Velocity dispersion of correlated energy spread electron beams in the free electron laser

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Campbell, L.T. and Maier, A. R. (2017) Velocity dispersion of correlated energy spread electron beams in the free electron laser. New Journal of Physics, 19. 033037. ISSN 1367-2630 (https://doi.org/10.1088/1367-2630/aa6205)

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Abstract

The effects of a correlated linear energy/velocity chirp in the electron beam in the FEL, and how to compensate for its effects by using an appropriate taper (or reverse-taper) of the undulator magnetic field, is well known. The theory, as described thus far, ignores velocity dispersion from the chirp in the undulator, taking the limit of a ‘small’ chirp. In the following, the physics of compensating for chirp in the beam is revisited, including the effects of velocity dispersion, or beam compression or decompression, in the undulator. It is found that the limit of negligible velocity dispersion in the undulator is different from that previously identified as the small chirp limit, and is more significant than previously considered. The velocity dispersion requires a taper which is non-linear to properly compensate for the effects of the detuning, and also results in a varying peak current (end thus a varying gain length) over the length of the undulator. The results may be especially significant for plasma driven FELs and low energy linac driven FEL test facilities.

ORCID iDs

Campbell, L.T. ORCID logoORCID: https://orcid.org/0000-0003-1375-1551 and Maier, A. R.;
  • Item type:Article
    ID code:59988
    Dates:
    Date
    Event
    27 March 2017
    Published
    22 February 2017
    Published Online
    22 February 2017
    Accepted
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:28 Feb 2017 11:32
    Last modified:11 Nov 2024 11:38
    URI:https://strathprints.strath.ac.uk/id/eprint/59988
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