MEMS-Based Solid Propellant Rocket Array Thruster with Electrical Feedthroughs.

Abstract

The prototype of a solid propellant rocket array thruster for simple attitude control of a 10 kg class micro-spacecraft was completed and tested. The prototype has 10 × 10 φ0.8 mm solid propellant micro-rockets arrayed at a pitch of 1.2 mm on a 20×22 mm substrate. To realize such a dense array of micro-rockets, each ignition heater is powered from the backside of the thruster through an electrical feedthrough which passes along a propellant cylinder wall. Boron/potassium nitrate propellant (NAB) is used with/without lead rhodanide/potassium chlorate/nitrocellulose ignition aid (RK). Impulse thrust was measured by a pendulum method in air. Ignition required electric power of at least 3-4 W with RK and 4-6 W without RK. Measured impulse thrusts were from 2 × 10 −5 Ns to 3 × 10 −4 Ns after the calculation of compensation for air dumping.

Reliability of freestanding polysilicon microheaters to be used as igniters in solid propellant microthrusters

“…Due to the major role played by the igniter in the device functioning, special attention should be paid to its design and to its characteristics in order to achieve a successful ignition. Joule effect microheaters as microigniters have been reported in the literature: polysilicon microheaters thermally insulated from the substrate by means of a thick dielectric membrane [2], polysilicon heaters on a thin dielectric membrane and fabricated by bulk micromachining [11,15], platinum/titanium microheaters on a diaphragm [3] or nickel chromium aluminum copper wire inserted in a slot of the microthruster [4]. All these methods present some drawbacks.…”

“…In [2], the power consumption is relatively high to an insufficient thermal insulation of the igniter from the substrate. In the case of igniters on membranes, lowpower is ensure but filling of the igniter with propellant becomes problematic, ignition success rate is an issue and debris are create due to the breaking of the membrane during the combustion [3,11]. Despite that polysilicon exhibits a long term drift of its electrical resistance at relatively high temperatures [21], it remains a suitable heating material for the micropropulsion application due to the short time required to ignite the solid propellants.…”

“…Their integration in microspacecrafts offers considerable advantages in terms of downscaling, mass and volume reduction as well as mission costs lowering. Several solutions are investigated, such as solid propellant microthrusters [1][2][3][4], cold-gas microthrusters [5,6], field emission electric propulsion (FEEP) [7], bi-or mono-propellant microthrusters [8,9] or vaporising liquid microthrusters [10]. By combining MEMS technology and energetic material science, large quantities of energy can be obtained.…”

Vacuum test of a micro-solid propellant rocket array thruster

“…In the previous study, we prototyped it and confirmed its basic operation in air [5]. In this study, we report the test to measure impulse thrust in vacuum.…”

Total Impulse Increase of a Micro-Solid Rocket Using a Stack of B/KNO₃ Pellets

“…In 2003, a digital micro-thruster using MEMS technology was developed at the University of Tohoku and JAXA 2,3) . The digital micro-solid rocket had 10,000 solid propellant pellets with diameters of 0.80 mm, and controlled the thrust using an integrated circuit.…”