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Objectives and configuration of the Multiple Pulse Propagation Experiment

Description: The Multiple Pulse Propagation Experiment (MPPE) was designed to determine the hose stability properties of an intense relativistic electron beam in a beam generated density channel and to investigate range extension with increasing pulse number in the burst. This experiment used a 10-MeV electron beam generated by the Advanced Test Accelerator (ATA). The electron beam current was expected to be at least 6-kA with an equilibrium radius of 0.5 cm (RMS) in the gas. This last constraint implied an… more
Date: October 1, 1990
Creator: Orzechowski, T. J.; Caporaso, G. J.; Chamber, F. W.; Chong, Y. P.; Deadrick, F. J.; Guethlein, G. et al.
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Partner: UNT Libraries Government Documents Department
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Novel accelerators employing high-current electron beams numerical simulations

Description: Numerical simulations codes are described which can be used to study the physical phenomena of high-current electron beams employed in some novel accelerator schemes. Examples are given of the study of transverse effects in the free electron laser part of a Two-Beam Accelerator, the study of ion guiding in a Relativistic Klystron, and a study of the acceleration phase of a Collective implosion Accelerator.
Date: January 1, 1986
Creator: Fawley, W. M.; Teague, M. R.; Caporaso, G. J.; Yu, S. S. & Sessler, A. M.
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Partner: UNT Libraries Government Documents Department
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High gain and high extraction efficiency from a free electron laser amplifier operating in the millimeter wave regime

Description: Experiments at the Electron Laser Facility have generated peak microwave power of 180 MW at 35 GHz. The facility is operated as a single pass amplifier. Gain in excess of 30 dB/m has been observed up to saturation of the amplifier. For the 3 MeV, 850 Amp electron beam, the radiation corresponds to 7% energy extraction from the electron beam. Beyond saturation, the electron beam output power exhibits oscillations corresponding to the synchrotron motion of the trapped electrons in the ponderomoti… more
Date: October 1, 1985
Creator: Orzechowski, T. J.; Anderson, B. R.; Fawley, W. M.; Prosnitz, D.; Scharlemann, E. T.; Yarema, S. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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MPPE (Multiple Pulse Propagation Experiment) results

Description: The Multiple Pulse Propagation Experiment (MPPE) was conducted by the Beam Research Group of the Lawrence Livermore National Laboratory from September 1989, through January 1990, using the Advanced Test Accelerator (ATA). This experiment represents the culmination of the three previous beam propagation experiments conducted at the ATA over the past half decade. Highlights of this experiment were the multiple pulse operation of ATA, and the diagnosis of the beam propagation, and channel producti… more
Date: October 1, 1990
Creator: Chambers, F. W.; Caporaso, G. J.; Chong, Y. P.; Deadrick, F. J.; Guethlein, G.; Fawley, W. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Time-dependent multi-dimensional simulation studies of the electron output scheme for high power FELs

Description: The authors examine the performance of the so-called electron output scheme recently proposed by the Novosibirsk group. In this scheme, the key role of the FEL oscillator is to induce bunching, while an external undulator, called the radiator, then outcouples the bunched electron beam to optical energy via coherent emission. The level of the intracavity power in the oscillator is kept low by employing a transverse optical klystron (TOK) configuration, thus avoiding excessive thermal loading on … more
Date: December 1, 1994
Creator: Hahn, S. J.; Fawley, W. M.; Kim, K. J. & Edighoffer, J. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Coherence and linewidth studies of a 4-nm high power FEL

Description: Recently the SSRL/SLAC and its collaborators elsewhere have considered the merits of a 2 to 4-nm high power FEL utilizing the SLAC linac electron beam. The FEL would be a single pass amplifier excited by spontaneous emission rather than an oscillator, in order to eliminate the need for a soft X-ray resonant cavity. We have used GINGER, a multifrequency 2D FEL simulation code, to study the expected linewidth and coherence properties of the FEL, in both the exponential and saturated gain regimes.… more
Date: May 1, 1993
Creator: Fawley, W. M.; Sessler, A. M. & Scharlemann, E. T.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Application of the Reduction of Scale Range in a Lorentz Boosted Frame to the Numerical Simulation of Particle Acceleration Devices

