Mingxiu Xu

Chemical Oxygen–Iodine Laser Diluted by CO2/N2 Buffer Gases with a Cryosorption Vacuum Pump

Experiments were carried out on a verti-chemical oxygen-iodine laser (COIL), which was designed for N-2 and energized by a square-pipe jet singlet oxygen generator (JSOG). A cryosorption vacuum pump was used as the pressure recovery system for CO2 and N-2 buffer gases. The output power with CO2 was 27.3% lower than that with N-2, but the zeolite bed showed an adsorption capacity threefold higher for CO2 than for N-2 in the continuous operation with a Cl-2 flow rate of 155 mmol/s and a total flow rate of 430 +/- 3 mmol/s. [DOI: 10.1143/JJAP.47.8446]

Fabrication of uniform Ge-nanocrystals embedded in amorphous SiO2 films using Ge-ion implantation and neutron irradiation methods

[Chen, Q.; Lu, T.; Hu, Y.] Sichuan Univ, Dept Phys, Chengdu 610064, Peoples R China. [Chen, Q.; Lu, T.; Hu, Y.] Sichuan Univ, Key Lab Radiat Phys & Technol Minist Educ, Chengdu 610064, Peoples R China. [Xu, M.] Sichuan Normal Univ, Inst Solid State Phys, Chengdu 610068, Peoples R China. [Xu, M.] Chinese Acad Sci, Int Ctr Mat Phys, Shenyang 110016, Peoples R China. [Meng, C.] China Acad Engn Phys, Inst Fluid Phys, Key Lab Shock Wave & Detonat Phys Res, Mianyang 621900, Peoples R China. [Sun, K.] Univ Michigan, Dept Mat Sci & Engn, Ann Arbor, MI 48109 USA. [Sun, K.] Univ Michigan, Elect Microbeam Anal Lab, Ann Arbor, MI 48109 USA. [Shlimak, I.] Bar Ilan Univ, Dept Phys, Minerva Ctr, IL-52900 Ramat Gan, Israel. [Shlimak, I.] Bar Ilan Univ, Jack & Pearl Resnick Inst Adv Technol, IL-52900 Ramat Gan, Israel.;Chen, Q (reprint author), Sichuan Univ, Dept Phys, Chengdu 610064, Peoples R China;lutiecheng@scu.edu.cn hsuming_2001@yahoo.com.cn

Shock-induced cation disorder in magnesium aluminate spinel

An increase in lattice constants and an order-disorder phase transition were observed in the magnesium aluminate spinel (MgAl(2)O(4)) powders after shock compression. Theoretical calculations on the basis of density functional theory confirm that the remarkable volume expansion in shocked MgAl(2)O(4) powders is closely related to the substantial site disorder in the MgAl(2)O(4) lattice. The calculations also show that the partially inverse MgAl(2)O(4) spinel with an inversion index of 0.7 represents the greatest disordered metastable phase and the most unstable structure

Research on COIL employing no-flake-nozzle and CO2 as buffer gas

The supersonic nozzles lower temperature to 170-180 K better for the small signal gain coefficient. But at this temperature, the CO2 buffer gas may become liquid state. A chemical oxygen-iodine laser (COIL) employing CO2 as buffer gas and no-flake-nozzle was studied. Some mathematical simulation in three-dimensional computation fluid dynamics was adopted first to validate its usability. New nozzles gave the temperature higher than 400 K and considerable small signal gain coefficient. In the same conditions as simulation, experiments gave a 23% of chemical efficiency and 2.5 kW of output power. And it have got rid of “black area”, which was familiar in the supersonic COIL both in simulation and experimental results.

Chemical oxygen-iodine laser with a cryosorption vacuum pump with different buffer gases

A traditional pressure recovery system is the major obstacle to mobile chemical oxygen-iodine laser (COIL) for its huge volume. A cryosorption vacuum pump was used as the pressure recovery system for different buffer gases. It made COIL become a flexible, quiet and pressure-tight. Experiments were carried out on a verti- COIL, which was designed for N2 and energized by a square-pipe jet singlet oxygen generator (JSOG). The output power with CO2 was 27.3% lower than that with N2, but the zeolite bed showed an adsorption capacity threefold higher for CO2 than for N2 in the continuous operation. The great volume efficiency interested researchers.

Iodine flow rate measurement for COIL with the chemical iodine generator based on absorption spectroscopy

A dual-components absorption method based on absorption spectroscopy was described in the paper. It can easily eliminate the influence of the serious contamination and aerosol scattering on IFR measurement by utilizing the absorptions of iodine vapor and chlorine on two different wavelengths respectively. According to the character that there is no other gaseous product in the reaction besides iodine vapor, IFR in real time can be obtained by the connections of the pressure and the flow rate among chlorine remainder, iodine vapor, and the buffer gas. We used this method to measure IFR for the first time at the exit of a chemical iodine generator. The average of IFR is coincident with that calculated by chemical weighting mass.

Diagnostic of supersonic O2(a1delta)/I2 mixing flow field with chemical fluorescence method

A fluorescence image detection system that can visualize the COIL hot mixing flow field by taking images of the fluorescence of active I2 with a high speed camera was set up. Based on the captured flow field image, O2(a1Δ)/I2 mixing quality was evaluated quantitively by an exclusive image processing program. With this method, the hot supersonic mixing flow field in COIL which uses parallel stream supersonic mixing nozzles with a set of trip tabs was investigated. Meanwhile the effectiveness of the trip tabs was demonstrated.