IPAC2014 - Classification: 03 Particle Sources and Alternative Acceleration Techniques / A15 New Acceleration Techniques

Paper	Title	Page
TUOBB01	Accelerator Physics Challenges towards a Plasma Accelerator with Usable Beam Quality	961
	R.W. Aßmann, J. Grebenyuk DESY, Hamburg, Germany
	Enormous progress in compact plasma accelerators has been demonstrated over the recent years in various experiments. These experiments rely on high power, pulsed lasers or short electron bunches to excite ultra-strong wakefields in plasmas. Accelerating gradients have reached several 10 GV/m up to 100 GV/m and the absolute energy gain of electron beams is in the regime of several GeV to 30 GeV. The principle and potential of plasma accelerators has been proven impressively and performance parameters are steadily improving. It is noted that particle accelerators are powerful tools that are ultimately justified by their applications in science, medicine or industry. The demonstration of useable beam quality and a realistic use case remains to be achieved for plasma accelerators. The accelerator physics challenges to arrive at this goal are analyzed and discussed.
	Slides TUOBB01 [12.407 MB]
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TUOBB02	Demonstration of Gigavolt-per-meter Accelerating Gradients using Cylindrical Dielectric-lined Waveguides	965
SUSPSNE017	use link to see paper's listing under its alternate paper code
	B.D. O'Shea, G. Andonian, K.L. Fitzmorris, J. Harrison, J.B. Rosenzweig, O. Williams UCLA, Los Angeles, California, USA M.J. Hogan, V. Yakimenko SLAC, Menlo Park, California, USA
	We present here the results of measurements made showing ~1 GV/m accelerating fields using a hollow dielectric-lined waveguide. The results are comprised of measurement of the energy loss of a high charge (~3 nC) ultrashort (~200 fs), ultra relativistic (20 GeV) beam and concomitant auto-correlation interferometeric techniques to obtain the frequency content of simultaneously generated coherent Cherenkov radiation (CCR). Experiments were conducted at the Facility for Advanced aCcelerator Experimental Tests (FACET) at the SLAC National Laboratory using metal-coated sub-millimeter diameter, ten-centimeter long fused silica tubes. We present simulation and theoretical results in support of the conclusions reached through experiment. These results build on previous work to provide a path towards high gradient accelerating structures for use in compact accelerator schemes, future linear colliders and free-electron lasers.
	Slides TUOBB02 [2.349 MB]
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TUOBB03	Recent Progress on High Quality Electron Beam Generation through Plasma-based Acceleration at Tsinghua University
	W. Lu, Y.-C. Du, J.F. Hua, W.-H. Huang, F. Li, C.H. Pai, J. Shi, C.-X. Tang, Y. Wan, Y.P. Wu, X.L. Xu, L.X. Yan, C.J. Zhang TUB, Beijing, People's Republic of China C. Joshi, W.B. Mori UCLA, Los Angeles, California, USA
	Recent progress of plasma based acceleration at Tsinghua University will be presented. On the theory and simulation part, several ideas on how to obtain high quality electron beams with extremely high brightness through wakefield acceleration will be discussed in details, including two recently published works based on ionization injection method(PRL 111, 015003, 2013; PRL 112, 035003, 2014); On the experiment part, our recent results of high quality 20-30MeV electron beams with very low energy spread, with minimal absolute energy spread of 0.18MeV RMS and relative energy spread 0.8% RMS, will be presented.
	Slides TUOBB03 [11.000 MB]
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TUPME030	The LIGHT Beamline at GSI: Shaping Intense MeV Proton Bunches from a Compact Laser-driven Source	1419
SUSPSNE016	use link to see paper's listing under its alternate paper code
	S. Busold, O. Deppert, M. Roth TU Darmstadt, Darmstadt, Germany V. Bagnoud, A. Blazevic, S. Busold HIJ, Jena, Germany V. Bagnoud, A. Blazevic, S. Busold, D. Schumacher GSI, Darmstadt, Germany C. Brabetz IAP, Frankfurt am Main, Germany F. Kroll TU Dresden, Dresden, Germany F. Kroll Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	Laser-based proton acceleration as a source of high intensity multi-MeV-range proton bunches became subject of extensive research during the last 15 years and is discussed as potential candidate for various applications. However, their usage often requires special ways of beam shaping first, as the particles are emitted in a wide energy spectrum and with a large divergence angle from the laser matter interaction point. To handle these characteristics, a test stand has been build at GSI Darmstadt, using a pulsed high field solenoid and a radiofrequency cavity to produce intense collimated proton bunches with low energy spread from a TNSA source. In recent experiments, energy compression of an intense proton bunch around 10 MeV central energy to an energy spread of less than 3% could be demonstrated. The particle numbers were in access of 10⁹ protons and the bunch duration was only a few nanoseconds. Even shorter bunches and thus higher particle intensities are possible. This compact laser-driven proton beamline, available now at GSI, will be introduced and latest experimental results presented.
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TUPME031	Radiation Pressure Acceleration and Transport Methods	1422
	P. Schmidt, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, O. Boine-Frankenheim, I. Hofmann GSI, Darmstadt, Germany I. Hofmann HIJ, Jena, Germany I. Hofmann IAP, Frankfurt am Main, Germany
