A. Doyuran

University of California, Los Angeles, Los Angeles, California, United States

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Publications (46)80.22 Total impact

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    ABSTRACT: It has recently been proposed to use a dispersionless translating section (dogleg) with sextupole correction magnets as a bunch compressor to create longitudinally shaped (linearly ramped) electron bunches. We discuss the experiment soon to be underway at the UCLA Neptune Linear Accelerator Laboratory to test this technique with the 300 pC, 13 MeV electron bunches produced by the Neptune S-Band photoinjector. The experiment will utilize a dipole-mode deflecting cavity, as a temporal diagnostic, and a final focus system of permanent magnet quadrupoles with field gradients of 110 T/m. We also discuss the potential scaling of this technique to bunches of high (i.e. >1nC) charge for the purpose of creating a suitable drive beam for the plasma wakefield accelerator, operating in the blowout regime.
    International Journal of Modern Physics A 01/2012; 22(23). DOI:10.1142/S0217751X07037706 · 1.09 Impact Factor
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    ABSTRACT: An Inverse Compton Scattering (ICS) experiment investigating the polarized harmonic production in the nonlinear regime has begun which will utilize the existing terawatt CO2 laser system and 15 MeV photoinjector in the Neptune Laboratory at UCLA. A major motivation for a source of high brightness polarized x-rays is the production of polarized positrons for use in future linear collider experiments. Analytical calculations have been performed to predict the angular and frequency spectrums for various polarizations and different scattering angles. We report on the experimental set-up and status.
    International Journal of Modern Physics A 01/2012; 22(23). DOI:10.1142/S0217751X07037895 · 1.09 Impact Factor
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    [Show abstract] [Hide abstract]
    ABSTRACT: It has recently been proposed to use a dispersionless translating section (dogleg) with sextupole correction magnets as a bunch compressor to create longitudinally shaped (linearly ramped) electron bunches. We discuss the experiment soon to be underway at the UCLA Neptune Linear Accelerator Laboratory to test this technique with the 300 pC, 13 MeV electron bunches produced by the Neptune S-Band photoinjector. The experiment will utilize a dipole-mode deflecting cavity, as a temporal diagnostic, and a final focus system of permanent magnet quadrupoles with field gradients of 110 T/m. We also discuss the potential scaling of this technique to bunches of high (i.e. >1nC) charge for the purpose of creating a suitable drive beam for the plasma wakefield accelerator, operating in the blowout regime.
    International Journal of Modern Physics A 09/2007; DOI:10.1142/9789812772176_0034 · 1.09 Impact Factor
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    ABSTRACT: An Inverse Compton Scattering (ICS) experiment investigating the polarized harmonic production in the nonlinear regime has begun which will utilize the existing terawatt CO2 laser system and 15 MeV photoinjector in the Neptune Laboratory at UCLA. A major motivation for a source of high brightness polarized x-rays is the production of polarized positrons for use in future linear collider experiments. Analytical calculations have been performed to predict the angular and frequency spectrums for various polarizations and different scattering angles. We report on the experimental set-up and status.
    09/2007; DOI:10.1063/1.2409172
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    ABSTRACT: In a recent paper it has been shown that single electron Thomson backscatter calculations can be performed including the effects of pulsed high intensity lasers. In this paper we present a more detailed treatment of the problem and present results for more general scattering geometries. In particular, we present new results for 90 degrees Thomson scattering. Such geometries have been increasingly studied as x-ray sources of short-pulse radiation. Also, we present a clearer physical basis for these different cases.
    Physical Review E 12/2005; 72(5 Pt 2):056502. DOI:10.1103/PhysRevE.72.056502 · 2.33 Impact Factor
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    ABSTRACT: We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a “figure-8” motion under the influence of the high-intensity laser field, where the con stant characterizing the field strength is expected to exceed unity: a L = eE L /m e cω L ≥ 1. With large a L this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals.
    Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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    ABSTRACT: An Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of scattering utilizing a terawatt CO 2 laser system with various polarizations, is ongoing at the UCLA Neptune Laboratory. When the normalized amplitude of the incident laser's vector potential a 0 is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. ICS can be used, e.g., for a polarized positron source by striking a thin target (such as tungsten) with the polarized X-rays. As such, it is critical to demonstrate the production of polarized scattered photons and to investigate the ICS process as it enters the nonlinear regime. We present the description of the experimental set up and equipment utilized, including diagnostics for electron and photon beam detection. We present the current status of the experiment.
    Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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    ABSTRACT: We report on the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in a 50 cm long undulator strongly tapered both in period and field amplitude. A CO 2 10.6 µ m laser with power > 400 GW is used as the IFEL driver. The Rayleigh range of the laser (∼ 1.8 cm) is shorter than the undulator length so that the interaction is diffraction dominated. Few per cent of the injected particles are trapped in stable accelerating buckets and electrons with energies up to 35 MeV are detected on the magnetic spectrometer. Three dimensional simulations are in good agreement with the electron energy spectrums observed in the experiment and indicate that substantial energy exchange between laser and electron beam only occurs in the first 25-30 cm of the undulator. An energy gradient of > 70 MeV is inferred. In the second section of the undulator higher harmonic IFEL interaction is observed.
    Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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    ABSTRACT: Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an inverse-free-electron-laser (IFEL) accelerator experiment. A 14.5 MeV electron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and field amplitude. The Rayleigh range of the laser, approximately 1.8 cm, is much shorter than the undulator length yielding a diffraction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator.
    Physical Review Letters 05/2005; 94(15):154801. DOI:10.1103/PhysRevLett.94.154801 · 7.73 Impact Factor
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    ABSTRACT: We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 mum laser with power larger than 400 GW. The Rayleigh range of the laser, ~ 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator.
    12/2004; 737(1). DOI:10.1063/1.1842541
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    ABSTRACT: A ramped electron bunch (i.e. one having a current density which rises linearly from the head to the tail and then drops sharply to zero) has been predicted to be an ideal drive beam for the plasma wake field accelerator due to the large transformer ratio it is capable of generating. A scheme was recently proposed for the creation of a relativistic electron bunch that approximates a ramped current profile [England, et al., AIP Conf. Proc. 647, p.884 (2002)], using a dogleg or dispersionless translating section as a bunch compressor. An experiment is underway at the Neptune laboratory using this scheme to create such a beam. The diagnostic being developed for measuring the temporal profile of the beam is an X-Band transverse deflecting mode cavity.
    12/2004; 737(1). DOI:10.1063/1.1842572
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    ABSTRACT: We propose an Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of the scattering utilizing the terawatt CO2 laser system with various polarizations in Neptune Laboratory at UCLA. When the normalized amplitude of the vector potential a0 is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. We present a calculation tool for the Double Differential Spectrum (DDS) distribution and total number of photons produced for both head-on and 90° scattering. We decided to do the experiment at 90° to avoid complications due to strong diffraction of the incoming laser. We discuss the electron and laser beam parameters for the experiment.
    12/2004; DOI:10.1063/1.1842618
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    ABSTRACT: Recently strong modulation of the electron bunch longitudinal phase space was obtained in the DUV-FEL accelerator at NSLS [1,2]. The chirped beam energy spectra exhibit a spiky structure with a subpicosecond spike separation. A model based on the longitudinal space-charge effect has been suggested as an explanation of the observed effect [3,10]. For characterization of the structure and comparison with the model we performed several experiments [4]. In this paper we present experimental data and discuss them in relation to the model.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 08/2004; 528(1). DOI:10.1016/j.nima.2004.04.119 · 1.32 Impact Factor
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    ABSTRACT: The DUV-FEL facility has been in operation in the High Gain Harmonic Generation (HGHG) mode producing a 266-nm output from 177-MeV electrons for 1 year. In this paper, we present preliminary results of the Chirped Pulse Amplification (CPA) of the HGHG radiation. In the normal HGHG process, a 1-ps electron beam is seeded by a chirped 9 ps long, 800-nm Ti:Sapphire laser. The electron beam sees only a narrow fraction of the seed laser bandwidth. However, in the CPA case, the seed laser pulse length is reduced to 1 ps, and the electron beam sees the full bandwidth. We introduce an energy chirp on the electron beam to match the chirp of the seed pulse, enabling the resonant condition for the whole beam. We present measurements of the spectrum bandwidth for various chirp conditions. r 2004 Elsevier B.V. All rights reserved.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 08/2004; 528:467-470. DOI:10.1016/j.nima.2004.04.133 · 1.32 Impact Factor
  • A Doyuran
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    ABSTRACT: The DUV-FEL facility has been in operation in the High Gain Harmonic Generation (HGHG) mode producing a 266-nm output from 177-MeV electrons for 1 year. In this paper, we present preliminary results of the Chirped Pulse Amplification (CPA) of the HGHG radiation. In the normal HGHG process, a 1-ps electron beam is seeded by a chirped 9 ps long, 800-nm Ti:Sapphire laser. The electron beam sees only a narrow fraction of the seed laser bandwidth. However, in the CPA case, the seed laser pulse length is reduced to 1 ps, and the electron beam sees the full bandwidth. We introduce an energy chirp on the electron beam to match the chirp of the seed pulse, enabling the resonant condition for the whole beam. We present measurements of the spectrum bandwidth for various chirp conditions.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2004; DOI:10.1016/S0168-9002(04)00772-7 · 1.32 Impact Factor
