A time-dependent analytical solution is found for the velocity of a plane ionization wave generated under nanosecond laser pulse action on the surface of a flat layer of low-Z porous substance with density less than t...A time-dependent analytical solution is found for the velocity of a plane ionization wave generated under nanosecond laser pulse action on the surface of a flat layer of low-Z porous substance with density less than the critical density of the produced plasma.With corrections for the two-dimensional nature of the problem when a laser beam of finite radius interacts with a flat target,this solution is in quantitative agreement with measurements of ionization wave velocity in various experiments.The solution compared with experimental data covering wide ranges of performance conditions,namely,(3-8)×10^(14)W cm^(−2)for laser pulse intensity,0.3-3 ns for pulse duration,0.35-0.53μm for laser wavelength,100-1000μm for laser beam radius,380-950μm for layer thickness,4.5-12 mg cm^(−3)for average density of porous substance,and 1-25μm for average pore size.The parameters of the laser beam that ensure the generation of a plane ionization wave in a layer of subcritical porous matter are determined for the problem statements and are found to meet the requirements of practical applications.展开更多
Collision of laser-driven subrelativistic high-density ion flows provides a way to create extremely compressed ion conglomerates and study their properties.This paper presents a theoretical study of the electrodynamic...Collision of laser-driven subrelativistic high-density ion flows provides a way to create extremely compressed ion conglomerates and study their properties.This paper presents a theoretical study of the electrodynamic implosion of ions inside a hollow spherical or cylindrical shell irradiated by femtosecond petawatt laser pulses.We propose to apply a very effective mechanism for ion acceleration in a self-consistent field with strong charge separation,based on the oscillation of laser-accelerated fast electrons in this field near the thin shell.Fast electrons are generated on the outer side of the shell under irradiation by the intense laser pulses.It is shown that ions,in particular protons,may be accelerated at the implosion stage to energies of tens and hundreds of MeV when a sub-micrometer shell is irradiated by femtosecond laser pulses with an intensity of 10^(21)–10^(23)W cm^(−2).展开更多
Thermo-luminescence （TL） is a kind of luminescence decay measured with varying temperature. In the process of TL the decay parameter itself involves the temperature effect of traps. Thus the trap depth is inseparabl...Thermo-luminescence （TL） is a kind of luminescence decay measured with varying temperature. In the process of TL the decay parameter itself involves the temperature effect of traps. Thus the trap depth is inseparable from the decay parameter. There are two separate peaks in the TL curve of ZnS：Cu,Co if the measurement starts from liquid nitrogen temperature. In the experiment we started from zero Celsius temperature to isolate the deeper traps. We have proposed and realized three methods for simultaneous determination of trap depth and decay parameter based on the quasi-equilibrium model and experimental data. If we treat the case of kinetic order a = 1 as a = 2, the error might be as large as 100%.展开更多
The results of optical properties investigations for some types of globular crystals, including artifical opals and amorphous substances, constructed from the globular nanoclusters are represented. The spectra of ligh...The results of optical properties investigations for some types of globular crystals, including artifical opals and amorphous substances, constructed from the globular nanoclusters are represented. The spectra of light reflection from the surface of received opals have investigated at different incident angle (under mirror-reflection geometry): 0, 20, 30, 45 and 60 degree.展开更多
文摘A time-dependent analytical solution is found for the velocity of a plane ionization wave generated under nanosecond laser pulse action on the surface of a flat layer of low-Z porous substance with density less than the critical density of the produced plasma.With corrections for the two-dimensional nature of the problem when a laser beam of finite radius interacts with a flat target,this solution is in quantitative agreement with measurements of ionization wave velocity in various experiments.The solution compared with experimental data covering wide ranges of performance conditions,namely,(3-8)×10^(14)W cm^(−2)for laser pulse intensity,0.3-3 ns for pulse duration,0.35-0.53μm for laser wavelength,100-1000μm for laser beam radius,380-950μm for layer thickness,4.5-12 mg cm^(−3)for average density of porous substance,and 1-25μm for average pore size.The parameters of the laser beam that ensure the generation of a plane ionization wave in a layer of subcritical porous matter are determined for the problem statements and are found to meet the requirements of practical applications.
基金supported by the Russian Science Foundation under Project No.21-11-00102。
文摘Collision of laser-driven subrelativistic high-density ion flows provides a way to create extremely compressed ion conglomerates and study their properties.This paper presents a theoretical study of the electrodynamic implosion of ions inside a hollow spherical or cylindrical shell irradiated by femtosecond petawatt laser pulses.We propose to apply a very effective mechanism for ion acceleration in a self-consistent field with strong charge separation,based on the oscillation of laser-accelerated fast electrons in this field near the thin shell.Fast electrons are generated on the outer side of the shell under irradiation by the intense laser pulses.It is shown that ions,in particular protons,may be accelerated at the implosion stage to energies of tens and hundreds of MeV when a sub-micrometer shell is irradiated by femtosecond laser pulses with an intensity of 10^(21)–10^(23)W cm^(−2).
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10374001, 10434030 and 60576016）, the State Key Development Program for Basic Research of China （Grant No 2003CB314707）, the Excellent Doctor＇s Science and Technology Innovation Foundation of Beijing Jiaotong University （Grant No 48011）, Russian Foundation of Basic Research （Grant Nos 04-02- 16942 and 02-02-39007）.
文摘Thermo-luminescence （TL） is a kind of luminescence decay measured with varying temperature. In the process of TL the decay parameter itself involves the temperature effect of traps. Thus the trap depth is inseparable from the decay parameter. There are two separate peaks in the TL curve of ZnS：Cu,Co if the measurement starts from liquid nitrogen temperature. In the experiment we started from zero Celsius temperature to isolate the deeper traps. We have proposed and realized three methods for simultaneous determination of trap depth and decay parameter based on the quasi-equilibrium model and experimental data. If we treat the case of kinetic order a = 1 as a = 2, the error might be as large as 100%.
文摘The results of optical properties investigations for some types of globular crystals, including artifical opals and amorphous substances, constructed from the globular nanoclusters are represented. The spectra of light reflection from the surface of received opals have investigated at different incident angle (under mirror-reflection geometry): 0, 20, 30, 45 and 60 degree.
