A short overview of the theory of acceleration of thin foils driven by the radiation pressure of superintense lasers is presented. A simple criterion for radiation pressure dominance at intensities around 5×1020W...A short overview of the theory of acceleration of thin foils driven by the radiation pressure of superintense lasers is presented. A simple criterion for radiation pressure dominance at intensities around 5×1020W cm-2is given, and the possibility for fast energy gain in the relativistic regime is discussed.展开更多
X/γ-rays have many potential applications in laboratory astrophysics and particle physics.Although several methods have been proposed for generating electron,positron,and X/γ-photon beams with angular momentum(AM),t...X/γ-rays have many potential applications in laboratory astrophysics and particle physics.Although several methods have been proposed for generating electron,positron,and X/γ-photon beams with angular momentum(AM),the generation of ultra-intense brilliant γ-rays is still challenging.Here,we present an all-optical scheme to generate a high-energy γ-photon beam with large beam angular momentum(BAM),small divergence,and high brilliance.In the first stage,a circularly polarized laser pulse with intensity of 10^(22) W/cm^(2) irradiates a micro-channel target,drags out electrons from the channel wall,and accelerates them to high energies via the longitudinal electric fields.During the process,the laser transfers its spin angular momentum(SAM)to the electrons’orbital angular momentum(OAM).In the second stage,the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed.In the third stage,the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the γ-photons via nonlinear Compton scattering.Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ-ray beam is∼10^(22) photons·s^(-1)·mm^(-2)·mrad^(-2) per 0.1% bandwidth at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of 10^(6)h/photon.The AM conversion efficiency from laser to the γ-photons is unprecedentedly 0.67%.展开更多
We study the properties of gravitational wave(GW)signals produced by first-order phase transitions during the inflation era.We show that the power spectrum of a GW oscillates with its wave number.This signal can be ob...We study the properties of gravitational wave(GW)signals produced by first-order phase transitions during the inflation era.We show that the power spectrum of a GW oscillates with its wave number.This signal can be observed directly by future terrestrial and spatial GW detectors and through the B-mode spectrum in the CMB.This oscillatory feature of the GW is generic for any approximately instantaneous sources occurring during inflation and is distinct from the GW from phase transitions after inflation.The details of the GW spectrum contain information about the scale of the phase transition and the later evolution of the universe.展开更多
基金Support from the Italian Ministry of University and Research via the FIR project ‘SULDIS’
文摘A short overview of the theory of acceleration of thin foils driven by the radiation pressure of superintense lasers is presented. A simple criterion for radiation pressure dominance at intensities around 5×1020W cm-2is given, and the possibility for fast energy gain in the relativistic regime is discussed.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0404802)National Natural Science Foundation of China(Grant Nos.11875319,11705280,11774430,and 11775144)the Science and Technology Innovation Program of Hunan Province(Grant No.2020RC4020)+2 种基金Research Project of NUDT(Grant Nos.ZK18-02-02 and ZK18-03-09)Fok Ying-Tong Education Foundation(Grant No.161007)financial support by Hunan Provincial Research and Innovation Foundation for Graduate Students of China(Grant Nos.CX20190017,CX20190018,CX20200002,and CX20200038)。
文摘X/γ-rays have many potential applications in laboratory astrophysics and particle physics.Although several methods have been proposed for generating electron,positron,and X/γ-photon beams with angular momentum(AM),the generation of ultra-intense brilliant γ-rays is still challenging.Here,we present an all-optical scheme to generate a high-energy γ-photon beam with large beam angular momentum(BAM),small divergence,and high brilliance.In the first stage,a circularly polarized laser pulse with intensity of 10^(22) W/cm^(2) irradiates a micro-channel target,drags out electrons from the channel wall,and accelerates them to high energies via the longitudinal electric fields.During the process,the laser transfers its spin angular momentum(SAM)to the electrons’orbital angular momentum(OAM).In the second stage,the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed.In the third stage,the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the γ-photons via nonlinear Compton scattering.Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ-ray beam is∼10^(22) photons·s^(-1)·mm^(-2)·mrad^(-2) per 0.1% bandwidth at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of 10^(6)h/photon.The AM conversion efficiency from laser to the γ-photons is unprecedentedly 0.67%.
基金supported by NSFC(11975134)the National Key Research and Development Program of China(2017YFA0402204)+4 种基金the Tsinghua University Initiative Scientific Research Programsupported in part by the National Science Foundation(NSF PHY-1748958)by the Heising-Simons Foundationsupported by the DOE(DE-SC0013642)supported in part by the Swedish Research Council(2015-05333,2018-03803)。
文摘We study the properties of gravitational wave(GW)signals produced by first-order phase transitions during the inflation era.We show that the power spectrum of a GW oscillates with its wave number.This signal can be observed directly by future terrestrial and spatial GW detectors and through the B-mode spectrum in the CMB.This oscillatory feature of the GW is generic for any approximately instantaneous sources occurring during inflation and is distinct from the GW from phase transitions after inflation.The details of the GW spectrum contain information about the scale of the phase transition and the later evolution of the universe.
