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Title: Laguerre-Gaussian and beamlet array as second generation laser heater profiles

Abstract

The microbunching instability is known to be detrimental to x-ray free electron laser performance. At the Linear Coherent Light Source, the microbunching instability is suppressed with a laser heater, which increases the uncorrelated energy spread of e-beam in the injector. While the current system has been shown to improve x-ray brightness, other laser architectures could further enhance performance. In this study, we model the interaction between a laser and e-beam with arbitrary transverse profiles and examine the effect of various laser designs on the energy distribution of the electrons after the injector and laser heater, as well as their ability to suppress microbunching instability. This simulation incorporates random transverse jitter in order to reproduce physically representative operation of the Linac Coherent Light Source. We compare Gaussian and Laguerre-Gaussian modes, and explore composite beams in the form of an array of Gaussian beamlets. We conclude that the Gaussian laser profile is highly susceptible to e-beam ellipticity and random transverse jitter. The Laguerre-Gaussian profile, a mathematically ideal solution to suppressing microbunching, is less susceptible to these effects and can provide effective suppression even with a distorted e-beam, though performance can be improved by increasing stabilization. The array of beamlets presents a solutionmore » that produces consistent and smooth energy distributions with significantly less variance in heating than the Laguerre-Gaussian profile.« less

Authors:
 [1];  [2];  [2];  [2];  [2];  [2];  [2]
  1. Rice Univ., Houston, TX (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States). Linac Coherent Light Source (LCLS)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Workforce Development for Teachers and Scientists (WDTS) (SC-27)
OSTI Identifier:
1469432
Alternate Identifier(s):
OSTI ID: 1475399
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review Accelerators and Beams
Additional Journal Information:
Journal Volume: 21; Journal Issue: 9; Journal ID: ISSN 2469-9888
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS

Citation Formats

Liebster, Nikolas, Tang, Jingyi, Ratner, Daniel, Liu, Wei, Vetter, Sharon, Huang, Zhirong, and Carbajo, Sergio. Laguerre-Gaussian and beamlet array as second generation laser heater profiles. United States: N. p., 2018. Web. doi:10.1103/physrevaccelbeams.21.090701.
Liebster, Nikolas, Tang, Jingyi, Ratner, Daniel, Liu, Wei, Vetter, Sharon, Huang, Zhirong, & Carbajo, Sergio. Laguerre-Gaussian and beamlet array as second generation laser heater profiles. United States. doi:10.1103/physrevaccelbeams.21.090701.
Liebster, Nikolas, Tang, Jingyi, Ratner, Daniel, Liu, Wei, Vetter, Sharon, Huang, Zhirong, and Carbajo, Sergio. Tue . "Laguerre-Gaussian and beamlet array as second generation laser heater profiles". United States. doi:10.1103/physrevaccelbeams.21.090701.
@article{osti_1469432,
title = {Laguerre-Gaussian and beamlet array as second generation laser heater profiles},
author = {Liebster, Nikolas and Tang, Jingyi and Ratner, Daniel and Liu, Wei and Vetter, Sharon and Huang, Zhirong and Carbajo, Sergio},
abstractNote = {The microbunching instability is known to be detrimental to x-ray free electron laser performance. At the Linear Coherent Light Source, the microbunching instability is suppressed with a laser heater, which increases the uncorrelated energy spread of e-beam in the injector. While the current system has been shown to improve x-ray brightness, other laser architectures could further enhance performance. In this study, we model the interaction between a laser and e-beam with arbitrary transverse profiles and examine the effect of various laser designs on the energy distribution of the electrons after the injector and laser heater, as well as their ability to suppress microbunching instability. This simulation incorporates random transverse jitter in order to reproduce physically representative operation of the Linac Coherent Light Source. We compare Gaussian and Laguerre-Gaussian modes, and explore composite beams in the form of an array of Gaussian beamlets. We conclude that the Gaussian laser profile is highly susceptible to e-beam ellipticity and random transverse jitter. The Laguerre-Gaussian profile, a mathematically ideal solution to suppressing microbunching, is less susceptible to these effects and can provide effective suppression even with a distorted e-beam, though performance can be improved by increasing stabilization. The array of beamlets presents a solution that produces consistent and smooth energy distributions with significantly less variance in heating than the Laguerre-Gaussian profile.},
doi = {10.1103/physrevaccelbeams.21.090701},
journal = {Physical Review Accelerators and Beams},
issn = {2469-9888},
number = 9,
volume = 21,
place = {United States},
year = {2018},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/physrevaccelbeams.21.090701

Figures / Tables:

Table I Table I: Relevant LCLS parameter values.

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Works referenced in this record:

Demonstration of self-seeding in a hard-X-ray free-electron laser
journal, August 2012