Thermal efficiency of a low power arcjet

Improvement of efficiencies will enhance applications of low power arcjets. An annular cavity placed around the anode of arcjet was designed to form a regenerative cooling channel on the base of an arcjet. Argon was used as propellant in the experiments. When the arcjet current was increased from 4 A to 12 A, the specific impulse of the original arcjet was from 980 Ns/kg to 1 323 Ns/kg, where the specific impulse of the new arcjet was from 1 450 Ns/kg to 1 627 Ns/kg. For the same conditions, the thermal efficiency of the original arcjet was from 21% to 32%, where the thermal efficiency of the new arcjet was from 32% to 52%. The results show that regenerative cooling can remarkably improve the efficiency of low power arcjets.