السلام عليكم ورحمة الله وبركاته

استكمالا للبحث سوف نبدأ باذن الله بالفصل الثاني:

chapter two

Co2 laser system

2.1i Introduction:

The first start to design CO2 laser system that we should know the relative optical output power that we wont to get it and the efficiency of the system that we should work with it .i

In this project the target optical power was 500W and the efficiency that we assume to work in 10%.So, the input electrical power should be of about 5000W and because we work in slow flow this mean that the available output power with respect to the length of the discharge tube of about 50 W/m.. So for 500W the overall active medium length of about 10m.i

The use of very long tube can introduce problem not encountered in smaller systems. So, long tube were divided into section with alternate anode and cathode to keep the excitation potential to reasonably low value .It divided into seven folds each folds consists from two discharge double jacket tubes with parallel input discharge voltage ( see figure 2.1) .By using stability condition of the optical resonator we found that the radius of curvature of the higher reflector mirror should be greater than or equal to 10m we chose hemispherical stable resonator to provide higher gain and easy in the alignment process..i

Using the above input parameters to the system and by using eq: (1-16) ,(1-17),(1-18),(1-22) and (1.23). at different variable parameter a compromise has been made between these parameters of the optical resonator using forward and backward calculation to specified the optimum values of diameter ,the best radius of curvature of higher reflector mirror ,the beam waist of the output window gain coefficient , Frenal number and the best output power that we can get from all these variable parameter (see table 2-1)..i

We found from the above calculation that the best discharge tube length equal to 0.75m, tube inner diameter equal to 0.17m. the best mirror reflectivity of 60%. Assume that we work at an output beam of TEM00 mode ..i



Fig.(2.1):Multi Folds Structure for Our Design System ..i

Table (2-1): Theoretical Calculation for Output Power at Different Variable..i



In the present work five different electrodes shapes and discharge tubes have been designed and constructed .The details for these terminals, discharge tubes and power supply unit, cooling system, vacuum circuit and gas supply have also been described. .i