| Paper | Title | Page |
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| TUPEA001 | Generation of Anomalous Intensive Transition Radiation for FEL | 1161 |
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| The 3D spin-glass system in the external standing electromagnetic field is considered. It is shown on an example of amorphous quartz, under the influence of a standing microwave field, at its certain parameters, superlattice is created in the medium where difference in values of dielectric constants of neighboring layers can be up to third order. Note that this superlattice exists during the nanosecond however it is sufficient for using it as a radiator for generation of transition radiation by relativistic electrons. | ||
| TUPEA003 | Components for CW and LP Operation of the XFEL Linac | 1164 |
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| The European XFEL will use superconducting TESLA cavities operating with 650 μs long bunch trains. With 220 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 high quality bunches/s will be delivered to insertion devices generating unprecedented high average brilliance photon beams at very short wavelength. While many experiments can take advantage of full bunch trains, others prefer an increased intra-pulse distance of several μ-seconds between bunches, or short bursts with a kHz repetition rate. In this contribution, we discuss progress in the R&D program for a future upgrade of the European XFEL linac, to operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for much more flexibility in the electron and photon beam time structure. Modifications and cw tests of XFEL cryomodules, recent tests result of the SRF injector, test of the second prototype of 120 kW IOT are presented. In addition, computer modeling of the cw-operating TESLA-like cavity with modified HOM couplers is briefly discussed. | ||
| TUPEA004 | The Free-electron Laser FLASH at DESY | 1167 |
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| The free-electron laser FLASH at DESY routinely produces up to several thousand photon pulses per second with wavelengths ranging from 44 nm down to as low as 4.25 nm and with pulse energies of up to 400μJoule. After a significant technical upgrade in 2010, which included an energy upgrade to 1.25 GeV and linearization of the longitudinal phase space by 3-rd harmonic cavities, emphasis was put on consolidation and automatization of operational procedures and better control of the electron/photon beam properties. Some highlights are: on-line measurements of the electron bunch-length in the regime of several 10 fs to 100 fs, reaching into the water window, increased photon pulse energies and the improved machine reproducibility. Moreover, first evidence of HHG seeding was found at the sFLASH experiment in spring 2012. Construction work is ongoing for a 2-nd beam-line (FLASH-2) for which commissioning will start in late 2013. | ||
| TUPEA005 | Effects of Quantum Diffusion on Electron Trajectories and Spontaneous Synchrotron Radiation Emission | 1170 |
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| For various cases, e.g. in the long undulator sections of the European XFEL, quantum diffusion and energy loss have a noticable effect on the electron trajectory, which in turn affects the properties of the emitted radiation. We discuss approaches to modelling the electron dynamics taking this into account and the effect it has on spontaneous radiation emission. | ||
| TUPEA006 | Towards Realistic Modelling of the FEL Radiation for the European XFEL | 1173 |
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| For the operation phase of the European XFEL the possibility to characterize the FEL radiation taking realistic machine model into account is important. To achieve this, a software framework is being developed. It allows for interoperability of various simulation codes by means of a common graphical user interfaces, common input and output files, and common programming model for scripting; it includes the possibility of modeling beam jitters and machine imperfections to set errorbars on the simulation results, and has a connection to the control system for data acquisition. We report on the progress in the developing of this framework and give examples of FEL property calculations performed with it. | ||
| TUPEA007 | Spontaneous Radiation Calculations for the European XFEL | 1176 |
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| Calculating spontaneous radiation emission from long undulators such as those present in the European XFEL, being background to FEL radiation, is still important for several diagnostics and science cases. For realistic setups, and including effects of electron beam focusing, emittance and energy spread in the electron beam, these calculations should be performed numerically. We present these calculations for several electron beam and undulator parameters performed by various codes. Sensitivity of different spontaneous radiation characteristics, in various collection schemes, to the electron beam and undulator magnetic field parameters is studied | ||
| TUPEA008 | Physics of the AWAKE Project | 1179 |
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The goal of the AWKAKE collaboration is the study of plasma wakefields driven by proton (p+) bunches through experiments, simulations and theory. Proton bunches are interesting wakefield drivers because they can be ultra-relativistic (TeVs/p+) and carry large amounts of energy (>kJ). It was demonstrated in simulations* that acceleration of an electron (e-) bunch from 10GeV to >500GeV can be achieved in ~500m of plasma driven by a 1TeV, 100micron-long, bunch with 1011 p+. Such short p+ bunches do not exist today. It was suggested** that a p+ bunch long compared to the plasma period can transversely self-modulate and resonantly drive wakefields to large amplitudes (~GV/m). Initial experiments based on self-modulation instability (SMI) will use single 12cm-long CERN SPS bunches with 1-3·1011, 450GeV p+ to study physics of SMI. With a plasma density of 7·1014/cc the plasma wave and modulation period is 1.3mm. The SMI saturates after ~3m with amplitude in the GV/m range. Later a low energy (~10MeV) witness e- bunch will be injected at the SMI saturation point. Energy gain over ~7m of plasma can reach the GeV level. Translation from physics to experimental plan and setup will be presented.
