WEPZ —  Poster Session   (07-Sep-11   16:00—18:00)
Paper Title Page
WEPZ002 Chromatic, Geometric and Space Charge Effects on Laser Accelerated Protons Focused by a Solenoid 2766
 
  • H.Y. Al-Omari, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  • I. Hofmann
    GSI, Darmstadt, Germany
 
  We studied numerically emittance and transmission effects by chromatic and geometric aberrations, with and without space charge, for a proton beam behind a solenoid in the laser proton experiment LIGHT at GSI. The TraceWin code was employed using a field map for the solenoid and an initial distribution with exponential energy dependence close to the experiment. The results show a strong effect of chromatic, and a relatively weak one of geometric aberrations as well as dependence of proton transmission on distance from the solenoid. The chromatic effect has an energy filtering property due to the finite radius beam pipe. Furthermore, a relatively modest dependence of transmission on space charge is found for p production intensity below 1011.  
 
WEPZ004 Solid Pulse Transforming Line for DWA 2769
 
  • L. Zhang
    CAEP/IFP, Mainyang, Sichuan, People's Republic of China
 
  This paper introduces the research work about solid pulse transforming line for dielectric wall accelerator(DWA). We will discuss the impedence of the solid pulse transforming line due to different material. Some research of PCSS(photoconductive semiconductor switch),which was used for DWA, will also be described.  
 
WEPZ005 Field Calculations to obtain Attosecond/Femtosecond Electron Bunches 2772
 
  • V.A. Papadichev
    LPI, Moscow, Russia
 
  Obtaining short electron bunches of attosecond and femtosecond duration in a combined quasi-static and laser electric field [* - ****] requires careful field formation in the cathode region. First, the maximum of laser electric field normal to the cathode plate, depending on the incidence angle, was found employing Fresnel formulae using complex dielectric permittivity of metals. Second, laser field enhancement on cathode spikes was calculated for the case of an ellipsoid in a qusi-static approximation (laser wavelength larger than spike dimensions). Field enhancement is approximately proportional to the square of the ratio of major to minor axes of ellipsoid. Thus, enhancement factors as large as 100 - 1000 are obtainable, allowing to reduce laser power by 10 thousand to 1 million times.
* V.A.Papadichev, Patent RU 2 269 877 C1, 10.02.06, Bull. 4.
** V.A.Papadichev, Proc. EPAC08, p.2812.
*** V.A.Papadichev, Proc. EPAC08, p.2815.
**** V.A.Papadichev, Proc. IPAC'10, p. 4372
 
 
WEPZ006 Forming Attosecond Electron Pulses in Space-charge Dominated Regime 2775
 
  • V.A. Papadichev
    LPI, Moscow, Russia
 
  Production of high-current attosecond electron pulses requires studying of the final bunching stage, which inevitably is space-charge dominated [*, **, ***]. Two models are studied, both allow solving a one-dimensional equation of motion. The first is for a spherical bunch, which corresponds to a short emitted pulse from a one-spike cathode of diameter approximately equal to its length. The second model is suited for pulses emitted from a multi-spike or multi-blade cathode. The bunch in the latter case is a thin plate and its evolution can be studied by also solving one-dimensional equation of motion. It was shown that bunches of 10-attosecond (as) duration with peak current of dozens of amperes can be obtained when using a carbon dioxide laser and less than 0.1-as duration with currents up to 1 MA when employing a neodymium laser. Beam focusing in transverse directions is also studied using a model. Possible applications of such electron bunches are reviewed, including obtaining attosecond pulses of tunable coherent radiation in UV and X-ray regions.
* V.A.Papadichev, Proceedings of EPAC08, p.2815.
** V.A.Papadichev, Proceedings of IPAC'10, Kyoto, Japan, p. 4372.
*** V.A.Papadichev, Proc. RUPAC-2010, TUPSAO10, p. 56.
 
 
WEPZ007 Multi-mode, Two-beam Accelerator with Feedback 2778
 
  • S.V. Kuzikov, M.E. Plotkin
    IAP/RAS, Nizhny Novgorod, Russia
 
  A high-gradient accelerator consisted of the test and the drive beam structures is reported. The accelerating structure can be based on dielectric or corrugated cavities separated each other by irises. Each cavity is operated by several axisymmetric, TM-like eigen-modes with longitudinal indices to be related to frequencies. These modes are excited at Fourier harmonics of the drive current which consists of bunches spaced with the same period as test bunches. The superposition of the excited modes introduces a short RF pulse propagated in-phase with a moving test bunch and after reflection by iris (a feedback) this pulse can accelerate next bunch. Such longitudinally-sweeping RF field promises a reduction of the exposure time and due to compact space shape can help to obtain high shunt impedance.  
 