	Funding: HGS-HIRe for FAIR, HIC for FAIR, Technische Universität Darmstadt, FB 18 TEMF Several projects worldwide such as LIGHT at GSI focus on laser ion acceleration. With the development of new laser systems and advances in the target production a new acceleration mechanism has become of interest: The Radiation Pressure Acceleration (RPA). An ultra short high intense laser pulse hits a very thin foil target and the emerging plasma is ideally accelerated as one piece (light sail regime). The ions reach kinetic energies up to GeV and nearly solid body densities. In this work, the distribution and transport of a RPA plasma is studied. 1D and 2D PIC simulations (software: VSim) are carried out to obtain the phase space distribution of the plasma. The results are compared to fluid models (software: FiPy and USim). A reference model an RPA plasma is obtained which is then used for advanced transport studies. Transport mechanisms (active and passive) are studied, such asμlenses and foil stacks.
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TUPME033	Scaling of TNSA-accelerated Proton Beams with Laser Energy and Focal Spot Size	4093
SUSPSNE018	use link to see paper's listing under its alternate paper code
	L. Obst, S. Kraft, J. Metzkes, U. Schramm, K. Zeil Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	By focusing an ultra-short high-intensity laser pulse on a solid target, pulses of protons and other positively charged ions with energies of several 10 MeV per nucleon are generated. The properties of these particle beams such as their energy and absolute number are highly dependent on experimental conditions like laser and target parameters. In order to achieve principal comparability between different experimental campaigns at the Draco laser system at the Helmholtz-Zentrum Dresden-Rossendorf, a reference setup for the laser ion acceleration experiment was established. A configuration is sought in which proton beams of reproducible characteristics are generated. To ensure a high stability of the proton spectra, the application of longer focal length parabolas (f ~ 1000 mm) will be tested for this setup, according preparatory studies being presented in this paper.
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TUPME034	Transport and Energy Selection of Laser Produced Beams for Medical Research and Multidisciplinary Applications	1425
	M.M. Maggiore INFN/LNL, Legnaro (PD), Italy G.A.P. Cirrone, F. Romano, F. Schillaci, A. Tramontana INFN/LNS, Catania, Italy V. Scuderi ELI-BEAMS, Prague, Czech Republic
	Ion beams produced by the interaction of high-power laser with thin targets are being characterized experimentally around the world in order to get a reasonable amount of particles with low divergence and narrow energy spread for medical and multidisciplinary applications. Several schemes about the energy selection and transport of laser accelerated beams have been considered and tested, however the energy spread of the selected particles remains rather high and the reproducibility has not been yet achieved. In the framework of the ELIMED network, we present a study of a possible layout to capture and transport in an efficient and reproducible way, the beams generated by the laser-target interaction. It consists of a combination of quadrupoles based on permanent magnets placed just downstream the target, coupled with a system composed by a series of 4 dipole magnets of inverted polarity, which provides the final energy selection of the previously focused beam. Such a system will be tested in 2014 at TARANIS facility to select proton beams in the energy range of 4-8 MeV; the main scheme can be scaled for the high energy beam that are expected at ELI-beamlines facility.
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TUPME035	Design Study of the Laser-driven Dielectric Accelerator	1428
	K. Koyama, M. Yoshida KEK, Ibaraki, Japan Y. Matsumura University of Tokyo, Tokyo, Japan S. Otsuki The University of Tokyo, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. Laser driven dielectric accelerators (LDA) are vigorously studied in order to apply to various fields in recent years. Characteristics of the LDA output such as sub-micron diameter, atto-second bunch and high acceleration field are suitable for in-situ investigating the biological effects of low doses of radiation in a living cell. The output energy of 1 MeV is sufficient for sniping a cell nucleus or DNA. Although the electronic charge in the bunch is in the order of 10 fC, the tightly focused beam enable to cause a local damage in the cell. We have reported optimum structure parameters of dielectric in the nonrelativistic regime. The low acceleration efficiency of slow electrons by short laser pulses is the serious problem. The accelerator length, laser intensity, pulse width, and optical system must be adjusted to design the practical LDA. We present the design principle of the LDA for nonrelativistic electrons and present status of the pumping laser of us.
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TUPME036	Simulation Study on Electron Beam Acceleration using Coherent Cherenkov Radiation	1431
	K. Kan, M. Gohdo, T. Kondoh, K. Norizawa, I. Nozawa, A. Ogata, T. Toigawa, J. Yang, Y. Yoshida ISIR, Osaka, Japan M. Hangyo ILE Osaka, Suita, Japan R. Kuroda, H. Toyokawa AIST, Tsukuba, Ibaraki, Japan
	Beam diagnostics for electron bunch length using spectrum analysis of multimode terahertz (THz) -wave have been studied in ISIR, Osaka University. The multimode THz-wave was generated by coherent Cherenkov radiation (CCR)* using hollow dielectric tubes and femtosecond/picosecond electron bunches. In this study, numerical calculation of acceleration and deceleration of electron beam using multimode THz-wave was carried out. * K. Kan et al., Appl. Phys. Lett. 99, 231503 (2011). ** A. M. Cook et al., Phys. Rev. Lett. 103, 095003 (2009).
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TUPME037	Development on On-chip Radiation Source using Dielectric Laser Accelerator	1434
SUSPSNE019	use link to see paper's listing under its alternate paper code
