Efficiency Enhancement Techniques for Free-Electron Lasers

Alan Mak

Research output: ThesisDoctoral Thesis (compilation)

449 Downloads (Pure)


The central question addressed in this thesis is how to make the free-electron laser (FEL) more efficient. In recent years, coherent diffraction imaging provides an important motivation for efficiency enhancement. This is because a more efficient FEL process enables converting a larger fraction of the electron beam's power into optical power. By increasing the average optical power to the terawatt level, an x-ray FEL will open the door to single-shot, single-molecule imaging with a sufficiently high signal-to-noise ratio.

This thesis examines two techniques for efficiency enhancement, namely, undulator tapering and the phase jump method.

For undulator tapering, the well-established analytical model by Kroll, Morton and Rosenbluth (KMR) is revisited and modified. With the aid of numerical simulations, it is demonstrated that the modified model results in a further enhancement in FEL efficiency beyond the original model.

For the phase jump method, a new physics model is developed to describe the energy extraction mechanism in the longitudinal phase space. The model reveals the possibility to extract energy from electrons outside the ponderomotive bucket, as well as the potential to increase the spectral purity by suppressing the synchrotron sidebands.
Original languageEnglish
Awarding Institution
  • Faculty of Science
  • Werin, Sverker, Supervisor
  • Curbis, Francesca, Supervisor
Award date2017 Jun 15
Place of PublicationLund
ISBN (Print)978-91-7753-305-4
ISBN (electronic) 978-91-7753-306-1
Publication statusPublished - 2017 May

Bibliographical note

Defence details
Date: 2017-06-15
Time: 13:00
Place: The MAX III seminar room at the MAX IV Laboratory, Fotongatan 2, Lund
External reviewer
Name: McNeil, Brian
Title: Dr.
Affiliation: University of Strathclyde, Glasgow, United Kingdom

Subject classification (UKÄ)

  • Accelerator Physics and Instrumentation

Free keywords

  • free-electron laser
  • accelerator physics
  • efficiency enhancement
  • undulator tapering
  • phase jump method
  • synchrotron radiation
  • Fysicumarkivet:2017:Mak


Dive into the research topics of 'Efficiency Enhancement Techniques for Free-Electron Lasers'. Together they form a unique fingerprint.

Cite this