WEPZ008 Experimental Plans to Explore Dielectric Wakefield Acceleration in the THz Regime 2781
 
  • F. Lemery, D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • C. Behrens, E. Elsen, K. Flöttmann, C. Gerth, G. Kube, B. Schmidt
    DESY, Hamburg, Germany
  • J. Osterhoff
    LBNL, Berkeley, California, USA
  • P. Stoltz
    Tech-X, Boulder, Colorado, USA
 
  Funding: This work was supported by the Defense Threat Reduction Agency, Basic Research Award \# HDTRA1-10-1-0051, to Northern Illinois University
Dielectric wakefield accelerators have shown great promise toward high-gradient acceleration. We investigate tow experiments in preparation to explore the performance of cylindrically-symmetric and slab-shaped dielectric-loaded waveguides. The planned experiments at Fermilab and DESY will use unique pulse shaping capabilities offered at these facilities. The superconducting test accelerator at FNAL will ultimately provide flat beams with variable current profiles needed for enhancing the transformer ratio. The FLASH facility at DESY recently demonstrated the generation of a ramped round beam current profile that will enable us to explore the performance of cylindrically-symmetric structures. Finally both of these facilities incorporate superconducting linear accelerator that could generate bunch trains with closely spaced bunches thereby opening the exploration of dynamical effects in dielectric wakefield accelerators. We present the planned layout and simulated experimental performances.
 
 
WEPZ009 Parametric-Resonance Ionization Cooling in Twin-Helix 2784
 
  • V.S. Morozov, Y.S. Derbenev
    JLAB, Newport News, Virginia, USA
  • A. Afanasev, R.P. Johnson
    Muons, Inc, Batavia, USA
  • B. Erdelyi, J.A. Maloney
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: Supported in part by DOE SBIR grant DE-SC0005589. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. For the implementation of PIC, we developed an epicyclic twin-helix channel with correlated optics. Wedge-shaped absorbers immediately followed by short rf cavities are placed into the twin-helix channel. Parametric resonances are induced in both planes using helical quadrupole harmonics. We demonstrate resonant dynamics and cooling with stochastic effects off using GEANT4/ G4beamline. We illustrate compensation of spherical aberrations and benchmark COSY Infinity, a powerful tool for aberration analysis and compensation.
 
 
WEPZ010 Modeling and Experimental Update on Direct Laser Acceleration 2787
 
  • I. Jovanovic, M.W. Lin
    Penn State University, University Park, Pennsylvania, USA
 
  Funding: This work is supported by the Defense Threat Reduction Agency under contract HDTRA1-11-1-0009.
Moderate-energy, high-repetition-rate electron beams are needed in a variety of applications such as those in security and medicine, while requiring that the acceleration be realized in a compact and relatively inexpensive package. Laser wakefield acceleration is an attractive technology which meets most of those requirements, but it requires the use of relatively high peak power lasers which do not scale readily to high repetition rates. We are developing the theoretical and experimental basis for advancing the science and technology of direct laser acceleration (DLA) of charged particles using the axial component of the electric field of a radially polarized intense laser pulse. DLA is an acceleration method which exhibits no threshold and is thus compatible with the use of lower peak power, but much higher repetition rate lasers. We are currently numerically investigating the conditions for quasi-phase-matched DLA of electrons in plasma waveguides and experimentally implementing the quasi-phase-matched waveguide structure in laser-produced plasmas.
 
 
WEPZ011 Fast Cooling of Bunches in Compton Storage Rings 2790
 
  • E.V. Bulyak
    NSC/KIPT, Kharkov, Ukraine
  • J. Urakawa
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
 
  We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling', the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.  
 
