Feasibility of a 5mN Laser-Driven Mini-Thruster

We have developed a next-generation thruster under a Phase II SBIR which we believe can meet NASA requirements after some modifications and improvements. It is the first practical example of chemically-augmented electric propulsion, using efficient laser diodes focused on an exothermic fuel tape to make a jet. We own the patents on this technology. Advantages of our thruster technology are large thrust/power ratio (up to 1.35mN/W) and thrust density, small minimum impulse bit (10nN-s) and instantaneous thrust control. Other advantages are absence of magnetic fields, high voltage, toxic chemicals, fuel and/or oxidizer storage tanks, heaters or valves, and the fact that the source of concentrated energy is physically removed from the thrust converter, so that only the fuel, not some engine component, wears or ablates during operation. Engine lifetime will be limited only by the amount of fuel onboard, not by the 200k year lifetime of the diode lasers which generate the ms pulses. Problems which we want to address in this Phase I effort are inadequate ablative layer thickness control which has led to excessive rms thrust noise, a footprint which is larger than we would like and plume contaminants generated by carbon doping used for laser absorption in the present fuel tape. Our goal is 1% rms thrust noise and an order-of-magnitude reduction in contaminants deposited by the thruster plume.