5-10 May 2019
Europe/Berlin timezone

Determining impact of LWFA injection schemes on electron bunch profiles and peak currents based on broadband, spectral CTR diagnostics at single shot

6 May 2019, 18:30
Main Hall (MedILS)

Main Hall


Oral Contribution Diagnostics


Dr Alexander Debus (Helmholtz-Zentrum Dresden-Rossendorf)


Laser-wakefield accelerators (LWFA) feature electron bunch durations on a fs-scale. Precise knowledge of the longitudinal profile of such ultra-short electron bunches is essential for the design of future compact X-ray light sources. Resolution limits, as well as the limited reproducibility of electron bunches, pose big challenges for LWFA beam diagnostics.

Spectral measurements of broadband transition radiation from LWFA electron bunches passing through a metal foil are especially promising for analyzing ultrashort longitudinal bunch characteristics ranging from of tens of fs down to sub-fs.

Our broadband, single-shot spectrometer combines the TR spectrum in UV/VIS (200-1000nm), NIR (0.9-1.7μm) and mid-IR (1.6-12μm). A complete characterization and calibration of the spectrometer has been done with regard to wavelengths, relative spectral sensitivities and absolute photometric sensitivity. Our spectrometer is able to characterize electron bunches with charges as low as 1 pC and resolve time-scales from 0.7 to 40 fs. In addition, complementary data on the transverse bunch profile is provided by simultaneously imaging the CTR in the far- and near-field.

We present recent experimental results of different LWFA injection mechanisms, such as self-truncated ionization-injection and self-injection. By analyzing the transition radiation spectra and reconstructing electron bunch profiles including error analysis, we determine electron bunch profiles and peak currents of the respective injection regimes. In addition to bunch durations and peak currents, we discuss sub-fs beam micro-structures and systematic experimental scans of the nitrogen doping concentration for ionization-induced injection.

Working group Diagnostics

Primary authors

Dr Alexander Debus (Helmholtz-Zentrum Dresden-Rossendorf) Mr Omid Zarini (Helmholtz-Zentrum Dresden-Rossendorf)


Mr Maxwell LaBerge Dr Jurjen Couperus Cabadağ (Helmholtz-Zentrum Dresden-Rossendorf) Mr Alexander Köhler (HZDR) Thomas Kurz (HZDR) Mrs Susanne Schöbel (HZDR) Mr Yen-Yu Chang (Helmholtz Zentrum Rossendorf Dresden) Mr Jakob Krämer (Helmholtz-Zentrum Dresden-Rossendorf) Ms Andrea Hannasch (University of Texas - Austin) Mr Brant Bowers (University of Texas - Austin) Dr Rafal Zgadzaj (University of Texas at Austin) Mr Hauke Mewes (Helmholtz-Zentrum Dresden-Rossendorf) Dr Heide Meissner (Helmholtz-Zentrum Dresden-Rossendorf) Michael Bussmann (Helmholtz-Zentrum Dresden-Rossendorf) Prof. Michael Downer (University of Texas at Austin) Prof. Ulrich Schramm (Helmholtz-Zentrum Dresden-Rossendorf) Dr Arie Irman (Helmholtz-Zentrum Dresden-Rossendorf)

Presentation Materials