	S. Otsuki The University of Tokyo, Tokyo, Japan K. Koyama, M. Yoshida KEK, Ibaraki, Japan Y. Matsumura University of Tokyo, Tokyo, Japan S. Mima RIKEN, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. One of the state-of-the-art acceleration schemes, where high intensity laser pulses are modulated by dielectric grating structure such as quartz to accelerate charged particles, is dielectric laser acceleration (DLA). The difference of our DLA concept from other schemes is installation of a prism: the tilted wave-front in a prism shape refractive medium leads the suitable delay to match the phase advance of the electron beam. We plan to apply this method to build an on-chip radiation source which can hit and damage target elements of the cells. Such an application is useful in radiation biology, i.e., for investigation on bystander effects. The x-rays with small radius and adequate intensity required for this goal can be obtained using sub-micron beams from the small accelerating structure at high repetition rate (such as 50 kHz). In addition, the mass productivity of the DLA based on the consumer-grade laser and the photolithography has advantage compared to the conventional RF accelerator using high power klystrons. We will present field simulation and preliminary experimental results for demonstration on our concept of DLA. Demonstration of electron acceleration in a laser-driven dielectric microstructure, Nature 2013 ** Laser-Based Acceleration of Nonrelativistic Electrons at a Dielectric Structure, Phys. Rev. 2013
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TUPME038	Wakefield excitation via a metasurface-loaded waveguide	1437
SUSPSNE020	use link to see paper's listing under its alternate paper code
	E. Sharples Cockcroft Institute, Lancaster University, Lancaster, United Kingdom R. Letizia Lancaster University, Lancaster, United Kingdom
	Funding: Work supported by STFC Quota Studentship grant ST/K520133/1 A metallic waveguide loaded with layers of complementary split ring resonator (CSRR) based metasurface is presented for accelerator and coherent source applications. This structure presents left handed behaviour arising from the strong electrical response of CSRRs which form the metasurface and the transverse field confined between the closely positioned metasurface layers. The loaded waveguide structure is known to have a TM-like mode at 5.47GHz suitable for acceleration. In this paper, the results of wakefield simulations are presented and a narrow band excitation identified around the frequency of the TM-like mode, indicating strong coupling between the beam and the field of this mode.
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TUPME039	System Integration of the Demonstration Siemens Electrostatic Accelerator	1440
	H. von Jagwitz-Biegnitz JAI, Oxford, United Kingdom P. Beasley, S. Goßmann-Levchuk, O. Heid Siemens AG, Erlangen, Germany D.C. Faircloth STFC/RAL, Chilton, Didcot, Oxon, United Kingdom R.G. Selway Inspired Engineering Ltd, Climping, United Kingdom
	Siemens has proposed a novel compact DC electrostatic tandem accelerator to produce protons of a few MeV. Siemens is currently building a prototype of the accelerator at the Rutherford Appleton Laboratory. This paper reports on recent progress on the different components of the system as well as the commissioning of the whole machine.
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TUPME040	Drive Beam Break-up Control and Practical Gradient Limitation in Collinear Dielectric Wakefield Accelerators	1443
	C. Li, W. Gai, J.G. Power, A. Zholents ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA C. Li, C.-X. Tang TUB, Beijing, People's Republic of China
	Dielectric wakefield accelerator (DWA) concept has gained significant attention for the need of the future large scale facilities. For a practical machine, one needs to overcome a major challenge for the DWA that is the efficient energy extraction and stable propagation at the same time for the drive beam. Typically, a slightly off axis beam become unstable in the dielectric channel due to transverse wakefield excitation, that could be controlled if a strong external alternating magnetic focusing channel applied at the same time. However, there is limitation on the practical magnetic field in the focusing channel (typically < 1 Tesla), thus imposing operating point for the DWA. In this article, we explore the operating point of the DWA for various structure frequencies and drive beam charge, particularly on the gradient and total acceleration distance, and provide guidance on the DWA design.
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TUPME041	The Advanced Superconducting Test Accelerator at Fermilab: Science Program	1447
	P. Piot, E.R. Harms, S. Henderson, J.R. Leibfritz, S. Nagaitsev, V.D. Shiltsev, A. Valishev Fermilab, Batavia, Illinois, USA
	Funding: This work is supported by DOE contract DE-AC02-07CH11359 to the Fermi Research Alliance LLC The Advanced Superconducting Test Accelerator (ASTA) currently in commissioning phase at Fermilab is foreseen to support a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop novel approaches to particle-beam generation, acceleration and manipulation. ASTA incorporates a superconducting radiofrequency (SCRF) linac coupled to a flexible high-brightness photoinjector. The facility also includes a small-circumference storage ring capable of storing electrons or protons. This report summarizes the facility capabilities, and provide an overview of the accelerator-science researches to be enabled.
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TUPME042	Planned High-gradient Flat-beam-driven Dielectric Wakefield Experiments at the Fermilab’s Advanced Superconducting Test Accelerator	1451
	F. Lemery, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot, J. Zhu Fermilab, Batavia, Illinois, USA J. Zhu CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	In beam driven dielectric wakefield acceleration (DWA), high-gradient short-wavelength accelerating fields are generally achieved by employing dielectric-lined waveguides (DLWs) with small aperture which constraints the beam sizes. In this paper we investigate the possibility of using a low-energy (50-MeV) flat beams to induce high-gradient wakes in a slab-symmetric DLW. We demonstrate via numerical simulations the possibility to produce axial electric field with peak amplitude close to 0.5 GV/m. Our studies are carried out using the Fermilab's Advanced Superconducting Test Accelerator (ASTA) photoinjector beamline. We finally discuss a possible experiment that could be performed in the ASTA photoinjector and eventually at higher energies.