Description: It has been shown [1] that it may be computationally advantageous to perform computer simulations in a boosted frame for a certain class of systems: particle beams interacting with electron clouds, free electron lasers, and laser-plasma accelerators. However, even if the computer model relies on a covariant set of equations, it was also pointed out that algorithmic difficulties related to discretization errors may have to be overcome in order to take full advantage of the potential speedup [2] … more
Date: May 1, 2009
Creator: Vay, J. L.; Fawley, W. M.; Geddes, C. G. R.; Cormier-Michel, E. & Grote, D. P.
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Partner: UNT Libraries Government Documents Department
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Simulating relativistic beam and plasma systems using an optimal boosted frame

Description: It was shown recently that it may be computationally advantageous to perform computer simulations in a Lorentz boosted frame for a certain class of systems. However, even if the computer model relies on a covariant set of equations, it was pointed out that algorithmic difficulties related to discretization errors may have to be overcome in order to take full advantage of the potential speedup. In this paper, we summarize the findings, the difficulties and their solutions, and review the applica… more
Date: May 1, 2009
Creator: Vay, J. L.; Bruhwiler, D. L.; Geddes, C. G. R.; Fawley, W. M.; Martins, S. F.; Cary, J. R. et al.
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Partner: UNT Libraries Government Documents Department
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Design of an XUV FEL Driven by the Laser-Plasma Accelerator at theLBNL LOASIS Facility

Description: We present a design for a compact FEL source of ultrafast, high-peak flux, soft x-ray pulses employing a high-current, GeV-energy electron beam from the existing laser-plasma accelerator at the LBNL LOASIS laser facility. The proposed ultra-fast source would be intrinsically temporally synchronized to the drive laser pulse, enabling pump-probe studies in ultra-fast science with pulse lengths of tens of fs. Owing both to the high current ({approx} 10 kA) and reasonable charge/pulse ({approx} 0.1… more
Date: September 1, 2006
Creator: Schroeder, Carl B.; Fawley, W. M.; Esarey, Eric & Leemans, W. P.
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Partner: UNT Libraries Government Documents Department
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Measurements of nonlinear harmonic generation at the Advanced Photon Source's SASE FEL

Description: SASE saturation was recently achieved at the Advanced Photon Source's SASE FEL in the low-energy undulator test line (LEUTL) at 530 nm and 385 nm. The electron beam microbunching becomes more and more prominent until saturation is achieved. This bunching causes nonlinear harmonic emission that extends the usefulness of a SASE system in achieving shorter FEL wavelengths for the same electron beam energy. They have investigated the intensity of the fundamental and second-harmonic undulator radiat… more
Date: March 1, 2002
Creator: Biedron, S. G.; Dejus, E. J.; Huang, Z.; Milton, S. V.; Sajaev, V.; Berg, W. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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LUX - A Recirculating Linac-Based Ultrafast X-Ray Source

Description: We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV ra… more
Date: August 1, 2003
Creator: Corlett, J. N.; Barletta, W. A.; DeSantis, S.; Doolittle, L.; Fawley, W. M.; Green, M. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Transverse combining of 4 beams in MBE-4

Description: Transverse beam combining is a cost-saving optio employed in many designs for induction linac heavy ion fusion drivers. But resultant transverse emittance increase, due predominantly to anharmonic space charoe forces, must be kept minimal so as not to sacrifice focusability at the target. A prototype combining experiment has been built, using the MBE-4 experiment. Four sources produce four 4 mA Cs{sup +} beams at 200 keV. The ion sources are angled toward each other, so that beams converge. Foc… more
Date: May 1, 1995
Creator: Celata, C. M.; Chupp, W.; Faltens, A.; Fawley, W. M.; Ghiorso, W.; Hahn, K. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Merits of a sub-harmonic approach to a single-pass, 1.5-{Angstrom} FEL

