The optimization of near infrared CW Gd3Ga5O12:Nd-,YAIO3:Nd- AND YVO4:Nd- microlasers
The modeling of CW GGG:Nd- (1.4237 mum), YAP:Nd- (1.34 mum), YVO4:Nd-microlasers (1.0643 mum) is carried out. At that for the each fixed value of the incident pumping power and the laser beam divergence the optimal values of the activator concentration, the active medium length and the reflectivity of the output mirror, i.e. the values that maximize the laser power, are determined.
Heating processes in cw four-level microlasers and their influence on the parameters of the laser mode
The heat processes are considered for continuous wave GGG:Nd, YAP:Nd, YVO4:Nd and YAG:Nd microlasers. The distribution of the temperature as well as the thermo-induced changes of the refraction index and the deformations is determined. At the given distributions of the refractive index and the deformations the components of (ABCD) - matrix, the laser beam waist and the divergence are determined in the wide range of the values of the pumping beam power and radius, the heat transfer coefficient and the geometrical sizes of the active element.
Turbine blade temperature calculation and life estimation - a sensitivity analysis
Abstract The overall operating cost of the modern gas turbines is greatly influenced by the durability of hot section components operating at high temperatures. In turbine operating conditions, some defects may occur which can decrease hot section life. In the present paper, methods used for calculating blade temperature and life are demonstrated and validated. Using these methods, a set of sensitivity analyses on the parameters affecting temperature and life of a high pressure, high temperature turbine first stage blade is carried out. Investigated uncertainties are: (1) blade coating thickness, (2) coolant inlet pressure and temperature (as a result of secondary air system), and (3) gas turbine load variation. Results show that increasing thermal barrier coating thickness by 3 times, leads to rise in the blade life by 9 times. In addition, considering inlet cooling temperature and pressure, deviation in temperature has greater effect on blade life. One of the interesting points that can be realized from the results is that 300 hours operation at 70% load can be equal to one hour operation at base load.