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RSS2023 Vol. 35, No. 1
Recommend Articles
2023, 35: 012002.
doi: 10.11884/HPLPB202335.220145
2023, 35: 012012.
doi: 10.11884/HPLPB202335.220197
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2023,
35: 1-2.
2023,
35: 012001.
doi: 10.11884/HPLPB202335.220215
Abstract:
The attainable upper limit of the laser intensity is a key concern in strong-field quantum electrodynamics (QED). For non-ideal vacuum conditions, the extreme laser fields interacting with the residual electrons could trigger QED cascade—the processes of gamma-photon emission and electron-positron pair production. It leads to strong depletion of the laser pulse hence limits the attainable laser intensity. Since the QED cascade is affected by the polarization, beam waist and duration of the laser pulse, we investigate the effects of these parameters based on particle-in-cell (PIC) simulations incorporating the QED modules. We also develop self-consistent dynamics equations to describe the laser depletion process, which agree well with the PIC simulations. According to the analysis, the upper limit of attainable intensity is about 1026−1027 W/cm−2 in the considered parameter range. Specifically, the circularly polarized pulses drive stronger QED cascade than in the linearly polarized case under the same circumstances, resulting lower upper limit threshold of intensity. In addition, tightly focused lasers correspond to smaller cascade durations and interaction volumes. Thus, the absorption of laser energy is inhibited, i.e., higher peak intensity can be achieved. Regarding the effect of pulse duration, the depletion energy will be dispersed along larger absorption volume so that the attainable intensity will be enhanced. It should be noted that for extremely short pulses (single cycle), the seeded particles of QED cascade (i.e., electrons and positrons) cannot be efficiently trapped in the laser field, and the analytical model tends to overrate the absorption of laser energy. Regarding the extreme low purity case (i.e., the low electron residual density), the stochastic position of the residual electrons will strongly affect the upper limit of the intensity. Overall, these results offer a guideline for further experiment setups of exploring strong field QED processes and construction of the state-of-art hundred-petawatt laser facilities.
The attainable upper limit of the laser intensity is a key concern in strong-field quantum electrodynamics (QED). For non-ideal vacuum conditions, the extreme laser fields interacting with the residual electrons could trigger QED cascade—the processes of gamma-photon emission and electron-positron pair production. It leads to strong depletion of the laser pulse hence limits the attainable laser intensity. Since the QED cascade is affected by the polarization, beam waist and duration of the laser pulse, we investigate the effects of these parameters based on particle-in-cell (PIC) simulations incorporating the QED modules. We also develop self-consistent dynamics equations to describe the laser depletion process, which agree well with the PIC simulations. According to the analysis, the upper limit of attainable intensity is about 1026−1027 W/cm−2 in the considered parameter range. Specifically, the circularly polarized pulses drive stronger QED cascade than in the linearly polarized case under the same circumstances, resulting lower upper limit threshold of intensity. In addition, tightly focused lasers correspond to smaller cascade durations and interaction volumes. Thus, the absorption of laser energy is inhibited, i.e., higher peak intensity can be achieved. Regarding the effect of pulse duration, the depletion energy will be dispersed along larger absorption volume so that the attainable intensity will be enhanced. It should be noted that for extremely short pulses (single cycle), the seeded particles of QED cascade (i.e., electrons and positrons) cannot be efficiently trapped in the laser field, and the analytical model tends to overrate the absorption of laser energy. Regarding the extreme low purity case (i.e., the low electron residual density), the stochastic position of the residual electrons will strongly affect the upper limit of the intensity. Overall, these results offer a guideline for further experiment setups of exploring strong field QED processes and construction of the state-of-art hundred-petawatt laser facilities.
2023,
35: 012002.
doi: 10.11884/HPLPB202335.220145
Abstract:
With the rapid development of laser technology and the continuous improvement of laser intensity, the process of electron-positron pair creation in vacuum under super strong external field, namely the process of energy conversion to mass, has become a research hot spot. In this paper, we mainly review the progress of quantum Vlasov equation and computational quantum field theory (numerical solution of Dirac equation) in the study of the electron-positron pair production in vacuum under intense laser field in recent years, and introduce two situations of particle pair generation spatially homogeneous field and spatially inhomogeneous field, separally. In the first case, there are electron-positron pair production in oscillating electric fields with double-pulse structure, electron-positron pair generation in the strong dual frequency oscillating electric field, electron-positron pair production in frequency modulated laser fields, and resolving rapidly chirped external fields with Dirac vacuum are introduced. The second case mainly introduces the optimization of spatially localized electric fields for electron-positron pair creation, enhanced pair creation by an oscillating potential with multiple well-barrier structures in space, electron-positron pair production in an oscillating Sauter potential, manipulation of the vacuum to control its field-induced decay and Dirac vacuum as a transport medium for information and transition between coherent and incoherent chirping mechanisms in electron-positron pair production.
