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Designing a Femtosecond-Resolution Bunch Length Monitor Using Coherent Transition Radiation Images

Guisao-Betancur, Ana ; Wolfenden, Joseph ; Mansten, Erik LU ; Thorin, Sara LU ; Lundquist, Johan LU ; Grimm, Oliver LU and Welsch, Carsten P. (2025) In Instruments 9(4).
Abstract

Ultrashort bunch length measurements are crucial for characterizing electron beams in short-pulse accelerators, including novel accelerators like EuPRAXIA and those used for free-electron lasers (FELs). This work provides an overview of the design process and the current status of a single-shot bunch length monitor prototype based on a broadband spatial imaging system for coherent transition radiation (CTR), which was recently installed at the MAX IV short-pulse facility (SPF). The THz-based imaging system was designed using optical system simulation software for full bunch simulation. CTR images were captured experimentally, followed by image analysis for comparison with reference bunch length data from the transverse deflecting cavity... (More)

Ultrashort bunch length measurements are crucial for characterizing electron beams in short-pulse accelerators, including novel accelerators like EuPRAXIA and those used for free-electron lasers (FELs). This work provides an overview of the design process and the current status of a single-shot bunch length monitor prototype based on a broadband spatial imaging system for coherent transition radiation (CTR), which was recently installed at the MAX IV short-pulse facility (SPF). The THz-based imaging system was designed using optical system simulation software for full bunch simulation. CTR images were captured experimentally, followed by image analysis for comparison with reference bunch length data from the transverse deflecting cavity (TDC). This paper presents the conceptualization and design choices for the optical system of the bunch length monitor, the current experimental set-up, the installation details, and preliminary positive observations confirming the potential of this method as a novel approach to bunch length monitoring using spatial CTR images and a scalar technique, with potential for future bunch profile measurements.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
bunch length monitor, coherent transition radiation, longitudinal diagnostics
in
Instruments
volume
9
issue
4
article number
29
publisher
MDPI AG
external identifiers
  • scopus:105026026805
ISSN
2410-390X
DOI
10.3390/instruments9040029
language
English
LU publication?
yes
id
21e94851-2a60-4265-b0bf-348328381c08
date added to LUP
2026-02-11 13:32:25
date last changed
2026-02-11 13:33:27
@article{21e94851-2a60-4265-b0bf-348328381c08,
  abstract     = {{<p>Ultrashort bunch length measurements are crucial for characterizing electron beams in short-pulse accelerators, including novel accelerators like EuPRAXIA and those used for free-electron lasers (FELs). This work provides an overview of the design process and the current status of a single-shot bunch length monitor prototype based on a broadband spatial imaging system for coherent transition radiation (CTR), which was recently installed at the MAX IV short-pulse facility (SPF). The THz-based imaging system was designed using optical system simulation software for full bunch simulation. CTR images were captured experimentally, followed by image analysis for comparison with reference bunch length data from the transverse deflecting cavity (TDC). This paper presents the conceptualization and design choices for the optical system of the bunch length monitor, the current experimental set-up, the installation details, and preliminary positive observations confirming the potential of this method as a novel approach to bunch length monitoring using spatial CTR images and a scalar technique, with potential for future bunch profile measurements.</p>}},
  author       = {{Guisao-Betancur, Ana and Wolfenden, Joseph and Mansten, Erik and Thorin, Sara and Lundquist, Johan and Grimm, Oliver and Welsch, Carsten P.}},
  issn         = {{2410-390X}},
  keywords     = {{bunch length monitor; coherent transition radiation; longitudinal diagnostics}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{MDPI AG}},
  series       = {{Instruments}},
  title        = {{Designing a Femtosecond-Resolution Bunch Length Monitor Using Coherent Transition Radiation Images}},
  url          = {{http://dx.doi.org/10.3390/instruments9040029}},
  doi          = {{10.3390/instruments9040029}},
  volume       = {{9}},
  year         = {{2025}},
}