* A. Caldwell et al., Nature Physics 5, 363 (2009) ** N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010) |
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| TUPEA010 | FERMI Seeded FEL Progress Report | 1182 |
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Funding: Work supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3 FERMI, the seeded Free Electron Laser located at the Elettra laboratory in Trieste, Italy, welcomed in December 2012 the first external users on the FEL-1 line. This line is based on a single stage of High Gain Harmonic Generation (HGHG), seeded by a UV laser, and covers wavelengths between 80 and 20 nm. The photon energy reached more than 300 μJ. The second FEL line, FEL-2, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, has generated its first coherent photons in October 2012. This is the first experimental demonstration of a seeded free electron laser configured as a two stages cascade operating in the "fresh bunch injection” mode, where the second stage is seeded by the light produced by the first stage. This paper describes the status of the operation and user experiments with FEL-1 and reports about the progress in the commissioning of FEL-2. |
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| TUPEA011 | Double Stage Seeded FEL with Fresh Bunch Injection Technique at FERMI@Elettra | 1185 |
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During the month of October 2012 the commissioning of the light source FEL-2 at FERMI was successfully concluded. Fermi FEL-2 is the first seeded FEL operating with a double stage cascade in the "fresh bunch injection" mode*. The two stages are two high gain harmonic generation FELs where the first stage is seeded by the 3rd harmonic of a Ti:Sa laser system, which is up converted to the 4th-12th harmonic. The output of the first stage is then used to seed the second stage. A final wavelength of 10.8 nm was obtained as the 24th harmonic of the seed wavelength at the end of the two frequency conversion processes, demonstrating that the FEL is capable of producing single mode narrow bandwidth pulses with an energy of several tens ofμjoules. We report on the experimental characterisation of the FEL performances in this configuration.
* I. Ben-Zvi, K. M. Yang, L. H. Yu, ”The ”fresh-bunch” technique in FELs”, NIM A 318 (1992), p 726-729 |
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| TUPEA012 | Rebunching Ultracold Neutrons by Magnetic Deceleration for the neutron EDM experiment at J-PARC | 1187 |
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| Ultra cold neutrons (UCN) - neutrons with energies less than 300 neV - can be accelerated or decelerated by means of static magnetic and RF fields. Neutron have a magnetic dipole moment, and hence their kinetic energies vary depending on their spin in magnetic fields. Their kinetic energies are restored when they get out from the magnetic field area if their spin did not flip. A spin flip can be triggered by applying an RF field whose frequency coincides with the spin precession frequency of a neutron in this magnetic field. This allows to tune the kinetic energy of neutrons. This method can be used to rebunch a pulsed beam of neutrons to a storage bottle that can store UCN. By open and close the storage bottle synchronously with the rebuncher, high UCN densities can be achieved for precision measurements of neutron properties such as the Electric Dipole Moment. The method and experimental setup are described in detail and the results of a recent first test experiments are presented. | ||
| TUPEA013 | Present Status of Mid-infrared Free Electron Laser Facility in Kyoto University | 1190 |
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A Mid-Infrared Free Electron Laser (MIR-FEL) facility named as KU-FEL has been constructed for energy science in Institute of Advanced Energy, Kyoto University*. The accelerator of KU-FEL consists of an S-band 4.5-cell thermionic RF gun, a Dog-leg section for energy filtering, a 3-m traveling-wave type accelerator tube, 180-degree arc section for bunch compression and a hybrid undulator. We have already succeeded in lasing of the FEL from 5.5 to 14.5 micro-meter. Present status and recent activity for the FEL development will be presented in the conference.
*H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385. |
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| TUPEA016 | Relativistic Theory for Laser-ion Acceleration | 1193 |
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Funding: The Key Project of Chinese National Programs for Fundamental Research (973 Program) under contract No. 2011CB808104 and the Chinese National Natural Science Foundation under contract No. 11105233. An analytical relativistic model is proposed to describe the relativistic ion acceleration in the interaction of ultra-intense laser pulses with thin-foil plasmas. It is found that there is a critical value of the ion momentum to make sure that the ions are trapped by the light sail and accelerated in the radiation pressure acceleration (RPA) region. If the initial ion momentum is smaller than the critical value, that is in the classical case of RPA, the potential has a deep well and traps the ions to be accelerated. There is a new ion acceleration region different from RPA, called ultra-relativistic acceleration, if the ion momentum exceeds the critical value. In this case, ions will experience a potential downhill. The dependence of the ion momentum and the self-similar variable at the ion front on the acceleration time has been obtained. The critical conditions of the laser and plasma parameters which identify the two acceleration modes have been achieved. No matter RPA or ultra-relativistic acceleration, the potential difference is a constant, which dedicates the maximum ion energy. |
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| TUPEA017 | Monoenergetic Electron Beams with Ultralow Normalized Emittance Generated from Laser-Gas Interaction | 1196 |
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| High quality electron bunches are generated by using 2 TW, 80 fs, high contrast laser pulses interacting with helium gas targets. In optimized condition, we get tens MeV monoenergetic electron beams with small energy spread and the normalized emittance 0.07π mm·mrad. Due to its ultra small emittance and high initial energy, such bunch is very suitable for high current linear accelerators. | ||
| TUPEA018 | Recent Progress of Laser Plasma Proton Accelerator at Peking University | 1199 |
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Funding: National Natural Science Foundation of China (Grant Nos.10935002, 10835003, 11025523) Recent a project called Laser plasma Proton Accelerator (LAPA) is approved by MOST in China. A prototype of laser driven proton accelerator (1~15MeV) based on the PSA mechanism and plasma lens is going to be built at Peking University in the next five years. It can be used for the applications such as cancer therapy, plasma imaging and fast ignition for inertial confine fusion. The recent progress of LAPA is reported here. |