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TUPME043	Temporal Electron-bunch Shaping from a Photoinjector for Advanced Accelerator Applications	1454
	F. Lemery, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Advanced-accelerator applications often require the production of bunches with shaped temporal distributions. An example of sought-after shape is a linearly-ramped current profile that can be improve the transformer ratio in beam-driven acceleration, or produce energy-modulated pulse for, e.g., the subsequent generation of THz radiation. Typically, such a shaping is achieved by manipulating ultra-relativistic electron bunches. In this contribution we discuss the possibility of shaping the bunch via photoemission and demonstrate using particle-in-cell simulations the production of MeV electron bunches with quasi-ramped current profile.
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TUPME045	Development of a High-Energy Short-pulse 5-μm Parametric Source for Dielectric Laser Acceleration	1460
	G. Xu, I. Jovanovic, S.F. Wandel Penn State University, University Park, Pennsylvania, USA
	A compact, high-peak-power 5-μm laser source with pulse duration of sub-100 fs has been designed and being constructed for pumping a dielectric photonic structure to produce an acceleration gradient of order GV/m in dielectric laser acceleration. Breakdown of dielectric structure induced by multiphoton ionization can be mitigated by adopting long wavelength driver laser. Since the dielectric structure scales with the laser wavelength, fabrication tolerances for dielectric structure are relaxed as well. The 5-μm laser source is based on two cascaded optical parametric amplifiers (OPA): a 2-μm BBO OPA with a mixed phase matching scheme is used as a pump source, and a type-I phase-matched ZGP OPA is designed to produce sub-mJ, <100 fs 5-μm laser pulses. The two-stage 2-μm OPA is pumped by a Ti:sapphire amplifier and produces pulse energy of ~2.2 mJ with a pulse duration of 42 fs (~6 optical cycles), and excellent pulse stability and beam quality. Preliminary result of ~50 μJ pulse energy at 5-μm is demonstrated by using single-stage ZGP OPA, and an improved two-stage OPA scheme for production of higher pulse energy at 5-μm is under development.
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TUPME046	3-D Particle-in-cell Simulations for Quasi-phase Matched Direct Laser Electron Acceleration in Density-modulated Plasma Waveguides	1463
	M.W. Lin The Pennsylvania State University, University Park, Pennsylvania, USA I. Jovanovic Penn State University, University Park, Pennsylvania, USA
	Funding: This work is supported by the Defense Threat Reduction Agency through contract HDTRA1-10-1-0034. Quasi-phase matched (QPM) direct laser acceleration (DLA) of electrons can be realized with guided, radially polarized laser pulses in density-modulated plasma waveguides,. A 3-D particle-in-cell (PIC) simulation model has been developed to study the scheme in which an electron bunch from a laser wakefield accelerator (LWFA) is injected into a plasma waveguide for the second-stage DLA to higher energies. In addition to being driven directly by the laser field, the electrons also experience the laser pondermotive force and the electrostatic force from the excited plasma waves. The results lead to better understanding of the interactions between the electron bunch, the laser pulse and the background plasma. Selected bunch lengths, bunch sizes and time delays with respect to the laser pulse are assigned for the injected electrons in a series of simulations. The energy spectrum and emittance of the accelerated electron bunch vary depending on those initial conditions, and they can be chosen to optimize the DLA performance. P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000). ** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012).
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WEOAB02	Wide-band Induction Acceleration in the KEK Digital Accelerator	1893
SUSPSNE021	use link to see paper's listing under its alternate paper code
	T. Yoshimoto, X. Liu, K. Takayama TIT, Yokohama, Japan T. Adachi, K. Takayama Sokendai, Ibaraki, Japan T. Adachi, T. Arai, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama, T. Yoshimoto KEK, Ibaraki, Japan H. Asao, Y. Okada NETS, Fuchu-shi, Japan M. Hirose, H. Kobayashi Tokyo City University, Tokyo, Japan
	Induction synchrotron can accelerate any ion species directly to higher energy without a large pre-accelerator, due to its intrinsic nature that there is no frequency band-width limitation below 1 MHz. KEK digital accelerator (DA) is a small scale prototype of fast cycling induction synchrotron. Recently it has been confirmed that heavy ion beams of mass to charge ratio A/Q = 4 are stably accelerated from 200 keV to a few tens of MeV in this accelerator ring, where the revolution frequency changes from82 kHz to 1 MHz. Acceleration and beam confinement are separately realized by pulse voltages generated in induction cells (1 to 1 pulse transformers) driven by the switching power supply (SPS). Everything is simply maneuvered by controlling of gate signals of solid-state switching elements employed in the SPS. For this purpose, the fully programmed acceleration control system based on the FPGA has been developed. In this paper, the wide-band induction acceleration is presented with experimental results. Further possibilities of beam handling in the induction synchrotron, such as super bunch and novel beam handling techniques, are discussed. K.Takayama et al., to be submitted to Phys. Rev. Lett. (2013). ** T.Iwashita et al., Phys. Rev. ST-AB 14, 071301(2011).
	Slides WEOAB02 [8.935 MB]
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Paper

