Time filter

Source Type

Urunchi, China

Ren W.,Dalian University of Technology | Ren W.,63655 Unit | Sang F.,CAS Dalian Institute of Chemical Physics | Jing C.,63655 Unit
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2010

The metallic supersonic nozzle of chemical oxygen-iodine laser (COIL) needs heating to keep warm in use, which makes its structure complicated and the failure rate is high. Several materials are considered to be suitable for fabricating non-heating supersonic nozzles. As an example, the temperature field of the nozzle made of polyimide is simulated numerically to verify the feasibility of the non-metallic non-heating nozzle. The results indicate that the nozzle made of polyimide can prevent heat transmitting and iodine vapor cooling effectively and meet the requirements of laser nozzles. Source

Li Y.,63655 Unit | Zong F.,63655 Unit | Qiang X.-W.,63655 Unit | Qiang X.-W.,Xian Jiaotong University | And 4 more authors.
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2010

Since the refractive index fluctuations in the atmosphere are caused mainly by random variations in temperature, turbulence can be artificially generated and its strength can be controlled via changing the temperature and velocity of air flow. Based on this principle, a turbulence chamber was designed and built for performing optical propagation experiments. The refractive index structure constant Cn 2 of atmosphere and inner scale l0 of turbulence along the optical propagation path inside the chamber were obtained from the simultaneous measurement of angle-of-arrival fluctuations and scintillation of the propagating light-wave. The experimental results show that the Cn 2 and l0 of the generated turbulence are mainly influenced by the temperature and wind velocity inside the chamber, respectively. C Cn 2=1.58 × 10-11 m-2/3 is obtained at 45°C with wind velocity 0.48 m/s and l0=2.33 mm at 25°C with wind velocity 1.04 m/s. And the temporal power spectrum analysis of log-intensity indicates that the generated turbulence is suitable for performing optical propagation experiments. Source

Li Y.,63655 Unit | Qiang X.,63655 Unit | Qiang X.,Xian Jiaotong University | Zong F.,63655 Unit | And 4 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2010

The temporal spectra of scintillation and angle-of-arrival fluctuations have been studied experimentally for light-waves traveling in turbulence of different inner scales. Because of the complexity and uncontrollability of the real atmosphere, the experiment was performed with an atmospheric turbulence chamber. The scintillation and angle-of-arrival fluctuations of the propagating light-wave were simultaneously measured by a position sensitive detector, and the turbulence inner scale along the optical propagation path was derived through inversion. Experimental results show that the high frequency region of both kinds of temporal spectra obey the same power law, and the absolute value of the power exponent and the turbulence inner scale are in linear relation. With the increase of the inner scale, the spectra decrease more sharply, and their ranges in power law move towards lower frequency. Source

Hu Y.-H.,63655 Unit | Wang K.,63655 Unit | Zhang Z.-G.,63655 Unit | Feng S.-L.,63655 Unit | Wu M.,63655 Unit
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

The atmospheric refractive index structure constant is an important parameter of atmospheric turbulence intensity. It was measured using AZZ10 micro-thermalmeter over desert where is a little or no vegetation cover. The vertical profile were investigated by analysis of experimental data over desert with 0~30km height range. And structure characteristics of atmospheric turbulence were given. Results can supply technological support for laser engineering applications to select suitable testing time and time-interval. © 2012 SPIE. Source

Feng S.,63655 Unit | Zhang Z.,63655 Unit | Qiang X.,63655 Unit | Hu Y.,63655 Unit | And 2 more authors.
Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams | Year: 2012

The refractive index structure constant (RISC) near the ground in Gobi region from April to December in 2010 was measured by using micro-thermal meter. The logarithmic average of measured data was calculated by the month, and then its daily variation characteristics were analyzed. Thus the times when the atmospheric turbulence was strong or weak in a day were given. In Gobi region, the atmospheric turbulence at sunset is weaker than at sunrise. At sunrise conversion time, the averaged RISC is below 10 -15 m -2/3. At sunset conversion time, the averaged RISC is about 10 -16 m -2/3. The atmospheric turbulence is stronger in April, June, August, and September, and weaker in November and December. Source

Discover hidden collaborations