The effects of laser polarization on super-hot electron (> 100 keV) generation have been studied in the interaction of femtosecond laser light (800 nm, 150 fs, 6 × 10^(15) W·cm^(-2)) with a pre-formed pla...The effects of laser polarization on super-hot electron (> 100 keV) generation have been studied in the interaction of femtosecond laser light (800 nm, 150 fs, 6 × 10^(15) W·cm^(-2)) with a pre-formed plasma from a slab Cu target. For p-polarized laser pulses, high-energy γ-rays of the energy ~400keV were detected. The electron temperatures deduced from the γ-ray spectra were 66 and 52keV, respectively, in normal and reflective directions of the solid target, and hot electrons were emitted out of the plasma mainly in the normal direction. In contrast, there were nearly no γ-rays >100keV found for s-polarized laser pulses. The hot electron temperature was 26keV and the emission of hot electrons was parallel to the laser field. The superposition of resonant field with electrostatic field excited by escaping electrons may contribute to the high-energy γ-ray or super-hot electron (> 100 keV) generation.展开更多
Loss of light yield of doped lead tungstate crystals after irradiation with a low dose rate has been observed.The La,Pr,and Y doping may improve radiation hardness,whereas Bi or Mo doping is harmful.
The γ-rays with energies up to 300keV have been observed from plasmas produced by femtosecond laser pulses at a focused intensity of 5 × 10^(15) W.cm^(-2).μm^(2) irradiating Ta,Mo,and Cu targets.By introducing ...The γ-rays with energies up to 300keV have been observed from plasmas produced by femtosecond laser pulses at a focused intensity of 5 × 10^(15) W.cm^(-2).μm^(2) irradiating Ta,Mo,and Cu targets.By introducing an 8% prepulse of 70ps before the main pulse,the fraction of high energy γ-ray photons(hv>l00keV)was significantly enhanced relative to low energy photons(hv<100 keV).展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos.19854001,10005014 and 19825110the National Hi-Tech ICF Programme。
文摘The effects of laser polarization on super-hot electron (> 100 keV) generation have been studied in the interaction of femtosecond laser light (800 nm, 150 fs, 6 × 10^(15) W·cm^(-2)) with a pre-formed plasma from a slab Cu target. For p-polarized laser pulses, high-energy γ-rays of the energy ~400keV were detected. The electron temperatures deduced from the γ-ray spectra were 66 and 52keV, respectively, in normal and reflective directions of the solid target, and hot electrons were emitted out of the plasma mainly in the normal direction. In contrast, there were nearly no γ-rays >100keV found for s-polarized laser pulses. The hot electron temperature was 26keV and the emission of hot electrons was parallel to the laser field. The superposition of resonant field with electrostatic field excited by escaping electrons may contribute to the high-energy γ-ray or super-hot electron (> 100 keV) generation.
基金Supported by the Chinese Academy of Sciences under Grant No.006.
文摘Loss of light yield of doped lead tungstate crystals after irradiation with a low dose rate has been observed.The La,Pr,and Y doping may improve radiation hardness,whereas Bi or Mo doping is harmful.
基金Supported by the National Natural Science Foundation of China under Grant No.19854001the National High Technology ICF Committee under Grant No.416-3.
文摘The γ-rays with energies up to 300keV have been observed from plasmas produced by femtosecond laser pulses at a focused intensity of 5 × 10^(15) W.cm^(-2).μm^(2) irradiating Ta,Mo,and Cu targets.By introducing an 8% prepulse of 70ps before the main pulse,the fraction of high energy γ-ray photons(hv>l00keV)was significantly enhanced relative to low energy photons(hv<100 keV).
