproth, O. Meusel, D. Noll, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  • S.G. Yaramyshev
    GSI, Darmstadt, Germany
  
  In order to provide high intensity and brightness of the uranium beam for the planned FAIR project, the existing High Current Injector (HSI) at GSI has to be upgraded*. A part of the upgrade program is the design and construction of a compact straight injection line into the 36 MHz Radio Frequency Quadrupole of the HSI. As an alternative to a conventional LEBT design consisting of magnetic systems such as solenoids or quadrupoles, the application of Gabor lenses has been investigated. The focusing force of the Gabor lens is created by the space charge of an electron cloud, confined by crossed magnetic and electric fields inside the lens volume. Therefore, the Gabor lens combines strong, electrostatic focusing with simultaneous space-charge compensation. In previously performed beam transport experiments at GSI a prototype Gabor lens has been tested successfully. Furthermore, the operation and performance of such a device in a real accelerator environment has been studied. In this contribution an alternative LEBT design will be discussed and an improved Gabor lens design will be presented.
*W. Barth et al., “HSI-Frontend Upgrade”, GSI Scientific Report, 2009 		 
 
THPP085 The Prototype of the Proton Injector for the European Spallation Source plasma, proton, extraction, simulation 1044
 
  • L. Celona, L. Andò, G. Castro, S. Gammino, D. Mascali, L. Neri, G. Torrisi
    INFN/LNS, Catania, Italy
  
  The update of the design of the PS-ESS source and of its LEBT has been carried out in 2013 and the construction is now ongoing. The Ion Source will be able to provide a proton beam current larger than 70 mA to the 3.6 MeV RFQ. Several innovative solutions have been implemented in the redesign phase in order to cope with high-reliability/high-performance requirements of the ESS project. A flexible magnetic system will allow to investigate alternative configurations for future ion current upgrade of the machine based on the formation of a denser plasma. Innovative set-ups have been also explored for beam extraction, transport and chopping. Calculations have shown that space charge compensation up to 95 % is needed to preserve the low emittance in the low energy beam transfer line (LEBT). In order to obtain the optimal proton beam pulse rise and fall time – that should be 100 ns – we propose a LEBT chopping configuration that permits hundred nanosecond rise times despite the LEBT compensation needs few microseconds. The ongoing development of a 3D PIC code will be also described, that should allow predicting and tuning the beam pulse for different source/LEBT operative configurations.  
 
THPP086 ESS DTL Error Study DTL, multipole, linac, dipole 1047
 
  • M. Comunian, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  
  The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. The error study is decisive to define the DTL manufacturing tolerances and to evaluate its robustness. In this paper the DTL performances are shown.  
 
THPP095 Design Study of Superconducting Linear Accelerator for Unstable Ion Beams in RISP linac, ion, simulation, ISOL 1071
 
  • J.G. Hwang, C. Kim, E.-S. Kim
    Kyungpook National University, Daegu, Republic of Korea
  • B.H. Choi, H. Jang, D. Jeon, H.J. Kim, H.J. Kim, I. Shin
    IBS, Daejeon, Republic of Korea
  • L. Lee
    KNU, Deagu, Republic of Korea
  
  The post accelerator of RAON can accelerate the unstable and stable ion beams up to 15 MeV/u for 132Sn16+ and 58Ni8+ for 16.5 MeV/u, which has the ratio of mass to charge, A/q, of 8.3. The unstable ion beam such as 132Sn16+ produced by an ISOL system has the large transverse and longitudinal emittances. The post-accelerator consists of post-LEBT, RFQ, MEBT and superconduction linac(SCL3 and we optimized acceptance and beam envelope based on the beam dynamics in the linac. The accelerated beam by post accelerator was transported by the post-to-driver transport (P2DT) line which consists of a charge stripper, two charge selection sections and a telescope section with the bunching cavities to the high energy linac(SCL2) and accelerated up to 200 MeV/u. In this presentation, we will show the criteria for the design of the post accelerator and result of beam tracking simulation from post-LEBT to end of high energy linac.  
 