Description: SLAC/SSRL and collaborators elsewhere are studying th physics of a single-pass, FEL amplifier operating in th 1 -- 2 {Angstrom}, wavelength region based on electron beams from the SLAC linac at {approximately} 15 GeV energy. Hoping to reduce the total wiggler length needed to reach saturation when starting from shot noise, we have examined the benefits of making the first part of the wiggler resonant at a subharmonic wavelength (e.g. 4.5 {Angstrom}) at which the gain length can be significantly… more
Date: March 1, 1995
Creator: Fawley, W. M.; Nuhn, H. D.; Bonifacio, R. & Scharlemann, E. T.
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Partner: UNT Libraries Government Documents Department
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{open_quotes}Optical Guiding{close_quotes} limits on extraction efficiencies of single-pass, tapered wiggler amplifiers

Description: Single-pass, tapered wiggler amplifiers have an attractive feature of being able, in theory at least, of extracting a large portion of the electron beam energy into light. In circumstances where an optical FEL wiggler length is significantly longer than the Rayleigh length Z{sub R} corresponding to the electron beam radius, diffraction losses must be controlled via the phenomenon of optical guiding. Since the strength of the guiding depends upon the effective refractive index n exceeding one, a… more
Date: August 1, 1995
Creator: Fawley, W. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulation studies of space-charge-dominated beam transport in large aperture ratio quadrupoles

Description: For many cases of interest in the design of heavy-ion fusion accelerators, the maximum transportable current in a magnetic quadrupole lattice scales as ({alpha}/L){sup 2} where {alpha} is the useful dynamic aperture and L is the half-lattice period. There are many cost benefits to maximizing the usable aperture which must be balanced against unwanted effects such as possible emittance growth and particle loss from anharmonic fringe fields. We have used two independent simulation codes to model … more
Date: May 1, 1993
Creator: Fawley, W. M.; Laslett, L. J.; Celata, C. M.; Faltens, A. & Haber, I.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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High order calculation of the multipole content of three dimensional electrostatic geometries

Description: We present an accurate and simple method of 3-D multipole decomposition of the field of arbitrary electrode geometries. The induced charge on the surface is obtained by inverting the capacity matrix. The multipole moment decomposition of the resulting potential is readily accomplished using Differential Algebra methodology. The method is applied to the focussing lattice geometry of the MBE-4 accelerator at LBL. Multipole terms of up to the order 5 are computed, and a numerical accuracy of < 1% … more
Date: April 1, 1991
Creator: Berz, M.; Fawley, W. M. & Hahn, K.
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Partner: UNT Libraries Government Documents Department
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Particle in cell simulations of disruption

Description: An improved numerical particle simulation code has been developed to study the electrodynamical interaction of colliding electron and positron beams. Contrary to previously reported work (which was in error due to a coding mistake), it is found that the maximum enhancement in luminosity due to the mutual pinch effect can exceed a factor of 6 for beams with Gaussian radial profiles and approaches 5 for uniform profiles. These new results are in much better agreement with those originally found b… more
Date: June 1, 1987
Creator: Fawley, W. M. & Lee, E. P.
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Partner: UNT Libraries Government Documents Department
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Design and construction of a large aperture, quadrupole electromagnet prototype for ILSE

Description: We are currently constructing a prototype quadrupole electromagnet for the proposed Induction Linac Systems Experiment (ILSE) at LBL. ILSE will address many physi and engineering issues relevant to the design of a heavy-ion fusion driver accelerator. The pulsed electromagnet has two layers of current windings and will produce a field gradient exceeding 25 T/m at a repetition rate of 1 Hz steady-state. In this paper, we discuss how the interaction of various concerns such as maximum dynamic aper… more
Date: April 1, 1995
Creator: Stuart, M.; Faltens, A.; Fawley, W. M.; Peters, C. & Vella, M. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Design and construction of a large aperture quadrupole electromagnet for ILSE