WEPZ012 Influence of Transition Radiation on Formation of a Bunch Wakefield in a Circular Waveguide 2793
 
  • T.Yu. Alekhina, A.V. Tyukhtin
    Saint-Petersburg State University, Saint-Petersburg, Russia
 
  Funding: The Education Agency of Russian Federation.
Investigation of a field of a particle bunch in a waveguide loaded with a dielectric is important for the wakefield acceleration (WFA) technique and other problems in the accelerator physics. One of subjects of investigation in this area consists in analysis of transition radiation generated by the bunch flying into (out of) the dielectric structure. This radiation can be both destructive (for WFA) and useful (for diagnostics of bunch or material). We investigate the total field of small bunch crossing a boundary between two dielectrics in the waveguide. It includes a “forced” field and a “free” one. The “forced” field is the field of the charge in the unbounded waveguide (it can contain the wakefield). The “free” field is connected with influence of the boundary (it includes transition radiation). Two cases are analyzed in detail: the bunch flies from vacuum into dielectric and from dielectric into vacuum. The behavior of the field depending on distance and time is explored analytically and numerically. Some interesting physical effects are noted. As well, we make a comparison with the case of intersection between vacuum and cold plasma.
 
 
WEPZ013 Design Status of LHeC Linac-Ring Interaction Region 2796
 
  • R. Tomás, J.L. Abelleira, S. Russenschuck, F. Zimmermann
    CERN, Geneva, Switzerland
  • N.R. Bernard
    UCLA, Los Angeles, California, USA
 
  The ECFA-CERN-NuPECC design study for a Large Hadron electron Collider (LHeC) based on the LHC, considers two options, using a ring accelerator like LEP on top of the LHC or adding a recirculating energy-recovery linac tangential to the LHC. In order to obtain the required luminosity with an e- beam from a linac, with average lepton beam current limited to a few mA, reaching the smallest possible proton beam size is essential. Another constraint is imposed by the need to separate e- and p beams after the collision without losing too much luminosity from a crossing angle. A further constraint is that the ep collision should occur simultaneously to pp collisions at other LHC interaction points such that the second LHC proton beam must be accommodated in the interaction region too. We present a conceptual layout using detector-integrated combination-separation dipoles and challenging Nb3Sn technology quadrupoles for focusing the colliding proton beam and providing a low-field “hole” to accommodate both the non-colliding proton beam and the lepton beam, and the optics for all three beams. We discuss synchrotron radiation fluxes and the chromatic correction for the lepton final focus.  
 
WEPZ014 Upgrade of the Argonne Wakefield Accelerator Facility (AWA): Commissioning of the RF Gun and Linac Structures for Drive Beam Generation 2799
 
  • 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.
Research at the AWA Facility has been focused on the development of electron beam driven wakefield structures. Accelerating gradients of up to 100 MV/m have been excited in dielectric loaded cylindrical structures operating in the microwave range of frequencies. Several upgrades, presently underway, will enable the facility to explore higher accelerating gradients, and also be able to generate longer RF pulses of higher intensity. The major items included in the upgrade are: (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 upgraded 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.
 
 
WEPZ015 Staging in Two Beam Dielectric Wakefield Accelerators 2802
 
  • J.G. Power, M.E. Conde, W. Gai, C.-J. Jing
    ANL, Argonne, USA
 
  Funding: The work is supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357 with Argonne National Laboratory.
A new experimental program to demonstrate staging in a two beam dielectric wakefield accelerator (DWA) is being planned at the Argonne Wakefield Accelerator facility. DWA uses a drive beam to generate acceleration fields to accelerate a main beam and is one of the most promising advanced acceleration methods being pursued for a future high-energy physics linear collider. Staging is the ability to use two accelerating modules back to back to accelerate a charged particle bunch and it is one of basic requirements of any acceleration method. In this paper, a new beamline design consisting of a fast kicker to pick pulses from the drive bunch train and deliver them to the individual acceleration modules will be presented.
 
 
WEPZ016 Generation and Characterization of Electron Bunches with Ramped Current Profiles at the FLASH Facility 2805
 
  • P. Piot
    Fermilab, Batavia, USA
  • C. Behrens, C. Gerth, M. Vogt
    DESY, Hamburg, Germany
  • F. Lemery, D. Mihalcea
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: This work was supported the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-10-1-0051, to Northern Illinois University and the German's Bundesministerium f\"ur Bildung und Forschung
We report on the successful generation of electron bunches with current profiles that have a quasi-linear dependency on the longitudinal coordinate. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a linac operating at two frequencies (1.3 and 3.9 GHz) and a bunch compressor. Data taken for various accelerator settings demonstrate the versatility of the method. The produced bunches have parameters well matched to drive high-gradient accelerating field with enhanced transformer ratio in beam-driven accelerators based on sub-mm-sizes dielectric or plasma structures.
 
