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W. M. Fawley

First Name: W

Middle Name: M

Last Name: Fawley

Full Name: W. M. Fawley

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4 papers

title: Current-Enhanced SASE Using an Optical Laser and its Application to the LCLS

format: journal article

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6 authors: A.A. Zholents | W.M. Fawley | P. Emma | Z. Huang | G. Stupakov | S. Reiche

abstract: We propose a significant enhancement of the electron peak current entering a SASE undulator by inducing an en- ergy modulation in an upstream wiggler magnet via res- onant interaction with an optical laser, followed by mi- crobunching of the energy-modulated electrons at the ac- celerator exit. This current enhancement allows a reduc- tion of the FEL gain length. The x-ray output consists of a series of uniformly spaced spikes, each spike being tem- porally coherent. The duration of this series is controlled by the laser pulse and in principle can be narrowed down to just a single, -attosecond spike. Given potentially absolute temporal synchronization of the x-ray spikes to the energy-modulating laser pulse, this scheme naturally makes pump-probe experiments available to SASE FEL’s. We also study various detrimental effects related to the high electron peak current .

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title: An injector-prebuncher for a plasma electron accelerator

format: conference procceeding

conference: 1995 Particle Accelerator Conference

year: 1995

5 authors: M. Lampel | C. Pellegrini | Zhang, R. | C. Joshi | W. M. Fawley

abstract: Optimum operation of a plasma beat-wave or wakefield accelerator requires an injected beam consisting of a train of electron bunches separated by the plasma wavelength, with each bunch in the train having a length much shorter than the plasma wavelength, and the capability of controlling the relative phase of the electron bunches and plasma wave. The typical plasma wavelength is about 0.1 mm, requiring a bunch length of about 10 to 20 mu m, which is difficult to achieve with conventional RF based injectors. In this paper we describe an electron accelerator-buncher system based on a photoinjector and an FEL, which can satisfy the plasma accelerator requirements. (4 References).

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title: Parametric study of an X-ray FEL

format: conference procceeding

conference: 16th International Free Electron Laser Conference

year: 1995

7 authors: G. Travish | W. M. Fawley | K. J. Kim | H. D. Nuhn | C. Pellegrini | H. Winick | M. Xie

abstract: An FEL utilizing a high energy, high current and low emittance beam to produce radiation shorter than 2 angstroms is investigated in this paper. This device is an extension of the previously proposed 40 AA Linac Coherent Light Source based on the Stanford linear accelerator. Here we investigate the performance characteristics and parameter sensitivities of this single pass, high gain FEL amplifier operating by self-amplified spontaneous emission (SASE). We begin by comparing various approaches to this short wavelength source and justify our choice of a helical undulator operating on the fundamental frequency. Numerical simulations as well as extensions of previous studies are used to show performance as a function of undulator parameters, startup noise, emittance, focusing, current and energy spread. Further studies and parameter modifications are proposed where needed.

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title: Short wavelength FELs using the SLAC linac

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year: 1994

30 authors: J. Cobb | D. Prosnitz | V. Vylet | J. Seeman | P. Pianetta | P. Morton | H. D. Nuhn | K. Bane | R. Boyce | G. Loew | R. Miller | J. Paterson | D. Palmer | T. Raubenheimer | R. Tatchyn | H. Winick | A. D. Yeremian | C. Pellegrini | J. B. Rosenzweig | G. Travish | E. T. Scharlemann | W. M. Fawley | K. Halbach | K. J. Kim | R. Schlueter | A. M. Sessler | M. Xie | R. Bonifacio | L. De Salvo | P. Pierini

abstract: We have studied the use of the SLAC linac to drive FELs at wavelengths down to a few angstroms. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy eelctron beam through a long undulator by Self-Amplified-Spontaneous-Emissin (SASE). About 10(13) photons per pulse can be produced in 100 fs pulses at a 120 Hz rate, corresponding to brightness levels of about 10(22) average and 10(32) peak. Peak power levels are tens of GW. Electron energies of 10-20 GeV are required. Signifcant imporvement of FEL performance seems possible using harmonic generation techniques according to results from numerical simulations.

