Development of Environmental-Friendly Solid Propellants for Laser Ablation Propulsion

C. RINALDI; M.L. AZCÁRATE; J. VOROBIOFF; N. BOGGIO; C. TORO

Conferencia; 2nd SDEWES conference; 2020

Micro-thrusters based on laser ablative propulsion seem very promising for precise control of nano and microsatellite attitude and orbit. The basic constraints to this are the size, the weight and the thrust and specific impulse (Isp) delivered. The fuel thus turns out to be a key component of the micro-thruster. In previous works, we have investigated the performance of different fuels. Initially, targets consisting of metal/salt mixtures (Zn/CaCO3) have been studied. The figure of merit for the impulse measurement was the coupling coefficient, Cm [dynes/W]. The Cm was determined with a PZT transducer calibrated with a torsional pendulum. Later, we have analyzed the benefits of adding nozzles and of using targets consisting of metal oxides matrices doped with nanoparticles.Isp can be determined from the ablated mass or from the exhaust velocity, ve, of the ejected particles during the ablation pulse. Since determining ablated masses on the order of nanograms in single pulse measurements by weighting the ablated targets is very difficult and imprecise, this quantity is usually calculated from the excavated craters. A more precise manner of determining Isp is form the measurement ve. In this work an interferometric system based on a Nomarsky interferometer has been implemented to determine the exhaust velocity of the ejected particles in the ablation plume. As shown in Figure 1, preliminary results of the ve measurement for two fuels used in previous works are presented and the resultant Isp is correlated to the Cm values previously found.