 
WEPZ017 ESTB: A New Beam Test Facility at SLAC 2808
 
  • M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, T.V.M. Maruyama, D.R. Walz, M. Woods
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515.
End Station A Test Beam (ESTB) is a beam line at SLAC using a small fraction of the bunches 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. ESTB will provide one of a kind test beam essential for developing accelerator instrumentation and accelerator R&D, performing particle and particle astrophysics detector research, linear collider machine and detector interface (MDI) R&D studies, development of radiation-hard detectors, and material damage studies with several distinctive features. In the past, 18 institutions participated in the ESA program at SLAC. In stage I, 4 new kicker magnets will be added to divert 5 Hz of the LCLS beam to ESA. A new beam dump is installed and a new Personnel Protection System (PPS) is built in ESA. In stage II, we plan to install a secondary hadron target, able to produce pions up to about 12 GeV/c at 1 particle/pulse. We report about the ESTB commissioning, status and plan for tests.
 
 
WEPZ021 Self-Consistent Dynamics of Electromagnetic Pulses and Wakefields in Laser-Plasma Interactions 2811
 
  • A. Bonatto, R. Pakter, F.B. Rizzato
    IF-UFRGS, Porto Alegre, Brazil
 
  In the present work we study the stability of laser pulses propagating in a cold relativistic plasma, which can be of interest for particle acceleration schemes. After obtaining a Lagrangian density from the one-dimensional equations for the laser pulse envelope and the plasma electron density, we define a trial function and apply the variational approach in order to obtain an analytical model which allows us to calculate an effective potential for the pulse width. Using this procedure, we analyze the stability of narrow and large laser pulses and then compare its results with numerical solutions for the envelope and density equations.  
 
WEPZ023 Results from Plasma Wakefield Acceleration Experiments at FACET 2814
 
  • S.Z. Li, C.I. Clarke, R.J. England, J.T. Frederico, S.J. Gessner, M.J. Hogan, R.K. Jobe, M.D. Litos, D.R. Walz
    SLAC, Menlo Park, California, USA
  • E. Adli
    University of Oslo, Oslo, Norway
  • W. An, C.E. Clayton, C. Joshi, W. Lu, K.A. Marsh, W.B. Mori, S. Tochitsky
    UCLA, Los Angeles, California, USA
  • P. Muggli
    USC, Los Angeles, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE- AC02-76SF00515.
We report initial results of the Plasma Wakefield Acceleration (PWFA) Experiments performed at FACET - Facility for Advanced aCcelertor Experimental Tests at SLAC National Accelerator Laboratory. At FACET a 23 GeV electron beam with 1.8x1010 electrons is compressed to 20 microns longitudinally and focused down to 10 microns x 10 microns transverse spot size for user driven experiments. Construction of the FACET facility completed in May 2011 with a first run of user assisted commissioning throughout the summer. The first PWFA experiments will use single electron bunches combined with a high density lithium plasma to produce accelerating gradients >10GeV/m benchmarking the FACET beam and the newly installed experimental hardware. Future plans for further study of plasma wakefield acceleration will be reviewed.
 
 
WEPZ024 Some Considerations in Realizing a TeV Linear Collider Based on the PDPWA Scheme 2817
 
  • G.X. Xia, A. Caldwell
    MPI-P, München, Germany
  • P. Muggli
    MPI, Muenchen, Germany
 
  Proton-driven plasma wakefield acceleration (PDPWA) has recently been proposed as an approach to bring the electron beam to the energy frontier in a single passage of acceleration. Particle-in-Cell (PIC) simulation shows that a TeV proton bunch, with a bunch intensity of 1011, and a bunch length as short as 100 microns can resonantly excite a large amplitude plasma wakefield and accelerate an externally injected electron bunch to 600 GeV in a single stage of 500 m long plasma. This novel PDPWA scheme may open a new path for designing a TeV linear lepton collider by using the currently available proton drivers. In this paper, we investigate some key issues, e.g. bunch length, centre-of-mass (CoM) energy, luminosity and dephasing in realizing a TeV linear collider based on the PDPWA scheme.  
 
