Dual-energy electron beams from a compact laser-driven accelerator

Nature Photonics, 13, 263–269 (2019)

Authors:

J. Wenz, A. Döpp et al.

Abstract:

Ultrafast pump–probe experiments open the possibility to track fundamental material behaviour, such as changes in electronic configuration, in real time. To date, most of these experiments are performed using an electron or a high-energy photon beam that is synchronized to an infrared laser pulse. Entirely new opportunities can be explored if not only a single, but multiple synchronized, ultrashort, high-energy beams are used. However, this requires advanced radiation sources that are capable of producing dual-energy electron beams, for example. Here, we demonstrate simultaneous generation of twin-electron beams from a single compact laser wakefield accelerator. The energy of each beam can be individually adjusted over a wide range and our analysis shows that the bunch lengths and their delay inherently amount to femtoseconds. Our proof-of-concept results demonstrate an elegant way to perform multi-beam experiments in the future on a laboratory scale.

Burst behavior due to the quasimode excited by stimulated Brillouin scattering in high-intensity laser–plasma interactions

High Power Laser Science and Engineering Cambridge University Press (CUP) 7 (2019) e58

Authors:

QS Feng, LH Cao, ZJ Liu, CY Zheng, XT He

Single-shot frequency-resolved optical gating for retrieving the pulse shape of high energy picosecond pulses

Review of Scientific Instruments AIP Publishing 89:10 (2018) 103509

Authors:

R Aboushelbaya, Alexander Savin, L Ceurvorst, J Sadler, PA Norreys, AS Davies, DH Froula, A Boyle, M Galimberti, P Oliveira, B Parry, Y Katzir, K Glize

Abstract:

Accurate characterization of laser pulses used in experiments is a crucial step to the analysis of their results. In this paper, a novel single-shot frequency-resolved optical gating (FROG) device is described, one that incorporates a dispersive element which allows it to fully characterize pulses up to 25 ps in duration with a 65 fs per pixel temporal resolution. A newly developed phase retrieval routine based on memetic algorithms is implemented and shown to circumvent the stagnation problem that often occurs with traditional FROG analysis programs when they encounter a local minimum.

Anti-Langmuir decay instability in Langmuir decay instability cascade

Physics of Plasmas AIP Publishing 25:9 (2018) 092112

Authors:

QS Feng, CY Zheng, ZJ Liu, LH Cao, Q Wang, CZ Xiao, XT He

Advantages to a diverging Raman amplifier

Communications Physics Nature Publishing Group 1 (2018) 19

Authors:

James Sadler, LO Silva, RA Fonseca, K Glize, Muhammad Kasim, Alex Savin, Ramy Aboushelbaya, Marko Mayr, Benjamin Spiers, Robin H-W Wang, R Bingham, RMGM Trines, Peter Norreys

Abstract:

The plasma Raman instability can efficiently compress a nanosecond long high power laser pulse to sub-picosecond duration. Although many authors envisaged a converging beam geometry for Raman amplification, here we propose the exact opposite geometry; the amplification should start at the intense focus of the seed. We generalise the coupled laser envelope equations to include this non-collimated case. The new geometry completely eradicates the usual trailing secondary peaks of the output pulse, which typically lower the efficiency by half. It also reduces, by orders of magnitude, the initial seed pulse energy required for efficient operation. As in the collimated case, the evolution is self-similar, although the temporal pulse envelope is different. A two-dimensional particle-in-cell simulation demonstrates efficient amplification of a diverging seed with only 0:3mJ energy. The pulse has no secondary peaks and almost constant intensity as it amplifies and diverges.