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| TUPEA019 | Proton Acceleration driven by High Energy Density Electrons | 1202 |
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| Resonance Electrons Driving Ion Acceleration S. Zhao, C. Lin, X. Q. Yan Institute of Heavy Ion Physics, Peking University Proton acceleration driven by resonance electrons is proposed. Energetic electron beam generated through direct laser acceleration in the near critical dense plasma is dense and directional. When interacting with a thin foil target, resonance electrons can transmit the target and drive periodical electrostatic field at the back surface, therefore protons are more efficiently accelerated in a much longer distance in propagation direction of resonance electrons, compared to the classical target normal sheath acceleration. For a Gaussian laser pulse with pulse duration of 80fs, peak intensity I=1.38*108W/cm2 , the cutoff energy of the output collimated proton beam is 14MeV, enhanced by a factor of 3 or 4. The scaling law predicts hundreds MeV Proton beam can be generated in laser intensity of 1020W/cm2. | ||
| TUPEA021 | Calculation of Wakefields in Plasma Filled Dielectric Capillaries Generated by a Relativistic Electron Beam | 1205 |
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| In this paper we give an analytical solution of TM0n mode for wakefields generated by a relativistic electron beam passing through plasma-filled capillary waveguides. The numerical solution shows that the fields of TM0n modes could not be ignored when the plasma wave length is comparable with the effective radius of the capillary tube, which means that the boundaries are not shielded completely by plasma. Numerical examples are given in several typical cases. | ||
| TUPEA028 | Echo-enabled Harmonic Generation based on Hefei Storage Ring | 1208 |
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| Echo-Enabled Harmonic Generation (EEHG) has been proposed and experimently demonstrated recently. In this paper, we numerically investigate the possibility of operating EEHG based on Hefei storage ring, which has a short circumference and a small momentum compaction factor. The difference to other similar reserch is that we use the whole ring as the first dispersive section and an optical klystron as the second one. | ||
| TUPEA029 | Theory Calculation of PASER in Gas Mixture Active Medium | 1211 |
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| In the PASER (particle acceleration by stimulated emission of radiation), the energy stored in an active medium transferred directly to the electron beam passing through in discrete amounts by emitting a photon when the bounded electron returns from upper to lower energy state. In this paper, the wake-field generated by a bunch of electrons traversing in an active medium has been discussed. The calculations of the development of amplitude for gas mixture active medium about CO2 and ArF were made respectively. The results show that the gradient can reach around 1GeV/m. In addition, the electron energy gain occurring as a train of electron micro-bunches traversing in gas mixture was analyzed by a two dimension model. The train of micro-bunches can obviously gain energy from the active medium and the energy exchange is linearly proportional to the interaction length d. The influence of the bunch figure and other quantities on the energy exchange occurring as a train of electron micro-bunches traversing CO2 gas mixture were investigated when the interaction length is 0.5m. The results illustrate that maximum electron energy gain can be obtained by the train of micro-bunches with optimized parameters. | ||
| TUPEA030 | High Brightness and Fully Coherent X-ray Pulses from XFELO Seeded High-gain FEL Schemes | 1214 |
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| The successful operation of the hard x-ray self-seeding experiment at the LCLS opens the era of fully coherent hard x-ray free electron lasers (FELs). However, the shot-to-shot radiation fluctuation is still a serious issue. In this paper, high-gain, single-pass x-ray FEL schemes seeded by the narrow bandwidth radiation signal from an x-ray FEL oscillator were proposed and investigated, which are expected to generate high brightness, fully coherent and stable x-ray pulse. A simple model has been developed to figure out the temporal and the spectral structures of the output pulses in x-ray FEL oscillator. And options using two synchronized accelerators and using one accelerator were considered, respectively. | ||
| TUPEA033 | Proposals for Chirped Pulse Amplification in HGHG and CHG at SDUV-FEL | 1217 |
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| In this paper, a proposal to generate intense ultra-short free-electron laser (FEL) pulses at Shanghai deep ultraviolet FEL (SDUV-FEL) by combining the chirped pulse amplification (CPA) technique with the high-gain harmonic generation (HGHG) technique is presented. In this proposal, a frequency chirped seed pulse obtained by stretching an ultra-short laser pulse is first used to create frequency-chirped bunching at the laser harmonics in an electron beam; then the frequency chirped harmonic radiation is amplified by an energy chirped electron beam; finally the output radiation pulse which inherits the properties of the seed pulse is compressed to provide an ultra-intense ultra-short radiation pulse. The feasibility and performance of this CPA-HGHG scheme are studied with start-to-end simulations using the parameters of the SDUV-FEL. | ||
| TUPEA035 | Plasma Effect in the Longitudinal Space Charge Induced Microbunching Instability | 1220 |
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Funding: National Science Foundation of China (NSFC), grant No. 11275253, and US DOE, contract DE-FG02-92ER40747. In many cases, the longitudinal space charge (LSC) is a dominant factor to bring in the microbunching instability in the LINAC of a Free-Electron-Laser (FEL) facility. The current model of LSC impedance* derived from the fundamental electromagnetic theor** is widely used to explain the physics of the LSC-induced microbunching instability***. However, in the case of highly bright electron beams, the plasma effect starts to play a role. In this paper, the basic model of the LSC impedance including the plasma effect is built up by solving the Vlasov and Poisson equations in 6 dimensional phase space, and the investigation is done to study the modification to the gain of the instability based on the model. The solutions indicate that the gain does not only depend on the spatial information of the beam, but also on the velocity (momentum) and time information. The comparison of the gains of the microbunching instability in the LINAC of Shanghai soft X-ray Free Electron Laser Facility (SXFEL) computed by various methods is also given and the discrepancy is illustrated. * Marco Venturini, Phys. Rev. ST Accel. Beams 11, 034401 (2008) ** J. D. Jackson, Classical Electrodynamics (Wiley, 1999) *** Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004) |
