A NEW CONCEPT IS PRESENTED FOR A DIRECT, SOLAR-PUMPED LASER USING ALKALI METAL VAPOR AS THE ACTIVE MEDIUM.

A NEW CONCEPT IS PRESENTED FOR A DIRECT, SOLAR-PUMPED LASER USING ALKALI METAL VAPOR AS THE ACTIVE MEDIUM. ALL ASPECTS OF THE COMPLEX MECHANISM FOR THIS LASER ARE BASED ON EXPERIMENTAL RESULTS IN THE CAE OF SODIUM VAPOR. ABSORPTION OF THE PEAK OF THE SOLAR SPECTRUM OCCURS VIA A BOUND-FREE TRANSITION IN SODIUM DIMERS TO PRODUCE EXCITED SODIUM ATOMS. TRAPPED NA D-LINE RADIATION PROVIDES A NOVEL EXCITATION SOURCE FOR THE A STATE OF NA(2) WHICH IS THE UPPER LASER LEVEL. THE LOW THRESHOLD AND HIGH GAIN FOR THISLASER TRANSITION PROVIDES THE POTENTIAL FOR OPERATION IN EITHER A PULSED OR CW MODE WITH SEVERAL PERCENT EFFICIENCY. AN EXPERIMENTAL PROGRAM IS CONDUCTED TO DEMONSTRATE THIS CONCEPT AND ITS POTENTIAL FOR OPERATION IN ORBIT PUMPED BY THE SUN. OPTIMAL PERFORMANCE OF A LASER BASED ON THIS CONCEPT SHOULD BE ACHIEVED IN A LARGE HIGH POWER SYSTEM. HIGH TEMPERATURE OPERATION WITH NO CHEMICAL RECYCLE OR GAS FLOW REQUIRED MAKE A LIGHT WEIGHT SYSTEM POSSIBLE. THESE FEATURES MEET CRITERIA FOR A USEFUL, SPACEBASED LASER.