Cascaded ion emissions from copper plasma produced by an X-ray free-electron laser

Ultrafast, high-power lasers operating in the near-infrared (NIR) region are key to accelerating ions to extremely high energies. By changing the laser wavelength from the NIR region to the hard X-ray range, the photon energy increases more than 10 000 times. The interaction mechanisms and, consequently, radiation attenuation lengths differ significantly between these two spectral ranges. Here we report the use of an X-ray free-electron laser (European XFEL, Germany) delivering 9.3 keV photons in 25 fs pulses and a total energy of 0.35 mJ on a solid target. Electrons and ions escaping from an irradiated 3 μm Cu foil into vacuum were investigated by a time-of-flight technique using windowless electron multipliers that enable the measurement of very weak currents. A model based on a shifted Maxwell–Boltzmann velocity distribution of species was used to analyze the detector signals. The method used made it possible to determine the temperatures of hot electrons and protons, their center-of-mass energy, the charge states of the isotopes 63Cu and 65Cu, and the magnitude of the voltage arising in the double layer that accelerated them, and to estimate the repetition frequency of their cascade emission from the plasma. Computer simulations revealed the evolution of the electron density and temperature, the ion charge state distribution, and the time scales of processes occurring in the bulk of irradiated matter. Good correlation of theoretical and experimental results over the range of high-energy-density states demonstrates the capability to provide critical data to develop plasma models in the warm dense matter regime.

Authors

Institutions

Publication Details

Journal
Matter and Radiation at Extremes
Published
2026-05-21
DOI
https://doi.org/10.1063/5.0314214
Primary Topic
Laser-Plasma Interactions and Diagnostics
Type
article
Field-Weighted Citation Impact
0.00

Funders

Controls
|||
ALL TIME
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
article

Cascaded ion emissions from copper plasma produced by an X-ray free-electron laser

J. Bulička, V. Bouffetier, V. Hájková, K. Falk et al.
Matter and Radiation at Extremes
Laser-Plasma Interactions and Diagnostics
article

Cascaded ion emissions from copper plasma produced by an X-ray free-electron laser

J. Bulička, V. Bouffetier, V. Hájková, K. Falk, T. Burian, X. Pan, W. Wang, V. Cerantola, M. Kozlová, M. Stransky, L. (Luděk) Vyšín, J. (Jaromír) Chalupský, J.-P. Schwinkendorf, U. Zastrau, T. E. Cowan, Z. Jurek, R. Santra, C. Baehtz, J. Kaa, T. R. Preston, E. Brambrink, L. Juha, M. Makita, Z. Konôpková, J. Krása, O. Humphries, M. Krupka, R. Štefaníková, Š. Jelínek, M. Šmíd, A. Horynová, A. Schropp, M. Mašek
article en

Abstract

Ultrafast, high-power lasers operating in the near-infrared (NIR) region are key to accelerating ions to extremely high energies. By changing the laser wavelength from the NIR region to the hard X-ray range, the photon energy increases more than 10 000 times. The interaction mechanisms and, consequently, radiation attenuation lengths differ significantly between these two spectral ranges. Here we report the use of an X-ray free-electron laser (European XFEL, Germany) delivering 9.3 keV photons in 25 fs pulses and a total energy of 0.35 mJ on a solid target. Electrons and ions escaping from an irradiated 3 μm Cu foil into vacuum were investigated by a time-of-flight technique using windowless electron multipliers that enable the measurement of very weak currents. A model based on a shifted Maxwell–Boltzmann velocity distribution of species was used to analyze the detector signals. The method used made it possible to determine the temperatures of hot electrons and protons, their center-of-mass energy, the charge states of the isotopes 63Cu and 65Cu, and the magnitude of the voltage arising in the double layer that accelerated them, and to estimate the repetition frequency of their cascade emission from the plasma. Computer simulations revealed the evolution of the electron density and temperature, the ion charge state distribution, and the time scales of processes occurring in the bulk of irradiated matter. Good correlation of theoretical and experimental results over the range of high-energy-density states demonstrates the capability to provide critical data to develop plasma models in the warm dense matter regime.

Matter and Radiation at ExtremesVol. 11(5)
Carl Zeiss (Germany) (DE), Universität Hamburg (DE), Charles University (CZ), Helmholtz-Zentrum Dresden-Rossendorf (DE), Deutsches Elektronen-Synchrotron DESY (DE), Extreme Light Infrastructure Beamlines (CZ), Czech Academy of Sciences, Institute of Plasma Physics (CZ), Institute of Physics (HR), Center for Free-Electron Laser Science (DE), Institute of Physics of the Slovak Academy of Sciences (SK), Czech Technical University in Prague (CZ), University of Milano-Bicocca (IT), HAW Hamburg (DE), Technische Universität Dresden (DE), European X-Ray Free-Electron Laser (DE)
Ministerstvo Školství, Mládeže a Tělovýchovy
Affordable and clean energy
Openalex Percentile: Top 6%
Laser-Plasma Interactions and Diagnostics
DOIOpen Access PDFOpenAlex
AI Navigator

Ask Laika to Summarize, Analyze, and Connect papers live on the map.

Summarize Papers & Methodologies

Extract key findings, datasets, and comparative methods across publications.

Benchmark Rankings & Visual Analytics

Rank top research institutions, authors, funders, topics, and journals by Field-Weighted Citation Impact (FWCI) and paper volume with instant charts.

Connect Distant Disciplines

Bridge topological clusters on the map to find hidden collaborative intersections.