Title

Page

Accelerator Physics Challenges towards a Plasma Accelerator with Usable Beam Quality

961

R.W. Aßmann, J. Grebenyuk
DESY, Hamburg, Germany

Enormous progress in compact plasma accelerators has been demonstrated over the recent years in various experiments. These experiments rely on high power, pulsed lasers or short electron bunches to excite ultra-strong wakefields in plasmas. Accelerating gradients have reached several 10 GV/m up to 100 GV/m and the absolute energy gain of electron beams is in the regime of several GeV to 30 GeV. The principle and potential of plasma accelerators has been proven impressively and performance parameters are steadily improving. It is noted that particle accelerators are powerful tools that are ultimately justified by their applications in science, medicine or industry. The demonstration of useable beam quality and a realistic use case remains to be achieved for plasma accelerators. The accelerator physics challenges to arrive at this goal are analyzed and discussed.

Slides TUOBB01 [12.407 MB]

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TUOBB02

Demonstration of Gigavolt-per-meter Accelerating Gradients using Cylindrical Dielectric-lined Waveguides

965

SUSPSNE017

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

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

We present here the results of measurements made showing ~1 GV/m accelerating fields using a hollow dielectric-lined waveguide. The results are comprised of measurement of the energy loss of a high charge (~3 nC) ultrashort (~200 fs), ultra relativistic (20 GeV) beam and concomitant auto-correlation interferometeric techniques to obtain the frequency content of simultaneously generated coherent Cherenkov radiation (CCR). Experiments were conducted at the Facility for Advanced aCcelerator Experimental Tests (FACET) at the SLAC National Laboratory using metal-coated sub-millimeter diameter, ten-centimeter long fused silica tubes. We present simulation and theoretical results in support of the conclusions reached through experiment. These results build on previous work to provide a path towards high gradient accelerating structures for use in compact accelerator schemes, future linear colliders and free-electron lasers.

Slides TUOBB02 [2.349 MB]

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TUOBB03

Recent Progress on High Quality Electron Beam Generation through Plasma-based Acceleration at Tsinghua University

W. Lu, Y.-C. Du, J.F. Hua, W.-H. Huang, F. Li, C.H. Pai, J. Shi, C.-X. Tang, Y. Wan, Y.P. Wu, X.L. Xu, L.X. Yan, C.J. Zhang
TUB, Beijing, People's Republic of China
C. Joshi, W.B. Mori
UCLA, Los Angeles, California, USA

Recent progress of plasma based acceleration at Tsinghua University will be presented. On the theory and simulation part, several ideas on how to obtain high quality electron beams with extremely high brightness through wakefield acceleration will be discussed in details, including two recently published works based on ionization injection method(PRL 111, 015003, 2013; PRL 112, 035003, 2014); On the experiment part, our recent results of high quality 20-30MeV electron beams with very low energy spread, with minimal absolute energy spread of 0.18MeV RMS and relative energy spread 0.8% RMS, will be presented.

Slides TUOBB03 [11.000 MB]

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TUPME030

The LIGHT Beamline at GSI: Shaping Intense MeV Proton Bunches from a Compact Laser-driven Source

1419

SUSPSNE016

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S. Busold, O. Deppert, M. Roth
TU Darmstadt, Darmstadt, Germany
V. Bagnoud, A. Blazevic, S. Busold
HIJ, Jena, Germany
V. Bagnoud, A. Blazevic, S. Busold, D. Schumacher
GSI, Darmstadt, Germany
C. Brabetz
IAP, Frankfurt am Main, Germany
F. Kroll
TU Dresden, Dresden, Germany
F. Kroll
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany

Laser-based proton acceleration as a source of high intensity multi-MeV-range proton bunches became subject of extensive research during the last 15 years and is discussed as potential candidate for various applications. However, their usage often requires special ways of beam shaping first, as the particles are emitted in a wide energy spectrum and with a large divergence angle from the laser matter interaction point. To handle these characteristics, a test stand has been build at GSI Darmstadt, using a pulsed high field solenoid and a radiofrequency cavity to produce intense collimated proton bunches with low energy spread from a TNSA source. In recent experiments, energy compression of an intense proton bunch around 10 MeV central energy to an energy spread of less than 3% could be demonstrated. The particle numbers were in access of 10⁹ protons and the bunch duration was only a few nanoseconds. Even shorter bunches and thus higher particle intensities are possible. This compact laser-driven proton beamline, available now at GSI, will be introduced and latest experimental results presented.

