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Ultrafast time-resolved 2D imaging of laser-driven fast electron transport in solid density matter using an x-ray free electron laser

Authors :
H. Sawada
T. Yabuuchi
N. Higashi
T. Iwasaki
K. Kawasaki
Y. Maeda
T. Izumi
Y. Nakagawa
K. Shigemori
Y. Sakawa
C. B. Curry
M. Frost
N. Iwata
T. Ogitsu
K. Sueda
T. Togashi
S. H. Glenzer
A. J. Kemp
Y. Ping
Y. Sentoku
Source :
Review of Scientific Instruments. 94:033511
Publication Year :
2023
Publisher :
AIP Publishing, 2023.

Abstract

High-power, short-pulse laser-driven fast electrons can rapidly heat and ionize a high-density target before it hydrodynamically expands. The transport of such electrons within a solid target has been studied using two-dimensional (2D) imaging of electron-induced Kα radiation. However, it is currently limited to no or picosecond scale temporal resolutions. Here, we demonstrate femtosecond time-resolved 2D imaging of fast electron transport in a solid copper foil using the SACLA x-ray free electron laser (XFEL). An unfocused collimated x-ray beam produced transmission images with sub-micron and ∼10 fs resolutions. The XFEL beam, tuned to its photon energy slightly above the Cu K-edge, enabled 2D imaging of transmission changes induced by electron isochoric heating. Time-resolved measurements obtained by varying the time delay between the x-ray probe and the optical laser show that the signature of the electron-heated region expands at ∼25% of the speed of light in a picosecond duration. Time-integrated Cu Kα images support the electron energy and propagation distance observed with the transmission imaging. The x-ray near-edge transmission imaging with a tunable XFEL beam could be broadly applicable for imaging isochorically heated targets by laser-driven relativistic electrons, energetic protons, or an intense x-ray beam.

Subjects

Subjects :
Instrumentation

Details

ISSN :
10897623 and 00346748
Volume :
94
Database :
OpenAIRE
Journal :
Review of Scientific Instruments
Accession number :
edsair.doi...........b7c0979e83596aec1dbf8afa525c0656
Full Text :
https://doi.org/10.1063/5.0130953