Conical nozzles for pulsed laser propulsion

A CO2 laser of 300 ns pulse length, operating at 10.6 μm wavelength and from 1-4 J pulse energy was used to ablate carbon-doped Delrin® (polyoxymethylene, or POM) targets in a set of conical aluminum minithrusters at standard temperature and pressure. Nozzles with lengths ranging from 0.5 - 5 cm were used (corresponding to expansion ratios of about 4 to 16), as well as a bare sample with no nozzle. A piezoelectric force sensor was used to record the imparted impulse for fluences in the range of 1-100 J/cm2 for each thruster. The effect of increasing the expansion ratio on the impulse generation for single pulse laser propulsion experiments will be described. The study will also clarify the effect of confining air from an ambient atmosphere in augmenting impulse generation.