Abstract: The constrictor is a key part of arcjet thrusters, which has a significant effect on the performance and efficiency of the arcjet thruster.A modeling study was performed to investigate the plasma flow through the constrictor of medium power arcjet thrusters based on the local thermal equilibrium (LTE) assumption. The effects of the current, inlet pressure, constrictor dimensions and different propellants on the plasma flow characteristics, including the nonuniform flow characteristics, within the arcjet constrictor were studied. And the effects of the current, inlet pressure and constrictor dimensions on the performance and efficiency were further presented. The numerical results show that the hot arc region radius and length increase with the increase of the current; with the increase of the inlet pressure, the radius of hot arc region decreases but length increases;with the decrease of the constrictor radius, the hot arc region radius decreases while length increases; the hot arc region length increases and radius shows no significant changes with the increase of the constrictor length; and the hot arc region with hydrogen as the propellant is apparently smaller than those with nitrogen and argon as the propellant. It is also found that a small amount of the gas passes through the hot arc region where the gas is ionized, and most of the gas flows through the low temperature region near the wall. The Joule heating within the constrictor approximately accounts for 60 %-80 % of the total Joule heating within the arcjet thruster, mainly affected by the constrictor length.

Key words: arcjet thruster, numerical simulation, constrictor, plasma, flow