NON-IMAGING SECONDARY CONCENTRATOR

THE SOLAR THERMAL ROCKET OFFERS THE OPTIMUM PROPULSION MEANS FOR LEO TO GEO TRANSFER VEHICLES, PROVIDED THAT SPECIFIC IMPULSE (ISP) ON THE ORDER OF 1,000 SECONDS AT MODERATE THRUST LEVELS CAN BE ACHIEVED. THESE ISP'S AND THRUST LEVELS ARE CONTINGENT ON THE SOLAR CONCENTRATOR SYSTEM PROVIDING HIGH CONCENTRATION RATIOS AT THE ABSORBER. A CONCENTRATOR SYSTEM WHICH USES TWO OPTICAL ELEMENTS IS A PROCTICAL METHOD OF OBTAINING THE DESIRED CONCENTRATION RATIO. A SECONDARY ELEMENT OF ANNULAR FORWARD FOCUSING GEOMETRY CAN INCREASE THE PERFORMANCE OF THE OPTICAL SYSTEM. A SECONDARY CONCENTRATOR CAN ALSO WIDEN THE ACCEPTANCE TOLERANCE BAND OF THE PROMARY COLLECTOR AND VEHICLE POINTING SYSTEM. THIS REDIRECTS ABERRANT RAYS WHICH WITHOUT A SECONDARY MAY HAVE BEEN LOST OR CAUSE DAMAGE TO THE VEHICLE. THE PHASE I RESEARCH WILL DETERMINE THE OPTIMUM GEOMETRY FOR A SECONDARY CONCENTRATOR BY PERFORMING GEOMETRIC RAY TRACE STUDIES. A SMALL EXPERIMENTAL SECONDARY WILL BE CONSTRUCTED BASED ON THE RESULTS OF THE RAY TRACE STUDIES. A SMALL EXPERIMENTAL SECONDARY WILL BE CONSTRUCTED BASED ON THE RESULTS OF THE RAY TRACE STUDY. LABORATORY LASER RAY TRACING WILL ALSO BE DONE WITH A COMPLETE OPTICAL SYSTEM TO PREDICT THE TOTAL CONCENTRATION RATIO. THE RESULTS OF THE PHASE I WILL LEAD TO A PROTOTYPE DESIGN FOR CONSTRUCTION AND TESTING AT THE PHILLIPS SOLAR LABORATORY IN PHASE II.