Arcjet thruster with improved arc attachment for enhancement of

Abstract

An arcjet thruster has a constrictor and nozzle defining an arc chamber. The constrictor has an insulator and an anode. The constrictor defines a subsonic-to-supersonic transition zone axially coextensive with the inculator and anode. The anode is disposed side-by-side with the insulator and located upstream therefrom. A rod defines a cathode spaced from the anode by a gap. An electrical potential is applied to the anode and cathode to generate an electrical arc in the chamber which produces thermal heating of propellant gases flowing through the chamber and expansion thereof through the nozzle. Location of the insulator downstream from the anode causes diffusion and attachment of the arc to occur at the region of the anode in the constrictor and prevents movement of the arc diffusion and attachment region downstream past the insulator to the nozzle in response to propellant gas mass flow variations through the constrictor. The thruster can also include an expansion and compression cavity in the arc chamber to provide a low pressure region at the anode for arc attachment and diffusion. Further, a zone of thermal and mechanical isolation can be provided between the anode and insulator to reduce the temperature at the insulator and displace its location farther away from the region of arc attachment and diffusion at the anode. Still further, a passage is defined through the insulator to provide a path for secondary flow of propellant gas into the chamber downstream of the arc attachment and diffusion region in order to reclaim frozen flow losses.