With the rapid development of laser technology and the continuous improvement of laser intensity, the process of electron-positron pair creation in vacuum under super strong external field, namely the process of energy conversion to mass, has become a research hot spot. In this paper, we mainly review the progress of quantum Vlasov equation and computational quantum field theory (numerical solution of Dirac equation) in the study of the electron-positron pair production in vacuum under intense laser field in recent years, and introduce two situations of particle pair generation spatially homogeneous field and spatially inhomogeneous field, separally. In the first case, there are electron-positron pair production in oscillating electric fields with double-pulse structure, electron-positron pair generation in the strong dual frequency oscillating electric field, electron-positron pair production in frequency modulated laser fields, and resolving rapidly chirped external fields with Dirac vacuum are introduced. The second case mainly introduces the optimization of spatially localized electric fields for electron-positron pair creation, enhanced pair creation by an oscillating potential with multiple well-barrier structures in space, electron-positron pair production in an oscillating Sauter potential, manipulation of the vacuum to control its field-induced decay and Dirac vacuum as a transport medium for information and transition between coherent and incoherent chirping mechanisms in electron-positron pair production.
2023,
35: 012003.
doi: 10.11884/HPLPB202335.220066
Abstract:
Enhancement of nonlinear chirped frequency on electron-positron pair creation in the potential well is studied by the computational quantum field theory. The density, number and energy spectrum of electrons created under a single oscillating potential well and combined potential wells are investigated. The frequency spectrum and instantaneous bound states are also analyzed. It is found that nonlinear chirp effect is more sensitive to the low frequency region. When appropriate chirp parameters are selected, compared with the fixed frequency, the number of electrons created under combined potential wells can be increased by 2 to 3 times. For a single oscillating potential well, the number can be increased by several orders of magnitude. In the subcritical field at low frequencies, Schwinger mechanism dominates pair creation, and the production is very low. After modulation, the frequency spectrum widens. The high frequency component enhances the multiphoton processes and the dynamical assisted mechanism, while the ultrahigh frequency component inhibits pair creation.
Enhancement of nonlinear chirped frequency on electron-positron pair creation in the potential well is studied by the computational quantum field theory. The density, number and energy spectrum of electrons created under a single oscillating potential well and combined potential wells are investigated. The frequency spectrum and instantaneous bound states are also analyzed. It is found that nonlinear chirp effect is more sensitive to the low frequency region. When appropriate chirp parameters are selected, compared with the fixed frequency, the number of electrons created under combined potential wells can be increased by 2 to 3 times. For a single oscillating potential well, the number can be increased by several orders of magnitude. In the subcritical field at low frequencies, Schwinger mechanism dominates pair creation, and the production is very low. After modulation, the frequency spectrum widens. The high frequency component enhances the multiphoton processes and the dynamical assisted mechanism, while the ultrahigh frequency component inhibits pair creation.
2023,
35: 012004.
doi: 10.11884/HPLPB202335.220208
Abstract:
With the advent of ultra-short ultra-intense laser pulses, the interaction between light and matter enters the nonlinear physics regime dominated by radiation damping and quantum electrodynamics (QED) effects. The strong-field QED effects contain a wealth of physical processes, including radiation damping effect, high-energy gamma radiation, electron-positron pairs generation, QED cascade, vacuum polarization, and so on. These effects are frontiers and hot topics in high energy density physics and strong field physics. Among them, QED cascade is an important mechanism, which can explain the formation of the ultra-dense radiation in the cosmos and the gamma-ray burst, and the resulting dense positron source has important application prospects in high-energy physics, nondestructive assay of materials, and cancer diagnosis. In this paper, the cascading process of QED and the theoretical model are introduced, then the QED cascade development in solid targets and the resulting nonlinear physical effects are discussed. Finally, the main research results of dense positron generation in solid targets are reviewed.
