SOLAR THERMAL THRUSTER MADE OF SINGLE CRYSTAL MOLYBDENUM

Abstract The heart element of solar thermal propulsion (STP) system is a thruster made of refractory metals such as tungsten, tantalum and molybdenum or advance high temperature ceramics because of the high operating temperature (1000–2500 K) involved. In this paper, design, fabrication and preliminary experimental results in the JSUS Research Plan are presented, using 20 mm diameter of thrusters made of single crystal molybdenum which NRIM has patented and is a perfect (non-defect) material, namely no brittleness due to recrystallization under high operating temperature conditions. The working gas temperature within the thruster chamber reached higher than 1850 K (namely, the Isp is approximately 700 s for hydrogen gas propellant) at 0.2 MPa of the plenum chamber pressure, using the small solar concentrator (1.6 m diameter of half paraboloid and 0.65 m of the focal length).