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TUPME031

Radiation Pressure Acceleration and Transport Methods

1422

P. Schmidt, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, O. Boine-Frankenheim, I. Hofmann
GSI, Darmstadt, Germany
I. Hofmann
HIJ, Jena, Germany
I. Hofmann
IAP, Frankfurt am Main, Germany

Funding: HGS-HIRe for FAIR, HIC for FAIR, Technische Universität Darmstadt, FB 18 TEMF
Several projects worldwide such as LIGHT at GSI focus on laser ion acceleration. With the development of new laser systems and advances in the target production a new acceleration mechanism has become of interest: The Radiation Pressure Acceleration (RPA). An ultra short high intense laser pulse hits a very thin foil target and the emerging plasma is ideally accelerated as one piece (light sail regime). The ions reach kinetic energies up to GeV and nearly solid body densities. In this work, the distribution and transport of a RPA plasma is studied. 1D and 2D PIC simulations (software: VSim) are carried out to obtain the phase space distribution of the plasma. The results are compared to fluid models (software: FiPy and USim). A reference model an RPA plasma is obtained which is then used for advanced transport studies. Transport mechanisms (active and passive) are studied, such asμlenses and foil stacks.

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TUPME033

Scaling of TNSA-accelerated Proton Beams with Laser Energy and Focal Spot Size

4093

SUSPSNE018

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L. Obst, S. Kraft, J. Metzkes, U. Schramm, K. Zeil
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany

By focusing an ultra-short high-intensity laser pulse on a solid target, pulses of protons and other positively charged ions with energies of several 10 MeV per nucleon are generated. The properties of these particle beams such as their energy and absolute number are highly dependent on experimental conditions like laser and target parameters. In order to achieve principal comparability between different experimental campaigns at the Draco laser system at the Helmholtz-Zentrum Dresden-Rossendorf, a reference setup for the laser ion acceleration experiment was established. A configuration is sought in which proton beams of reproducible characteristics are generated. To ensure a high stability of the proton spectra, the application of longer focal length parabolas (f ~ 1000 mm) will be tested for this setup, according preparatory studies being presented in this paper.

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TUPME034

Transport and Energy Selection of Laser Produced Beams for Medical Research and Multidisciplinary Applications

1425

M.M. Maggiore
INFN/LNL, Legnaro (PD), Italy
G.A.P. Cirrone, F. Romano, F. Schillaci, A. Tramontana
INFN/LNS, Catania, Italy
V. Scuderi
ELI-BEAMS, Prague, Czech Republic

Ion beams produced by the interaction of high-power laser with thin targets are being characterized experimentally around the world in order to get a reasonable amount of particles with low divergence and narrow energy spread for medical and multidisciplinary applications. Several schemes about the energy selection and transport of laser accelerated beams have been considered and tested, however the energy spread of the selected particles remains rather high and the reproducibility has not been yet achieved. In the framework of the ELIMED network, we present a study of a possible layout to capture and transport in an efficient and reproducible way, the beams generated by the laser-target interaction. It consists of a combination of quadrupoles based on permanent magnets placed just downstream the target, coupled with a system composed by a series of 4 dipole magnets of inverted polarity, which provides the final energy selection of the previously focused beam. Such a system will be tested in 2014 at TARANIS facility to select proton beams in the energy range of 4-8 MeV; the main scheme can be scaled for the high energy beam that are expected at ELI-beamlines facility.

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TUPME035

Design Study of the Laser-driven Dielectric Accelerator

1428

K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Y. Matsumura
University of Tokyo, Tokyo, Japan
S. Otsuki
The University of Tokyo, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120.
Laser driven dielectric accelerators (LDA) are vigorously studied in order to apply to various fields in recent years. Characteristics of the LDA output such as sub-micron diameter, atto-second bunch and high acceleration field are suitable for in-situ investigating the biological effects of low doses of radiation in a living cell. The output energy of 1 MeV is sufficient for sniping a cell nucleus or DNA. Although the electronic charge in the bunch is in the order of 10 fC, the tightly focused beam enable to cause a local damage in the cell. We have reported optimum structure parameters of dielectric in the nonrelativistic regime. The low acceleration efficiency of slow electrons by short laser pulses is the serious problem. The accelerator length, laser intensity, pulse width, and optical system must be adjusted to design the practical LDA. We present the design principle of the LDA for nonrelativistic electrons and present status of the pumping laser of us.

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TUPME036

Simulation Study on Electron Beam Acceleration using Coherent Cherenkov Radiation

1431

K. Kan, M. Gohdo, T. Kondoh, K. Norizawa, I. Nozawa, A. Ogata, T. Toigawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan
M. Hangyo
ILE Osaka, Suita, Japan
R. Kuroda, H. Toyokawa
AIST, Tsukuba, Ibaraki, Japan

Beam diagnostics for electron bunch length using spectrum analysis of multimode terahertz (THz) -wave have been studied in ISIR, Osaka University*. The multimode THz-wave was generated by coherent Cherenkov radiation (CCR)** using hollow dielectric tubes and femtosecond/picosecond electron bunches. In this study, numerical calculation of acceleration and deceleration of electron beam using multimode THz-wave was carried out.
* K. Kan et al., Appl. Phys. Lett. 99, 231503 (2011).
** A. M. Cook et al., Phys. Rev. Lett. 103, 095003 (2009).

