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Sawada H, Yabuuchi T, Higashi N, Iwasaki T, Kawasaki K, Maeda Y, Izumi T, Nakagawa Y, Shigemori K, Sakawa Y, Curry CB, Frost M, Iwata N, Ogitsu T, Sueda K, Togashi T, Glenzer SH, Kemp AJ, Ping Y, Sentoku Y. Ultrafast time-resolved 2D imaging of laser-driven fast electron transport in solid density matter using an x-ray free electron laser. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2023; 94:033511. [PMID: 37012804 DOI: 10.1063/5.0130953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 03/08/2023] [Indexed: 06/19/2023]
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.
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Affiliation(s)
- H Sawada
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - T Yabuuchi
- Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan
| | - N Higashi
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - T Iwasaki
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - K Kawasaki
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - Y Maeda
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - T Izumi
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - Y Nakagawa
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - K Shigemori
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - Y Sakawa
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - C B Curry
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - M Frost
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - N Iwata
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
| | - T Ogitsu
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - K Sueda
- RIKEN SPring-8 Center, Hyogo 679-5148, Japan
| | - T Togashi
- Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan
| | - S H Glenzer
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - A J Kemp
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Y Ping
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Y Sentoku
- Institute of Laser Engineering, Osaka University, Suita 565-0871, Osaka, Japan
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Thermal excitation signals in the inhomogeneous warm dense electron gas. Sci Rep 2022; 12:1093. [PMID: 35058531 PMCID: PMC8776784 DOI: 10.1038/s41598-022-05034-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/30/2021] [Indexed: 12/16/2022] Open
Abstract
We investigate the emergence of electronic excitations from the inhomogeneous electronic structure at warm dense matter parameters based on first-principles calculations. The emerging modes are controlled by the imposed perturbation amplitude. They include satellite signals around the standard plasmon feature, transformation of plasmons to optical modes, and double-plasmon modes. These modes exhibit a pronounced dependence on the temperature. This makes them potentially invaluable for the diagnostics of plasma parameters in the warm dense matter regime. We demonstrate that these modes can be probed with present experimental techniques.
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