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title:	Current-Enhanced SASE Using an Optical Laser and its Application to the LCLS
format:	journal article
year:
6 authors:	A.A. Zholents \| W.M. Fawley \| P. Emma \| Z. Huang \| G. Stupakov \| S. Reiche
abstract:	We propose a significant enhancement of the electron peak current entering a SASE undulator by inducing an en- ergy modulation in an upstream wiggler magnet via res- onant interaction with an optical laser, followed by mi- crobunching of the energy-modulated electrons at the ac- celerator exit. This current enhancement allows a reduc- tion of the FEL gain length. The x-ray output consists of a series of uniformly spaced spikes, each spike being tem- porally coherent. The duration of this series is controlled by the laser pulse and in principle can be narrowed down to just a single, -attosecond spike. Given potentially absolute temporal synchronization of the x-ray spikes to the energy-modulating laser pulse, this scheme naturally makes pump-probe experiments available to SASE FEL’s. We also study various detrimental effects related to the high electron peak current .
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title:	An injector-prebuncher for a plasma electron accelerator
format:	conference procceeding
conference:	1995 Particle Accelerator Conference
year:	1995
5 authors:	M. Lampel \| C. Pellegrini \| Zhang, R. \| C. Joshi \| W. M. Fawley
abstract:	Optimum operation of a plasma beat-wave or wakefield accelerator requires an injected beam consisting of a train of electron bunches separated by the plasma wavelength, with each bunch in the train having a length much shorter than the plasma wavelength, and the capability of controlling the relative phase of the electron bunches and plasma wave. The typical plasma wavelength is about 0.1 mm, requiring a bunch length of about 10 to 20 mu m, which is difficult to achieve with conventional RF based injectors. In this paper we describe an electron accelerator-buncher system based on a photoinjector and an FEL, which can satisfy the plasma accelerator requirements. (4 References).
keywords:
Download \| View \| Details \| edit \| delete

title:	Parametric study of an X-ray FEL
format:	conference procceeding
conference:	16th International Free Electron Laser Conference
year:	1995
7 authors:	G. Travish \| W. M. Fawley \| K. J. Kim \| H. D. Nuhn \| C. Pellegrini \| H. Winick \| M. Xie
abstract:	An FEL utilizing a high energy, high current and low emittance beam to produce radiation shorter than 2 angstroms is investigated in this paper. This device is an extension of the previously proposed 40 AA Linac Coherent Light Source based on the Stanford linear accelerator. Here we investigate the performance characteristics and parameter sensitivities of this single pass, high gain FEL amplifier operating by self-amplified spontaneous emission (SASE). We begin by comparing various approaches to this short wavelength source and justify our choice of a helical undulator operating on the fundamental frequency. Numerical simulations as well as extensions of previous studies are used to show performance as a function of undulator parameters, startup noise, emittance, focusing, current and energy spread. Further studies and parameter modifications are proposed where needed.
keywords:
Download \| View \| Details \| edit \| delete

title:	Short wavelength FELs using the SLAC linac
format:	journal article
year:	1994
30 authors:	J. Cobb \| D. Prosnitz \| V. Vylet \| J. Seeman \| P. Pianetta \| P. Morton \| H. D. Nuhn \| K. Bane \| R. Boyce \| G. Loew \| R. Miller \| J. Paterson \| D. Palmer \| T. Raubenheimer \| R. Tatchyn \| H. Winick \| A. D. Yeremian \| C. Pellegrini \| J. B. Rosenzweig \| G. Travish \| E. T. Scharlemann \| W. M. Fawley \| K. Halbach \| K. J. Kim \| R. Schlueter \| A. M. Sessler \| M. Xie \| R. Bonifacio \| L. De Salvo \| P. Pierini
abstract:	We have studied the use of the SLAC linac to drive FELs at wavelengths down to a few angstroms. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy eelctron beam through a long undulator by Self-Amplified-Spontaneous-Emissin (SASE). About 10(13) photons per pulse can be produced in 100 fs pulses at a 120 Hz rate, corresponding to brightness levels of about 10(22) average and 10(32) peak. Peak power levels are tens of GW. Electron energies of 10-20 GeV are required. Signifcant imporvement of FEL performance seems possible using harmonic generation techniques according to results from numerical simulations.
keywords:
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