Vacuum test of a micro-solid propellant rocket array thruster

A φ0.8mm micro-solid propellant rocket array thruster for simple attitude control of a 10kg class micro-spacecraft was tested in vacuum. The micro-thruster uses boron/potassium nitrate propellant (NAB), because NAB has ignition temperature as low as 500°C, and easily start to burn in vacuum. For a half of the rockets, an ignition aid (RK) was also loaded. Ignition was succeeded in vacuum with NAB + RK and NAB. The maximum impulse thrust of 4.6 × 10-4 Ns, which is approximately a half of our requirement, was obtained with NAB. Compared to NAB, NAB + RK generated lower impulse thrust. The success rate of ignition was as low as 30%, although RK was used. These results suggest that RK has no benefit for the ignition of NAB, and other kinds of ignition aid should be found.