Momentus is a YC Summer 2018 batch company developing the in-space rockets powered by water plasma engines and based in Santa Clara, CA
OurTheir expert analysis and review of extant literature suggests that at achievable temperatures, specific impulse can approach 1,000 s due to extremely high survivable bulk gas temperature and thermal dissociation of the water molecules to the atomic state. Rocket propulsion technologists will be interested in Figure The 6following whichfigure shows howkey moleculardesign dissociationfeatures of water serves to increase specific impulse at a givenMicrowave temperatureElectroThermal beyond(MET) thatthruster whichshowing wouldthe beTM001 expectedMode atField 18Pattern gImolin forthe waterresonant bycavity. reducingThis cavity mode provides excellent power coupling and positions the averagedischarge molecularin weightan optimal location upstream of the nozzle.
Rocket propulsion technologists will be interested in this next figure which shows how molecular dissociation of water serves to increase specific impulse at a given temperature beyond that which would be expected at 18 gImol for water by reducing the average molecular weight. The following figure shows a plot of frozen flow, fractional dissociation, and thermal efficiency versus chamber temperature for an expansion ratio of 100:1 with water propellant as modeled in TDK, a two-dimensional kinetic code maintained by Sierra Engineering for combustion simulation. An 8,000 K chamber temperature, which is not unreasonable given data in the literature, yields a specific impulse of about 750 s.
FigureThe next figure shows an image of an S-Band (2.45 GHz) MET operating in the Momentus laboratory using water propellant at a power Level of 3 kW.