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A. Lutman

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Last Name: Lutman

Full Name: A. Lutman

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2 papers
title: HIGH EFFICIENCY, HIGH BRIGHTNESS X-RAY FREE ELECTRON LASERS VIA FRESH BUNCH SELF-SEEDING
format: conference proceeding
conference: IPAC 2016
year: 2016
6 authors: C. Emma | C. Pellegrini | A. Lutman | M. Guetg | A. Marinelli | J. Wu
abstract: High efficiency, terawatt peak power X-ray Free Electron Lasers (XFELs) are a promising tool for enabling 3D atomic resolution single molecule imaging and nonlinear science using X-ray beams. Increasing the efficiency of XFELs while maintaining good longitudinal coherence can be achieved via self-seeding and tapering the undulator magnetic field. The efficiency of tapered self seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to electron beam shot noise. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread electron bunch. This can be achieved by selectively suppressing lasing for part of the electron beam in the SASE section and using the rest of the bunch to generate the seed radiation. In this manner one can reach saturation with the seeding electrons and the strong seed pulse can be overlapped with the “fresh" electrons downstream of the self-seeding monochromator. Simulations of this scenario demonstrating an increased efficiency are presented for two systems, an optimal superconducting undulator design and the Linac Coherent Light Source. In the case of the LCLS we examine how the betatron oscillations leading to selective suppression can be induced by using the transverse wakefield of a parallel plate corrugated structure, a dechirper.
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title: FEMTOSECOND X-RAY PULSE GENERATION WITH AN ENERGY CHIRPED ELECTRON BEAM
format: conference proceeding
conference: FEL 2015 37th
year: 2015
7 authors: C. Emma | C. Pellegrini | Y. Ding | G. Marcus | A. Lutman | Z. Huang | A. Marinelli
abstract: We study the generation of short (sub 10 fs) pulses in the X-ray spectral region using an energy chirped electron beam in a Self Amplified Spontaneous Emission Free Electron Laser (SASE FEL) and a self-seeding monochromator [1-4]. The monochromator filters a small bandwidth, short duration pulse from the frequency chirped SASE spectrum. This pulse is used to seed a small fraction of the long chirped beam, hence a short pulse with narrow bandwidth is amplified in the following undulators. We present start-to-end simulation results for LCLS operating in the soft X-ray self-seeded mode with an energy chirp of 1% over 30 fs and a bunch charge of 150 pC. We show the possibility to generate 5 fs pulses with a bandwidth 0.3 eV. We also assess the possibility of further shortening the pulse by utilizing one more chicane after the self-seeding stage and shifting the radiation pulse to a “fresh” part of the electron beam. Experimental study on this short pulse seeding mode has been planned at the LCLS.
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