With the advent of ultra-short ultra-intense laser pulses, the interaction between light and matter enters the nonlinear physics regime dominated by radiation damping and quantum electrodynamics (QED) effects. The strong-field QED effects contain a wealth of physical processes, including radiation damping effect, high-energy gamma radiation, electron-positron pairs generation, QED cascade, vacuum polarization, and so on. These effects are frontiers and hot topics in high energy density physics and strong field physics. Among them, QED cascade is an important mechanism, which can explain the formation of the ultra-dense radiation in the cosmos and the gamma-ray burst, and the resulting dense positron source has important application prospects in high-energy physics, nondestructive assay of materials, and cancer diagnosis. In this paper, the cascading process of QED and the theoretical model are introduced, then the QED cascade development in solid targets and the resulting nonlinear physical effects are discussed. Finally, the main research results of dense positron generation in solid targets are reviewed.
2023,
35: 012005.
doi: 10.11884/HPLPB202335.220216
Abstract:
Laser driven positron source has the advantages of high yield, short pulse width and high energy. In this paper, particle-in-cell simulation and Monte-Carlo simulation are combined to simulate the process of positron production in the interaction of relativistic femtosecond laser with a micro-structured surface target (MST) with a micron-scale wire array on the surface. The results show that when the laser energy is about 6 J and the pulse width is about 40 fs, fast electrons with the yield of 1011 orders of magnitude and the cut-off energy of about 120 MeV can be obtained. When the electrons bombard a high-Z conversion target, positrons with the yield of 109 orders of magnitude, and cut-off energy about 50 MeV are obtained. The divergence angle of the positron beam is 4.92°. Compared with planar targets, the use of MSTs can benefit the yield, energy and directivity of positrons.
Laser driven positron source has the advantages of high yield, short pulse width and high energy. In this paper, particle-in-cell simulation and Monte-Carlo simulation are combined to simulate the process of positron production in the interaction of relativistic femtosecond laser with a micro-structured surface target (MST) with a micron-scale wire array on the surface. The results show that when the laser energy is about 6 J and the pulse width is about 40 fs, fast electrons with the yield of 1011 orders of magnitude and the cut-off energy of about 120 MeV can be obtained. When the electrons bombard a high-Z conversion target, positrons with the yield of 109 orders of magnitude, and cut-off energy about 50 MeV are obtained. The divergence angle of the positron beam is 4.92°. Compared with planar targets, the use of MSTs can benefit the yield, energy and directivity of positrons.
2023,
35: 012006.
doi: 10.11884/HPLPB202335.220222
Abstract:
With the continuous development of technology, the laser power has exceeded 10 PW. The interaction between such intense laser pulse and matter enters the near quantum electrodynamics (QED) regime. From the non-relativistic laser pulse, relativistic one, to ultra-relativistic one, the coupling of light field and matter can produce X/γ-rays with the photon energy from keV, MeV to even GeV. These radiation sources have the characteristics of large flux, high brilliance, high energy and short duration, which have a wide range of application prospects in material science, imaging, and medicine fields and fundamental researches in nuclear physics, high-energy-density physics and astrophysics. In this review, we systematically introduce the recent advances in X/γ-ray generation through the interaction of relativistic high intensity laser with gas, near-critical-density plasma and solid targets via synchrotron radiation, betatron radiation, betatron-like radiation, Thomson scattering and nonlinear Compton scattering. The characteristics and potential applications of high energy X/γ-ray from various schemes are also summarized, which provide theoretical reference for the future experimental researches based on laser facilities.
With the continuous development of technology, the laser power has exceeded 10 PW. The interaction between such intense laser pulse and matter enters the near quantum electrodynamics (QED) regime. From the non-relativistic laser pulse, relativistic one, to ultra-relativistic one, the coupling of light field and matter can produce X/γ-rays with the photon energy from keV, MeV to even GeV. These radiation sources have the characteristics of large flux, high brilliance, high energy and short duration, which have a wide range of application prospects in material science, imaging, and medicine fields and fundamental researches in nuclear physics, high-energy-density physics and astrophysics. In this review, we systematically introduce the recent advances in X/γ-ray generation through the interaction of relativistic high intensity laser with gas, near-critical-density plasma and solid targets via synchrotron radiation, betatron radiation, betatron-like radiation, Thomson scattering and nonlinear Compton scattering. The characteristics and potential applications of high energy X/γ-ray from various schemes are also summarized, which provide theoretical reference for the future experimental researches based on laser facilities.