Description: We are currently constructing a prototype quadrupole electromagnet for the proposed Induction Linac Systems Experiment (ILSE) at LBNL. ILSE will address many physics and engineering issues relevant to the design of a heavy-ion fusion driver accelerator. The pulsed electromagnet has two layers of current windings and will produce a field gradient of 28 T/m, wi a usable aperture of 6 cm. It operates at a repetition rate of 1 Hz, steady-state. In this paper, we discuss how the interaction of vario… more
Date: August 1, 1995
Creator: Fawley, W. M.; Vella, M. C.; Peters, C.; Stuart, M. & Faltens, A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Numerical simulation studies of the LBNL heavy-ion beam combiner experiment

Description: Transverse beam combining is a cost-saving option employed in many designs for heavy-ion inertial fusion energy drivers. A major area of interest, both theoretically and experimentally, is the resultant transverse phase space dilution during the beam merging process. Currently, a prototype combining experiment is underway at LBNL and we have employed a variety of numerical descriptions to aid in both the initial design of the experiment data. These range from simple envelope codes to detailed 2… more
Date: January 1, 1997
Creator: Fawley, W. M.; Seidl, P.; Haber, I.; Friedman, A. & Grote, D. P.
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Partner: UNT Libraries Government Documents Department
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Critical issues for high-power FEL based on microtron recuperator/electron out-coupling scheme

Description: The FELs based on the RF accelerator-recuperator and the electron outcoupling is promising for obtaining average output power of hundreds of kilowatts. We present basic considerations for the system stability and performance optimization for this scheme.
Date: March 1, 1997
Creator: Vinokurov, N. A.; Zholents, A. A.; Fawley, W. M. & Kim, K. J.
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Partner: UNT Libraries Government Documents Department
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Multidimensional simulation studies of the SELENE FEL oscillator/buncher followed by a radiator/amplifier output scheme

Description: We analyze and present numerical simulations of the so-called electron output scheme [G. I. Erg et al., 15th Int. FEL Conf., The Hague, The Netherlands, 1993, Book of Abstracts p. 50; Preprint Budker INP 93-75] applied to the SELENE proposal of using a high power FEL to illuminate satellite solar cells. In this scheme, a first stage FEL oscillator bunches the electron beam while a second stage ``radiator`` extracts high power radiation. Our analysis suggests only in the case where the radiator … more
Date: February 1, 1995
Creator: Hahn, S. J. & Fawley, W. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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GINGER simulations of short-pulse effects in the LEUTL FEL

Description: While the long-pulse, coasting beam model is often used in analysis and simulation of self-amplified spontaneous emission (SASE) free-electron lasers (FELs), many current SASE demonstration experiments employ relatively short electron bunches whose pulse length is on the order of the radiation slippage length. In particular, the low-energy undulator test line (LEUTL) FEL at the Advanced Photon Source has recently lased and nominally saturated in both visible and near-ultraviolet wavelength regi… more
Date: July 1, 2001
Creator: Huang, Z. & Fawley, W. M.
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Partner: UNT Libraries Government Documents Department
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Life on the edge: squirrel-cage fringe fields and their effects in the MBE-4 combiner experiment

Description: The MBE-4 combiner experiment employs an electrostatic combined-function focusing/bending element, the so-called ``squirrel-cage`` just before the actual merging region. There has been concern that non-linear fields, primarily in the fringe regions at the beginning and end of the cage, may be strong enough to lead to significant emittance degradation. This note present the results of numerical calculations which determined the anharmonic, non-linear components of the 3D fields in the cage and t… more
Date: February 1, 1996
Creator: Fawley, W. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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