Dresden 2026 – scientific programme

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AKBP: Arbeitskreis Beschleunigerphysik

AKBP 10: Plasma Accelerators, Diagnostics I

AKBP 10.1: Topical Talk

Wednesday, March 11, 2026, 15:00–15:30, SCH/A117

Multiscale longitudinal electron bunch characteristics of LWFA bunches determined by single-shot CTR spectroscopy — •Alexander Debus¹, Maxwell LaBerge¹, Omid Zarini^1,2, Susanne Schöbel¹, Jessica Tiebel^1,2, Finn-Ole Carstens^1,2, Nico Wrobel^1,2, Richard Pausch¹, Klaus Steiniger¹, Yen-Yu Chang¹, Jurjen Couperus Cabadağ¹, Alexander Köhler^1,2, Thomas Kurz^1,2, Rafal Zgadzaj³, Michael Downer³, Michael Bussmann¹, Ulrich Schramm¹, and Arie Irman¹ — ¹HZDR, Dresden, Germany — ²TU Dresden, Germany — ³UT Austin, USA

The longitudinal structure of ultra-short electron bunches produced in laser-wakefield accelerators (LWFAs) is strongly influenced by the rapid injection dynamics as well as by ongoing interactions between the driving laser and the accelerated beam. Gaining a detailed picture of these bunch structures is key for progressing toward compact FELs and other advanced secondary light sources.

We report experimental findings derived from single-shot broadband coherent transition radiation (CTR) spectroscopy (spanning UV to mid-IR, 250 nm - 11.35 µm) generated as LWFA electron bunches traverse a metal foil. Through analysis of the CTR spectra, we reconstruct the corresponding electron bunch profiles. Our results reveal that electron bunches originating from different injection processes exhibit intricate longitudinal structures spanning multiple temporal scales, from the overall envelope down to sub-micrometer features. These patterns vary systematically with the injection regime and align with signatures observed in the electron spectrometer.

Keywords: Laser-wakefield accelerator; CTR spectroscopy; electron bunch duration diagnostic