THPP097 3D Effects in RFQ Accelerators rfq, simulation, quadrupole, cavity 1077
 
  • S.S. Kurennoy
    LANL, Los Alamos, New Mexico, USA
  
  RFQ accelerators are usually designed and modeled with standard codes based on electrostatic approximations. Recent examples show that this approach fails to accurately predict the performance for 4-rod RFQs: 3D RF effects near the vane ends can noticeably influence the beam dynamics. The same applies to any RFQ where the quadrupole symmetry is broken, e.g., 4-vane RFQ with windows. We analyzed two 201.25-MHz 4-rod RFQs – one recently commissioned at FNAL and a new design for LANL – using 3D modeling with CST Studio. In both cases the manufacturer CAD RFQ model was imported into CST. The electromagnetic analysis with MicroWave Studio (MWS) was followed by beam dynamics modeling with Particle Studio (PS). For the LANL RFQ with duty factor up to 15%, a thermal-stress analysis with ANSYS was also performed. The simulation results for FNAL RFQ helped our Fermilab colleagues fix the low output beam energy. The LANL RFQ design was modified after CST simulations indicated insufficient tuning range and incorrect output energy; the modified version satisfies the design requirements.  
 
THPP102 On Nonlinear Dynamics of a Sheet Electron Beam plasma, electron, electronics, brightness 1090
 
  • H.Y. Barminova
    MEPhI, Moscow, Russia
  
  In collisionless approximation the nonlinear dynamics of a charged particle beam is studied. Nonlinear oscillations of the beam radius appear due to external and self-consistent nonlinear forces. To study such oscillations the model is applied based on the kinetic distribution function dependent on the particle motion integrals. The 4th-order equation for the beam radius is obtained. The numerical solutions of the equation are analyzed. The cases of strong and weak nonlinearities caused by the own beam fields are discussed. In the case of weak deviation of the beam parameters from equilibrium ones the effective emittance growth isn't observed.  
 
THPP118 Design of a New Superconducting Linac for the RIBF Upgrade linac, cyclotron, acceleration, ion 1127
 
  • K. Yamada, O. Kamigaito, N. Sakamoto, K. Suda
    RIKEN Nishina Center, Wako, Japan
  
  An upgrade plan for the RIKEN RI-Beam Factory[1] is under discussion, the objective being to significantly increase the uranium beam intensity. In the upgrade plan, the existing ring cyclotron called RRC[2] will be replaced by a new linac, mainly consisting of superconducting (SC) cavities. The new linac is designed to accelerate heavy ions with a mass-to-charge ratio of ~7, such as 238U35+, up to an energy of 11 MeV/u in the cw mode. The present injector linac, RILAC2[3], will be used for the low-energy end, and a short room-temperature (RT) section will be added to RILAC2, which will boost the beam energy up to 1.4 MeV/u. The succeeding SC section consists of 14 cryomodules, each of which contains four quater-wavelength resonators (QWRs) with two gaps operated at 73 MHz. A RT quadrupole doublet is placed in each gap between the cryomodules. The modular configuration of the SC section was optimized based on the first-order approximation for the transverse and longitudinal motions. The designs of SC QWR were carried out using CST Microwave Studio 2013. Further study is under way on the SC QWR including the mechanical considerations, and we also start a design of cryostats.
[1] Y. Yano, Nucl. Instr. Meth. B 261, 1009 (2007).
[2] Y. Yano, Proc. 13th Int. Cyclo. Conf., 102 (1992).
[3] K. Yamada et al., Proc. of IPAC'12, TUOBA02, 1071 (2012).
 		 
 
THPP127 The Status of the Construction of MICE Step IV solenoid, experiment, coupling, cavity 1159
 
  • S. Ricciardi
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  
  Funding: NSF, DOE, STFC, INFN and more
The International Muon Ionisation Cooling Experiment in its next step IV will provide the first precise measurements of emittances and first evidence of cooling in 2015. The pair of MICE "emittometers" must be in place for this, upstream and downstream of the ionization cooling module. Each required the construction of a tracker (sci-fibers) measuring muon helices in solenoid coils that surround it. Solenoid coils confine muons to spiral in all components of a ionization cooling module. The first of these, that is now ready for Step IV, will be the first of three AFC (absorber-focus coil) modules: a Li-H vessel inside its own FC "focusing" coils. Li-H and other simpler, possibly competitive, liquid and solid absorber samples are also being prepared. The assembly process is in progress. Construction, performances, lessons learned will be described. Final step V and step VI demonstration requires two more AFC modules and two re-acceerating modules, RFCC's made of RF cavities inside their own focusing CC ("coupling" coils). The choices made and challenges being faced in this longer term construction efforts simultaneosly in progress will also briefly be pointed to.
The abstract is submitted by the chair of the MICE Speakers Bureau.
The presentation would be delivered by Dr Stefania Ricciardi (RAL)
Promotion to Oral would be most welcome