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Title: Coherence Properties of the LCLS

Abstract

The LINAC Coherent Light Source (LCLS), an X-Ray free-electron laser(FEL) based on the self amplified spontaneous emission principle, has recently come on-line. For many users it is desirable to have an idea of the level of transverse coherence of the X-Ray beam produced. In this paper, we analyze the output of GENESIS simulations of electrons traveling through the FEL. We first test the validity of an approach that ignores the details of how the beam was produced, and instead, by assuming a Gaussian-Schell model of transverse coherence, predicts the level of transverse coherence simply through looking at the beam radius at several longitudinal slices. We then develop a Markov chain Monte Carlo approach to calculating the degree of transverse coherence, which offers a {approx}100-fold speedup compared to the brute-force algorithm previously in use. We find the beam highly coherent. Using a similar Markov chain Monte Carlo approach, we estimate the reasonability of assuming the beam to have a Gaussian-Schell model of transverse coherence, with inconclusive results.

Authors:
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
992935
Report Number(s):
SLAC-TN-10-013
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Ocko, Samuel. Coherence Properties of the LCLS. United States: N. p., 2010. Web. doi:10.2172/992935.
Ocko, Samuel. Coherence Properties of the LCLS. United States. https://doi.org/10.2172/992935
Ocko, Samuel. 2010. "Coherence Properties of the LCLS". United States. https://doi.org/10.2172/992935. https://www.osti.gov/servlets/purl/992935.
@article{osti_992935,
title = {Coherence Properties of the LCLS},
author = {Ocko, Samuel},
abstractNote = {The LINAC Coherent Light Source (LCLS), an X-Ray free-electron laser(FEL) based on the self amplified spontaneous emission principle, has recently come on-line. For many users it is desirable to have an idea of the level of transverse coherence of the X-Ray beam produced. In this paper, we analyze the output of GENESIS simulations of electrons traveling through the FEL. We first test the validity of an approach that ignores the details of how the beam was produced, and instead, by assuming a Gaussian-Schell model of transverse coherence, predicts the level of transverse coherence simply through looking at the beam radius at several longitudinal slices. We then develop a Markov chain Monte Carlo approach to calculating the degree of transverse coherence, which offers a {approx}100-fold speedup compared to the brute-force algorithm previously in use. We find the beam highly coherent. Using a similar Markov chain Monte Carlo approach, we estimate the reasonability of assuming the beam to have a Gaussian-Schell model of transverse coherence, with inconclusive results.},
doi = {10.2172/992935},
url = {https://www.osti.gov/biblio/992935}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Aug 25 00:00:00 EDT 2010},
month = {Wed Aug 25 00:00:00 EDT 2010}
}