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    ABSTRACT: Saturation of a high-gain harmonic-generation free-electron laser (HGHG-FEL) at 266 nm has been accomplished at the Brookhaven National Laboratory/Deep Ultra Violet Free Electron Laser Facility (BNL/DUV-FEL) by seeding with an 800 nm Ti:sapphire laser. We describe the diagnostics used to characterize the electron beam and the FEL output. Analytic and simulation calculations of the HGHG output are presented and compared with the experimental data. We also discuss the chirped pulse amplification of a frequency chirped seed by an energy chirped electron beam. The third harmonic at 88 nm accompanying the 266 nm fundamental has been used in an ion pair imaging experiment in chemistry, the first application of the BNL/DUV-FEL.
    Physical Review Special Topics - Accelerators and Beams 05/2004; 7(5). DOI:10.1103/PhysRevSTAB.7.050701 · 1.52 Impact Factor
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    ABSTRACT: We present the first experimental results obtained with a high-gain harmonic generation extreme ultraviolet free electron laser. The experiment probes decay dynamics of superexcited states of methyl fluoride via ion pair imaging spectroscopy. Velocity mapped ion images of the fluoride ion, obtained with excitation via intense, coherent, subpicosecond pulses of 86-89 nm radiation, reveal low translational energy, implying very high internal excitation in the methyl cation cofragment. Angular distributions show changing anisotropy as the excitation energy is tuned through this region. The dynamics underlying the dissociation are discussed with the aid of theoretical calculations.
    Physical Review Letters 03/2004; 92(8):083002. DOI:10.1103/PhysRevLett.92.083002 · 7.73 Impact Factor
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    ABSTRACT: We report on the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator ex- periment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in a 50 cm long undulator strongly tapered both in period and field amplitude. A CO2 10.6 µm laser with power > 300 GW is used as the IFEL driver. The Rayleigh range of the laser (∼ 1.8 cm) is shorter than the undulator length so that the interaction is diffraction dom- inated. Few per cent of the injected particles are trapped in stable accelerating buckets and electrons with energies up to 35 MeV are detected on the magnetic spectrometer. Three dimensional simulations are in good agreement with the electron energy spectrums observed in the experiment and indicate that substantial energy exchange between laser and electron beam only occurs in the first 25-30 cm of the undulator. An energy gradient of > 70 MeV is inferred. In the second section of the undulator higher harmonic IFEL interaction is observed.
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    ABSTRACT: We report the first experimental results on a high-gain harm onic-generation (HGHG) free-electron laser (FEL) operating in the ultraviolet. An 800 nm seed from a Ti-Sapphire laser has been used to produce saturated amplified output at the 266 nm third-harmonic. The results confirm the advantages of the HGHG FEL: stable central wavelength, narrow bandwidth and small pulse energy fluctuation. The harmonic output at 88 nm, which accompanies the 266 nm radiation, has been used in an ion pair imaging experiment in chemistry.
    Physical Review Letters 09/2003; 91(7):074801. DOI:10.1016/j.nima.2004.04.127 · 7.73 Impact Factor
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    ABSTRACT: The Deep Ultra-Violet Free Electron Laser (DUVFEL) at the National Synchrotron Light Source consists of a 5 MeV photoinjector, a 200 MeV S-band linear accelerator, a four-magnet chicane compressor and a 10 m wiggler with a 3.9 cm period. The commissioning of the SDL accelerator was completed recently and it is routinely producing a high-quality electron beam with a peak current of B400 A and a normalised emittance of 3–4 mm mrad. The first SASE lasing of the DUV FEL has been demonstrated at both 266 and 400 nm. The gain length of the SASE experiments was measured to be 66 cm in both cases and up to 20 nJ per pulse was obtained. A laser seeded FEL at 266 nm is in the very early stages of commissioning and amplification of the laser seed has been observed. The goal of the seeded laser FEL is to saturate the FEL and thereby generate sufficient third harmonic at 89 nm for experimental applications. Here we report the observation and measurements of SASE at 400 and 266 nm and the first results of seeded FEL. r 2003 Elsevier Science B.V. All rights reserved.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 07/2003; 507:15-18. DOI:10.1016/S0168-9002(03)00825-8 · 1.32 Impact Factor

Publication Stats

478 Citations
80.22 Total Impact Points

Institutions

  • 2005–2012
    • University of California, Los Angeles
      • Department of Physics and Astronomy
      Los Angeles, California, United States
  • 2000–2004
    • Brookhaven National Laboratory
      • • National Synchrotron Light Source
      • • Accelerator Test Facility
      New York City, New York, United States
  • 2001
    • Argonne National Laboratory
      Lemont, Illinois, United States