WEPZ025 Study of Self-injection of an Electron Beam in a Laser-driven Plasma Cavity 2820
 
  • S. Krishnagopal, S.A. Samant, D. Sarkar
    BARC, Mumbai, India
  • P. Jha
    Lucknow University, Lucknow, India
  • A.K. Upadhyay
    CBS, Mumbai, India
 
  Over the last few years, remarkable advances in laser wakefield acceleration of electrons have been achieved, including quasi-monoenergetic beams and GeV energy in a few centimeters. However, it is necessary to achieve good beam quality (large current, low energy-spread and low emittance) for applications such as free-electron lasers. We study self-injection in two regimes of the laser-plasma interaction: the moderate intensity, self-guiding regime, and the low intensity, near-injection-threshold regime, both in a homogeneous plasma that completely fills the simulation volume. We find good beam quality with injection of on-axis electrons, especially at lower intensity. We also study the case when the laser has to travel through vacuum before entering the plasma. We find that injection here is completely different, from off-axis electrons, and the beam quality is poorer.  
 
WEPZ027 Stabilization of the LWFA and its Application to the Single-shot K-edge Densitometry 2823
 
  • K. Koyama, H. Madokoro, Y. Matsumura
    University of Tokyo, Tokyo, Japan
  • R. Kuroda, K. Yamada
    AIST, Tsukuba, Ibaraki, Japan
  • H. Masuda, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • S. Masuda
    Osaka University, Suita, Osaka, Japan
 
  Funding: This work was supported in part by Global COE Program “Nuclear Education and Research Initiative,” MEXT, Japan
Injection of electrons into a laser wakefield accelerator (LWFA) via a wavebreaking process was investigated in order to obtain stable output of electron bunches. A density down ramp for occurring the wavebreaking was formed by an oblique shockwave, which was excited by setting a little flow-deflector on an edge of the supersonic nozzle of high-Mach number (M=5). Parameters of the jet were examined by using PIC code and evaluated by using an interferometer, the density was 1019cm-3, density ratio was 2, and the characteristic length was 70 microns. Injection experiments using 7-TW laser pulses suggested that electrons were injected in the density ramp. Since the all-optical Compton X-ray is attractive source for an accurate densitometry, a preliminary experiment of a single-shot K-edge densitometry was performed by using X-ray pulses generated by the laser-Compton scattering (LCS) device based on a compact S-band 40 MeV linac at AIST. The single-shot K-edge densitometry was also applicable to evaluate the transverse emittance of electron bunches.
 
 
WEPZ028 Status of Plasma Electron Hose Instability Studies in FACET 2826
 
  • E. Adli
    University of Oslo, Oslo, Norway
  • W. An, W.B. Mori
    UCLA, Los Angeles, California, USA
  • R.J. England, J.T. Frederico, M.J. Hogan, S.Z. Li, M.D. Litos, Y. Nosochkov
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported by the Research Council of Norway, the Fulbright Visiting Scholar Program and US DOE contract DE-AC02-76SF00515.
In the FACET plasma-wakefield acceleration experiments a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability.
 
 
WEPZ030 Study on a Gas-filled Capillary Waveguide for Laser Wakefield Acceleration 2829
 
  • M.S. Kim, D. Jang, D. Jang, H. Suk
    APRI-GIST, Gwangju, Republic of Korea
 
  In gas-filled capillary waveguide for lase wakefield accelerators the gas flows through the two gas feed lines used to sustain constant pressure. Compared to the supersonic gas-jet system operated under high pressure, the gas at low pressure (<1atm) is injected inside capillary waveguide, so that this waveguide has experimental limit to the measurement of the neutral density. In order to investigate the gas pressure in capillary system we used computational fluid dynamics (CFD) simulation. In this paper, we presented the gas pressure changed by a variety of parameters, such as length and sizes of gas feed lines, and the method to decrease the turbulence effect at the ends of capillary.  
 
