1
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Cho MS, Chung HK, Foord ME, Libby SB, Cho BI. Numerical investigation of nonequilibrium electron effects on the collisional ionization rate in the collisional-radiative model. Phys Rev E 2024; 109:045207. [PMID: 38755933 DOI: 10.1103/physreve.109.045207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 03/21/2024] [Indexed: 05/18/2024]
Abstract
The interplay of kinetic electron physics and atomic processes in ultrashort laser-plasma interactions provides a comprehensive understanding of the impact of the electron energy distribution on plasma properties. Notably, nonequilibrium electrons play a vital role in collisional ionization, influencing ionization degrees and spectra. This paper introduces a computational model that integrates the physics of kinetic electrons and atomic processes, utilizing a Boltzmann equation for nonequilibrium electrons and a collisional-radiative model for atomic state populations. The model is used to investigate the influence of nonequilibrium electrons on collisional ionization rates and its effect on the population distribution, as observed in a widely known experiment [Young et al., Nature (London) 466, 56 (2010)0028-083610.1038/nature09177]. The study reveals a significant nonequilibrium electron presence during XFEL-matter interactions, profoundly affecting collisional ionization rates in the gas plasma, thereby necessitating careful consideration of the Collisional-Radiative model applied to such systems.
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Affiliation(s)
- M S Cho
- Gwangju Institute of Science and Technology, Department of Physics and Photon Science, Gwangju 61005, South Korea
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - H-K Chung
- Korea Institute of Fusion Energy, Daejeon 34133, South Korea
| | - M E Foord
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - S B Libby
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - B I Cho
- Gwangju Institute of Science and Technology, Department of Physics and Photon Science, Gwangju 61005, South Korea
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2
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Bae LJ, Kang GB, Kim M, Lee GS, Sohn JH, Nam CH, Cho BI. Diagnosis of ultrafast surface dynamics of thin foil targets irradiated by intense laser pulses. Opt Express 2023; 31:5767-5776. [PMID: 36823849 DOI: 10.1364/oe.474759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
The temporal modulation of an electron bunch train accelerated from a foil target irradiated by an intense laser pulse is studied by measuring the coherent transition radiation (CTR) from the rear surface of a target. We experimentally obtained CTR spectra from a 1 µm thick foil target irradiated at a maximum intensity of 6.5 × 1019 W/cm2. Spectral redshifts of the emitted radiation corresponding to increases in laser intensity were observed. These measurements were compared with the theoretical calculation of CTR spectra considering ultrafast surface dynamics, such as plasma surface oscillation and relativistically induced transparency. Plasma surface oscillations induce a spectral redshift, while relativistic transparency causes a spectral blueshift. Both effects are required to find reasonable agreement with the experiment over the entire range of laser intensities.
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3
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Cho BI, Cho MS, Kim M, Chung HK, Barbrel B, Engelhorn K, Burian T, Chalupský J, Ciricosta O, Dakovski GL, Hájková V, Holmes M, Juha L, Krzywinski J, Lee RW, Nam CH, Rackstraw DS, Toleikis S, Turner JJ, Vinko SM, Wark JS, Zastrau U, Heimann PA. Observation of Reverse Saturable Absorption of an X-ray Laser. Phys Rev Lett 2017; 119:075002. [PMID: 28949680 DOI: 10.1103/physrevlett.119.075002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Indexed: 06/07/2023]
Abstract
A nonlinear absorber in which the excited state absorption is larger than the ground state can undergo a process called reverse saturable absorption. It is a well-known phenomenon in laser physics in the optical regime, but is more difficult to generate in the x-ray regime, where fast nonradiative core electron transitions typically dominate the population kinetics during light matter interactions. Here, we report the first observation of decreasing x-ray transmission in a solid target pumped by intense x-ray free electron laser pulses. The measurement has been made below the K-absorption edge of aluminum, and the x-ray intensity ranges are 10^{16} -10^{17} W/cm^{2}. It has been confirmed by collisional radiative population kinetic calculations, underscoring the fast spectral modulation of the x-ray pulses and charge states relevant to the absorption and transmission of x-ray photons. The processes shown through detailed simulations are consistent with reverse saturable absorption, which would be the first observation of this phenomena in the x-ray regime. These light matter interactions provide a unique opportunity to investigate optical transport properties in the extreme state of matters, as well as affording the potential to regulate ultrafast x-ray free-electron laser pulses.