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| TUPEA038 | Pre-chirp Control Broadband Non-collinear Optical Parametric Amplifier for the Future Laser Weak-field Accelerator | 1223 |
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| Ultra-short pulse has been proved to be a very useful tool for accelerating electron close to GeV now. But limited by gain narrowing effect, conventional CPA technology is quite hard to get less than 30fs at high energy level. Non-collinear optical parametric amplification (NOPA) looks more and more attractive for generating super-broadbandwidth pulses which is possible to be compressed to ultra-short pulses. Previous NOPAs, pumped by 400nm pulses, were using BBO crystals to reach shorter signal pulse durations. But the associated spectral bandwidths are still strongly linked with higher order nonlinear effects. which make it quite difficult to get higher energy with short pulse duration. Here we proposed to use pre-chirped few nm bandwidths around 515nm pumped pulses to amplify ultra-short pulses centered at 800nm. In our setup, we have found just one dramatical geometry configuration which support that we have possibility to get amplification from 720nm to 900nm, which will support to less than 10fs by well re-compression. This design is well adapted for BBO crystals. But the idea could be used also for other crystals. | ||
| TUPEA042 | Linac Design for Dalian Coherent Light Source | 1226 |
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| Dalian Coherent Light (DCL) Source is a FEL user facility in which HGHG scheme is adopted. Beam quality requirements for the linear accelerator (linac) are critical, including not only the beam brightness, but also the stability and the reliability. In this paper, optimization study is performed for the linac. Based on beam stability simulation in the longitudinal direction, the tolerant budget is formed for the short period jitter. For the transverse orbit error, beam based alignment (BBA) technique is implemented by beam dynamics simulations and the transverse jitter is also presented accordingly. Measurement method for the beam quality is also described in the paper. | ||
| TUPEA043 | Linac Design for Nuclear Data Measurement Facility | 1229 |
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| Pulsed neutrons based on an electron linear accelerator (linac) are effective for measuring energy dependent cross-sections with high resolution by using the time-of-flight (TOF) technique. In this paper, we describe the 15-MeV linac design for the Nuclear Data project in Shanghai Institute of Applied Physics (SINAP). The linac has three operating modes and the maximum average power is 7.5kW. We describe the characteristics of the linac and the study of the beam dynamics is also presented. | ||
| TUPEA044 | The Design of Control System for the Optical Cavity Adjuster of a FEL-THz Source | 1232 |
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| The optical cavity adjuster is an important sub-system in a FEL-THz source, which is used to adjust the position and angle of the optical cavity with a high precision. In view of the requirements of the optical cavity adjuster of the FEL-THz source, this paper presents the design of the control system of the optical cavity adjuster. The design of the control system based on a PC and a motion controller is adopted. The motion controller controls high-precision linear stage to adjust linear direction and picomotors are controlled to enable the adjustment of roll and yaw. According to relevant calculation, the range of linear direction and the accuracy can be reached at ±3mm and 0.2~0.5μm; the range of the adjustment of roll and yaw and the accuracy can be reached at ±2° and 20″. In summing up it can be stated that the design meets the requirements and it also lays the foundation for engineering on developing the optical cavity adjuster. | ||
| TUPEA045 | Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas | 1235 |
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Funding: This work has been partially supported by Humboldt Foundation. The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN*. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times**. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored. *G. Xia et al., J. Plasma Phys., 1-7 (2012). **J. Vieira et al., Phys. Plasmas 19, 063105 (2012). |
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| TUPEA048 | Simulation of Self-modulating Particle Beams in Plasma Wakefield Accelerators | 1238 |
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Funding: The Ministry of education and science of Russia, project 14.B37.21.0784. Controlled self-modulation of long proton or electron beams is a new trend in plasma wakefield acceleration which sets a new goal for simulation codes. Long interaction lengths (tens of meters), long beams (up to hundred of plasma wave periods), motion of plasma ions, and violation of fluid approximation are factors that makes the problem too heavy for general purpose codes. Only specialized codes can attack this problem in real geometry. We describe recent upgrades of the code LCODE which enabled simulations of long dense proton beams and report results of numerical studies of proton beam-plasma interaction in the context of AWAKE project. |
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| TUPEA049 | Wakefields of Ultrarelativistic Bunches in Cold Magnetized Plasma | 1241 |
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Funding: Work is supported by Russian Foundation for Basic Research and the Dmitry Zimin "Dynasty" Foundation. We deal with electromagnetic field of various bunches moving in a cold magnetized plasma along the external magnetic field. The main attention is paid to the case of ultrarelativistic motion. First, for the case of point charge, we obtain the approximate formulas which are valid in the far-field zone and in the vicinity of the charge trajectory. These expressions predict the beating behavior of the far field and the harmonic behavior of the near field. Moreover, the magnitude of the longitudinal components of both electric and magnetic field as well as the transversal electric field possess singularity on the charge trajectory. Second, using formulas for the point charge field as Green function, we develop an effective algorithm for calculation of the bunch wakefield. Plots of wakefields produced by typical bunches are given. Prospects of using the bunch field properties for further development of the plasma wakefield acceleration technique are discussed. |
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| TUPEA050 | Extension of the MAX IV Linac for a Free Electron Laser in the X-ray Region | 1244 |
