The rapid development of ultrafast ultraintense laser technology continues to create opportunities for studying strong-field physics under extreme conditions.However,accurate determination of the spatial and temporal ...The rapid development of ultrafast ultraintense laser technology continues to create opportunities for studying strong-field physics under extreme conditions.However,accurate determination of the spatial and temporal characteristics of a laser pulse is still a great challenge,especially when laser powers higher than hundreds of terawatts are involved.In this paper,by utilizing the radiative spin-flip effect,we find that the spin depolarization of an electron beam can be employed to diagnose characteristics of ultrafast ultraintense lasers with peak intensities around 10^(20)–10^(22) W/cm^(2).With three shots,our machine-learning-assisted model can predict,simultaneously,the pulse duration,peak intensity,and focal radius of a focused Gaussian ultrafast ultraintense laser(in principle,the profile can be arbitrary)with relative errors of 0.1%–10%.The underlying physics and an alternative diagnosis method(without the assistance of machine learning)are revealed by the asymptotic approximation of the final spin degree of polarization.Our proposed scheme exhibits robustness and detection accuracy with respect to fluctuations in the electron beam parameters.Accurate measurements of ultrafast ultraintense laser parameters will lead to much higher precision in,for example,laser nuclear physics investigations and laboratory astrophysics studies.Robust machine learning techniques may also find applications in more general strong-field physics scenarios.展开更多
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.11874295,12022506,U2267204,11905169,12275209,11875219,and 12171383)the Open Fund of the State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)+1 种基金the Foundation of Science and Technology on Plasma Physics Laboratory(Grant No.JCKYS2021212008)The work of Y.I.S.is supported by an American University of Sharjah Faculty Research(Grant No.FRG21).
文摘The rapid development of ultrafast ultraintense laser technology continues to create opportunities for studying strong-field physics under extreme conditions.However,accurate determination of the spatial and temporal characteristics of a laser pulse is still a great challenge,especially when laser powers higher than hundreds of terawatts are involved.In this paper,by utilizing the radiative spin-flip effect,we find that the spin depolarization of an electron beam can be employed to diagnose characteristics of ultrafast ultraintense lasers with peak intensities around 10^(20)–10^(22) W/cm^(2).With three shots,our machine-learning-assisted model can predict,simultaneously,the pulse duration,peak intensity,and focal radius of a focused Gaussian ultrafast ultraintense laser(in principle,the profile can be arbitrary)with relative errors of 0.1%–10%.The underlying physics and an alternative diagnosis method(without the assistance of machine learning)are revealed by the asymptotic approximation of the final spin degree of polarization.Our proposed scheme exhibits robustness and detection accuracy with respect to fluctuations in the electron beam parameters.Accurate measurements of ultrafast ultraintense laser parameters will lead to much higher precision in,for example,laser nuclear physics investigations and laboratory astrophysics studies.Robust machine learning techniques may also find applications in more general strong-field physics scenarios.