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Affiliation(s)
- B I Cho
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005, Korea
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - M S Cho
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005, Korea
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - M Kim
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005, Korea
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - H-K Chung
- Atomic and Molecular Data Unit, Nuclear Data Section, IAEA, P.O. Box 100, A-1400 Vienna, Austria
| | - B Barbrel
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - K Engelhorn
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - T Burian
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - J Chalupský
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - O Ciricosta
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - G L Dakovski
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - V Hájková
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - M Holmes
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - L Juha
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - J Krzywinski
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - R W Lee
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - Chang Hee Nam
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 61005, Korea
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, Korea
| | - D S Rackstraw
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S Toleikis
- Deutsches-Elektronensynchrotron DESY, Notkestrasse 85, D-22603 Hamburg, Germany
| | - J J Turner
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - S M Vinko
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - J S Wark
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - U Zastrau
- European XFEL, Holzkoppel 4, 22869 Schenefeld, Germany
| | - P A Heimann
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
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4
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Beckwith MA, Jiang S, Schropp A, Fernandez-Pañella A, Rinderknecht HG, Wilks SC, Fournier KB, Galtier EC, Xing Z, Granados E, Gamboa E, Glenzer SH, Heimann P, Zastrau U, Cho BI, Eggert JH, Collins GW, Ping Y. Imaging at an x-ray absorption edge using free electron laser pulses for interface dynamics in high energy density systems. Rev Sci Instrum 2017; 88:053501. [PMID: 28571471 DOI: 10.1063/1.4982166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Tuning the energy of an x-ray probe to an absorption line or edge can provide material-specific measurements that are particularly useful for interfaces. Simulated hard x-ray images above the Fe K-edge are presented to examine ion diffusion across an interface between Fe2O3 and SiO2 aerogel foam materials. The simulations demonstrate the feasibility of such a technique for measurements of density scale lengths near the interface with submicron spatial resolution. A proof-of-principle experiment is designed and performed at the Linac coherent light source facility. Preliminary data show the change of the interface after shock compression and heating with simultaneous fluorescence spectra for temperature determination. The results provide the first demonstration of using x-ray imaging at an absorption edge as a diagnostic to detect ultrafast phenomena for interface physics in high-energy-density systems.
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Affiliation(s)
- M A Beckwith
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S Jiang
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A Schropp
- Deutsches Elektronen-Synchrotron DESY, Hamburg D-22607, Germany
| | | | - H G Rinderknecht
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S C Wilks
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - K B Fournier
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E C Galtier
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - Z Xing
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - E Granados
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - E Gamboa
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - S H Glenzer
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - P Heimann
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - U Zastrau
- European XFEL, Schenefeld D-22869, Germany
| | - B I Cho
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 61005, South Korea
| | - J H Eggert
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G W Collins
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Y Ping
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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5
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Cho BI, Ogitsu T, Engelhorn K, Correa AA, Ping Y, Lee JW, Bae LJ, Prendergast D, Falcone RW, Heimann PA. Measurement of Electron-Ion Relaxation in Warm Dense Copper. Sci Rep 2016; 6:18843. [PMID: 26733236 PMCID: PMC4702138 DOI: 10.1038/srep18843] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/26/2015] [Indexed: 11/09/2022] Open
Abstract
Experimental investigation of electron-ion coupling and electron heat capacity of copper in warm and dense states are presented. From time-resolved x-ray absorption spectroscopy, the temporal evolution of electron temperature is obtained for non-equilibrium warm dense copper heated by an intense femtosecond laser pulse. Electron heat capacity and electron-ion coupling are inferred from the initial electron temperature and its decrease over 10 ps. Data are compared with various theoretical models.