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| The 3 GeV linac for the MAX IV laboratory is currently under construction in Lund (Sweden). As full energy injector for the MAX IV rings, a thermionic gun will be used to create electrons. However a photocathode gun planned for a short pulse facility (SPF) will deliver small emittance and ultra-short electron bunches that will be suitable to also drive a Free-Electron Laser. Moreover extending the linac energy with 1 or 2 GeV will give the opportunity to get closer to 1 Angstrom radiation with much more flexibility and better performances. Given these opportunities at the MAX IV laboratory, a free electron laser is envisaged in the long term perspective of the facility. In this study we investigate the case of a 5 GeV machine which can produce radiation in the X-ray region. The FEL design will benefit from the implementation of self-seeding, to enhance stability of the central wavelength and spectral bandwidth. Tapering along variable gap undulators will help to extract the maximum photon flux and increase the brilliance of the source. Among others, this kind of machine would be suitable for time resolved experiments and imaging. | ||
| TUPEA051 | Beam Transfer Line Design for a Plasma Wakefield Acceleration Experiment (AWAKE) at the CERN SPS | 1247 |
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| The world’s first proton driven plasma wakefield acceleration experiment is presently being studied at CERN. The experiment will use a high energy proton beam extracted from the SPS as driver. Two possible locations for installing the AWAKE facility are considered: the West Area and the CNGS long baseline beam-line. The previous transfer line from the SPS to the West Area was completely dismantled in 2000 and it would need to be fully re-designed and re-built. For this option, geometric constraints for radio protection reasons would limit the maximum proton beam energy to 300 GeV. The existing CNGS line could be used by applying only minor changes to the final part of the lattice for the final focusing and the interface between the proton beam and the laser, required for plasma ionisation and bunch-modulation seeding. The beam line design studies performed for the two options are presented. | ||
| TUPEA052 | Design Study for a CERN Short Base-Line Neutrino Facility | 1250 |
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| A design study has been initiated at CERN for the conception and construction of a short base line neutrino facility, using a proton beam from the CERN Super Proton Synchrotron (SPS) that will be transferred to a new secondary beam production facility, which will provide a neutrino beam for experiments and detector R&D. This paper resumes the general layout of the facility together with the main primary and secondary beam parameters and the choices favoured for the neutrino beam production. | ||
| TUPEA053 | Feasibility Study of the AWAKE Facility at CERN | 1253 |
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| Plasma Wakefield acceleration is a rapidly developing field which appears to be a promising candidate technology for future high-energy accelerators. The Proton Driven Plasma Wakefield Acceleration has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof-of-principle demonstration experiment, AWAKE, is proposed using 400 GeV proton bunches from the SPS. Detailed studies on the identification of the best site for the installation of the AWAKE facility resulted in proposing the CNGS facility as best location. Design and integration layouts covering the beam line, the experimental area and all interfaces and services will be shown. Among other issues, radiation protection, safety and civil engineering constraints will be raised. | ||
| TUPEA055 | Quasistatic Field Influence on Bunches Focusing by Wakefields in the Plasma-dielectric Waveguide | 1256 |
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Funding: The research is supported in part by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522). Acceleration of charged particles by wakefields, excited by a drive electron bunch in the dielectric waveguide, is a perspective method in accelerator physics. We have previously proposed using plasma, filling the drift channel of the dielectric structure (DS), for focusing of the accelerated bunch*. The analytical expressions, obtained for the components of the electromagnetic field, considered only the propagating wake field, and did not consider quasi-static fields of electron bunches that are important for calculating bunches dynamics. In this paper we report the result of numerical calculations of the influence of quasistatic field of bunches on focusing by wake fields in the plasma-dielectric accelerator. We refine analytical expressions for the electromagnetic field by adding components of bunch quasi-static fields and show the correlation of total force and their quasi-static components. * R.R. Knyazev, G.V. Sotnikov. Focusing of accelerated particles by wakefields of a drive bunch in a plasma-dielectric waveguide. Proc. of IPAC2012, New Orleans, Louisiana, USA, paper weppp003.pdf |
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| TUPEA056 | Concept of Dielectric Wakefield Accelerator Driven by a Long Sequence of Electron Bunches | 1259 |
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Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522) The scheme of a two-beam accelerator type is considered that is based on wakefield excitation in rectangular dielectric resonator by a sequence of electron bunches with the aim to enhance wakefield intensity due to multi-bunch coherent excitation, multi-mode summation, and wakefield accumulation in resonator. The sequence of bunches can be divided into exciting and accelerated parts in any proportion by means at the proper detuning of bunch repetition frequency relative to the frequency of principle eigen mode of the resonator. A train of 6000 electron bunches, each of energy 4.5МeV, charge 0.16nC, duration 60psec, diameter 1.0cm, and angular spread 0.05 mrad is produced with the linear resonant accelerator. Bunch repetition frequency is 2805 MHz and can be varied within 2MHz by changing master oscillator frequency. Bunches are injected into copper rectangular waveguide of cross-section 8.5x18.0cm2 and length 75cm along wide sides of which Teflon plates are placed. The plate thickness is chosen 1.67cm so that the frequency of excited eigen mode coincides with bunch repetition frequency. |
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| TUPEA057 | Optimization of Rectangular Dielectric Structures for the Planned Wakefield Acceleration Experiments in KIPT | 1262 |
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Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522). We, at the Kharkov Institute of Physics and Technology, planned experimental test of the basic principles of the multi-bunch multi-mode wakefield accelerator. For this purpose we carried out a series of calculations of wakefield excitation and dynamics of the drive and witness bunches in rectangular structures with a dielectric substrate. For optimization two rectangular vacuum waveguides of R32 (72.14mm x 34.04mm) and R26 (86.36mm x 43.18mm) which were filled with the dielectric covering two any opposite metal walls of a waveguide were chosen. As possible dielectric Alumina, Cordierite, or Teflon were tested. It was supposed that the structure will be energized by sequence of electron bunches (bunch repetition frequency is 2.805 GHz), having energy of 4.5 MeV. As the candidate for operating mode LSM-wave or LSE-wave, with frequency to equal the bunch repetition frequency or its doubled frequency were tested. The gradient of an accelerating field, small transverse deflection (or divergence) of drive and witness bunches were the main criteria of optimization. As a result of optimization we propose some dielectric structures for future wakefield experiments in KIPT. |
