Dense ceramic oxide coatings of about 50 μm may be prepared on Ti-6AI-4V alloy surface by alternating-current microarc oxidation in aluminate and silicate solutions, respectively. Their phase constituent and microstr...Dense ceramic oxide coatings of about 50 μm may be prepared on Ti-6AI-4V alloy surface by alternating-current microarc oxidation in aluminate and silicate solutions, respectively. Their phase constituent and microstructure were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the electrolytic ions have incorporated into the interior of the coatings. The coating formed in aluminate solution is composed of the rutile TiO2 and TiAl2O5 phases rather than the rutile, anatase and amorphous SiO2 phases for the coating formed in silicate solution. However, TiAl2O5 content in the outer layer of the two coatings is much higher than in the inner layer. It is suggested that all these oxides may result from a rapid solidification of the molten coating in the microarc discharge zone.展开更多
Changes of the average brightness and non-uniformity of dark output images,and quality of pictures captured under natural lighting for the color CMOS digital image sensorsirradiated at different electron doses have be...Changes of the average brightness and non-uniformity of dark output images,and quality of pictures captured under natural lighting for the color CMOS digital image sensorsirradiated at different electron doses have been studied in comparison to those from theγ-irradiated sensors. For the electron-irradiated sensors, the non-uniformity increases obviouslyand a small bright region on the dark image appears at the dose of 0.4 kGy. The average brightnessincreases at 0.4 kGy, increases sharply at 0.5 kGy. The picture is very blurry only at 0.6 kGy,showing the sensor undergoes severe performance degradation. Electron radiation damage is much moresevere than γ radiation damage for the CMOS image sensors. A possible explanation is presented inthis paper.展开更多
The theoretical signal-pressure curves are calculated from approximate analytical solutions of the coupledequations describing the third order parametric wave mixing in a gas-filled capillary of femto-second laser pul...The theoretical signal-pressure curves are calculated from approximate analytical solutions of the coupledequations describing the third order parametric wave mixing in a gas-filled capillary of femto-second laser pulses. Thecomparison with the corresponding experimental curves suggests that the following three factors exert important influ-ences on the degree of fitting between the theoretical and experimental results: the walk-off, the phase modulation, andthe third order harmonic of idler pulse.展开更多
The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled c...The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled capillary by fs pulses are calculated. With a comparison between the theoretical and experimental SPC we have discussed the influence of the walk-off and Phase modulation on the SPC. At the same time, we have discussed the possible origin of the first three peaks of the SPC.展开更多
The effects of re-scattering on the supra-thermal electron (STE) produced in moderate laser fields are analytically considered (laser intensity is up to ) with a simple model. The electron kinetic energy distribution...The effects of re-scattering on the supra-thermal electron (STE) produced in moderate laser fields are analytically considered (laser intensity is up to ) with a simple model. The electron kinetic energy distribution given by the model is consistent to that given by the particle-in-cell simulation. Based on this fact, it is shown that the scattering of electron in intense laser by the ion in plasma plays an important role in the generation of STE in a moderate laser field.展开更多
Nonlinear screening of a test charge in plasma by electrons trapped or untrapped is studied. The obtained results are in rigorous estimations mathematically in comparison with the corresponding Debye screening forms.M...Nonlinear screening of a test charge in plasma by electrons trapped or untrapped is studied. The obtained results are in rigorous estimations mathematically in comparison with the corresponding Debye screening forms.Meanwhile their validity is physically discussed and some confusions in literature are clarified.展开更多
The efficient production of energetic γ photons is a significant physical process in the relativistic ultrashortpulse laser-plasma inducing photonuclear action. Based on the interaction of laser-solid-target, an anal...The efficient production of energetic γ photons is a significant physical process in the relativistic ultrashortpulse laser-plasma inducing photonuclear action. Based on the interaction of laser-solid-target, an analytical theory onstimulated γ photon emission from a hot electron firing the target-nucleus is developed by a relativistic full quantummethod. The emitting power or probability of γ photon in arbitrary space direction can be calculated for laser irradiatingsolid-target normally. It is valid only if the scatter-centre is immovable or its motion can be neglected compared withthat of the scattered electrons.展开更多
In this paper, we theoretically discuss the soliton properties of light pulse transportation on the surface of an ionic crystal having strong nonlinear interactions between ions of unit cells. We analyze in detail the...In this paper, we theoretically discuss the soliton properties of light pulse transportation on the surface of an ionic crystal having strong nonlinear interactions between ions of unit cells. We analyze in detail the dark solitons when the nonlinear coefficient g is positive and negative, respectively. It is found that whether the nonlinear coefficient g is positive or negative, the dark solitons can be formed over the whole dispersion relation area of surface polaritons considering nonlinear effects. Attention should be paid to the fact that around , the light pulse can form advanced dark solitons, and there is a switching area from advanced dark soliton to retarded dark soliton near . We also discuss the effects of higher nonlinear dispersion on the solitons.展开更多
Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagn...Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagnetic field propagating the solitary waves can exist in both cases, where the vector potential frequency is larger or smaller than the plasma characteristic frequency.展开更多
基金This rescarch was sponsored by the National"863"High-tech Progran of China(No.715-011-020)the National Natural Science Foundation of China(No.59801003)Beijing New-Star Progratn for Science and Technology(No.9558102500).