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TUPME037

Development on On-chip Radiation Source using Dielectric Laser Accelerator

1434

SUSPSNE019

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S. Otsuki
The University of Tokyo, Tokyo, Japan
K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Y. Matsumura
University of Tokyo, Tokyo, Japan
S. Mima
RIKEN, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120.
One of the state-of-the-art acceleration schemes, where high intensity laser pulses are modulated by dielectric grating structure such as quartz to accelerate charged particles, is dielectric laser acceleration (DLA)*. The difference of our DLA concept from other schemes is installation of a prism: the tilted wave-front in a prism shape refractive medium leads the suitable delay to match the phase advance of the electron beam. We plan to apply this method to build an on-chip radiation source which can hit and damage target elements of the cells. Such an application is useful in radiation biology, i.e., for investigation on bystander effects. The x-rays with small radius and adequate intensity required for this goal can be obtained using sub-micron beams from the small accelerating structure at high repetition rate (such as 50 kHz). In addition, the mass productivity of the DLA based on the consumer-grade laser and the photolithography has advantage compared to the conventional RF accelerator using high power klystrons. We will present field simulation and preliminary experimental results for demonstration on our concept of DLA.
* Demonstration of electron acceleration in a laser-driven dielectric microstructure, Nature 2013
** Laser-Based Acceleration of Nonrelativistic Electrons at a Dielectric Structure, Phys. Rev. 2013

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TUPME038

Wakefield excitation via a metasurface-loaded waveguide

1437

SUSPSNE020

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E. Sharples
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
R. Letizia
Lancaster University, Lancaster, United Kingdom

Funding: Work supported by STFC Quota Studentship grant ST/K520133/1
A metallic waveguide loaded with layers of complementary split ring resonator (CSRR) based metasurface is presented for accelerator and coherent source applications. This structure presents left handed behaviour arising from the strong electrical response of CSRRs which form the metasurface and the transverse field confined between the closely positioned metasurface layers. The loaded waveguide structure is known to have a TM-like mode at 5.47GHz suitable for acceleration. In this paper, the results of wakefield simulations are presented and a narrow band excitation identified around the frequency of the TM-like mode, indicating strong coupling between the beam and the field of this mode.

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TUPME039

System Integration of the Demonstration Siemens Electrostatic Accelerator

1440

H. von Jagwitz-Biegnitz
JAI, Oxford, United Kingdom
P. Beasley, S. Goßmann-Levchuk, O. Heid
Siemens AG, Erlangen, Germany
D.C. Faircloth
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
R.G. Selway
Inspired Engineering Ltd, Climping, United Kingdom

Siemens has proposed a novel compact DC electrostatic tandem accelerator to produce protons of a few MeV. Siemens is currently building a prototype of the accelerator at the Rutherford Appleton Laboratory. This paper reports on recent progress on the different components of the system as well as the commissioning of the whole machine.

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TUPME040

Drive Beam Break-up Control and Practical Gradient Limitation in Collinear Dielectric Wakefield Accelerators

1443

C. Li, W. Gai, J.G. Power, A. Zholents
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
C. Li, C.-X. Tang
TUB, Beijing, People's Republic of China

Dielectric wakefield accelerator (DWA) concept has gained significant attention for the need of the future large scale facilities. For a practical machine, one needs to overcome a major challenge for the DWA that is the efficient energy extraction and stable propagation at the same time for the drive beam. Typically, a slightly off axis beam become unstable in the dielectric channel due to transverse wakefield excitation, that could be controlled if a strong external alternating magnetic focusing channel applied at the same time. However, there is limitation on the practical magnetic field in the focusing channel (typically < 1 Tesla), thus imposing operating point for the DWA. In this article, we explore the operating point of the DWA for various structure frequencies and drive beam charge, particularly on the gradient and total acceleration distance, and provide guidance on the DWA design.

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TUPME041

The Advanced Superconducting Test Accelerator at Fermilab: Science Program

1447

P. Piot, E.R. Harms, S. Henderson, J.R. Leibfritz, S. Nagaitsev, V.D. Shiltsev, A. Valishev
Fermilab, Batavia, Illinois, USA

Funding: This work is supported by DOE contract DE-AC02-07CH11359 to the Fermi Research Alliance LLC
The Advanced Superconducting Test Accelerator (ASTA) currently in commissioning phase at Fermilab is foreseen to support a broad range of beam-based experiments to study fundamental limitations to beam intensity and to develop novel approaches to particle-beam generation, acceleration and manipulation. ASTA incorporates a superconducting radiofrequency (SCRF) linac coupled to a flexible high-brightness photoinjector. The facility also includes a small-circumference storage ring capable of storing electrons or protons. This report summarizes the facility capabilities, and provide an overview of the accelerator-science researches to be enabled.

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TUPME042

Planned High-gradient Flat-beam-driven Dielectric Wakefield Experiments at the Fermilab’s Advanced Superconducting Test Accelerator

1451

F. Lemery, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot, J. Zhu
Fermilab, Batavia, Illinois, USA
J. Zhu
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

In beam driven dielectric wakefield acceleration (DWA), high-gradient short-wavelength accelerating fields are generally achieved by employing dielectric-lined waveguides (DLWs) with small aperture which constraints the beam sizes. In this paper we investigate the possibility of using a low-energy (50-MeV) flat beams to induce high-gradient wakes in a slab-symmetric DLW. We demonstrate via numerical simulations the possibility to produce axial electric field with peak amplitude close to 0.5 GV/m. Our studies are carried out using the Fermilab's Advanced Superconducting Test Accelerator (ASTA) photoinjector beamline. We finally discuss a possible experiment that could be performed in the ASTA photoinjector and eventually at higher energies.