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| TUPEA058 | The Conceptual Design of CLARA, A Novel FEL Test Facility for Ultrashort Pulse Generation | 1265 |
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| The conceptual design of CLARA, a novel FEL test facility focussed on the generation of ultrashort photon pulses with extreme levels of stability and synchronisation is described. The ultimate aim of CLARA is to experimentally demonstrate, for the first time, that sub-coherence length pulse generation with FELs is viable. The results will translate directly to existing and future X-Ray FELs, enabling them to generate attosecond pulses, thereby extending the science capabilities of these intense light sources. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven. | ||
| TUPEA059 | CLARA Accelerator Design and Simulations | 1268 |
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Funding: Science & Technology Facilities Council We present the accelerator design for CLARA (Compact Linear Advanced Research Accelerator) at Daresbury Laboratory. CLARA will be a testbed for novel FEL configurations. The accelerator will consist of an RF photoinjector, S-band acceleration and transport to 250 MeV including X-band linearisation and magnetic bunch compression. We describe the transport in detail including dedicated diagnostic sections. Beam dynamics simulations are then used to define a set of operating working points suitable for the different FEL schemes intended to be tested on CLARA. |
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| TUPEA060 | Jitter Tolerance for CLARA | 1271 |
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Funding: Science & Technology Facilities Council CLARA (Compact Linear Accelerator for Research and Applications) at Daresbury Laboratory will be a test-bed for novel FEL configurations. CLARA will consist of an RF photoinjector, S-band acceleration and transport to 250 MeV including X-band linearisation and magnetic bunch compression. Ensuring stability of the VUV radiation pulses is a key aim of the project. To this end, we investigate in detail the jitter tolerance of the machine. This will ultimately determine the pulse stability. |
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| TUPEA061 | High-Brightness SASE Studies for the CLARA FEL | 1274 |
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| The Compact Linear Accelerator for Research and Applications (CLARA) is a proposed 250 MeV FEL test facility to be constructed at STFC Daresbury Laboratory in the UK [1]. This paper presents study of a scheme for the temporal and spectral stabilisation of the SASE output. A feasibility study for the operation of the FEL in a novel High-Brightness SASE mode is presented. Electron beam delays are introduced between undulator sections to disrupt the localised collective FEL process, increase the radiation coherence length and reduce the rms bandwidth. This may extend the range of electron bunch lengths appropriate for the generation of temporally coherent single spike SASE FEL pulses. | ||
| TUPEA062 | Advanced Gabor Lens Lattice for Medical Applications | 1277 |
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| The widespread introduction of Hadron therapy for cancer treatment is inhibited by the large costs for the accelerator and treatment facility and the subsequent maintenance costs which reflects into the cost per treatment. In the long term future (laser) plasma wakefield accelerated hadrons could offer compact treatment devices with significantly reduced treatment costs. In the moment the particle distributions produced by such accelerators do not fulfill the medical requirements. Beside the reliable production of a sufficient number of ions at the required energy the formation of a particle beam suitable for treatment from the burst of ions created in the acceleration process is one of the major challenges. While conventional optical systems will be operating at the technical limits which would be contradictory to the cost argument, space charge lenses of the Gabor type might be a cost effective alternative. An advanced beam line consisting of Gabor lenses, a few cavities and an dipole will be presented together with results from particle transport simulations. | ||
| TUPEA064 | A Proposed Plasma Accelerator Research Station at CLARA Facility | 1280 |
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| We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury lab. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in the electron beam driven plasma wakefield acceleration, e.g. the two bunch acceleration for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and the related beam instabilities. This paper discusses the feasibility studies of electron beam parameters to meet the requirements for beam driven wakefield acceleration and the possible experiments which can be conducted at PARS beam line. | ||
| TUPEA065 | Design of a Photonic Crystal Accelerator for Basic Radiation Biology | 1283 |
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Funding: This work is supported by the EU under Grant Agreement 289485, the STFC Cockcroft Institute Core Grant No. ST/G008248/1 and KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. The application of photonic crystals to realize an on-chip electron beam source for fundamental radiation biology is highly interesting for a number of applications. The unique combination of nanometer beam size and attosecond-short pulses has a very promising potential for use in microscopic and ultra-fast analyses of damage and repair of radiation-irradiated DNA and chromosomes. Simulations studies indicate an output electron beam energy, beam intensity and device size of the order of MeVs, fCs and a few cm, respectively. In this contribution, first results from numerical studies into the design of such compact accelerator structure are presented. The dimensions of a novel dual grating-based acceleration structure are shown together with the estimated laser parameters. Finally, a system consisting of an electron injector and multi-stage accelerating structures is proposed, which corresponds to a miniaturized optical linear accelerator. |
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| TUPEA066 | Metamaterial-based Accelerating, Bending and Focusing Structures | 1286 |