2023,
35: 012007.
doi: 10.11884/HPLPB202335.220204
Abstract:
Nonlinear Compton scattering is one of the dominant processes in future ultra-short ultra-intense laser-matter interactions. Today, most related researches are based on the mainstream model of nonlinear Compton scattering, which assumes short radiation formation interval, ignores effects of involved laser photon energy and is not spin-resolved. To depict nonlinear Compton scattering more precisely in wider parameter space, improved theories beyond these assumptions have been proposed in recent years. In this paper, we reviewe the major recent improvements, analyze their applicability, discusse their basic characteristics and physical effects on nonlinear Compton scatterings.
Nonlinear Compton scattering is one of the dominant processes in future ultra-short ultra-intense laser-matter interactions. Today, most related researches are based on the mainstream model of nonlinear Compton scattering, which assumes short radiation formation interval, ignores effects of involved laser photon energy and is not spin-resolved. To depict nonlinear Compton scattering more precisely in wider parameter space, improved theories beyond these assumptions have been proposed in recent years. In this paper, we reviewe the major recent improvements, analyze their applicability, discusse their basic characteristics and physical effects on nonlinear Compton scatterings.
2023,
35: 012008.
doi: 10.11884/HPLPB202335.220375
Abstract:
The interaction between an ultra-intense laser pulse and a relativistic electron beam is the main experimental method of strong-field quantum electrodynamics (QED). However, how to measure the accuracy of laser-electron-beam interaction, and then realize the accurate collision of micron precision, is a crucial reason limiting the development of strong-field QED experiments. Here, the dynamics of electrons and photons emitted during the interaction of an ultra-intense laser pulse and a relativistic electron beam is investigated via Monte Carlo numerical simulations. The correlation between the dynamics of electrons and emitted photons with the collision offset of laser pulse and electron beam is explored. Our simulations show that the spatial distribution information of emitted photons can effectively reflect the collision offset of the laser pulse and the electron beam. Based on the research results, the information of photon spatial distribution detected can be used to adjust the accuracy of laser- electron-beam interactions, which is expected to promote the development of strong field QED experimental technology.
The interaction between an ultra-intense laser pulse and a relativistic electron beam is the main experimental method of strong-field quantum electrodynamics (QED). However, how to measure the accuracy of laser-electron-beam interaction, and then realize the accurate collision of micron precision, is a crucial reason limiting the development of strong-field QED experiments. Here, the dynamics of electrons and photons emitted during the interaction of an ultra-intense laser pulse and a relativistic electron beam is investigated via Monte Carlo numerical simulations. The correlation between the dynamics of electrons and emitted photons with the collision offset of laser pulse and electron beam is explored. Our simulations show that the spatial distribution information of emitted photons can effectively reflect the collision offset of the laser pulse and the electron beam. Based on the research results, the information of photon spatial distribution detected can be used to adjust the accuracy of laser- electron-beam interactions, which is expected to promote the development of strong field QED experimental technology.
2023,
35: 012009.
doi: 10.11884/HPLPB202335.220229
Abstract:
In the past decades, great progress has been made in laser wakefield acceleration of electron beam inspired by ultra-short intense lasers in plasma. The high-energy electron beam obtained by this method can be applied to the generation of the high-brightness and intense radiation sources, which have attracted extensive attention. In this paper, the basic principle and research status of Betatron radiation generated by laser wakefield acceleration are briefly introduced. The development trend of Betatron radiation is analyzed in combination with the X-ray application requirements. It is found that there is an urgent need to develop a new scheme of laser wakefield electron acceleration based on compact laser device to break through the limit of beam-loading effect on electron charge. By this means, one can generate large charge electron beam and high flux Betatron radiation source. Finally, a new scheme is briefly introduced to generate 10 nC high-energy electron beam and the photon number of Betatron radiation source reach\begin{document}$ 1.0\times {10}^{12} $\end{document} ![]()
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In the past decades, great progress has been made in laser wakefield acceleration of electron beam inspired by ultra-short intense lasers in plasma. The high-energy electron beam obtained by this method can be applied to the generation of the high-brightness and intense radiation sources, which have attracted extensive attention. In this paper, the basic principle and research status of Betatron radiation generated by laser wakefield acceleration are briefly introduced. The development trend of Betatron radiation is analyzed in combination with the X-ray application requirements. It is found that there is an urgent need to develop a new scheme of laser wakefield electron acceleration based on compact laser device to break through the limit of beam-loading effect on electron charge. By this means, one can generate large charge electron beam and high flux Betatron radiation source. Finally, a new scheme is briefly introduced to generate 10 nC high-energy electron beam and the photon number of Betatron radiation source reach
2023,
35: 012010.