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Affiliation(s)
- B I Cho
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju, 500-712, Korea.,Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712, Korea
| | - T Ogitsu
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - K Engelhorn
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - A A Correa
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - Y Ping
- Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
| | - J W Lee
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju, 500-712, Korea.,Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712, Korea
| | - L J Bae
- Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju, 500-712, Korea.,Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju, 500-712, Korea
| | - D Prendergast
- Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - R W Falcone
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - P A Heimann
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
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6
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Vinko SM, Ciricosta O, Preston TR, Rackstraw DS, Brown CRD, Burian T, Chalupský J, Cho BI, Chung HK, Engelhorn K, Falcone RW, Fiokovinini R, Hájková V, Heimann PA, Juha L, Lee HJ, Lee RW, Messerschmidt M, Nagler B, Schlotter W, Turner JJ, Vysin L, Zastrau U, Wark JS. Investigation of femtosecond collisional ionization rates in a solid-density aluminium plasma. Nat Commun 2015; 6:6397. [PMID: 25731816 DOI: 10.1038/ncomms7397] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/26/2015] [Indexed: 11/09/2022] Open
Abstract
The rate at which atoms and ions within a plasma are further ionized by collisions with the free electrons is a fundamental parameter that dictates the dynamics of plasma systems at intermediate and high densities. While collision rates are well known experimentally in a few dilute systems, similar measurements for nonideal plasmas at densities approaching or exceeding those of solids remain elusive. Here we describe a spectroscopic method to study collision rates in solid-density aluminium plasmas created and diagnosed using the Linac Coherent light Source free-electron X-ray laser, tuned to specific interaction pathways around the absorption edges of ionic charge states. We estimate the rate of collisional ionization in solid-density aluminium plasmas at temperatures ~30 eV to be several times higher than that predicted by standard semiempirical models.
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Affiliation(s)
- S M Vinko
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - O Ciricosta
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - T R Preston
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - D S Rackstraw
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - C R D Brown
- Department of Plasma Physics, AWE Aldermaston, Reading RG7 4PR, UK
| | - T Burian
- Institute of Physics ASCR, Na Slovance 2, Prague 8 18221, Czech Republic
| | - J Chalupský
- Institute of Physics ASCR, Na Slovance 2, Prague 8 18221, Czech Republic
| | - B I Cho
- 1] Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, Korea [2] Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea
| | - H-K Chung
- Atomic and Molecular Data Unit, Nuclear Data Section, IAEA, PO Box 100, Vienna A-1400, Austria
| | - K Engelhorn
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, California 94720, USA
| | - R W Falcone
- 1] Lawrence Berkeley National Laboratory, 1 Cyclotron Road, California 94720, USA [2] Department of Physics, University of California, Berkeley, California 94720, USA
| | - R Fiokovinini
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - V Hájková
- Institute of Physics ASCR, Na Slovance 2, Prague 8 18221, Czech Republic
| | - P A Heimann
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - L Juha
- Institute of Physics ASCR, Na Slovance 2, Prague 8 18221, Czech Republic
| | - H J Lee
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - R W Lee
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - M Messerschmidt
- National Science Foundation BioXFEL Science and Technology Center, 700 Ellicott Street, Buffalo, New York 14203, USA
| | - B Nagler
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - W Schlotter
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - J J Turner
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - L Vysin
- Institute of Physics ASCR, Na Slovance 2, Prague 8 18221, Czech Republic
| | - U Zastrau
- IOQ, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, Jena 07743, Germany
| | - J S Wark
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK
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7
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Rackstraw DS, Ciricosta O, Vinko SM, Barbrel B, Burian T, Chalupský J, Cho BI, Chung HK, Dakovski GL, Engelhorn K, Hájková V, Heimann P, Holmes M, Juha L, Krzywinski J, Lee RW, Toleikis S, Turner JJ, Zastrau U, Wark JS. Saturable absorption of an x-ray free-electron-laser heated solid-density aluminum plasma. Phys Rev Lett 2015; 114:015003. [PMID: 25615475 DOI: 10.1103/physrevlett.114.015003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Indexed: 06/04/2023]
Abstract
High-intensity x-ray pulses from an x-ray free-electron laser are used to heat and probe a solid-density aluminum sample. The photon-energy-dependent transmission of the heating beam is studied through the use of a photodiode. Saturable absorption is observed, with the resulting transmission differing significantly from the cold case, in good agreement with atomic-kinetics simulations.