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TUPME043

Temporal Electron-bunch Shaping from a Photoinjector for Advanced Accelerator Applications

1454

F. Lemery, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Advanced-accelerator applications often require the production of bunches with shaped temporal distributions. An example of sought-after shape is a linearly-ramped current profile that can be improve the transformer ratio in beam-driven acceleration, or produce energy-modulated pulse for, e.g., the subsequent generation of THz radiation. Typically, such a shaping is achieved by manipulating ultra-relativistic electron bunches. In this contribution we discuss the possibility of shaping the bunch via photoemission and demonstrate using particle-in-cell simulations the production of MeV electron bunches with quasi-ramped current profile.

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TUPME045

Development of a High-Energy Short-pulse 5-μm Parametric Source for Dielectric Laser Acceleration

1460

G. Xu, I. Jovanovic, S.F. Wandel
Penn State University, University Park, Pennsylvania, USA

A compact, high-peak-power 5-μm laser source with pulse duration of sub-100 fs has been designed and being constructed for pumping a dielectric photonic structure to produce an acceleration gradient of order GV/m in dielectric laser acceleration. Breakdown of dielectric structure induced by multiphoton ionization can be mitigated by adopting long wavelength driver laser. Since the dielectric structure scales with the laser wavelength, fabrication tolerances for dielectric structure are relaxed as well. The 5-μm laser source is based on two cascaded optical parametric amplifiers (OPA): a 2-μm BBO OPA with a mixed phase matching scheme is used as a pump source, and a type-I phase-matched ZGP OPA is designed to produce sub-mJ, <100 fs 5-μm laser pulses. The two-stage 2-μm OPA is pumped by a Ti:sapphire amplifier and produces pulse energy of ~2.2 mJ with a pulse duration of 42 fs (~6 optical cycles), and excellent pulse stability and beam quality. Preliminary result of ~50 μJ pulse energy at 5-μm is demonstrated by using single-stage ZGP OPA, and an improved two-stage OPA scheme for production of higher pulse energy at 5-μm is under development.

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TUPME046

3-D Particle-in-cell Simulations for Quasi-phase Matched Direct Laser Electron Acceleration in Density-modulated Plasma Waveguides

1463

M.W. Lin
The Pennsylvania State University, University Park, Pennsylvania, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Funding: This work is supported by the Defense Threat Reduction Agency through contract HDTRA1-10-1-0034.
Quasi-phase matched (QPM) direct laser acceleration (DLA) of electrons can be realized with guided, radially polarized laser pulses in density-modulated plasma waveguides*,**. A 3-D particle-in-cell (PIC) simulation model has been developed to study the scheme in which an electron bunch from a laser wakefield accelerator (LWFA) is injected into a plasma waveguide for the second-stage DLA to higher energies. In addition to being driven directly by the laser field, the electrons also experience the laser pondermotive force and the electrostatic force from the excited plasma waves. The results lead to better understanding of the interactions between the electron bunch, the laser pulse and the background plasma. Selected bunch lengths, bunch sizes and time delays with respect to the laser pulse are assigned for the injected electrons in a series of simulations. The energy spectrum and emittance of the accelerated electron bunch vary depending on those initial conditions, and they can be chosen to optimize the DLA performance.
* P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000).
** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012).

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WEOAB02

Wide-band Induction Acceleration in the KEK Digital Accelerator

1893

SUSPSNE021

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T. Yoshimoto, X. Liu, K. Takayama
TIT, Yokohama, Japan
T. Adachi, K. Takayama
Sokendai, Ibaraki, Japan
T. Adachi, T. Arai, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama, T. Yoshimoto
KEK, Ibaraki, Japan
H. Asao, Y. Okada
NETS, Fuchu-shi, Japan
M. Hirose, H. Kobayashi
Tokyo City University, Tokyo, Japan

Induction synchrotron can accelerate any ion species directly to higher energy without a large pre-accelerator, due to its intrinsic nature that there is no frequency band-width limitation below 1 MHz. KEK digital accelerator (DA) is a small scale prototype of fast cycling induction synchrotron. Recently it has been confirmed that heavy ion beams of mass to charge ratio A/Q = 4 are stably accelerated from 200 keV to a few tens of MeV in this accelerator ring*, where the revolution frequency changes from82 kHz to 1 MHz. Acceleration and beam confinement are separately realized by pulse voltages generated in induction cells (1 to 1 pulse transformers) driven by the switching power supply (SPS)**. Everything is simply maneuvered by controlling of gate signals of solid-state switching elements employed in the SPS. For this purpose, the fully programmed acceleration control system based on the FPGA has been developed. In this paper, the wide-band induction acceleration is presented with experimental results. Further possibilities of beam handling in the induction synchrotron, such as super bunch and novel beam handling techniques, are discussed.
* K.Takayama et al., to be submitted to Phys. Rev. Lett. (2013).
** T.Iwashita et al., Phys. Rev. ST-AB 14, 071301(2011).

Slides WEOAB02 [8.935 MB]

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