WEPZ031 Accelerator Studies on a Possible Experiment on Proton-driven Plasma Wakefields at CERN 2832
 
  • R.W. Assmann, I. Efthymiopoulos, S.D. Fartoukh, G. Geschonke, B. Goddard, C. Heßler, S. Hillenbrand, M. Meddahi, S. Roesler, F. Zimmermann
    CERN, Geneva, Switzerland
  • A. Caldwell, G.X. Xia
    MPI-P, München, Germany
  • P. Muggli
    MPI, Muenchen, Germany
 
  There has been a proposal by Caldwell et al to use proton beams as drivers for high energy linear colliders. An experimental test with CERN's proton beams is being studied. Such a test requires a transfer line for transporting the beam to the experiment, a focusing section for beam delivery into the plasma, the plasma cell and a downstream beam section for measuring the effects from the plasma and safe disposal of the beam. The work done at CERN towards the conceptual layout and design of such a test area is presented. A possible development of such a test area into a CERN test facility for high-gradient acceleration experiments is discussed.  
 
WEPZ032 Energy Spectrometer Studies for Proton-driven Plasma Acceleration 2835
 
  • S. Hillenbrand, R.W. Assmann, F. Zimmermann
    CERN, Geneva, Switzerland
  • S. Hillenbrand, A.-S. Müller
    KIT, Karlsruhe, Germany
  • T. Tückmantel
    HHUD, Dusseldorf, Germany
 
  Plasma-based acceleration methods have seen important progress over the last years. Recently, it has been proposed to experimentally study plasma acceleration driven by proton beams, in addition to the established research directions of electron and laser driven plasmas. Here, we present the planned experiment with a focus on the energy spectrometer studies carried out.  
 
WEPZ034 Double Resosnant Plasma Wakefields 2838
 
  • B.D. O'Shea, A. Fukasawa, B. Hidding, J.B. Rosenzweig, S. Tochitsky
    UCLA, Los Angeles, California, USA
  • D.L. Bruhwiler
    Tech-X, Boulder, Colorado, USA
 
  Present work in Laser Plasma Accelerators focuses on a single laser pulse driving a non-linear wake in a plasma. Such single pulse regimes require ever increasing laser power in order to excite ever increasing wake amplitudes. Such high intensity pulses can be limited by instabilities as well engineering restrictions and experimental constraints on optics. Alternatively we present a look at resonantly driving plasmas using a laser pulse train. In particular we compare analytic, numerical and VORPAL simulation results to characterize a proposed experiment to measure the wake resonantly driven by four Gaussian laser pulses. The current progress depicts the interaction of 4 CO2 laser pulses, λlaser = 10.6μm, of 3 ps full width at half max- imum (FWHM) length separated peak-to-peak by 18 ps, each of normalized vector potential a0 ≃ 0.7. Results con- firm previous discourse (*,**) and show, for a given laser pro- file, an accelerating field on the order of 900 MV/m, for a plasma satisfying the resonant condition, ωp=π/tfwhm.
* Umstadter, D., et al, Phys. Rev. Lett. 72, 1224
** Umstadter, D., et al, Phys. Rev. E 51, 3484
 
 
WEPZ036 A Multi-Parameter Optimization of Plasma Density for an Advanced Linear Collider 2841
 
  • P. Muggli
    USC, Los Angeles, California, USA
  • R.W. Assmann
    CERN, Geneva, Switzerland
  • S. Hillenbrand
    KIT, Karlsruhe, Germany
  • P. Muggli
    MPI, Muenchen, Germany
 
  Funding: Work supported by US DoE
Recent plasma wakefield accelerator (PWFA) experiments showed that an accelerating gradient as high as 50GV/m can be driven and sustained over a meter-long plasma*. Based on this result, a strawman design for a future, multi-stage, PWFA-based electron/positron collider with an energy gain of ~25GeV/stage has been generated**. However, the choice of plasma density remains open. On one hand, high density means large accelerating gradients and possibly a shorter collider. On the other it means that the accelerating structure dimensions become very small, on the order of the plasma wavelength (<100 microns in each dimension?). Operating at high gradient and with such small structure imposes very strong constraints on the particle bunches: small dimensions and spacing, large current or limited charge, etc. These constraints result in challenges in producing bunches (compression, shaping for optimum loading, etc.) and could limit the achievable collider luminosity (beam-beam effects, etc.). We explore the global implications of operating at a lower accelerating gradient with the goal of relaxing the beam and plasma parameters while meeting the requirements of the collider.
* P. Muggli and M.J. Hogan, Comptes Rendus Physique, 10(2-3), 116 (2009).
** A. Seryi, M.J. Hogan, T. Raubenheimer, private communication.