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Affiliation(s)
- D S Rackstraw
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - O Ciricosta
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - S M Vinko
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
| | - B Barbrel
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - T Burian
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - J Chalupský
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - B I Cho
- Department of Physics and Photon Science, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea and Center for Relativistic Laser Science, Institute for Basic Science (IBS), Gwangju 500-712, Republic of Korea
| | - H-K Chung
- Atomic and Molecular Data Unit, Nuclear Data Section, IAEA, P.O. Box 100, A-1400 Vienna, Austria
| | - G L Dakovski
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - K Engelhorn
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA
| | - V Hájková
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - P Heimann
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - M Holmes
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - L Juha
- Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czech Republic
| | - J Krzywinski
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - R W Lee
- Department of Physics, University of California, Berkeley, California 94720, USA
| | - S Toleikis
- Deutsches-Elektronensynchrotron DESY, Notkestrasse 85, 22603 Hamburg, Germany
| | - J J Turner
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - U Zastrau
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA and IOQ, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
| | - J S Wark
- Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom
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8
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Cho BI, Engelhorn K, Vinko SM, Chung HK, Ciricosta O, Rackstraw DS, Falcone RW, Brown CRD, Burian T, Chalupský J, Graves C, Hájková V, Higginbotham A, Juha L, Krzywinski J, Lee HJ, Messersmidt M, Murphy C, Ping Y, Rohringer N, Scherz A, Schlotter W, Toleikis S, Turner JJ, Vysin L, Wang T, Wu B, Zastrau U, Zhu D, Lee RW, Nagler B, Wark JS, Heimann PA. Resonant Kα spectroscopy of solid-density aluminum plasmas. Phys Rev Lett 2012; 109:245003. [PMID: 23368333 DOI: 10.1103/physrevlett.109.245003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Indexed: 06/01/2023]
Abstract
The x-ray intensities made available by x-ray free electron lasers (FEL) open up new x-ray matter interaction channels not accessible with previous sources. We report here on the resonant generation of Kα emission, that is to say the production of copious Kα radiation by tuning the x-ray FEL pulse to photon energies below that of the K edge of a solid aluminum sample. The sequential absorption of multiple photons in the same atom during the 80 fs pulse, with photons creating L-shell holes and then one resonantly exciting a K-shell electron into one of these holes, opens up a channel for the Kα production, as well as the absorption of further photons. We demonstrate rich spectra of such channels, and investigate the emission produced by tuning the FEL energy to the K-L transitions of those highly charged ions that have transition energies below the K edge of the cold material. The spectra are sensitive to x-ray intensity dependent opacity effects, with ions containing L-shell holes readily reabsorbing the Kα radiation.
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Affiliation(s)
- B I Cho
- Lawrence Berkeley National Laboratory, 1 Cyclotron Road, California 94720, USA
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9
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Ciricosta O, Vinko SM, Chung HK, Cho BI, Brown CRD, Burian T, Chalupský J, Engelhorn K, Falcone RW, Graves C, Hájková V, Higginbotham A, Juha L, Krzywinski J, Lee HJ, Messerschmidt M, Murphy CD, Ping Y, Rackstraw DS, Scherz A, Schlotter W, Toleikis S, Turner JJ, Vysin L, Wang T, Wu B, Zastrau U, Zhu D, Lee RW, Heimann P, Nagler B, Wark JS. Direct measurements of the ionization potential depression in a dense plasma. Phys Rev Lett 2012; 109:065002. [PMID: 23006275 DOI: 10.1103/physrevlett.109.065002] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Indexed: 06/01/2023]
Abstract
We have used the Linac Coherent Light Source to generate solid-density aluminum plasmas at temperatures of up to 180 eV. By varying the photon energy of the x rays that both create and probe the plasma, and observing the K-α fluorescence, we can directly measure the position of the K edge of the highly charged ions within the system. The results are found to disagree with the predictions of the extensively used Stewart-Pyatt model, but are consistent with the earlier model of Ecker and Kröll, which predicts significantly greater depression of the ionization potential.
