Yasuhiro Mizobuchi

Characteristics Of C6H6-O2-N2 Type CO2 Gasdynamic Laser

Characteristics of a C6116-02-N2 type combustion-driven CO2 gasdynamic laser, which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically investigated. Small-signal gain coefficients are obtained for supersonic nozzle expansion ratios of 5, 7.5, 10, 15 and 20. The result shows : 1) qualitative agreement is obtained between the present measurements and the numerical analysis, 2) the small-signal gain grows as the nozzle expansion ratio is increased, and 3) there exists an optimum plenum pressure for small-signal gain coefficient under a certain expansion ratio of supersonic nozzle.Characteristics of a C6116-02-N2 type combustion-driven CO2 gasdynamic laser, which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically investigated. Small-signal gain coefficients are obtained for supersonic nozzle expansion ratios of 5, 7.5, 10, 15 and 20. The result shows : 1) qualitative agreement is obtained between the present measurements and the numerical analysis, 2) the small-signal gain grows as the nozzle expansion ratio is increased, and 3) there exists an optimum plenum pressure for small-signal gain coefficient under a certain expansion ratio of supersonic nozzle.

Characteristics of Combustion-Driven CO_2 Gasdynamic Laser (III) Characteristics of Laser Output Power

Laser output power characteristics of the combustion-driven CO2 Gasdynamic Laser (CO2GDL) are presented. Laser extraction is carried out with supersonic nozzle of circular-circular (CC) and shock free (SF), which has common area-ratio (A/A*=20) and various expansion length (CC nozzle with expansion length of 30mm and SF nozzle of 45, 33, 20mm). In laser output power measurements, maximum power of 24.5W is obtained at CC 20 nazzle of expansion length of 30mm, which has maximum small-signal gain of 0.5m-1. However, at SF nozzle which has small-signal gain of 0.2-0.3 m-1, laser output power can not be obtained. Investigation of the laser excitation condition suggests that the system requires the threshold value for small-signal gain over 0.23m-1. It is concluded that, with these results a feasible laser excitation system by the CO2GDL with CC nozzle has been established. Increase of small-signal gain, extension of cavity width and selection of most suitable laser light resonator will provide a radiative heating simulator for thermal protection research.

Numerical analysis of vibrational nonequilibrium flows in supersonic nozzles of CO2 gas dynamic laser

The effects of the supersonic nozzle shape on the performance of CO2 gasdynamic laser are analyzed by solving time-averaged two-dimensional Navier-Stokes equations coupled with the vibrational relaxation equations for a CO2 - N2 system. The solver is based on a finite difference method with an implicit high accuracy TVD scheme. Numerical simulations are carried out for various types of supersonic nozzles. The performance is estimated with the indicator of the small signal gain coefficient. The results show possibility of improvement for small signal gain coefficient by nozzle shape modification and suggest a suitable nozzle shape.

Characteristics Of C 6 H 6 -O 2 -N 2 Type CO 2 Gasdynamic Laser

Characteristics of a C6116-02-N2 type combustion-driven CO2 gasdynamic laser, which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically investigated. Small-signal gain coefficients are obtained for supersonic nozzle expansion ratios of 5, 7.5, 10, 15 and 20. The result shows : 1) qualitative agreement is obtained between the present measurements and the numerical analysis, 2) the small-signal gain grows as the nozzle expansion ratio is increased, and 3) there exists an optimum plenum pressure for small-signal gain coefficient under a certain expansion ratio of supersonic nozzle.Characteristics of a C6116-02-N2 type combustion-driven CO2 gasdynamic laser, which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically investigated. Small-signal gain coefficients are obtained for supersonic nozzle expansion ratios of 5, 7.5, 10, 15 and 20. The result shows : 1) qualitative agreement is obtained between the present measurements and the numerical analysis, 2) the small-signal gain grows as the nozzle expansion ratio is increased, and 3) there exists an optimum plenum pressure for small-signal gain coefficient under a certain expansion ratio of supersonic nozzle.

Characteristics Of C[sub]6[/sub]H[sub]6[/sub]-O[sub]2[/sub]-N[sub]2[/sub] Type CO[sub]2[/sub] Gasdynamic Laser

Characteristics of a C6116-02-N2 type combustion-driven CO2 gasdynamic laser, which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically investigated. Small-signal gain coefficients are obtained for supersonic nozzle expansion ratios of 5, 7.5, 10, 15 and 20. The result shows : 1) qualitative agreement is obtained between the present measurements and the numerical analysis, 2) the small-signal gain grows as the nozzle expansion ratio is increased, and 3) there exists an optimum plenum pressure for small-signal gain coefficient under a certain expansion ratio of supersonic nozzle.Characteristics of a C6116-02-N2 type combustion-driven CO2 gasdynamic laser, which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically investigated. Small-signal gain coefficients are obtained for supersonic nozzle expansion ratios of 5, 7.5, 10, 15 and 20. The result shows : 1) qualitative agreement is obtained between the present measurements and the numerical analysis, 2) the small-signal gain grows as the nozzle expansion ratio is increased, and 3) there exists an optimum plenum pressure for small-signal gain coefficient under a certain expansion ratio of supersonic nozzle.

Characteristics of combustion-driven CO2 gasdynamic laser. (I). Influence of expansion ratio of a supersonic nozzle.:(I) Influence of Expansion Ratio of a Supersonic Nozzle

Characteristics of a combustion-driven CO2 Gasdynamic Laser (CO2 GDL), which should be a radiation heating simulator for re-entry of a planetary probe and AOTV, are experimentally and theoretically obtained. In the present GDL system carbon dioxide CO2 produced in the combustion process of liquid benzene C6H6 with gaseous oxygen CO2 is used as lasing media associated with the energy-pumping gaseous nitrogen N2. The influence of gas components on the small-signal gain is investigated using four expansion ratios of 5, 7.5, 10 and 15, which have common throat height 1.0mm. The experimental results show that the small-signal gain increases as the nozzle expansion ratio increases and that the maximum gain obtained is 0.2m-1 at the expansion ratio of 10 and 15. Comparison is made between the experimental and theoretical results based on the Anderson model, and fairly reasonable agreement is obtained. The theoretical results show that the small-signal gain decreases when combustion pressure increases and the maximum small-signal gain is obtained by optimum composition of combustion pressure and expansion ratio which are able to be produced in several GDL system.