Time filter

Source Type

Chang H.,Academy of Equipment Command and Technology | Jin X.,State Key Laboratory of Laser Propulsion and Application | Chen Z.,Beijing University of Chemical Technology
Guangxue Xuebao/Acta Optica Sinica | Year: 2013

In the process of laser ablation, the target's absorption coefficient, thermal conductivity, density and surface reflectivity are dependent on its temperature. When the target surface temperature approaches the thermodynamic critical temperature Tc, the high-temperature part of the target transits from metal to nonmetal. The target is divided into two temperature regions (below and above 0.8Tc) and a model is built up to calculate the above physical parameters. The temporal and spatial distribution of temperature, absorption coefficient and thermal conductivity of Al target are obtained by a one-dimensional heat conduction equation. Ablation depth is calculated as a function of laser pulse energies. Numerical results are in good agreement with the experimental results, which validate the presented model.


Yang Y.,Academy of Equipment Command and Technology | Zhang D.,Academy of Equipment Command and Technology | Li X.,Academy of Equipment Command and Technology | Li X.,State Key Laboratory of Laser Propulsion and Application
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

Future space missions may use laser power beaming systems with a high power laser to transmit light to a photovoltaic array receiver. The photovoltaic array receiver can be mounted to a satellite or a spacecraft. To investigate the V-I and P-V characteristics of photovoltaic cells (PV cells) under laser illumination, a mathematical model and simulation model related to the voltage and current of PV cells is studied. Based on the MATLAB simulation tool, the simulated V-I and P-V characteristics of PV cells for various irradiances are presented. To validate the simulated results, three experiments are designed. The results obtained by experimenting are compared with the simulated results, and the difference between them is not apparent.. © 2015 SPIE.


Zhang D.,Academy of Equipment Command and Technology | Yang Y.,Academy of Equipment Command and Technology | Li X.,Academy of Equipment Command and Technology | Li X.,State Key Laboratory of Laser Propulsion and Application
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

A thermal effect model is presented in this paper, with the background of ground-based laser irradiating moving and rotating target in the air. Firstly, the encounter scene of laser irradiating target is assumed, and the main parameters of laser and target are given. Secondly, the calculation model of irradiating parameters is derived, including irradiating area, power density distribution and convection heat transfer per unit area. Thirdly, the thermal effect model is established to describe heat conduction and thermal ablation during laser irradiating. Finally, the thermal effects are calculated by assuming the parameters in encounter scene of laser irradiating target. As shown in the example, the thermal effect model can minutely describe the temperature field and ablation results of moving and rotating target irradiated by laser. © 2015 SPIE.


Song Y.L.,China Agricultural University | Huang F.,China Agricultural University | Chen Z.Y.,Beijing University of Chemical Technology | Chen Z.Y.,State Key Laboratory of Laser Propulsion and Application | And 3 more authors.
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2016

Negatively charged dust particles immersed in 2-dimensional dusty plasma system are investigated by molecular dynamics simulations. The effects of the confinement potential and attraction interaction potential on dust particle self-organization are studied in detail and two typical dust particle distributions are obtained when the system reaches equilibrium. The average radial velocity (ARV), average radial force (ARF) and radial mean square displacement are employed to analyze the dust particles' dynamics. Both ARVs and ARFs exhibit oscillation behaviors when the simulation system reaches equilibrium state. The relationships between the oscillation and confinement potential and attraction potential are studied in this paper. The simulation results are qualitatively similar to experimental results. © 2015 Elsevier B.V. All rights reserved.


Wang Y.,Jilin University | Chen A.,Jilin University | Chen A.,State Key Laboratory of Laser Propulsion and Application | Li S.,Jilin University | And 5 more authors.
Journal of Analytical Atomic Spectrometry | Year: 2016

In this paper, we propose and demonstrate a study of Fe plasma using collinear dual-wavelength femtosecond double-pulse laser-induced breakdown spectroscopy (LIBS) with a fundamental wavelength (800 nm) and a second harmonic wavelength (400 nm) from Ti:sapphire laser. By varying the time separation of the dual-wavelength femtosecond double-pulse, the experimental results clearly show the signal enhancement up to a factor of 10 and more than 10 times, in comparison with it at 0 ps time separation. The electron temperature and electron density are analyzed as the basic parameters of plasma properties, and they are respectively based on the theory of Boltzmann plot and Stark broadening. It proves that dual-wavelength femtosecond double-pulse LIBS is excellent for enhancing the emission intensity of the signal. © 2016 The Royal Society of Chemistry.


Xu Q.,State Key Laboratory of Laser Propulsion and Application | Zhong W.,State Key Laboratory of Laser Propulsion and Application | Li L.,State Key Laboratory of Laser Propulsion and Application | Yang B.,State Key Laboratory of Laser Propulsion and Application
ASPACC 2015 - 10th Asia-Pacific Conference on Combustion | Year: 2015

Laminar combustion properties of isooctane-air mixtures were studied under different initial pressures and equivalence ratios in a constant combustion bomb by using schlieren photography technique. The stretched flame speed, Markstein length and laminar burning velocity were obtained by analyzing the spherically expanded flame. The results show that the stretched flame speed increases with the increase of initial pressure while it decreases with the increase of stretch rate. Markstein length decreases with the increase of initial pressure and equivalence ratio. Laminar burning velocity reaches their maximum values at the equivalence ratio of 1.1, and decreases with the increase of initial pressure.


Chang H.,State key Laboratory of Laser Propulsion and Application | Jin X.,State key Laboratory of Laser Propulsion and Application | Zhou W.,State key Laboratory of Laser Propulsion and Application
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2013

In order to investigate the plume dynamic property ablated by nanosecond laser ablation, a systematic investigation of plasma plume expansion, generated by a Q-switched Nd-YAG at 1064 nm with laser power density ~ 1.3 × 108 W/cm2 on Al target, was done for a residual pressure of ~ 260 Pa using a fast gated intensified CCD camera with a gate width of 3 ns to capture the images. The expansion studies were done up to a distance of about 5 mm from the target surface. The high magnification near-target imaging results and digital image processing technique determine the plasma edge contours. The results show that the plume expansion is axisymmetrical distributed with respectively normal to the target surface. In addition, the fitting function based on the theory of Sedov can depict position distribution of the plasma plume well.


Li J.,China Aerodynamics Research And Development Center | Wang D.,State Key Laboratory of Laser Propulsion and Application | Hong Y.,State Key Laboratory of Laser Propulsion and Application | Huang J.,China Aerodynamics Research And Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Structures which are similar to double wedges usually exist in a supersonic inlet. When a supersonic flow goes through double wedges, oblique shock waves intersect and shock wave reflection appears. In an off design condition, Mach Reflection (MR), one kind of shock wave reflection, probably appears. The laser energy deposition helps decrease the Mach stem height and reduce the total pressure loss. Numerical simulation on the influence of deposition location and laser energy in reducing the Mach stem height was investigated in Mach 3.45, 5, 6, 7. Mach Reflection was achieved at different Mach number. The simulations and analysis showed that proper increase of distance between energy deposition location and Mach stem where was near by the upstream oblique shock waves would have a better effect on decreasing Mach stem height. When inflow Mach number changed, the influence of laser energy deposition became different at a variety of deposition location. © 2014 SPIE.

Loading State Key Laboratory of Laser Propulsion and Application collaborators
Loading State Key Laboratory of Laser Propulsion and Application collaborators