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Affiliation(s)
- O Ciricosta
- Department of Physics, Clarendon Laboratory, University of Oxford, Oxford, United Kingdom
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10
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Cho BI, Engelhorn K, Correa AA, Ogitsu T, Weber CP, Lee HJ, Feng J, Ni PA, Ping Y, Nelson AJ, Prendergast D, Lee RW, Falcone RW, Heimann PA. Electronic structure of warm dense copper studied by ultrafast x-ray absorption spectroscopy. Phys Rev Lett 2011; 106:167601. [PMID: 21599412 DOI: 10.1103/physrevlett.106.167601] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Revised: 02/21/2011] [Indexed: 05/30/2023]
Abstract
We use time-resolved x-ray absorption spectroscopy to investigate the unoccupied electronic density of states of warm dense copper that is produced isochorically through the absorption of an ultrafast optical pulse. The temperature of the superheated electron-hole plasma, which ranges from 4000 to 10 000 K, was determined by comparing the measured x-ray absorption spectrum with a simulation. The electronic structure of warm dense copper is adequately described with the high temperature electronic density of state calculated by the density functional theory. The dynamics of the electron temperature is consistent with a two-temperature model, while a temperature-dependent electron-phonon coupling parameter is necessary.
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Affiliation(s)
- B I Cho
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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11
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Cho BI, Osterholz J, Bernstein AC, Dyer GM, Karmakar A, Pukhov A, Ditmire T. Characterization of two distinct, simultaneous hot electron beams in intense laser-solid interactions. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:055402. [PMID: 20365036 DOI: 10.1103/physreve.80.055402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 08/27/2009] [Indexed: 05/29/2023]
Abstract
The transport of energetic electron beams generated from aluminum foils irradiated by ultraintense laser pulses has been studied by imaging coherent transition radiation from the rear side of the target. Two distinct beams of MeV electrons are emitted from the target rear side at the same time. This measurement indicates that two different mechanisms, namely resonance absorption and jxB heating, accelerate the electrons at the targets front side and drive them to different directions, with different temperatures. This interpretation is consistent with 3D-particle-in-cell simulations.
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Affiliation(s)
- B I Cho
- Department of Physics, University of Texas, Austin, Texas 78712-0263, USA
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Churina IV, Cho BI, Bernstein A, Stoker DS, Dalton A, Symes DR, Ditmire T. Single-shot optical conductivity measurement of dense aluminum plasmas. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:015401. [PMID: 19658765 DOI: 10.1103/physreve.80.015401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 06/16/2009] [Indexed: 05/28/2023]
Abstract
The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.
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Affiliation(s)
- I V Churina
- Department of Physics, The University of Texas at Austin, Austin, TX 78712, USA
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Renard-Le Galloudec N, d'Humières E, Cho BI, Osterholz J, Sentoku Y, Ditmire T. Guiding, focusing, and collimated transport of hot electrons in a canal in the extended tip of cone targets. Phys Rev Lett 2009; 102:205003. [PMID: 19519036 DOI: 10.1103/physrevlett.102.205003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Indexed: 05/27/2023]
Abstract
Hot electrons are produced, guided into a beam, and transported over 60 microm in a small canal to the outside tip of a structured cone target. The diameter of the electron beam is defined by the inside tip diameter. This carries the potential to create electron beams of specific diameters propagating over specific distances of interest for several applications.
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Affiliation(s)
- N Renard-Le Galloudec
- Nevada Terawatt Facility, Department of Physics, University of Nevada, Reno, Nevada 89521-0042, USA
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Dyer GM, Bernstein AC, Cho BI, Osterholz J, Grigsby W, Dalton A, Shepherd R, Ping Y, Chen H, Widmann K, Ditmire T. Equation-of-state measurement of dense plasmas heated with fast protons. Phys Rev Lett 2008; 101:015002. [PMID: 18764119 DOI: 10.1103/physrevlett.101.015002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Indexed: 05/26/2023]
Abstract
Using an ultrafast pulse of mega-electron-volt energy protons accelerated from a laser-irradiated foil, we have heated solid density aluminum plasmas to temperatures in excess of 15 eV. By measuring the temperature and the expansion rate of the heated Al plasma simultaneously and with picosecond time resolution we have found the predictions of the SESAME Livermore equation-of-state (LEOS) tables to be accurate to within 18%, in this dense plasma regime, where there have been few previous experimental measurements.
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Affiliation(s)
- G M Dyer
- Texas Center for High Intensity Laser Science, Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA
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