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| We report on the progress of our research into metamaterial-based accelerating, bending and focusing structures at the Cockcroft Institute. The effort during the last year has been directed towards designing and investigating practical RF structures that are suitable for industrial and medical applications. We have shown that, by introducing structures based on metamaterial resonators, RF accelerating structures can be made more compact and higher gradient. This year, we will concentrate on focusing and bending structures. | ||
| TUPEA068 | Wake-field Reduction in Hybrid Photonic Crystal Accelerator Cavities | 1289 |
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Funding: This work is supported by the U.S. Dept. of Energy, grant DE-FG02-04ER41317. Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping. |
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| TUPEA071 | THz Bench Tests of a Slab-symmetric Dielectric Waveguide | 1292 |
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Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359. Dielectric-lined waveguides (DLW) are becoming more popular for beam driven acceleration applications. An experiment to demonstrate beam-driven acceleration using a slab-symmetric dielectric-lined waveguide driven by a flat beam is in preparation at the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In this paper we characterize the structure using a THz pulse obtained from optical rectification using an amplified laser pulse. After propagation through the DLW structure, the THz pulse is analyzed using a Michelson interferometer and single-shot electro-optical imaging. Data for various gap size will be presented. |
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| TUPEA072 | Toward a Dielectric-Wakefield Energy Doubler at the Fermilab's Advanced Superconducting Test Accelerator | 1295 |
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Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359. The Advanced Superconducting Test Accelerator (ASTA), presently under construction at Fermilab, will produce high-charge (~<3 nC) electron bunches with energies ranging from 50 to eventually 750 MeV. The facility is based on a superconducting linac capable of producing up to 3000 bunches in 1-ms macropulses repeated at 5 Hz. In this paper we explore the use of a short dielectric-lined-waveguide (DLW) linac to significantly increase the bunch energy. The method consists in (1) using advanced phase space manipulation techniques to shape the beam distribution and enhance the transformer ratio, and (2) optimize the generation and acceleration of a low-charge witness bunches. Start-to-end simulations of the proposed concept are presented. This DLW module could also be used to test some aspects of a recently proposed concept for a multiuser short-wavelength free-electron laser utilizing a series of DLW linacs*. * C. Jing et al., “A Compact Soft X-ray Free-Electron Laser Facility based on a Dielectric Wakefield Accelerator”, Advanced Photon Source LS Note LS-332, Argonne National Laboratory (2012). |
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| TUPEA073 | Performances of VORPAL-GPU Slab-symmetric DLW | 1298 |
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Funding: HDTRA1-10-1-0051, DOE(Grant No will be specified later) GPU-based computing has gained popularity in recent years due to its growing software support and greater processing capabilities than its CPU counterpart. GPU computing was recently added in the finite-difference time-domain program VORPAL. In this paper we carry electromagnetic simulations and optimization of a flat beam passing through a slab-symmetric dielectric-lined waveguide (DLW). We use this simulation model to explore the scaling of the GPU version of VORPAL on a new TOP1000-grade hybrid GPU/CPU computer cluster available at Northern Illinois University. |
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| TUPEA074 | Protection of VUV FEL Mirrors using Soft Orbit Bump at Duke FEL/HIGS facility | 1301 |
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Funding: This work is supported in part by the US DoE grant # DE-FG02-97ER41033 The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an electron beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Presently, the energy range of the gamma-beam is from 1 MeV to about 100 MeV, with the maximum total gamma-flux of more then 1010 gammas per second around 10 MeV. Production of high intensity, high energy gamma-beams of 60 to 100 MeV, using UV-VUV mirrors of 240 to 190 nm, requires high energy, high current electron beams of 0.9 to 1.05 GeV. Synchrotron radiation damage to the FEL mirrors becomes crucial for VUV FEL operation at or below 190 nm. The edge radiation (ER) from the End-of-Arc (EOA) bending magnet, instead of the radiation of FEL wigglers, is the dominant cause of a rapid degradation of the downstream FEL mirror. In this work, we describe a further development of the “soft” orbit bump concept to significantly reduce the radiation exposure to the mirror from the EOA dipole magnet. The bump uses designated "soft" orbit correctors with magnetic field limited to produce a radiation with a critical wavelength close or below the FEL wavelength. |
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| TUPEA075 | Passively Driving X-band Structures to Achieve Higher Beam Energies | 1304 |
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| Particle accelerators at X-band frequencies have gradients of around 100 MV/m. This technology permits more compact accelerators. One of our aims at the Colorado State University Accelerator Laboratory is to adapt this technology to our L-band (1.3 GHz) accelerator system to increase our overall beam energy; however, we would like to do this in a passive manner, i.e. one that does not require investment in an expensive, custom, high-power klystron system. In this paper we explore using the beam from our L-band 6 MeV photoinjector to power an x-band structure tuned to the 9th harmonic of our L-band system, 11.7 GHz. Electron bunches will be generated at a repetition rate of 81.25 MHz and passed through a high shunt impedance x-band accelerating structure where they will resonantly excite the fundamental field. We will optimize the system to create the highest accelerating potential within this structure. Once the peak gradient is achieved we will send a single electron bunch through the system at a phase that places it on the crest of the X-band accelerating wave thereby increasing the electron bunch energy by some amount without need for additional external power sources. | ||
| TUPEA079 | Experimental Search For Acceleration in the Micro-accelerator Platform | 1307 |
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| The results of recent experimental efforts to observe acceleration in the Micro-Accelerator Platform (MAP) are detailed. The MAP is a slab-symmetric dielectric laser accelerator that when side illuminated by an optical laser, accelerates electrons via a standing wave resonance. This structure has been placed in the beamline at the NLCTA experimental hall at SLAC. A 60 MeV electron beam traverses the MAP when it is illuminated by a laser and, using a camera placed around a spectrometer bend magnet, signs of acceleration in the energy spectrum of the beam are searched for. The details of this search, as well as simulations that motivate the search, are elaborated on below. | ||