doi: 10.11884/HPLPB202335.220114
Abstract:
Spin-polarized plasma induced by the radiative spin flips in ultrarelativistic laser-matter interaction attracts great attention. Spin-polarized electron beams are broadly utilized in probing the structure of solid-state materials, exploring nucleon structure, and facilitating the analyses of the electroweak interaction. Electron spin, an intrinsic property of the electrons, could provide a new degree of freedom of information in characterizing plasma collective behaviors. In this manuscript, we review the mechanism of the production of radiative spin-polarized plasma and discuss its potential application in retrieving the transient ultrarelativistic plasmas.
Spin-polarized plasma induced by the radiative spin flips in ultrarelativistic laser-matter interaction attracts great attention. Spin-polarized electron beams are broadly utilized in probing the structure of solid-state materials, exploring nucleon structure, and facilitating the analyses of the electroweak interaction. Electron spin, an intrinsic property of the electrons, could provide a new degree of freedom of information in characterizing plasma collective behaviors. In this manuscript, we review the mechanism of the production of radiative spin-polarized plasma and discuss its potential application in retrieving the transient ultrarelativistic plasmas.
2023,
35: 012011.
doi: 10.11884/HPLPB202335.220209
Abstract:
Warm dense matter is an important stage of material development in the process of inertial confinement fusion and the evolution of the universe. As the density increases, quantum effects gradually manifest, and the collective excitations in warm dense region show behavior different from the classical cases. Density-functional kinetic theory (DFKT) is a statistical model based on the time-dependent-density-functional theory and Wigner distribution function (phase-space quantum theory), which can effectively compensate for the neglect of quantum effects by classical plasma theory. Based on the DFKT, we found that properties such as Fermi-Dirac distribution, exchange-correlation effects, and quantum diffraction effects in the warm-dense characteristic parameters can inhibit the two-stream instabilities. DFKT is expected to provide a first-principle theoretical platform for the study of the transport properties of the warm dense systems from the perspective of plasmas.
Warm dense matter is an important stage of material development in the process of inertial confinement fusion and the evolution of the universe. As the density increases, quantum effects gradually manifest, and the collective excitations in warm dense region show behavior different from the classical cases. Density-functional kinetic theory (DFKT) is a statistical model based on the time-dependent-density-functional theory and Wigner distribution function (phase-space quantum theory), which can effectively compensate for the neglect of quantum effects by classical plasma theory. Based on the DFKT, we found that properties such as Fermi-Dirac distribution, exchange-correlation effects, and quantum diffraction effects in the warm-dense characteristic parameters can inhibit the two-stream instabilities. DFKT is expected to provide a first-principle theoretical platform for the study of the transport properties of the warm dense systems from the perspective of plasmas.
2023,
35: 012012.
doi: 10.11884/HPLPB202335.220197
Abstract:
Methods, as well as challenges, in experimental studies on Hawking-Unruh radiation (HUR) with high-intensity laser (HIL) will be reviewed in this paper. Hawking-Unruh radiation is one of the most important effects in quantum gravity. Experimental studies on it are critical for the development of quantum gravity theories, or theories like the Theory of Everything etc. Various experimental methods have been developed to study the HUR, including high-intensity laser, storage ring, Penning trap, Bose-Einstein condensate, acoustic methods etc. There are two major types of HUR studies with HILs today, the artificial optical blackhole method and the laser acceleration method. In the 1st method, nonlinear properties of optical media are used to generate artificial blackholes as platforms for studies on related phenomena including HUR. In the 2nd method, electrons’ HUR radiation spectra under extreme HILs are expected.
Methods, as well as challenges, in experimental studies on Hawking-Unruh radiation (HUR) with high-intensity laser (HIL) will be reviewed in this paper. Hawking-Unruh radiation is one of the most important effects in quantum gravity. Experimental studies on it are critical for the development of quantum gravity theories, or theories like the Theory of Everything etc. Various experimental methods have been developed to study the HUR, including high-intensity laser, storage ring, Penning trap, Bose-Einstein condensate, acoustic methods etc. There are two major types of HUR studies with HILs today, the artificial optical blackhole method and the laser acceleration method. In the 1st method, nonlinear properties of optical media are used to generate artificial blackholes as platforms for studies on related phenomena including HUR. In the 2nd method, electrons’ HUR radiation spectra under extreme HILs are expected.