文摘Dense ceramic oxide coatings of about 50 μm may be prepared on Ti-6AI-4V alloy surface by alternating-current microarc oxidation in aluminate and silicate solutions, respectively. Their phase constituent and microstructure were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the electrolytic ions have incorporated into the interior of the coatings. The coating formed in aluminate solution is composed of the rutile TiO2 and TiAl2O5 phases rather than the rutile, anatase and amorphous SiO2 phases for the coating formed in silicate solution. However, TiAl2O5 content in the outer layer of the two coatings is much higher than in the inner layer. It is suggested that all these oxides may result from a rapid solidification of the molten coating in the microarc discharge zone.
基金This project is financially supported by the Narional Natural Science Foundation of China(Nos 10375034 and 10075029) and the Basic Research Foundation of Tsinghua University (No. JC2002058).
文摘Changes of the average brightness and non-uniformity of dark output images,and quality of pictures captured under natural lighting for the color CMOS digital image sensorsirradiated at different electron doses have been studied in comparison to those from theγ-irradiated sensors. For the electron-irradiated sensors, the non-uniformity increases obviouslyand a small bright region on the dark image appears at the dose of 0.4 kGy. The average brightnessincreases at 0.4 kGy, increases sharply at 0.5 kGy. The picture is very blurry only at 0.6 kGy,showing the sensor undergoes severe performance degradation. Electron radiation damage is much moresevere than γ radiation damage for the CMOS image sensors. A possible explanation is presented inthis paper.
文摘The theoretical signal-pressure curves are calculated from approximate analytical solutions of the coupledequations describing the third order parametric wave mixing in a gas-filled capillary of femto-second laser pulses. Thecomparison with the corresponding experimental curves suggests that the following three factors exert important influ-ences on the degree of fitting between the theoretical and experimental results: the walk-off, the phase modulation, andthe third order harmonic of idler pulse.
文摘The theoretical framework for the cascaded four waves mixing (CFWM) in gas-filled capillary by fs pulses is constructed. Based on the theoretical framework, the signal-pressure curves (SPC) of the CFWM in gas-filled capillary by fs pulses are calculated. With a comparison between the theoretical and experimental SPC we have discussed the influence of the walk-off and Phase modulation on the SPC. At the same time, we have discussed the possible origin of the first three peaks of the SPC.
文摘The effects of re-scattering on the supra-thermal electron (STE) produced in moderate laser fields are analytically considered (laser intensity is up to ) with a simple model. The electron kinetic energy distribution given by the model is consistent to that given by the particle-in-cell simulation. Based on this fact, it is shown that the scattering of electron in intense laser by the ion in plasma plays an important role in the generation of STE in a moderate laser field.
文摘Nonlinear screening of a test charge in plasma by electrons trapped or untrapped is studied. The obtained results are in rigorous estimations mathematically in comparison with the corresponding Debye screening forms.Meanwhile their validity is physically discussed and some confusions in literature are clarified.
文摘The efficient production of energetic γ photons is a significant physical process in the relativistic ultrashortpulse laser-plasma inducing photonuclear action. Based on the interaction of laser-solid-target, an analytical theory onstimulated γ photon emission from a hot electron firing the target-nucleus is developed by a relativistic full quantummethod. The emitting power or probability of γ photon in arbitrary space direction can be calculated for laser irradiatingsolid-target normally. It is valid only if the scatter-centre is immovable or its motion can be neglected compared withthat of the scattered electrons.
文摘In this paper, we theoretically discuss the soliton properties of light pulse transportation on the surface of an ionic crystal having strong nonlinear interactions between ions of unit cells. We analyze in detail the dark solitons when the nonlinear coefficient g is positive and negative, respectively. It is found that whether the nonlinear coefficient g is positive or negative, the dark solitons can be formed over the whole dispersion relation area of surface polaritons considering nonlinear effects. Attention should be paid to the fact that around , the light pulse can form advanced dark solitons, and there is a switching area from advanced dark soliton to retarded dark soliton near . We also discuss the effects of higher nonlinear dispersion on the solitons.
文摘Solitary waves in relativistic electromagnetic plasmas are obtained numerically. The longitudinal momentum of electrons has been taken into account in the problem. It is found that in the moving frame with electromagnetic field propagating the solitary waves can exist in both cases, where the vector potential frequency is larger or smaller than the plasma characteristic frequency.