| TUPEA080 | Numerical Modeling and Experimental Data Analysis for Dielectric Laser Accelerators | 1310 |
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Funding: Work supported by a grant for the US Defense Threat Reduction Agency (DTRA). Work on Dielectric Laser Accelerators (DLAs) has been ongoing for the past decade. These devices come in a variety of configurations but share the use of lasers as power sources and dielectrics as the primary building material. While these devices have many of the same characteristics and dynamics as conventional accelerating structures, they operate in a dramatically different regime. One version of these DLAs is the Micro Accelerator Platform (MAP): a slab-symmetric device operated with a standing wave (Pi-mode) and powered by a transversely coupled laser. The coupler is essentially a transmissive diffraction grating and therefore reinforced the desired mode. The remainder of the structure is composed of two Distributed Bragg Reflectors (DBRs) which serve to form a resonant cavity in an evacuated bounded by the reflectors. The MAP has now undergone experimental testing at SLAC’s E-163. As with many advanced accelerators, identifying the best data analysis approach demands extensive numerical modelling of the anticipated beam parameters and development of data visualization tools. We present the latest numerical results and data analysis tools developed for dielectric laser acceleration experiments with MAP. |
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| TUPEA085 | Optics Tuning and Compensation in LCLS-II | 1313 |
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Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515. The LCLS-II is a future upgrade of the Linear Coherent Light Source (LCLS) at SLAC. It will include two new Free Electron Lasers (FELs) to generate soft and hard X-ray radiation. The 2.9 km LCLS-II lattice will include 1/3 of the SLC linac located just before the existing LCLS, the 1.2 km bypass line, the bend section, the beam separation and diagnostic regions, and the FEL undulators and dump. The LCLS operation showed that occasionally the beam phase space may be significantly mismatched due to various errors in the beamline. This requires correction to ensure good beam quality in the undulators. Similarly, the LCLS-II must have lattice correction system with a large tuning range to cancel such errors. Since the various LCLS-II regions are connected using matching sections, the latter naturally can be used for correction of the mismatched lattice functions. In addition, the large tuning capability is required to provide a wide range of focusing conditions at the FEL undulators. The compensation and tuning abilities of the LCLS-II lattice have been studied for incoming beam errors equivalent to 160% of beta beat and for a factor of 5 in the range of undulator quadrupole strengths. |
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| TUPEA086 | Femtosecond Electron Beam and X-ray Beams at the Linac Coherent Light Source | 1316 |
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| Generation of ultrashort x-ray pulses (femtoseconds to attoseconds) is attracting much attention within the x-ray FEL user community. At the Linac Coherent Light Source (LCLS), we have successfully delivered femtosecond x-ray pulses to the users with two operating modes – low-charge (20-40pC) scheme and emittance spoiling foil method. Diagnostics on the femtosecond beams is also a challenging topic and good progresses have been made at LCLS. In this paper we report the experimental studies on the two femtosecond operation schemes, the x-ray performance and also the diagnostic progress. | ||
| TUPEA087 | Experiment on Multipactor Suppression in Dielectric-loaded Accelerating Structures with a Solenoid Field | 1319 |
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Funding: US DoE SBIR Phase I project under contract #DE-SC0007629 Efforts by numerous institutions have been ongoing over the past decade to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external rf source. Multipactor is the major issue limiting the gradient that was revealed in earlier experiments. A theoretical model predicts that the strength of solenoid field within an optimal range applied to DLA structures may completely block the multipactor. To demonstrate this approach, two DLA test structures have been built and the first high power test will be conducted in December 2012. The results will be reported. |
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| TUPEA088 | Argonne Flexible Linear Collider | 1322 |
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| We propose a linear collider based on a short rf pulse (~22ns flat top), high gradient (~120MV/m loaded gradient), high frequency (26GHz) two beam accelerator design. This is a modular design and its unique locally repetitive drive beam structure allows a flexible configuration to meet different needs. Major parameters of a conceptual 250GeV linear collider are presented. This preliminary study shows that an efficient (~5% overall), 4MW beam power collider may be achievable. The concept is extendable to the TeV scale. | ||
| TUPEA089 | Modeling and Experimental Update on Quasi-phase Matched Direct Laser Electron Acceleration In Density-modulated Plasma Waveguides | 1325 |
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Funding: This work has been supported by the Defense Threat Reduction Agency through Contract HDTRA1-11-1-0009. Direct laser acceleration (DLA) of electrons using the axial electric field of a radially polarized, guided intense laser pulse has the potential to lead to compact laser-driven accelerators* for security and medical applications. A density-modulated plasma waveguide could be applied to extend the laser beam propagation distance and to achieve quasi-phase matching (QPM) between laser and electron pulses for efficient DLA**. We conduct numerical simulations to design the appropriate plasma structure of the waveguides and investigate the properties of accelerated electron beams. An all-optical method, based on the igniter-heater scheme for plasma waveguide fabrication, is experimentally implemented to machine the density-modulated plasma waveguides with low-Z gas targets. A novel angle-multiplexed diagnostic technique has been developed to extract the polarization state and temporal characteristics of a radially polarized femtosecond laser pulse using spatial-spectral interferometry***. The goal of our experiments is to characterize the propagation of femtosecond radially polarized pulses in plasma waveguides. * P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000). ** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012). ***P. Bowlan, et al., Opt. Exp. 14, 11892 (2006) |
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